petrom standard wells catalogue - version jan-jun 2012

Standard Wells Catalogue

Prepared by Well Engineering Partners B.V.

Author: GvO, DB, BJK, WK

Version: 1

Publication date: March 7th, 2012

Approved:

Version January June, 2012

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Standard Wells Catalogue | January June, 2012

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Document Control

Amendments have to be recorded in the register shown below. Suggestions for additions and improvements should be passed to the custodians (see 1.5) by a

change request form which can be found in Appendix E.

Document release- and change registry

Revision

/ Update

Date: Revised section (chapter, page nos

etc.)

Revised pages,

contributed by

Initials

1

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Table of Contents

1 Introduction ......................................................................................... 7 2 General Data & Information ........................................................ 15 PART I: STANDARD CASING DESIGNS:

3 Heavy Oil Wells ................................................................................. 25 4 Shallow Gas Wells ........................................................................... 32 5 Shallow Oil Wells .............................................................................. 40 6 Medium Gas Wells ........................................................................... 48 7 Medium Gas Wells - 7 liner ........................................................ 58 8 Medium Oil Wells ............................................................................. 67 9 Medium Oil Wells - 7 liner .......................................................... 76 PART II: STANDARD COMPLETION DESIGNS:

10 Heavy Oil Completion..................................................................... 87 11 Oil Completion #1 ........................................................................... 92 12 Oil Completion #2 ........................................................................... 96 13 Gas Completion #1 ....................................................................... 100 14 Gas Completion #2 ....................................................................... 104 15 Gas Completion #3 ....................................................................... 108 16 Gas Completion #4 ....................................................................... 112 PART III: APPENDICES:

A. Abbreviations................................................................................... 119 B. Standardized gradients (T, pore pres., fracture) .............. 121 C. Reference Database OMV-Petrom Wells ............................... 124 D. Wellhead Assemblies .................................................................... 125 E. Change Request Form ................................................................. 127 F. References ........................................................................................ 129

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1 Introduction

1.1 Purpose of the catalogue

The Standard Wells Catalogue (SWC) describes a set of standardized well designs for the most common wells drilled by OMV-Petrom in Romania. The catalogue contains a set of designs including both casing designs as completions designs. Therefore, the various departments involved in the construction of a well will be aligned by using the catalogue which functions as a bridging document. In order to allow standardization, compromises will be made. The procurement process will be streamlined because the main equipment requirements are known once a drilling schedule is approved. The well approval procedure will also be shortened. Formation evaluation requirements are defined in order to ensure proper data collection for future wells. Main drilling and completion fluid properties are included for correct well delivery.

1.2 How to use the catalogue

The SWC is aligned with the OMV-Petrom well delivery process and uses the Well Data Pack (WDP) as input. First, it is to be determined if a well is considered either standard or non-standard based on specific criteria. Non-standard wells are not covered in this catalogue. Standard and non-standard wells are defined in 1.3 and 1.4, respectively. Next, the casing design type needs to be determined. Casing design is based on the expected pore pressure gradient and reservoir pressure. Heavy oil wells have their own casing design type. Within this catalog the casing design type for Gas and Oil wells are based on either 2 or 3 casing string designs, with or without a liner. A graph is used to determine if a liner is to be used for the production section. Once the casing design type has been determined, the casing depths will need to be chosen. The well catalogue provides a guide chart based on kick tolerances. The casing will be strong enough for the applicable load cases if the depth limitations are followed. Once the casing design type is determined, the completion design type is to be determined. Again the WDP is the driver for the choice to make. The combination of the casing and completion type gives the well design as it will be delivered to the asset. The SWC consists of a set of documents:

This document, the master document, containing: o All standard wells; o Standard Well Selection procedure (based on casing and completion

design types); o Technical considerations and standardized data; o Other relevant (technical) reference data (see Appendices).

A series of bundled documents, compiled from this document (master

document), each containing one complete well design. The bundled documents will be the work documents for the employees involved in the construction of a standard well. The definition and naming of the bundled documents are described in 1.8.

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1.3 Definition of standard wells

This well catalogue will cover standard wells. These wells are defined by the following characteristics:

Wells with deviation less than 30; 3 casing strings max; Reservoir pressure less than 5000 psi or 345 bar; Temperature less than 125 C; Non CO2 or sour wells according to NACE MR0175.

Note: horizontal Suplac wells are an exemption on these criteria. They are considered standard as well.

1.4 Definition of non-standard wells

The following wells are not considered to be standard wells:

Offshore wells; Exploration wells; Wells with working pressures over 5000 psi or 345 bar; High temperature wells with temperatures over 125 C; Wells to which NACE MR0175 applies (H2S and CO2 wells); Deviated wells with over 30 inclination with the exemption of the

horizontal heavy oil wells; Wells > 3000m TVD; Wells with abnormal pressure profiles; Wells using non-standard well construction operations such as casing

drilling, rotating casing while running, managed pressure drilling or under balanced drilling.

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1.5 SWC update process

The Standard Wells Catalogue is considered to be a life document which will require regular updating to reflect:

Changes in current standard well configurations; Addition of new well types as standard; Adherence to procedural changes.

1.5.1 Updating frequency and control

In view of the rapid changes and improvements to the OMV-Petrom drilling and completion operations, the SWC will be updated on a yearly basis. The first update/revision is planned for July 2012. The versions are controlled by a colour coding in order to identify obsolete versions, which is especially applicable to printed copies of the bundled well design documents for the specific wells. Each page will have a coloured tag. The colour scheme is in line with the lifting colour coding:

Start colour period Colour

Current 1 July 2012

The proposed SWC update frequency is lower than the frequency that is applied to control the documents to make it possible to issue urgent fixes and to increase control on the use of obsolete versions. Also, the lifting colour coding is an yet available control system.

1.5.2 Updating Process

The following custodians will who will be the focal point for all issues related to the catalogue:

OMV-Petrom Well Engineering department to appoint a custodian who will be responsible for content of the casing design part of the catalogue.

OMV-Petrom Production Operations department to appoint a custodian who will be responsible for content of the completions part of the catalogue.

A third party, i.e. Well Engineering Partners for the initial two years, will be responsible for introduction part and the process.

A change request form (see Appendix E) has been designed to provide the individual catalogue user a means to propose changes or improvements to the latest version of the document. It is part of the Standard Well Catalogue documentation. The custodians will evaluate the proposal and bring it to the attention of the decision makers. Decisions are made by mutual consent by the Technical Authorities, mainly for Well Engineering and Production Operations and as the case may be in close cooperation with other well related Technical Authorities (Petrophysicists, Reservoir Engineers and Geologists).

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1.5.3 SWC future content

Wells to be considered for future issues of the SWC. Water injection wells:

OMV-Petrom is embarking on a number of field re-development projects, mainly with water injection. Many of those injection wells will be shallow with depth between 500-1500 m TVD. Injection will be typically into 3-7 different sand units. Temperatures are considered to be moderate. The injection water quality will be variable. Planned injection rates are 50-500 m3/day with injection pressures in the range of 10-100 bar, for which 2-7/8" or 3-1/2" tubing will suffice. Material selection for the wetted parts of X-mass tree, tubing and completion accessories will require further investigation. GRE (Duoline) coated/lined carbon steel tubing or carbon steel tubing with continuous corrosion inhibition and oxygen scavenging are being considered. Slimhole wells:

Slim hole wells with for example 4-1/2 or 5 liners instead of 7 casing or liners are an option that may become part of the set of standard wells. Such slim holes have cost effective designs with an optimal production conduit. Slim holes have multiple advantages:

Lower day rate due to smaller rigs Less materials with less logistics Lower location preparation costs with less environmental impact Lower Mob / Demob costs Less waste disposal Smaller crew resulting in safer operations

Such wells will require various modifications to the operations and designs. For example, slim hole logging tools are required or improved slurries are required while cementing.

