130317384 chevron drilling fluids manual

8/20/2019 130317384 Chevron Drilling Fluids Manual

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The

ChevronTexaco and BP

Drilling Fluid Manual


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Drilling Fluids Manual

“Proprietary - for the exclusive use of BP & ChevronTexaco”

Table of Contents i Rev. 01/2002

Table of Contents

Section 1: Drilling Fluid Management:

Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1

Preparation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2

Contract Appraisal . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2Engineering & Support Staff Selection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2Competency Evaluation Process . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3Roles and Responsibilities . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4The Provision of Drilling Fluid Chemicals and Materials . . . . . . . . . . . . . . . . . . . . . . . . . . 7Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9

Contract Implementation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10

Planning . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10Basis of Design (BOD) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10Drilling Fluid Programming . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10Program Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17

Implementation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18

The Mud Report . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18Reading the Mud Report . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18

Continual Assessment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22Post Well Evaluation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23

Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23Mud Recap . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23Performance Results . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24Performance Evaluation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24

Section 2: Introduction to Drilling Fluids:

Drilling Fluid Classifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1

Pneumatic Fluids . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1Oil-Based Fluids . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2Water-Based Fluids . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

Functions of Drilling Fluids . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4

Major Functions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4


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Minor Functions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .6Additional Benefits . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8

Drilling Fluids Selection Criteria . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13

Cost . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .13Application and Performance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .13

Production Concerns . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .13Logistics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .13Exploration Concerns . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .13Environmental Impact and Safety . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14

Section 3: Engineering:

Basic Engineering Calculations. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1

Specific Gravity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1Volume, Capacity and Displacement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1Annular Velocity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5Mud Circulation Time . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5Pressures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6Weight-Up and Dilution . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7Concentrations - Weight Percent and Volume Percent . . . . . . . . . . . . . . . . . . . . . . . . . . . 8Parts Per Million and Milligrams Per Litre . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9

Material Balance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .10

Weight-Up of Water-Based Muds . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11Dilution of Water-Based Muds . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13Mixing Two Fluids . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .15System Building . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .17Solids Analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .22

Calculating Maintenance and Treatment Requirements for an Active Mud System . . . . . . . . . . .26

The Drilling Mud Report . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .36

Given Data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37Mud Pit Capacity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .38Mud Volume in Pits . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .38Hole Volume . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .39Drill String Displacement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .39Drill String Capacity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40

Mud Volume . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .40Total Circulating Volume . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .41Pump Output . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42Annular Velocity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 44Bottoms-Up Time . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45Total Circulation Time . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46Surface-to-Bit Travel Time . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46Hydrostatic Pressure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .47


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Bottom Hole Circulating Pressure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47Equivalent Circulating Density . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47

Section 4: Testing:

Water-Based Drilling Fluids Testing Procedures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1

Mud Density . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1Marsh Funnel Viscosity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1Rheology . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2Static Filtration Tests . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4Retort -Water, Oil and Solids . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14Sand Content . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16Methylene Blue Capacity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18pH . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20Alkalinity and Lime Content . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21

Chloride . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24Total Hardness [Table 6 ] . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28Sulfide . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31Carbonate/Bicarbonate . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35Potassium . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38

Oil-Based Drilling Fluids Testing Procedures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41

Mud Density . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41Marsh Funnel Viscosity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41Rheology . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42Static Filtration Tests . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43Retort - Water, Oil and Solids . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45

Whole Mud Alkalinity (VSA) and Lime Content (LimeOM) . . . . . . . . . . . . . . . . . . . . . . . . 47Whole Mud Chloride (ClOM) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48Whole Mud Calcium (CaOM) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48Electrical Stability (ES) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 49Sulfide . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50Aqueous Phase Activity (AWOM) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 54Water-Wet Solids . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 58Lime, Solids and Salinity Calculations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 60

Permeability Plugging Test (PPT) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 70

Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 70PPT Principles . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 71

Pilot Testing. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 78

Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 78Designing Pilot Tests . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 79Pilot Testing Equipment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 80Interpretation of Pilot Test Results . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 80

Testing for Tracer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 83


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Calcium Carbonate Determination in Whole Mud . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 83Iodide Ion Analysis Procedure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 83Bromonapthalene Analysis Procedure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .86

