Empirical Factors Empirical Factors Leading to a Leading to a

Good Fractured Good Fractured ReservoirReservoir

• Early recognition of fractures

• High fracture intensity & good connections

• Good interaction between fracture & matrix

• High reservoir energy

• Low water influx

• If deep or fine grained, partial mineralization along fractures

Exploration & Exploration & Development Development

Drilling Score CardDrilling Score Card

• Picking optimum well locations - Good

• Picking optimum drilling directions - Great

• Assigning reservoir properties– Rates - Good– Volumes - Poor– Cross flow - Poor

E & D Drilling Score E & D Drilling Score CardCard

(cont.)(cont.)

• Determining drainage area - Fair

• Predicting well & reservoir response – Recovery - Poor– Longevity - Poor– Well history - Fair

• Assigning risk & economic success rate - Poor to Fair

Modern Approaches Modern Approaches are Based On:are Based On:

• New quantitative techniques in fracture characterization

• Multidisciplinary & integrated analyses

• More available reservoir simulation

• Better use of directional & horizontal drilling techniques

• More in-depth use of Risk Analysis

General OutlineGeneral Outline

1. Introduction

2. Fracture Origin

3. Fracture Morphology

4. Fracture Porosity

5. Fracture Permeability

6. F/M Interaction

7. Fracture Intensity

8. Intensity Prediction

9. Orientations

10. Reservoir Types

11. Well Directions

12. Simulation

13. Fracture Reservoir Production

14. Reservoir Screening

15. Summary

(Field Examples)

SummarySummary

• 6 phase approach to study of fractured reservoirs.

• Build from rock data first.

• Geophysical and rock mech. data can be used to highlight “sweet spots”.

• Reservoir prop. in fractures are different than matrix.

• Res. Mgmt. Strategies are very important.

Summary (cont.)Summary (cont.)

• Future advances will include upscaling fracture descriptions for reservoir simulation and defining connectedness in natural fracture systems.

• Because we can better quantify fractured reservoirs and predict their properties we should no longer fear or avoid them.

ApplyScreening

Tools

Gather Fracture Distribution Data

(Static Data)

Interpret Fracture System Origin &

Apply Distribution

Models (Static Data)

Gather Reservoir

Property Data for Matrix &

Fractures(Static Data)

Gather Fluid & Pressure

Data (Dynamic

Data)

Determine Fracture/Matrix

Interaction

Measure or Infer In Situ Stress Field

Create Dynamic

Conceptual Model

Create Static

Conceptual Model

Determine Fractured

Reservoir Type

Estimate Resources,

Reserves, Rates

Define Inhomogeneity, Anisotropy & Shape Factor

Develop Integrated Static & Dynamic

Reservoir Description for

Simulation

History Match to Wells & Tests

and Iterate

Select Optimum Well Locations

& Well Paths

Develop Depletion

Scheme and Reservoir

Management Strategies

Monitor Field Performance and

Adjust

Obtain Subsurface

Flow & Test Data

(Dynamic Data)

Economic?

Restudy?

Sanction?

Is this a Fractured Reservoir?

R.A. Nelson 9/00

Decision Steps,

Critical Modeling Steps