Stand alone screens with swell packers:

Stand alone screens are a cost effective way to implement sand control. The screens are faster and easier to install then gravelpacks. A well engineered screen allows the fines to be produced through the screen and plugging is prevented. On the downside, the screens are subject to erosion and less reliable at high rates what will not be a problem for the relative low production rates of the standard wells. Another disadvantage is the risk of damaging the screen during installation. The screens in combination with swell packers and possibly blank pipes are easy to install but will have zonal isolation capabilities. Several layers can be produced simultaneously while maintaining sand control during the life of the well. Continuous rod products:

A continuous pump rod can be used in deviated and high dog leg wells, i.e. heavy oil horizontal wells. The rod distributes the contact loads over the surface of the entire rod instead of having these loads applied to the connections only. The benefit is a reduction in tubing and rod failures and therefore less non-productive time of the well. The initial investment and the work-over costs will increase therefore further investigation is required on which wells to be equipped with such a system. Artificial Lift options for oil wells:

Almost 98% of all oil wells in OMV-Petrom use an artificial lift method. The remaining wells are free flowing oil wells. In this catalogue the oil wells using the Rotating Rod Pumping (RRP) or the Progressive Cavity Pumping (PCP) systems are

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described because these are currently the most common artificial lift systems used in OMV-Petrom. In the future, other methods of artificial lift may become the standard, e.g. gaslift and the Electric Submersible Pump (ESP) system. Such systems are gaining in interest and volume and are likely to be documented in future issues of this Standard Well Catalogue when necessary.

Monobore wells:

Another variation on using the limited radial space in well better is the monobore well design. Such a well has a uniform production conduit from reservoir to surface. Therefore, a monobore well design allows a larger production conduit than a conventional well. Also, the completion could be cemented directly instead of using a final production string so that the well could be downsized and requires one less casing string. Possible drawbacks are the lack of contingency string options, limited on the possible downhole equipment to be used or that the string will need to be chosen before the reservoir fluid characteristics are known. Potential early savings in wellbore construction costs need to be offset by possible compromised production later in the well life and higher cost due to the use of special equipment. Specific technical challenges of drilling a successful monobore must also be recognised and addressed.

Figure 1: Example of a potential monobore gas well design with cemented

completion

Nr. Item Description

1 13 3/8" conductor 68 ppf

SSSV

2 9 5/8" casing 47 ppf

Nipple

3 7" casing 29 ppf

Perforations

4 2 7/8" cemented completion 8,6 ppf

Wellhead and Xmastree

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1.6 Casing design selection

The following flow chart is to be used to choose the applicable casing design once the well has been verified to be a standard well. The Well Data Pack is used as input and the result will be a casing design. Each casing design is described in detail further in this document.

Figure 2: Casing design selection. Note that further selection is required

for the 2 wells in the green box

Two types of casing designs for medium depth wells are existing; either 3 casing strings, or 2 casing strings with a 7 liner. These designs are the wells enclosed by the green box. The choice criterion is based on the relationship between the 9-5/8 shoe setting depth and the total well depth. A rough cost estimation is used for this criterion: a liner is to be used when the 8- section is less than one third of the total well depth. In reality, most medium wells will have a liner.

Figure 3: Criterion to choose between a liner or casing design for medium

depth wells

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1.7 Completion design selection

Once it has been determined that a well is considered standard and a casing design has been identified, a completion type must be chosen. The well data pack is being used as input and the options are visualized below.

Figure 4: Completion design type selection process

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1.8 Naming of Standard Wells Bundles

A combination of the commodity, the casing design and the upper & lower completions define a specific well design. This is reflected in its name. For example, a medium depth oil well with a gravelpack and PCP completion is named O,M / GP-P,PP. This specific well design is found in the well specific document (Bundle #) number 4. All 16 possible and applicable combinations are listed in the table below. Table 1: Standard wells combinations, naming and bundles

The complete list of SWC bundles:

1. H,SV-SH / SL,RP

2. O,S / GP-P,PP

3. O,S / GP-P,RP 4. O,M / GP-P,PP

5. O,M / GP-P,RP 6. O,L / GP-P,PP

7. O,L / GP-P,RP 8. G,S / P,T

9. G,S / P,TSV 10. G,S / GP,T

11. G,S / GP,TSV 12. G,M / P,T 13. G,M / P,TSV

14. G,M / GP,T 15. G,M / GP,TSV

16. G,L / P,TSV

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2 General Data & Information

2.1 General remarks

This document is using average pressure profiles and can therefore only be used as guideline for casing setting depths. The actual casing design parameters are based on local geology which always has to be verified. All information that has been used to write this manual has been provided by OMV-Petrom and all wells are based on OMV-Petrom standards and OMV-Petrom well designs. No further verification against Romanian law has been performed. All depths are referring to ground level measured along hole unless mentioned otherwise. Appendix C gives an overview of the wells considered, which resulted in the standard well types.

2.2 General input

Kick tolerances and casing loads and its design factors are calculated as per OMV-Petrom Drilling Standards.

BOP stack to comply with OMV-Petrom Drilling Standards. Analysis and simulations in this document have been performed on Halliburton

Landmark software. o Casing design: StressCheck; o Tubing analysis: WELLCAT; o Drag: WELLPLAN.

Geothermal, pore pressure and fracture gradients have been standardized for

modeling (casing design & tubing analysis) purposes. Drilling programs of over 20 applicable wells (oil, gas, exploration, injection), have been analyzed resulting in the following gradients (refer to Appendix B for database file):

o Geothermal gradient: Heavy Oil 200m TVD: 27 C BHT (@200m TVD) Shallow & deep wells: 3.39 C/100m Surface Ambient: 15 C

o Pore pressure and fracture gradients:

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Figure 5: Standardized pore pressure and fracture gradients vs depth

Formation strength:

o The average formation strength is visualized in Figure 6 as function of depth. The curve presented here is an estimated curve and has to be used with great care. It must be noted that large variations in formation strength can be expected over the reservoir section. The input data for the average pressure curves and the data presented in a table can be found in Appendix B.

Figure 6: Avg. formation strength vs. depth

Surface equipment pressure ratings:

o Required pressure ratings for surface equipment (e.g. wellhead & X-mas tree) are well specific. The look-up table below is to be used to determine the wellhead pressure rating. The total well depth and the

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reservoir pressure (BHP) are taken from the well data pack. The closest table value that is higher than the WDP value for depth and reservoir pressure will need to be used. The hydrostatic pressure calculation uses the average pore pressure as presented above. For the purpose of this catalog the following matrix is prepared:

Table 2: Surface equipment pressure rating decision matrix

For example, a well with a planned total depth of 1730 m TVD and with an

expected bottom hole pressure of 45 bar is assumed. A depth of 2000 m needs to be used in the table. At this depth, there are only 2 wellhead ratings possible: 210 bar and 345 bar. The expected reservoir pressure lies between 3 bar and 138 bar so 138 bar needs to be used in the table hence a 5k psi or 345 bar rated wellhead needs to be used. Note that standard wells have a maximum depth of 3000 m MD and a maximum well head pressure of 345 bar.

2.3 Completion design specifics

2.3.1 Completion fluid

Well completion brine density depends on the reservoir pressure and reservoir depth. Clean, filtered to 2m brine of an appropriate density has to be used during completion and perforation phase. Completion brines used in OMV-Petrom are:

Potassium chloride (KCl) which is highly regarded as a inhibiting completion fluid and can achieve a density of 1,16 (10,0 ppg). KCl sack material can be added directly to fresh or sea water.

Calcium chloride (CaCl2) which can achieve a density of 1,39 (11,6 ppg). The brine can be prepared from sack material which is available in 77-80% pure and in 94-97% pure.