Section 5: Chemistry and Filtration:

Basic Chemistry. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1

Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1Aqueous Chemistry . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5Chemical Analysis - Mud Check . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6Mud Chemistry . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .9

Clay Chemistry . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .12

Structure of Clays . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .12Clay Properties . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .17Commercial Bentonite . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .21

Polymer Chemistry . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .24

Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .24Polymer Types . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24Polymer Uses . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .27

Filtration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29

Filtration Fundamentals . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .29Types of Filtration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .29Problems Caused by Poor Filtration Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30

Factors Affecting Filtration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .30Filtration Measurement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34

Section 6: Contamination:

Contamination of Water-Based Drilling Fluids . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1

Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1Salt Contamination . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2Calcium Contamination . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4

Magnesium Contamination . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .6Carbonate/Bicarbonate Contamination . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7Acid Gases . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .9Contamination Due to Bacteria . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10

Contamination of Oil-Based Drilling Fluids . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11

Undesired Water . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11Drilled Solids . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11


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Soluble Gas . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11Massive Salt . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11

Solids Contamination . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12

Section 7: Solids Control:

Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1

Solids Calculations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3Mud Test Data for Solids Calculations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5Densities Required to Perform Solids Calculations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6Salinity Corrections . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8Solids Calculations - Water-Based Muds . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8Differentiating Drill Solids from Bentonite by CEC Ratio . . . . . . . . . . . . . . . . . . . . . . . . . . 9Example - Solids Calculations for Water-Based Muds . . . . . . . . . . . . . . . . . . . . . . . . . . 11

Solids Management . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13

Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13Characteristics of Solids . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13Methods for Solids Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17Principles of Mechanical Solids Separation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18Sequence of Solids Control Devices . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19Dewatering and Zero-Discharge Solids Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31

Solids Control Performance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33

Mud and Waste Volumes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33

Section 8: Rheology and Hydraulics:

Rheology . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1

Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1

Velocity Profile . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1

Shear Stress (t) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2Shear Rate (g) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2Viscosity (m) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3Newtonian Fluids . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

Non-Newtonian Fluids . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4

Bingham Plastic Fluids . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5Yield-Power Law (Herschel-Bulkley) Fluids . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13


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Pseudoplastic Fluids . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .13Thixotropic Fluids . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .14

Flow Regimes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .14

Laminar Flow . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .14Transition Flow . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .14

Turbulent Flow . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .15Yield-Power Law Rheology, Hydraulics, and Hole Cleaning . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15

Section 9: Pneumatic Drilling Fluids:

Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1

Dry Gas Drilling Fluids. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2

Air . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3Natural Gas . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4

Mist Drilling Fluids . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4

Foam Drilling . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

Stiff Foam . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5Stable Foam . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6

Gasified (Aerated) Mud Drilling Fluids. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .8

Air Application . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .9Nitrogen Application . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .9

Advantages/Disadvantages of Air Drilling Fluids . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .12

Section 10: Water-Based Drilling Fluids:

Simple Fluids. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1

Clear Water . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1Native Clays Muds . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1

Dispersed Drilling Fluids . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1

Lignite-Lignosulfonate (Deflocculated) Muds . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2Principal Additives of Lignite/Lignosulfonate (Deflocculated) Muds . . . . . . . . . . . . . . . . .2

Inhibitive Dispersed Fluids . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .6

Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .6Calcium-Based Muds . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .6Lime Muds . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .6


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Lime/MOR-REX Muds . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12Gyp Muds . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16Salt-Based Muds . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21Saturated Salt Muds . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21Saltwater Muds . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26Brackish-Water Muds . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31

Non-Dispersed Muds . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34

Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34BEN-EX Muds . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34Low Solids PAC/CMC Muds . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36Low-Solids PHPA Muds . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38Potassium-Based Muds . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43KCl-Polymer (KCl-PHPA) Muds . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 44Glycol . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50Silicate System . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 54

HTHP Fluids . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 58

Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 58Definitions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 58Mechanisms of Thermal Degradation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 58Bentonite Muds . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 59Polymer Muds . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 59Oil Based Muds . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 60Temperature Limits . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 61Mud Properties . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 62Symptoms and Remedial Action . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 63Remedial Action - Water Based Mud . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 63Planning . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 64Mud Selection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 65

Section 11: Oil-Based Drilling Fluids:

Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1

Oil Mud Applications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1

Disadvantages of Oil Muds . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

Oil Mud Products Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

Types of Base Oils . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6Oil Mud Formulations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9

Mixing Procedures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10

Oil Mud Properties . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11

Displacement of Water-Based Mud. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14


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Special Equipment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14

Recommendations for Using Oil-based Muds . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15

Oil Mud Calculations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .17

Trouble Shooting Oil Muds . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .19

Electric Logging in Oil Muds . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .20

Advantages using oil muds . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20Disadvantages of using oil muds while logging . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20

Gas Solubility in Oil Muds . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .20

Solids Control In Oil Muds. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .21

Shale Shakers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .21Mud Cleaners . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .22Hydrocyclones . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .23Centrifuges . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .23

Degassers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .24

Section 12: Environment:

Drilling Waste & Environment Management . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1

Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1Environmental Strategy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1Environmental Management Systems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1Waste Management . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4

Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .10

Section 13: Operational Concerns:

Hole Cleaning:

Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1

Engineering Calculations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1

General Factors Effecting Hole Cleaning . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2

Cuttings Transport . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2Rheology . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3Low Shear Rate Yield Point (LSRYP) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3Pump Rate . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3


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Hole Geometry . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4Mud Weight . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4Cuttings Properties . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4Rate of Penetration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4Drillpipe Rotation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4Rig Site Monitoring . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4

Vertical and Near Vertical Wells . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6

High Angle, Extended-Reach Wells . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6

Hole Cleaning in Deviated Wells - Guidelines . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7Drillpipe Rotation/ Reciprocation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9

Washed Out Hole . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11

Hole Cleaning Charts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11

Wellbore Stability:

Part 1: Before the Wellbore. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19

Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19In Situ Conditions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19In Situ Earth Stress . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22Effective Stress . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23Rock Strength . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24

Part 2: After The Wellbore . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28

Near Wellbore Stress-State . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28

Mechanical Stability . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30Chemical Stability . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38

Part 3: Providing A Stable Wellbore . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42

Planning A Stable Wellbore . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42Warning Signs and Corrective Action . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 44Mechanical Stability . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45Preventing Mechanical Stability Problems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46Controlling Stability Problems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47

Part 4: Leak Off Testing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48

Leak-Off Tests . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48

The Lithology Factor (k) Calculated from LOT Data . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50Using Poisson's Ratio (v) to Calculate the Lithology Factors . . . . . . . . . . . . . . . . . . . . . 50Wellbore Stress Equations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51Nomenclature . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 52

Cementing:


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Mud Preparation and Removal . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .53

Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .53Wellbore Conditioning . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .53Different Mud Types . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .54Cementing in Oil Based Mud (OBM) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 54Cementing in Water Based Mud (WBM) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 56Contamination of WBM with Cement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 56

Engineering Recommendations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 58

Planning Phase . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .58Drilling Phase . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .58Cementing Phase . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .59

Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .61

Barite Sag Management:

Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .63Definition of Sag . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .63How Sag Is Initiated . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .63History of Sag . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .64Indications of Sag . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .65Measurement and Prediction of Sag . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 65Impact of Sag . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .66Practices to Minimize Barite Sag in Oil Based Fluids . . . . . . . . . . . . . . . . . . . . . . . . . . .67

Drilling Practices . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .69

Drilling Fluid Selection for Wells with Small Pore / Fracture Pressure Windows . . . . . . . 70Tertiary Mud Recovery Equipment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .71Sag Experienced . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .72

Bit Balling:

Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .73

Clay Properties . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .73

Prevention . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .73

Drilling Fluid Design . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .73Drilling Fluid Maintenance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 74

Treatment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .74

Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .75


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Shale Stability:

Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 77

Problems Caused by Shale Instability. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 78Factors Causing Shale Instability . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 78

Mechanically Induced Shale Instability . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 78

Classification of Problem Shales. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 79

Hydratable and Dispersing Shales . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 80Brittle Shales . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 80Abnormally Pressured Shales . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 81Tectonically Stressed Shales . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 81