Total Well

Depth

Hydrostatic

pressure

[m TVD] [bar] [bar] [bar] [bar]

250 25 115 185 320

500 50 90 160 295

750 76 64 134 269

1000 102 38 108 243

1500 154 n/a 56 191

2000 207 n/a 3 138

2500 264 n/a n/a 81

3000 325 n/a n/a 20

2k psi / 140 bar 3k psi / 210 bar 5k psi / 345 bar

Maximum BHP as per WDP

Wellhead / Tree rating:

Ma

xim

um

close

d in

we

llhe

ad

pre

ssure

[ba

r]

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Physical properties of the KCl and CaCl2 solutions can be found in the Completions Operations Manual. 1

2.3.2 Sand control

For the horizontal Suplac sections SAS (Stand Alone Screens) will be used over the reservoir section. Slot size will be based on the PSD (Particle Size Distribution) of a representative sample of the reservoir sand collected from the same field through coring or side wall sampling. For the standard oil and gas wells, where needed internal gravel packing is performed primarily to control sand production and reduce the formation damage in the vicinity of the wellbore. The gravel packing system in perforated cased hole (7 OD casing) is either using a mechanically set domestic HOVA packer or a hydraulic set Baker packer. The screens are mainly Wire Wrapped Screens (WWS) which are manufactured locally by Stimpex using CRA material on a Sandvik Duplex 22 base pipe.

2.3.3 Perforating

Within OMV-Petrom 2 methods for gun conveyance are used.

1. The Wireline method whereby the gun is run on braided wire in either casing or tubing and retrieved afterwards. Applications are for short zones, overbalance shooting, selective completions and remedial activities.

2. The most common is the Tubing Conveyed method where the gun is run

at the end of the tubing and depending on the activities thereafter retrieved, left on the tubing or dropped in a rathole. Applications are underbalance shooting, shooting many zones in one time, large intervals and horizontal wells.

Tubing conveyed perforating is mostly used in the OMV-Petrom perforating activities. The most common size used in OMV-Petrom is the 4- OD gun with either charges for deep penetration to enhance flow or with charges to create a big entrance hole for gravelpacking afterwards.

2.3.4 Artificial lift

Within OMV-Petrom 2 pump types are mainly used; either PCP or RRP. 2

1. PCP is recommended for: Maximum recommended pump setting depth is some1400m; Presence of sand over 2%, solids handling is good; Wells with GOR < 100; Medium-high viscosity of oil or emulsions; Up to 70 deviation @ pump depth.

1 OMV, COM Completions Operations Manual, April 1997, Section 6 Completion Practices; Chapter Completion fluids; Part 7; page 1, 3 & 4. 2 OMV-Petrom L. Firu; S. Blazekovic, Best practices related to downhole pumps, sucker rods and tubing, July 2010

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2. RRP is recommended for:

Maximum recommended pump setting depth 3000m; No or little sand presence (max. 1,5 - 2%); Low to medium viscosity of oil; Up to 20 deviation @ pump depth; DLS maximum 12 / 30m.

2.4 Standardized equipment and materials

2.4.1 Standard casings & connections

Table 3: Standard Casings pricing 3

Item OD

(inch) WT

(mm) Weight (ppf)

Grade Connection Range USD/ton USD/m

1 13-3/8 9,65 54,5 K55 N TSH ER Range 3 2.003 162,6

2 9-5/8 8,94 36 K55 N BTC Range 3 1.903 102,04

3 9-5/8 10,03 40 L80 BTC Range 3 2.003 119,34

4 7 8,05 23 K55 N BTC Range 3 1.826 62,56

5 7 10,36 29 L80 BTC Range 3 1.923 83,07

6 7 8,05 23 L80 BTC Range 3 1.923 65,87

7 9-5/8 11,99 47 L80 TSH BLUE Range 3 2.501 175,11

8 7 10,36 29 L80 TSH BLUE Range 3 2.592 111,97 Table 4: Standard Connections for Casings

CSG Size: Well Type:

Gas Non-Gas (oil, water injection)

13-3/8 TSH ER (Easy Running) TSH ER

9-5/8 TSH Blue BTC

7 * TSH Blue BTC

* 7" slotted liners and blanks are equipped with Extremeline connections

More information and technical data on the TSH BLUE and TSH ER pipes can be found on www.tenaris.com.

2.4.2 Standard conductors

Table 5: Standard Hammer/Driving Surface Conductor Pipes 4

Conductor Pipes

Size: 16 20

Pipe Details:

Specs: Plain end, beveled and

ready for welding Plain end, beveled and

ready for welding

3 Petrom OMV, Exhibit M4 to Addendum No.15 to the long term agreement No. 8460001561 (OMV Petrom SAP no. 8460012570, tubing and casing prices valid from 1st of August 2011 to 31st of January 2012, page 1 4 TRS equipment.xls

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Standard: B36 or better B36 or better

Length: 10m 10m

Drive Shoe

Steel grade: X 52 or better X 52 or better

OD: 16,5 20,5

Length: 1 1,5m 1 1,5m

2.4.3 Standard tubing

Table 6: Standard Tubing 5

Item OD

(inch) WT

(mm) Weight (ppf)

Grade End Range USD/ton USD/m

1 2-7/8 5,51 6,5 J55 N EUE Range 2 2.224 21,53

2 2-7/8 5,51 6,5 L80 EUE Range 2 2.327 22,53

3 2-7/8 7,82 8,7 L80 EUE Range 2 2.327 30,15

4 3-1/2 6,45 9,3 J55 N EUE Range 2 2.118 29,34

5 3-1/2 6,45 9,3 L80 EUE Range 2 2.216 30,70

6 3-1/2 9,52 12,95 L80 EUE Range 2 2.217 42,75

7 2-7/8 7,82 8,6 L80 TSH BLUE Range 2 3.279 42,00

8 2-7/8 5,51 6,4 L80 TSH BLUE Range 2 3.279 31,26

9 3-1/2 9,52 12,7 L80 TSH BLUE Range 2 3.123 59,07

10 3-1/2 6,45 9,2 L80 TSH BLUE Range 2 3.122 42,79

In majority of oil wells tubing with J55 Grade is used.

Table 7: Standard Connections for Tubing

Well Type: Gas Non-Gas (oil, water

injection) TSH Blue EUE

More information and technical data on the TSH BLUE tubing can be found on www.tenaris.com.

5 Petrom OMV, Exhibit M4 to Addendum No.15 to the long term agreement No. 8460001561 (OMV Petrom SAP no. 8460012570, tubing and casing prices valid from 1st of August 2011 to 31st of January 2012, page 1

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2.4.4 Standard casing cementing accessories

In general Weatherford Equipment Table 8: Standard Casing Cementing Accessories

Casing Cementing Accessories

CSG/liner Size: 7 9-5/8 13-3/8

BASIC ACCESSORIES:

Float equipment Sure-Seal 3

Float shoes Model 303 / 323

Float collars Model 402 Model 402 / 402 1

stab-in-latch

Cementing plugs WiperLok system Non-Rotating

Centralisers Bow Spring STA0, STA1, STA2, STA3, STA4

Stop collars x x x

Stab-In arrangement Model 154 stinger

OPTIONAL ACCESSORIES:

Reamer shoes Diamond Back Model 303 n/a

Centralisers Low friction Spira Glider /

Rotating Centraliser Model STT-1SL (=welded) / Centek S2 (non Weatherford)

Scratchers x x n/a

P&A kit ACP n/a n/a

Cement basket Welded, slip-on, open top n/a

Accessories placement:

As minimum two joints of casing have to be installed between float shoe and float collar. 6

The exact number of centralisers per joint depends on variations in local hole conditions. Generally: 7

o 1 per 1-3 joints, in vertical well o 1 per 1-2 joints, wells up to 45 o 1 per joint, wells > 45