Shale Stabilization with Drilling Fluids. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 82

Oil-Based Muds . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 82Water-Based Muds . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 82

Stuck Pipe:

Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 84

Differential Pressure Sticking . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 85

Mechanics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 85

Prevention . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 86Remedial Measures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 87

Keyseating . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 88

Mechanics of key-seat sticking are: . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 88Prevention . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 89Remedial Measures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 89

Cuttings Accumulation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 89

Mechanics of Cuttings Accumulation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 89Prevention . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 89Remedial . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 90

Loss of Circulation:

Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 90


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Induced Lost Circulation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .90

Prevention . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .90Remedial Measures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 91

Naturally Occurring Loss of Circulation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 92

Remedial Measures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 93Plug Choices and Techniques . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .93

Corrosion:

Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .96

Types of Corrosion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .96

Dry Corrosion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .96Wet Corrosion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .96

EMF Series . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .99

Factors Affecting Corrosion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .100

Metallurgy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .100Drilling Fluids . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .100Temperature . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .100

Corrosion in Drilling Fluids. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .100

Oxygen Corrosion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .101Carbon Dioxide Corrosion (Sweet Corrosion) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 104Scale . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .105Hydrogen Sulfide Corrosion (Sour Corrosion) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 106Bacteria . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 110

Corrosion Rates. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 111

Ring Coupon Monitoring Procedure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 111

Section 14: Special Fluids:

Formation Damage:

Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1Minimizing Damage Whilst Drilling . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1To minimize filtrate incompatibility . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3General Guidelines . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5Drill - In Fluids (DIF) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .6


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Minimizing Damage During Well Completion/Workover . . . . . . . . . . . . . . . . . . . . . . . . . . 6

Wellbore Clean-Up:

Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9Debris Categorization . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10Displacement Pill Design . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12Displacement Design . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14Filtration Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16Determination Of Well Cleanliness . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17Equipment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18Surface Clean Up . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20Reporting and Performance Measures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21Wellhead and Riser . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22

Coring Fluids:

Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25Water-Based Coring Fluids . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26Oil-Based Coring Fluids . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29

Tracers:

Displacements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38Solids Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41

Packer Fluids:

Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42Water-Based Drilling Muds . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42Clear Fluids . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43Viscosifying Agents . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 44Bridging and Fluid Loss Agents . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 44

Weight Materials . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 44pH Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 44Corrosion Inhibition . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 44Oil-Based Muds . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45Casing Packer Fluids . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45Arctic Casing Packs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45


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Rev. 01/2002 xiv Table of Contents

Gas Hydrates Control for Deep Water Drilling Operations:

Some Questions:. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .48

General Description of Gas Hydrates . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .48Crystal Structure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .49Elements Necessary to Stabilize Hydrates . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 49

Hydrate Phase Behavior and Inhibition . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50

Thermodynamic Inhibition . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .52Prediction of The Hydrate Phase Behavior . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 54

Drilling through Hydrates. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .56

Remedial Actions. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .59

Hydrate Melting Schemes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .59

Conclusions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .65Minimizing the Risk of Hydrates . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .65

Sound mud design practices . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 65Spotting fluid . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .65Lost circulation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .66Selection of a well control technique . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 66Planning for remedial actions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .66Personnel experience with hydrates . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 66Conclusion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .66

Operations. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .67

Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .67Summary and Conclusions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 67Participant’s Experience with Hydrate Incidents . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .69A case history summary is shown in Table 3.1 (below) . . . . . . . . . . . . . . . . . . . . . . . . . . 72Conclusions from Case Histories . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .72

Appendices:

Appendix 1: Competency Assessment

Competency Assessment Guidelines . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1

Aims of the process . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1Deliverables . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1Process. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1

Appendix 2: Performance Indicators-Key Definitions

General Definitions:. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1


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Table of Contents xv Rev. 01/2002

General Well Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1Drilling Mud . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

Appendix 3: Additional Information

Settling Plug Mixing Procedure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2Preparation of Oil-Base Plugs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

Recommended Plug Procedures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

Index:

General Index . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1


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Rev. 01/2002 xvi Table of Contents


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Drilling Fluid Management 1-1 Rev. 01/2002

Section 1: Drilling Fluid Management

Introduction

The provision of drilling fluids is an important process and requires a high degree of technical skill.Therefore, we depend greatly on our contractors’ competence to ensure this service is carried outproficiently. Nevertheless, it is not advisable to simply hand over the control of the contract to thecontractor. To maximise the contractors’ contribution and to manage the learning process, it isimportant that the drilling staff has an understanding of the fluid contract, are comfortable with thetechnology, are in control of costs and can manage the interface with the contractor.