6 DOM; Chapter: Cementing, page 20 7 DOM; Chapter: Casing and liner running, page 22

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2.4.5 Standard mud types

Table 9: Standard Mud types

Section Well Conditions Type & Properties

Top hole

Normal Non dispersed Gypsum mud

Clay formation Spud mud (thin)

Sand formation Spud mud (thick)

Deviation > 30, horizontal well Non Aqueous Fluid (NAF) Shales, montmorillonite content > 3% KCl polymer mud Drilling months: December to March KCl polymer mud

Intermediate &

Production


Deviation > 30, horizontal well Non Aqueous Fluid (NAF)

AH Depth > 2000m Non Aqueous Fluid (NAF) Shales, montmorillonite content > 3% KCl polymer mud Drilling months: December to March KCl polymer mud

LCM to be used for cementing of the surface casing to prevent losses Two slurries to be used for cementing of surface casing with depths > 500 m Two slurries to be used for cementing of intermediate casing with depths >

1600 m Gasblock to be added to the tail slurry of liners and production casing of

medium depth gas wells to prevent inflow and gas migration Scavenger slurry to be used for cementing of casing drilled with WBM mud

type for an efficient cleaning and better mud displacement To cementing of casing drilled with NAF mud type, will be used the scavenger

slurry and spacer to prevent contamination of the slurry with mud.

2.4.6 Standard cement types

Table 10: Standard Cement types

Well Type Cement Type

Suplac injection Thermal

Other Class G

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PART I - Standard Casing designs

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3 Heavy Oil Wells

3.1 Description and limits

Heavy oil wells are drilled vertical / slightly deviated, but also horizontal. Examples of vertical / slightly deviated wells are (refer to Appendix C):

Suplac 398, 1237, 1240, 4076 Examples of horizontal wells are:

Suplac H4, H5, H6, H7, H8, H9

3.2 Casing scheme

Vertical or deviated casing designs reach a maximum measured depth of 250m, whereas the horizontal heavy oil casing designs reach a maximum measured depth of 700m (200m TVD). All heavy oil designs consist of a 9-5/8 casing string and a 7 liner string both with BTC connections. The surface casing applied for these wells is a 9-5/8 casing, 40ppf, L80. The casing weight and grade of the 7 slotted liner is 26ppf, L80. 13-3/8 conductors are driven to 10-15m (54,5ppf, K55). Table 11: Heavy Oil Well vertical well vs. horizontal well casing shoes

Section Vertical / Deviated Horizontal

Shoe depth MD Shoe depth TVD Shoe depth MD Shoe depth TVD 9-5/8 180 180 380 200

7 200 200 700 200 Additional well design parameters for Suplac Horizontal Wells: 8

KOP: 10-15m (as soon as possible) BUR: 8 or 9.5/30m DLS: < 12/30m

Figure 7: Heavy Oil Well Typical horizontal casing design 9

8 Well review board meeting 2011 Suplac Horizontals WDP1, 15 June 2011. 9 Legcevic, D., Suplac Heavy Oil Well Designs 01.doc, 01-2012.

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Figure 8: Heavy Oil Well Typical vertical or deviated casing design 10

10 Legcevic, D., Suplac Heavy Oil Well Designs 01.doc, 01-2012.

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3.3 Material / Equipment list

Table 12: Heavy Oil Well Material / Equipment list

# Description: Min. Specifications: Unit: Comments:

1 13-3/8" Conductor 54.5ppf, K55 10- 15

m

2 11" x 9-5/8" Casing head housing

140 bar / 2k psi 1 pcs Refer to 3.7

3 9-5/8" casing 40ppf, L80, BTC - m

4 9-5/8" casing float shoe Model 303 / 323, BTC 1 pcs

5 9-5/8" casing float collar Model 402, BTC 1 pcs

6 Cementing plugs WiperLok system 1 pcs

7 Centralisers 9-5/8 x 12-1/4 - pcs Vertical/deviated: bow spring type Horizontal: combination of slip-on spiragliders and bow spring type

8 Stop collars - pcs

9 7" slotted liner 26ppf, L80, Extremeline - m 0.360mm slots

10 7" blank liner 26ppf, L80, Extremeline 20 m

11 7" liner hanger/packer Extremeline 1 pcs with thermal compen-sator in vertical/ deviated wells only

12 7" float shoe Model 303 / 323, Extremeline

1 pcs

13 11" x 3-1/2" Tubing hanger flange

140 bar / 2k psi 1 pcs Refer to 3.7

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3.4 Casing Design

Casing Design is executed for 9-5/8 casing only. 7 slotted liner has not been considered. For the StressCheck analysis a horizontal well has been considered. 9-5/8 Casing:

The minimum casing weight and grade for the 9-5/8 casing is 40ppf, L80 with BTC connections. The critical load case is pressure test (triaxial). Steam injection load case has not been considered during casing design for this type of well.

Figure 9: Tri-axial plot Heavy Oil Well 9-5/8, 40ppf, L80

Burst load cases:

Pressure test to 100 bar with 1.15 s.g. mud = heaviest burst load case Green cement pressure test to 100 bar with 1.15 s.g. mud (wet cement)

Collapse load cases:

Partial evacuation with mud level at 380m (1.15s.g.) Cementing to surface with 1.9 s.g. slurry

Axial load cases:

Running in hole (0.5m/s) Overpull: 24 ton (1.5 safety factor)

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3.5 Kick-tolerances

Due to the shallowness of the well and the low pressures involved is only mud used for well control purposes, i.e. no BOP is used. Therefore kick tolerance is not relevant.

3.6 Minimum mud and cement requirements

Table 13: Heavy Oil Well - Minimum mud and cement requirements

Section

Mud Cement

Well Conditions: Type &

Properties: Density (sg):

Cement Type:

Cement Density (sg):

TOC:

12-1/4" hole

- 9-5/8" CSG


1,05 -

1,15 Thermal 1,8

to surface

Sand formation Spud mud (thick) Deviation > 30, horizontal well

Non Aqueous Fluid (NAF)

Shales, montmorillonite content >3% KCl polymer mud Drilling months: December to March KCl polymer mud

8-1/2" hole

- 7" liner

Deviation > 30, horizontal well


1,05 N/A N/A N/A Shales, montmorillonite content >3% KCl polymer mud Drilling months: December to March KCl polymer mud

3.7 Wellhead

Standard required: API 6A Material Class: DD Temperature rating: X (max. 180C) Product specification level: PSL2 Performance level: PR1 Pressure rating: 2000psi (140 bar) Currently Heavy Oil Wells are equipped with the wellhead assembly as displayed in Table 14 and Figure 10 below. OMV-Petrom is in the process of upgrading the wellhead assembly to the specifications as displayed in Table 15. Table 14: Heavy Oil Well Wellhead Assembly (current)

Component: Bottom

connection:

Bottom connection (casing head housing)

or Bottom pack-off (casing/tubing head

spool) for:

Top connection:

Hanger & Annular pack-off

for:

(in x bar) (in) (in x bar) (in)

11 (2k) x 9-5/8 + 11 (2k) x [3-1/2]

Casing head housing Box: 9-5/8 x 140 9-5/8 casing Flange: 11 x 140 -

Tubing hanger flange Flange: 11 x 140 3-1/2 tubing Flange: 3-1/2 x 140 3-1/2 tubing

30


Figure 10: Heavy Oil Well Wellhead Assembly (current)

Table 15: Heavy Oil Well Wellhead Assembly (future)

Component: Bottom

connection:

Bottom connection (casing head housing)

or Bottom pack-off (casing/tubing head

spool) for:

Top connection:


for:

(in x bar) (in) (in x bar) (in)

11 (2k) x 9-5/8 x [3-1/2]

Casing/tubing head housing Box: 9-5/8 9-5/8 casing Flange: 11 x 140 3-1/2 tubing

3.8 Survey and formation evaluation requirements

Anti-collision report to be made for each section as per OMV-Petrom drilling standards. Gyro instead of MWD or MMS to be used when collision risk is present and magnetic interference can be present. The sonic tool which is used in the reservoir section will be used to log the cement bounding of the entire well.