Drilling fluids are not significantly different to other third party contracts, but there is enough techni-cal content to require additional guidance and the following section has been prepared to aid those

operational staffs that do not have access to a full time fluid specialist.

This Section of the manual will provide information on the following phases of Drilling Fluid Man-agement:

Phase 1. Contract preparation and appraisal

Contractor staff selection, including competency assessment process

Phase 2. Contract implementation, including

Basis of Design (BOD) process

Drilling Fluid selection and engineering program design

Setting objectives and performance evaluation

Phase 3. Monitoring

Mud Report reading and assessment

Phase 4. Post well evaluations

Performance and contractor assessments

The process of ‘Drilling Fluid Management’ starts with the managing of the contract. Themost important phase of the listed processes, is the preparation and comprehension of thecontract. An intimate understanding of the contract’s Scope of Service will be critical if all themeasures, required at each phase of the operation, are to be fulfilled.


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Rev. 01/2002 Drilling Fluid Management 1-2

Preparation

Contract Appraisal

The initial step in planning, is the reading of the contract scope of service. This formal process

must be carried out to ensure there is a clear understanding of what can be legally expected fromyour contractor.

The provision of drilling fluids services can be divided into separate contracts, with a contract forengineering and another for the supply of chemicals, and in some cases an additional contract forthe supply of barite and bentonite. When this is not the case, and the contracts policies call for theintegration these and other associated services into a single contract. each aspect of the contractshould still be prepared and assessed separately, as the provision of services and materials sup-ply require very different assessment techniques.

The engineering aspects of the contract should state the cost of each person employed at the wellsite and the degree of support being provided. The level of service should be defined including astandard of competency of each person providing and supporting the service.

The following example lists many of the points, which the contract may include:

Engineering & Support Staff Selection

The inclusion of key statements concerning the level of engineering input and support will set the stan-dard required for the duration of the contract. The following examples of text have been used in con-tracts:

Well Site Engineers

Provide drilling fluid engineering services, as required, on the drilling rig.

• Fluid engineering service on the rig is required at the Company’s discretion

• The number of personnel will be dictated by operational need as advised by the BU.

• All engineers must have been trained in all relevant health and safety regulation. No engineers will be allowed to work on BU operations unless this has been completed.

• Attending as necessary any off rig site planning or wash up meetings for a well. It will also be expected that the engineer will visit the BU operating office either prior to a trip or on return to discuss ongoing operations, provide feed back to the Business Unit and gain greater understanding of the operations.

• All mud engineers must have competency assessment performed on them by the contractor in a timely and professional manner and agreed with the BU prior to going to the work site. Where an engineer does not have the required skills, the contractor is to agree with the BU a plan to rectify this and an agreed time frame. Actual requirements for the specific post must be agreed with the technical representative in the business unit (BU) and the BU’s representative (Technical) prior to performing the competency assessment. 5 years field engineering

experience. Two years of which should have been in the local operating area.

• Rated within the top quartile of the contractor’s engineers

• Educated to University standard in science or engineering or have sufficient industry experience to compensate

• Capable of performing all Environmental Management reporting in a highly proficient manner

Support Engineers

• A Senior Engineer is required to support this service.


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• The engineer to be located in the contractor’s office. Office space and access to a computer with the BU’s reporting system may be provided by the business unit at their discretion if this is deemed to be necessary.

• Minimum requirements for this position:

• 3 years office based engineering experience. Two years of which should have been in the local operating area.