Table 16: Heavy Oil Well - Survey and formation evaluation requirements

no collision risk

survey mud-logging EWL FEWD

tophole vertical totco no x x

horizontal MWD no x x

production

section

vertical MMS yes GR+Res x

horizontal MWD yes x GR+Res

collision risk present


tophole vertical MWD/Gyro no x x

horizontal MWD/Gyro no x x

production

section

vertical MWD/Gyro yes GR+Res+Sonic/CBL GR1

horizontal MWD/Gyro yes x GR+Res

Ad 1: only if MWD is being used

31


3.9 Rig requirements

Drag values are generated by Halliburtons Wellplan software using the following input variables:

Weight of mud (MW): 1,10 sg Friction factors: Cased Hole: 0,25 /Open Hole: 0,30 Tortuosity:

o Model: Random inclination and azimuth o Angle change period: 30,5 m (100ft) o Magnitude: 2

Travelling Assembly Weight: 10 ton Additional Margin (e.g. overpull): 25 ton (vertical) / 50 ton (horizontal)

Table 17: Vertical Heavy Oil Well Minimum Hookload

2-string heavy oil well VERTICAL

Csg/Liner Size

Weight Csg

Depth Weight in air

Max Drag* MW @ 1,10 sg

Min. Hookload** MW @ 1,10 sg

(inch) (ppf) (m) (ton) (ton) (ton)

9-5/8 40 180 11 19 44

7 liner:

1) 5 DP 19,5 165 5

2) 7 liner 26,0 33 1

Total: 198 6 16 41 * Max. Drag does include travelling assembly weight

** Min. Hookload does include Additional Margin

Table 18: Horizontal Heavy Oil Well Minimum Hookload

2-string heavy oil well - HORIZONTAL

Csg/Liner Size

Weight Csg

Depth Weight in air




9-5/8 40 380 23 25 75

7 liner:

1) 5 DP 19,5 330 10

2) 7 liner 26,0 370 14

Total: 700 24 21 71 * Max. Drag does include travelling assembly weight

** Min. Hookload does include Additional Margin Based on the above, the Minimum Hookload capacity is 50 ton for vertical wells and for horizontal heavy oil wells is a 75 ton hookload stroking mast (pushing) rig needed.

32


4 Shallow Gas Wells


The shallow gas wells reach a maximum measured depth of 2000m. The design consists of a 9-5/8 and a 7 casing string. Examples of wells are (refer to Appendix C):

Valeni 21 Sinesti 1

4.2 Casing scheme

The setting depth of the 9-5/8 casing string will be between 500 and 775m. Actual setting depth depends on TD & specific pore pressure data. The minimum casing weight and grade of the 9-5/8 casing is 36ppf K55. The maximum depth of the 7 production is 2000m and the minimum casing weight and grade is 23ppf L80. Both strings are equipped with Premium Connections: TSH Blue. A 16 Conductor is driven to 10m.

* This depth exceeds kick tolerance allowance and is based on existing / reference

wells (see Appendix C)

Figure 11: Shallow Gas Well - Typical two string casing design

8-1/2 hole 7 CSG Max. 2000m

12-1/4 hole 9-5/8 CSG Max. 1100m *

33



Table 19: Shallow Gas Well Material / Equipment list


1 16" Conductor 10 m


210, 350bar / 3, 5k psi

1 pcs Refer to 4.7

3 9-5/8" casing 47ppf, L80, TSH Blue - m

4 9-5/8" casing float shoe Model 303 / 323, TSH Blue

1 pcs

5 9-5/8" casing float collar Model 402, TSH Blue 1 pcs


7 Centralisers 9-5/8 x 12-1/4 - pcs Bow spring type

8 Stop Collars - pcs

9 7-1/16" x 11" tubing spool 210, 350bar / 3, 5k psi

1 pcs Refer to 4.7

10 7" casing 29ppf, L80, TSH Blue - m

11 7" casing float shoe Model 303 / 323, TSH Blue

1 pcs

12 7" casing float collar Model 402, TSH Blue 1 pcs


14 Centralisers 7 x 8-1/2 - pcs Bow spring type

15 Stop Collars 1 pcs

34


4.4 Casing Design

9-5/8 casing:

Within OMV-Petrom a 47 ppf, L80, TSH Blue casing is applied for this type of well. The critical load case is full/partial evacuation (collapse).

Figure 12: Tri-axial plot Shallow Gas Well 9-5/8, 47ppf, L80, TSH Blue

Burst load cases:

Full displacement to gas This drilling load case models displacement of the drilling mud in the casing by gas. In case the formation strength is insufficient to withstand the pressure the load case will be reset with frac at shoe. For most intermediate casings this will be the case.

Pressure test to 100 bar with 1.15 s.g. mud. Green cement pressure test to 100 bar with 1.15 s.g. mud (wet cement).


Full evacuation - This drilling load case models casing evacuation due to lost circulation. The internal pressure profile is air, the outside pressure profile is constructed with the pore pressure gradients.

Cementing to surface with 1.6 s.g. lead slurry and 200 meter tail of 1.8 s.g.

Axial load cases:

Running in hole (0.5m/s). Overpull with 75 ton.

35


7 casing:

Within OMV-Petrom a 29 ppf, L80, TSH Blue casing is applied for this type of well. The critical load case is full evacuation production (collapse).

Figure 13: Tri-axial plot Shallow Gas Well 7, 29ppf, L80, TSH Blue

Burst load cases:

Tubing leak The internal pressure is based on a gas gradient of 0.7 (air = 1) and reservoir pressure which is pore pressure times TVD depth.




Cementing to surface with 1.9 s.g. slurry, TOC at 500 m. Axial load cases:


36


4.5 Kick-tolerances

The minimum setting depth of the 9-5/8 casing is based on kick tolerance which depends mainly on pore pressure and formation strength. The kick tolerances are calculated according OMV-Petrom drilling standards. The minimum allowable 9-5/8 casing depth as function of total well depth, for different pore pressure gradients, is visualized below. This is a guideline for the depth where the casing point should be picked. The chosen depth needs to have an above average formation strength.

Figure 14: Approximated 9-5/8" casing depths for various pore pressures

and required 8-1/2" section depth

Note that for inclined wells and for lighter mud the kick tolerance is higher.

400

450

500

550

600

650

700

750

800

1000 1100 1200 1300 1400 1500 1600 1700 1800 1900 2000

Min

imu

m s

urf

ace

ca

sin

g d

ep

th [

m]

Total well depth [m]

1,00 sg

1,05 sg

1,10 sg

1,15 sg

37



Table 20: Shallow Gas Well - Minimum mud and cement requirements

Section

Mud Cement

Well Conditions: Type & Properties: Density (sg):

Cement Type:


TOC:

12-1/4" hole

- 9-5/8" CSG


1,1-1,15*

G 1,8 to

surface





Shales, montmorillonite content >3%

KCl polymer mud

Drilling months: December to March

KCl polymer mud

8-1/2" hole

- 7" CSG


1,1-1,25*

G 1,9

100m into

previous CSG**



AH Depth > 2000m Non Aqueous Fluid (NAF)


KCl polymer mud


KCl polymer mud

* Mud weight based on local geology >> pore pressure & fracture gradients

** If log data is available which conclusively identifies the shallowest hydrocarbon zone and if the hole allows (no losses, in-gauge hole), the top of cement can be reduced to a minimum of 150m above the shallowest hydrocarbon zone.

4.7 Wellhead

Standard required: API 6A Material Class: AA Temperature rating: P + U Product specification level: PSL2 Performance level: PR1 Pressure rating: 3k or 5k psi (210 or 345 bar) In Figure 15 and Table 21 general specifications of the wellhead assembly can be found. A detailed wellhead assembly schematic can be found in Appendix D.

38


Figure 15: Shallow Gas Well Wellhead Assembly

Table 21: Shallow Gas Well Wellhead Assembly 11 12

Component: Bottom

connection:

Bottom connection (casing head housing) or

Bottom pack-off (casing/tubing

head spool) for:

Top connection:


for:

(in) (in) (in) (in)

11 x 9-5/8 x 7 + 11 x 4-1/2 x [tubing] + contingency 7-1/16 x [tubing] - 3k or 5k

Casing head housing Box: 9-5/8 9-5/8 casing Flange: 11 7 casing

Casing/tubing head spool Flange: 11 7 casing Flange: 11 4-1/2 csg or tbg sz

Tubing head spool (conting,) Flange: 11 4-1/2 casing Flange: 7-1/16 Tubing size


Anti-collision report to be made for each section. Gyro instead of MWD or MMS to be used when collision risk is present and magnetic interference can be present. The sonic tool which is used in the reservoir section will be used to log the cement bounding of the entire well. Table 22: Shallow Gas Well - Survey and formation evaluation

requirements

no collision risk


tophole vertical totco yes x x

deviated MWD yes x x

production

section

vertical MMS yes GR+Res+Sonic/Cbl x

deviated MWD yes Sonic/CBL GR+Res

11 M. Anghelache et al., Petrom E&P Standardization proposal Wellhead Assembly Standardization, 2011/2012? 12 D. Popescu et al, Wellheads equipment and related services, Scope of Work (Detailed technical specification) (Draft), 2011/2012?

39




tophole vertical MWD/Gyro yes x x

deviated MWD/Gyro yes x x

production

section


deviated MWD/Gyro yes Sonic/CBL GR+Res






Travelling Assembly Weight: 10 ton Additional Margin (e.g. overpull): 50 ton

Table 23: Shallow Gas Well Minimum Hookload

2-string gas well

Csg Size Weight Csg

Depth Weight in air




9-5/8 47 1100 77 82 132

7 29 2000 86 95 145 * Max. Drag does include travelling assembly weight


Based on the above, the Minimum Hookload capacity is 150 ton.

40


5 Shallow Oil Wells


The shallow oil wells reach a maximum measured depth of 2000m. The design consists of a 9-5/8 and a 7 casing string. Examples of wells are (refer to Appendix C):

Independenta 1454, Glogoveanu 1800, Filipesti 103, Filipesti 104, Carbunesti 34, Moreni 562.

5.2 Casing scheme

The setting depth of the 9-5/8 casing string will be between 500 and 775m. Actual setting depth depends on TD & specific pore pressure data. The minimum casing weight and grade of the 9-5/8 casing is 36ppf K55. The maximum depth of the 7 production is 2000m and the minimum casing weight and grade is 23ppf L80. Both strings are equipped with BTC connections. A 16 Conductor is driven to 10m.

* This depth exceeds kick tolerance allowance and is based on existing / reference

wells (see Appendix C)

Figure 16: Shallow Oil Well - Typical two string casing design


12-1/4 hole 9-5/8 CSG Max. 1100m*

41



Table 24: Shallow Oil Well Material / Equipment list




210, 345bar / 3, 5k psi

1 pcs Refer to 5.7

3 9-5/8" casing 36ppf, K55, BTC - m

4 9-5/8" casing float shoe Model 303/323, BTC 1 pcs





9 7-1/16" x 11" tubing spool

210, 345bar / 3, 5k psi

1 pcs Refer to 5.7

10 7" casing 23ppf, L80, BTC - m

11 7" casing float shoe Model 303/323, BTC 1 pcs

12 7" casing float collar Model 402, BTC 1 pcs




42


5.4 Casing Design

9-5/8 casing:

The minimum casing weight and grade is 36 ppf, K55. The critical load case is full/partial evacuation (collapse).

Figure 17: Tri-axial plot Shallow Oil Well 9-5/8, 36ppf, K55, BTC

Burst load cases:

Full displacement to gas This drilling load case models displacement of the drilling mud in the casing by gas. In case the formation strength is insufficient to withstand the pressure the load case will be reset with frac at shoe. For most intermediate casings this will be the case.





Axial load cases:


43


7 casing:

The minimum casing weight and grade is 23 ppf, L80. The critical load case is full evacuation production (collapse).

Figure 18: Tri-axial plot Shallow Oil Well 7, 23ppf, L80, BTC

Burst load cases:

Tubing leak The internal pressure is based on a gas gradient of 0.7 (air = 1) and reservoir pressure which is pore pressure times TVD depth.




Cementing to surface with 1.9 s.g. slurry, TOC at 500 m. Axial load cases:


44


5.5 Kick-tolerances

Minimum setting depth of the 9-5/8 casing is based on kick tolerance which depends on pore pressure and formation strength. The minimum allowable 9-5/8 casing depth as function of total well depth, for different pore pressure gradients, is visualized below. This is a guideline for the depth where the casing point should be picked. The chosen depth needs to have an above average formation strength.

Figure 19: Approximated 9-5/8" casing depths for various pore pressures

and required 8-1/2" section depth


300

350

400

450

500

550

600

650

700

1000 1200 1400 1600 1800 2000 2200 2400 2600 2800 3000

13

-3/

8"

ca

sin

g d

ep

th [

m]

12-1/4" section depth [m]

1,00 sg

1,05 sg

1,10 sg

1,15 sg

45



Table 25: Shallow Oil Well - Minimum mud and cement requirements

Section

Mud Cement


Cement Type:


TOC:

12-1/4" hole

- 9-5/8" CSG


1,1-1,15*

G 1,8 to surface






KCl polymer mud


KCl polymer mud

8-1/2" hole

- 7" CSG


1,1-1,25*

G 1,9 100m into previous CSG**





KCl polymer mud


KCl polymer mud



5.7 Wellhead

Standard required: API 6A Material Class: AA Temperature rating: P + U Product specification level: PSL2 Performance level: PR1 Pressure rating: 3k or 5k psi (210 or 345 bar) In Figure 20 and Table 26 general specifications of the wellhead assembly can be found. A detailed wellhead assembly schematic can be found in Appendix D.

46


Figure 20: Shallow Oil Well Wellhead Assembly

Table 26: Shallow Oil Well Wellhead Assembly 13 14

Component: Bottom

connection:



head spool) for:

Top connection:


for:

(in) (in) (in) (in)

11 x 9-5/8 x 7 + 11 x 4-1/2 x [tubing] + contingency 7-1/16 x [tubing] - 3k or 5k

Casing head housing Box: 9-5/8 9-5/8 casing Flange: 11 7 casing

Casing/tubing head spool Flange: 11 7 casing Flange: 11 4-1/2 csg or tbg sz



Anti-collision report to be made for each section. Gyro instead of MWD or MMS to be used when collision risk is present and magnetic interference can be present. The sonic tool which is used in the reservoir section will be used to log the cement bounding of the entire well. Table 27: Shallow Oil Well - Survey and formation evaluation

requirements

no collision risk



deviated MWD yes x x

production

section




47




tophole vertical MWD/Gyro yes x x

deviated MWD/Gyro yes x x

production

section









Table 28: Shallow Oil Well Minimum Hookload

2-string oil well

Csg Size Weight Csg

Depth Weight in air




9-5/8 36 1100 59 65 115


** Min. Hookload does include Additional Margin Based on the above, the Minimum Hookload capacity is 150 ton.

48


6 Medium Gas Wells


The medium gas wells reach a maximum measured depth of 3000m. The design consists of a 13-3/8, 9-5/8 and a 7 casing string. Examples of wells are (refer to Appendix C):

Colibasi 260, Colibasi 261.