• 4 years field experience of which 2 years must have been in the contract area of operations

• Educated to University standard in science or engineering or have sufficient industry experience to compensate

• Capable of performing all Environmental Management reporting in a highly proficient manner

• “STOP” trained

• Capable of performing advanced safety audits

• The engineer must meet the requirements of a “Competency Assessment”. The assessment will be performed by the contractor and agreed with the business unit representative. When a engineer fails to meet all the requirements, a strategy for either training agreed upon, or an alternative engineer must be assessed.

Competency Assessments

As mentioned in the text, the appropriate engineering and technical support staff must be selected andapproved. The contract must therefore contain a process, which stipulates the method and criteria forselection. The following example could be included in the contract and when applied, will provide boththe contractor and the BU with a clear understanding of the skills required at each level to meet the BUrequirements.

Competency Evaluation Process

Aims of the process:

• The selection of able and competent people to fill engineering support positions for thecontract. The support positions will have a major role and have a large effect on capitalspend and the control of non-productive costs.

• To highlight the skills and competencies that are seen as important to contract for thedelivery of business results. The skills identified and called for in this process may not bethe same as the contractors because of different business priorities. It is therefore, impor-tant that the two criteria’s for competency be integrated and seen as complementary.

Outcome from The Assessment.

The assessment is to highlight the candidate’s strengths and the areas that need development.However, the process may indicate when a candidate is either not suitable or that a candidate issuitable, but only after additional training.

Process.

The following pages should be completed within the context of the Scope of Work provided by thebusiness unit.

When completing the “assessed box”, the competence level should first be determined numeri-cally where;

1.Is has no experience in this area

2. Is basic only in the assessed area


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3. Is competent in the assessed area

4. Is highly competent in the assessed area

Narrative should then be used to indicate the reasons for the indicated level.

The “forward” action box should be used to indicate what training is suggested to develop and

grow the candidate in post.

Example:

The assessed competence for computer literacy may be 1. The FORWARD ACTION could be:

“To attend MS Excel training, to be followed by re - assessment in 3 months”

Examples of the Assessment Forms and Guidelines can be found in the Appendices

Roles and Responsibilities

Having included in the contract a process for staff selection, next is their role and responsibilities.

This will provide both guidance and a reference point for all parties prior to commencing opera-tions and throughout the life of the contract. The following paragraphs are examples taken fromcontracts:

Well Site Engineers

• To perform a minimum of 3 (every 8 hours) complete chemical and physical tests of circulating and static fluid systems maintained on site. The BU representatives may call for additional tests.

• Preparation of a daily drilling fluid report, as per the BU’s specification in a timely and professional manner. This will be prepared using the BU’s reporting system or as specified. The engineers must be familiar with the BU’s computer reporting system and the hole cleaning/surge and swab engineering software applications. The Con- tractor’s reporting system will be considered to be secondary and will only be completed if time allows.

• The reporting of all the materials being utilised by the contractors staff on site. The report must be issued at least once per 24-hour period and report must include an inventory of all materials being used or kept in stock for pos- sible future use by the contractor, to including materials not supplied by the contractor. The report must include materials in stock, used, received and returned during the previous 24 hours. The report must include the value of each and all products used, moved on or off site. The report must also include the value of all breakages.

• The engineer must prepare and submit to the BU’s on site representative, as part of the reporting process, daily written recommendations for continuous performance improvement.

• Providing engineering and safety related toolbox talks to the rig crew. All engineers must be STOP trained and be capable of performing a safety audit on the mud processing and chemical storage areas.

• Providing information and guidance to the drilling contractor as to the hazardous nature of chemicals that are

recommended for use.• To monitor and ensure recommendations as to the optimization of the solids control equipment and their per-

formances are made to the BU’s on site representative. If another contractor is given this task, it shall be the contractor’s responsibility to work in co-operation with this contractor.

• Issue a report at the end of every trip, which reflects the lessons learned, good and bad, with respect to the contents of the well programme, the implementation of the programme, rig equipment and logistics. This is to be sent in an email to the contractor’s senior engineer with a copy being sent to the BU’s representative (Technical).This must be done before leaving the rig and is seen as critical to the BU’s learning process.