6.2 Casing scheme

The setting depth of the 13-3/8 casing string will be between 350 and 650m. Actual setting depth depends on TD & specific pore pressure data. The minimum casing weight and grade of the 13-3/8 casing is 54ppf K55. The maximum depth of the 9-5/8 casing is 2500m and the minimum casing weight and grade is 40ppf L80. The maximum depth of the 7 casing is 3000m and the minimum casing weight and grade is 26ppf L80. Tenaris connections are applied; 13-3/8 CSG is equipped with TSH ER and the 9-5/8 and 7 CSG are equipped with TSH Blue. A 20 conductor is driven to 10m.

Figure 21: Medium Gas Well - Typical three string casing design


12-1/4 hole 9-5/8 CSG Max. 2500m

16 hole 13-3/8 CSG Max. 650m

49


6.3 Materials / Equipment list

Table 29: Medium Gas Well Material / Equipment list



2 13-5/8" x 13-3/8" Casing head housing

345bar / 5k psi 1 pcs Refer to 6.7

3 13-3/8" casing 54,5ppf, K55, TSH ER - m

4 13-3/8" casing float shoe Model 303/323, TSH ER

1 pcs

5 13-3/8" casing float collar Model 402/402 1 stab-in-latch, TSH ER

1 pcs


7 Centralisers 13-3/8 x 16 - pcs Bow spring type


9 11" x 13-5/8" Casing head spool



11 9-5/8" casing float shoe Model 303/323, TSH Blue

1 pcs





16 7-1/16" x 11" Tubing spool 345bar / 5k psi 1 pcs Refer to 6.7

17 7" casing 29ppf, L80, TSH Blue - m

18 7" casing float shoe Model 303/323, TSH Blue

1 pcs





50


6.4 Casing Design

13-3/8 casing:

The minimum casing weight and grade is 54,5ppf, K55. The critical load case is full evacuation (collapse).

Figure 22: Tri-axial plot Medium Gas Well 13-3/8, 54.5ppf, K55, TSH ER

Burst Load cases:

Full displacement to gas This drilling load case models displacement of the drilling mud in the casing by gas from section TD of the 12 hole. In case the formation strength is insufficient to withstand the pressure the load case will be reset with frac at shoe. For surface casings this will be the case. Gas gravity applied: 0.7.

Pressure test to 100 bar with 1.15 s.g. mud. Green cement pressure test to 100 bar with 1.15 s.g. mud (wet cement)

Collapse Load cases:


Cementing to surface with 1.8 s.g.

Axial load cases: Running in hole (0,5m/s). Overpull with 75 ton.

51


9-5/8 casing:

Within OMV-Petrom a 47 ppf, L80, TSH Blue casing is applied for this type of well. The critical load case is cementing (collapse).

Figure 23: Tri-axial plot Medium Gas Well 9-5/8, 47ppf, L80, TSH Blue

Burst Load cases:

Full displacement to gas - This drilling load case models displacement of the drilling mud in the casing by gas from section TD of the 8 hole. In case the formation strength is insufficient to withstand the pressure the load case will be reset with frac at shoe. For surface casings this will be the case. Gas gravity applied: 0.7.





Axial load cases:


52


7 casing:

Within OMV-Petrom a 29 ppf, L80, TSH Blue casing is applied for this type of well. The critical load case is full evacuation (collapse).

Figure 24: Tri-axial plot Medium Gas Well 7, 29ppf, L80, TSH Blue

Burst Load cases:

Tubing leak The internal pressure is based on a gas gravity of 0.7 (air = 1) and reservoir pressure which is pore pressure times TVD depth.

Pressure test to 100 bar with 1.25 s.g. mud Green cement pressure test to 100 bar with 1.25 s.g. mud (wet cement)



Cementing with 1.9 s.g. slurry. Axial load cases:


53


6.5 Kick tolerances

Minimum setting depth of the 13-3/8 and 9-5/8 casings are based on kick tolerances which depends on pore pressure and formations strength. Large variations in formation strength can be expected over the reservoir section and thus the 9-5/8 casing will be set just above the reservoir followed by a short 7 section. The 12-1/4 section should therefore be able to reach the maximum TD of 3000m. This will require certain minimum formation strength around the 13-3/8 casing shoe. The minimum allowable 9-5/8 casing depth as function of total well depth is for different pore pressure gradients visualized below. This is a guideline for the depth where the casing point should be picked. The chosen depth needs to have an above average formation strength.

Figure 25: Approximated 13-3/8" casing depths for various pore

pressures and required 12-1/4" section depth


300

350

400

450

500

550

600

650

700

1000 1200 1400 1600 1800 2000 2200 2400 2600 2800 3000

13

-3/

8"

ca

sin

g d

ep

th [

m]


1,00 sg

1,05 sg

1,10 sg

1,15 sg

54



Table 30: Medium Gas Well - Minimum mud and cement requirements

Section

Mud Cement


Cement Type:


TOC:

16" hole -

13-3/8" CSG


1,1-1,15*

G 1,8 to

surface



Deviation > 30 Non Aqueous Fluid (NAF)


KCl polymer mud


KCl polymer mud

12-1/4" hole

- 9-5/8" CSG


1,1-1,25*

G 1,9

100m into

previous CSG**




KCl polymer mud


KCl polymer mud

8-1/2" hole

- 7" CSG


1,1-1,25*

G 1,9

100m into

previous CSG**




KCl polymer mud


KCl polymer mud



6.7 Wellhead

Standard required: API 6A Material Class: AA Temperature rating: P + U Product specification level: PSL2 Performance level: PR1 Pressure rating: 5000psi (345bar) In Figure 26 and Table 31 general specifications of the wellhead assembly can be found. A detailed wellhead assembly schematic can be found in Appendix D.

55


Figure 26: Medium Gas Well Wellhead Assembly

Table 31: Medium Gas Well Wellhead Assembly 15 16

Component: Bottom

connection:



head spool) for:

Top connection:


for:

(in) (in) (in) (in)

13-5/8 x 13-3/8 x 9-5/8 + 11 x 7 x or [4-1/2 or tubing] + contingency 7-1/16 x [tubing] - 5k

Casing head housing Box: 13-3/8 13-3/8 casing Flange: 13-5/8 9-5/8 casing

Casing/tubing head spool Flange: 13-5/8 9-5/8 casing Flange: 11 7 csg or 4- tbg sz



56



Anti-collision report to be made for each section. Gyro instead of MWD or MMS to be used when collision risk is present and magnetic interference can be present.

Table 32: Medium Gas Well - Survey and formation evaluation

requirements

no collision risk



deviated MWD yes x GR

intermed.

section

vertical MMS yes x x


production

section





tophole vertical MWD/Gyro yes x GR1

deviated MWD/Gyro yes x GR1

intermed.

section

vertical MWD/Gyro yes x GR1

deviated MWD/Gyro yes x GR

production

section




57







Table 33: Medium Gas Well Minimum Hookload

3-string gas well

Csg Size Weight Csg

Depth Weight in air




13 3/8 54,5 650 53 57 132

9 5/8 47 2500 175 191 266




58


7 Medium Gas Wells - 7 liner


The medium gas wells reach a maximum measured depth of 3000m. The design consists of a 13-3/8, 9-5/8 casing strings and a 7 liner. Examples of wells are (refer to Appendix C):

Coltesti 3007.

7.2 Casing scheme

The setting depth of the 13-3/8 casing string will be between 350 and 650m. Actual setting depth depends on TD & specific pore pressure data. The minimum casing weight and grade of the 13-3/8 casing is 54ppf K55. The maximum depth of the 9-5/8 casing is 2900m and the minimum casing weight and grade is 40ppf L80. The maximum depth of the 7 liner is 3000m and the minimum casing weight and grade is 29ppf L80. Tenaris connections are applied; 13-3/8 CSG is equipped with TSH ER and the 9-5/8 and 7 CSG are equipped with TSH Blue. A 20 conductor is driven to 10m.

Figure 27: Medium Gas Well 7 liner design

8-1/2 hole 7 liner Max. 3000m

12-1/4 hole 9-5/8 CSG Max. 2900m

16 hole 13-3/8 CSG Max. 650m

59



Table 34: Medium Gas Well (liner) Material / Equipment list







1 pcs


1 pcs







11 9-5/8" casing float shoe Model 303/323, TSH Blue

1 pcs





16 7" liner 29ppf, L80, TSH Blue - m Liner laps = 50m

17 7 liner hanger TSH Blue 1 pcs

18 7" casing float shoe Model 303/323, TSH Blue

1 pcs



21 Stinger Model 154 1 pcs



60


7.4 Casing Design

13-3/8 casing:

The minimum casing weight and grade is 54,5ppf, K55. The critical load case is full evacuation (collapse).

Figure 28: Tri-axial plot Medium Gas Well (liner) 13-3/8, 54.5ppf, K55,

TSH ER

Burst Load cases:

Full displacement to gas This drilling load case models displacement of the drilling mud in the casing by gas from section TD of the 12 hole. In case the formation strength is insufficient to withstand the pressure the load case will be reset with frac at shoe. For surface casings this will be the case. Gas gravity applied: 0.7.


Collapse Load cases:


Cementing to surface with 1.8 s.g. Axial load cases:

Running in hole (0,5m/s). Overpull with 75 ton.

61


9-5/8 casing:

Within OMV-Petrom a 47ppf, L80, TSH Blue casing is applied for this type of well. The critical load case is cementing (collapse).

Figure 29: Tri-axial plot Medium Gas Well (liner) 9-5/8, 47ppf, L80,

TSH Blue

Burst Load cases:

Full displacement to gas - This drilling load case models displacement of the drilling mud in the casing by gas from section TD of the 8 hole. In case the formation strength is insufficient to withstand the pressure the load case will be reset with frac at shoe. For surface casings this will be the case. Gas gravity applied: 0.7.

Tubing leak - The internal pressure is based on a gas gradient of 0.7 (air = 1) and reservoir pressure which is pore pressure times TVD depth.





Axial load cases:


62


7 liner:

The minimum casing weight and grade is 29 ppf, L80. The critical load case is full evacuation (collapse).

Figure 30: Tri-axial plot Medium Gas Well (liner) 7, 29ppf, L80, TSH

Blue

Burst Load cases:

Tubing leak The internal pressure is based on a gas gravity of 0.7 (air = 1) and reservoir pressure which is pore pressure times TVD depth.

Pressure test to 100 bar with 1.25 s.g. mud Green cement pressure test to 100 bar with 1.25 s.g. mud (wet cement)



Cementing with 1.9 s.g. slurry. Axial load cases:


63


7.5 Kick tolerances

Minimum setting depth of the 13-3/8 and 9-5/8 casings are based on kick tolerances which depends on pore pressure and formations strength. Large variations in formation strength can be expected over the reservoir section and thus the 9-5/8 casing will be set just above the reservoir followed by a short 7 section. The 12-1/4 section should therefore be able to reach the maximum TD of 3000m. This will require certain minimum formation strength around the 13-3/8 casing shoe. The minimum allowable 9-5/8 casing depth as function of total well depth is for different pore pressure gradients visualized below. This is a guideline for the depth where the casing point should be picked. The chosen depth needs to have an above average formation strength.

Figure 31: Approximated 13-3/8" casing depths for various pore

pressures and required 12-1/4" section depth


300

350

400

450

500

550

600

650

700

1000 1500 2000 2500 3000

13

-3/8

" ca

sin

g d

ep

th [

m]


1,00 sg

1,05 sg

1,10 sg

1,15 sg

64



Table 35: Medium Gas Well (liner) - Minimum mud and cement

requirements

Section

Mud Cement


Cement Type:


TOC:

16" hole -

13-3/8" CSG


1,1-1,15*

G 1,8 to

surface





KCl polymer mud


KCl polymer mud

12-1/4" hole

- 9-5/8" CSG


1,1-1,25*

G 1,9

100m into

previous CSG**




KCl polymer mud


KCl polymer mud

8-1/2" hole

- 7" liner


1,1-1,25*

G 1,9

100m into

previous CSG**




KCl polymer mud


KCl polymer mud



7.7 Wellhead

Standard required: API 6A Material Class: AA Temperature rating: P + U Product specification level: PSL2 Performance level: PR1 Pressure rating: 5000psi (345bar) In Figure 32 and Table 36 general specifications of the wellhead assembly can be found.

65


Figure 32: Medium Gas Well (liner) Wellhead Assembly

Table 36: Medium Gas Well (liner) Wellhead Assembly 17 18

Component: Bottom

connection:



head spool) for:

Top connection:


for:

(in) (in) (in) (in)

13-5/8 x 13-3/8 x 9-5/8 + 11 x 13-5/8 x [tubing size] - 5k

Casing head housing Box: 13-3/8 13-3/8 casing Flange: 13-5/8 9-5/8 casing

Casing/Tubing head spool Flange: 13-5/8 9-5/8 casing Flange: 11 Tubing size


Anti-collision report to be made for each section. Gyro instead of MWD or MMS to be used when collision risk is present and magnetic interference can be present.

Table 37: Medium Gas Well (liner) - Survey and formation evaluation

requirements

no collision risk




intermed.

section

vertical MMS yes x x


production

section




66




tophole vertical MWD/Gyro yes x GR1

deviated MWD/Gyro yes x GR1

intermed.

section

vertical MWD/Gyro yes x GR1

deviated MWD/Gyro yes x GR

production

section









Table 38: Medium Gas Well (liner) Minimum Hookload

3-string (liner) gas well

Csg/Liner Size

Weight Csg

Depth Weight in air




13 3/8 54,5 650 53 57 132

9 5/8 47 2900 203 230 305

7 Liner:

A) 5 DP 19,5 2850 83

B) 7 liner 29 150 6

Total 3000 89 127 202 * Max. Drag does include travelling assembly weight



67


8 Medium Oil Wells


The medium oil wells reach a maximum measured depth of 3000m. The design consists of a 13-3/8, 9-5/8 and a 7 casing string. Examples of wells are (refer to Appendix C):

Colibasi 256 Abramut 300 E

8.2 Casing scheme

The setting depth of the 13-3/8 casing string will be between 350 and 650m. Actual setting depth depends on TD & specific pore pressure data. The minimum casing weight and grade of the 13-3/8 casing is 54ppf K55. The maximum depth of the 9-5/8 casing is 2500m and the minimum casing weight and grade is 40ppf L80. The maximum depth of the 7 casing is 3000m and the minimum casing weight and grade is 26ppf L80. The 13-3/8 CSG is equipped with TSH ER connections whereas the 9-5/8 and 7 CSG are equipped with BTC connections. A 20 conductor is driven to 10m.

Figure 33: Medium Oil Well - Typical three string casing design


12-1/4 hole 9-5/8 CSG Max. 2500m

16 hole 13-3/8 CSG Max. 650m

68



Table 39: Medium Oil Well Material / Equipment list







1 pcs


1 pcs






10 9-5/8" casing 40ppf, L80, BTC - m

11 9-5/8" casing float shoe Model 303/323, BTC 1 pcs





16 7-1/16" x 11" Tubing spool 345bar / 5k psi 1 pcs Refer to 8.7

17 7" casing 29ppf, L80, BTC - m

18 7" casing float shoe Model 303/323, BTC 1 pcs

19 7" casing float collar Model 402, BTC 1 pcs

20 Cementing plugs WiperLo

petrom standard wells catalogue - version jan-jun 2012

Documents

medium oil wells

standard wells catalogue

medium gas wells

common wells

heavy oil wells

shallow oil wells

shallow gas wells

gas completion