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Operations Support Engineers (office based)

The selection process will have ensured the highly experienced skill staff will be supporting thecontract and all that is now needed is a list of instructions, which will ensure the BU’s expectationsare fulfilled:

• Duties will include but will not be limited to :

• Setting up an engineering design process for the BU that is compatible with the system within the BU. This should include, documents to be produced for the project and individual wells, information required to prepare the documentation and a Roles, Responsibility, Accountability and Consult (RACI) chart for the process

• Supply and maintain a complete range of fluid testing equipment at the work site to allow testing of drilling fluids and completion fluids to API specifications as a minimum, modified as required by the BU. A record of calibration to be kept available for inspection by the BU at all times. All rheometers (Fann 35A etc.) are to be kept within tol- erance (API standard) at all times.

• Provide off site engineering support to supervise the operation and provide a full and comprehensive technical back up to the operation.

• Contractor may provide drilling fluids and associated engineering services. In addition, the Contractor may be required to sub-contract and manage non-core services such as brine filtration, solids control and waste man-

agement .

• Supply technical assistance at the work site in the form of laboratory testing and oral / written advice.

• Ensuring that all produced documentation pertaining to the BU comes under a document control system where signatory authorities will be described through the RACI. Electronic copies of all documentation will be required,copies of which must be lodged within the business unit system and also with the BU’s representative (Techni- cal).

• For a project where there are more than one well to be drilled, a Basis of Design (BOD) document will be required for the project, this shall cover all background engineering as required to put in place the generic field fluids program. This document will include:

• previous area experience

• an understanding of potential and actual formation damage

• well bore stability

• corrosion management

• displacements procedures for one fluid to another

• logistics

• rig constraints

• commercial balance

• cementing interface considerations

• environmental controls

• hole cleaning procedures, including suggested gpm/max ROP and trip procedures

• lost circulation procedures. This should include a loss rate decision LCM tree and detailed spotting procedures

• Differentially stuck pipe-freeing procedures (spotting fluids and procedures). This is considered to be the minimum acceptable.

• The BOD document will be required to be signed off by a BU representative and the BU’s representative (Tech- nical).

• Individual well programmes will be written with reference to the Basis of Design Document.


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• Designing cementing spacers for all casing cementation except where the open hole interval contains moveable hydrocarbons. The same will apply for abandonment plugs. Simple rules of thumb will be agreed for spacer design (rheology and density), these should be optimised through the use of DEAP (or the BU’s accepted equivalent) when outside any previously agreed design envelopes.

• It is the responsibility of the engineer to agree the details for the spacer design with the Cementing Company during the planning phase and include these in the Basis of design. The final spacer design for a well, taking into

account any changes in mud properties during drilling, should be provided in writing to the cement contractor a minimum of 24 hours prior to running casing. The BU reserves the right to provide a surfactant from a single source if this is commercially effective and technically acceptable. The designs must be agreed with he business unit and with the BU’s representative (Technical).

• The use of risk based engineering in preparing the BOD, individual well programme and all associated engineering. The results of such risk-based engineering must be documented.

• Producing for all wells a drilling fluid AFE. The AFE will provide a P10, P50 and a P90 cost estimate. Back up engineering must be available to demonstrate the validity of the proposal particularly with respect to the volume of fluid consumed during each interval. This must consider that lost with cuttings, left behind casing and potential losses to the formation. All such AFE’s must include all associated costs for the project, not just expected chemical requirements. This will include, mud lost in transit, likely reconditioning costs of fluid returned to shore, solids control rental and shaker screen costs. It is appreciated that the contractor does not provide some of these services. However, they are part of the overall cost of the services and as such the contractor will be accountable for tracking the costs.

• Being part of the BU’s well planning team contributing on all wellbore engineering issues such as formation damage, wellbore stability, mud weight programmes, casing setting depths, hole cleaning, mud loss and environmental concerns. This will involve attending well planning meetings. Close working will be expected with other engineering service providers such as cementing and directional drilling. The engineer is to be capable of performing down hole simulations of pressure form the mud column using the contractor’s in house software and running the DEAP or alternative system to perform hole cleaning and surge/swab calculations.

• On critical wells, holding a peer review of the planning and the final programme with his own people of suitable technical standing.

• Producing daily and cumulative cost tracking mud property and product concentration reports.

• Making recommendations for continuous performance improvement.

• Producing end of well reports with recommendations for continuous performance improvement, problem description/analysis and cost analysis. The format of the end of well report will be standardised across the BU’s and must be approved by the Drilling Fluids contract manger. The end of well report will contain a complete rec- onciled cost close out on the well. In addition to those chemicals used on the well, the reconciliation will also detail as a minimum, shipping transit losses, chemicals written off, solids control costs such as equipment rental and shaker screen consumption. Transit losses are those taken to be the difference between manifested loads to and from the rig compared to those received on the rig and returned back to the supply base.

• The end of well report must contain the BU’s Global Fluid Performance measures for the well plus the Global Well Services data.

• The end of well report must contain all required SCOPEC data for the well. A separate copy of the SCOPEC data must be lodged with the UTG Technical Assistant responsible for the maintenance of BU’s records in this area.

• Two hard copies of the report are required plus one electronic copy.

• The end of well report must be received and accepted within 1 month of the completion of activities involving the contractor.

• Provision of chemical use and discharge data for chemical discharge report submission. In completing this, the engineer must use the BU guidelines. A system must be in place during the operations on the well to monitor


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use and discharge against the stated quantities in the chemical discharge report and advise the business unit ahead of time of any likely breech of the chemical discharge regulations.

• Monitoring projected and chemical use on the project against the Harmonised Chemical Notification Scheme (HOCNS) trigger figures. This should be performed in conjunction with other service providers using chemicals on the well. The engineer must advise the business unit in advance of any likely breach of the usage trigger figures.

• Implementing a system for tracking variations from expected service levels and producing recommendations for future avoidance.

• Undertaking rig visits on an ad-hoc basis but as a minimum once per well for single well programmes and a minimum of 2 times per year for multi well projects. The purpose of the visit is to ensure that the contractor’s people are working in a safe and efficient manner. An inspection system is to be developed which will cover as a minimum chemical stacking and handling, record keeping, mud lab’ procedures, quality of service provided to the BU and interface skills with the rig contractor. The findings of these inspections will be shared with the business unit and the BU’s representative (Technical).

• Keeping records of man-hours worked per week on the companies business. Records of this will be provided once per month to the BU’s representative (Technical).

Contract Manager • The contractor shall appoint a contract manager who will act as a focal point for all contractual matters.

Laboratory and Support Facilities

• Contractor shall provide a full and comprehensive fluid test kit and the appropriate fluid testing chemicals for each work site. This must include Garret gas Train, pressurised mud balance and bacterial test slides when water based mud is in use.

• Necessary computer and software must be available at the work site to run all contractors’ field engineering pro- grams.

• Contractor will provide the companies access to its well-qualified personnel, and to its best technology, processes, and equipment on a global basis.

• Contractor will provide a full laboratory service in Aberdeen capable of performing all field testing of drilling fluids and brines. It should also be capable of running FANN 70, FANN 90, particle size determination and barite sag analysis.

• Contractor will provide new technology or processes, whether developed internally or externally by a third party,if both the BU and contractor agree that the technology or processes are best in class and will add value to the business.

• In the event that special problems arise, contractor shall immediately utilise its full expertise to restore the situa- tion. The contractor is expected to utilise its full global support when such problems are encountered.

• Contractor is to have a system in place for prioritising technical service work, internal costing of that work and resource allocation. When a piece of work is required by the BU, the Technical Service Request document is to be used to define these areas.

The Provision of Drilling Fluid Chemicals and Materials

As the requirements are very different, the contract for the supply of drilling fluid materials shouldbe separate to that prepared for the provision of engineering services. This will allow for changingeither contract without compromising either part.

The contractual requirements must be for the supply of materials needed to formulate the drillingfluid and ancillary materials needed for drilling operations. The contract must ensure the imple-


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mentation and maintenance of a quality assurance/quality control (QA/QC) system, to ensure thestandard set for the materials at the commencement are maintained throughout the life of the con-tract.

There are several aspects to the supply contract:

• quality of the material and its use

• cost• accounting procedures

• discount schedules

Note: To assess the technical standards and quality of each product calls for a high degree of exper-tise and will not be included in this document.

This document will advise on the wording of the contract to ensure the contr

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