Drilling Fluids Operations Manual

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The present document is CONFIDENTIAL and it is property of AGIP It shall not be shown to third parties nor shall it be used for reasons different from those owing to which it was given

DRILLING FLUIDS OPERATIONS MANUAL

DISTRIBUTION LIST

Eni - Agip Division Italian Districts Eni - Agip Division Affiliated Companies

Eni - Agip Division Headquarter Drilling & Completion Units STAP Archive

Eni - Agip Division Headquarter Subsurface Geology Units Eni - Agip Division Headquarter Reservoir Units

Eni - Agip Division Headquarter Coordination Units for Italian Activities Eni - Agip Division Headquarter Coordination Units for Foreign Activities

NOTE: The present document is available in Eni Agip Intranet (http://wwwarpo.in.agip.it) and a CD-Rom version can also be distributed (requests will be addressed to STAP Dept. in Eni - Agip Division Headquarter)

Date of issue:

f e d c

b Issued by G. Ferrari C. Lanzetta A. Galletta

28/06/99 28/06/99 28/06/99

REVISIONS PREP'D CHK'D APPR'D

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1. MANUAL USER’S GUIDE

5

1.1 INTRODUCTION 5

1.2 GUIDE TO USING THE MANUAL 6

1.3 UPDATING, AMENDMENT, CONTROL & DEROGATION 8

2. GUIDE TO DRILLING FLUID PROGRAMMING

9

2.1 DEVELOPMENT OF THE DRILLING FLUID PROGRAMME 10

2.2 CHOICE OF DRILLING FLUIDS 11

2.2.1 Non-Circulating, Start-Up Drilling Fluids 11

2.2.2 Circulating, Start-Up Drilling Fluids 11

2.2.3 Drilling Formations With Gradients Less Than 1.0kg/cm2/10m 11

2.2.4 Drilling Fluids For Non-Reactive Formations 11

2.2.5 Drilling Fluids For Reactive Formations 12

2.2.6 Drilling Fluids For Temperatures Greater Than 200oC 12

2.2.7 Inhibitive And/Or Environmentally Friendly Speciality Fluids 13

2.3 CHARACTERISTICS OF THE FLUID SYSTEM 14

2.4 EXAMPLES OF DRILLING FLUID CHOICE 16

2.4.1 Concomitant Problems 16

2.4.2 Type Of Drilling Fluid Preferred 16

2.5 CHOICE OF THE FLUID SYSTEM (Dependent On Its Main Variables) 16

2.6 DRILLING FLUID CHARACTERISTIC PROGRAMMING 17

2.7 WATER-BASED FLUIDS 18

2.7.1 Optimum Values Of Marsh Viscosity, Solids And Gel 18

2.7.2 Optimum Values Of Plastic Viscosity And Yeld Point 19

3. FLUID CHARACTERISTICS

20

3.1 NON-INHIBITIVE WATER BASED FLUIDS 20

3.2 INHIBITED WATER-BASE FLUIDS 37

3.3 OIL BASED FLUID 50

3.4 INHIBITED AND/OR ENVIRONMENTAL FLUIDS 55

4. FLUID MAINTENANCE

72

4.1 WATER BASED FLUIDS MAINTENANCE 73

4.1.1 Analysing Flow Chart For Water Based Fluid Reports 73

4.1.2 Maintenance Problems 74

4.1.3 Chemical Treatment of Contaminents 77

4.1.4 H2S Scavengers 78

4.1.5 Poylmer Structures/Relationship 79

4.2 OIL BASED FLUIDS MAINTENANCE 80

4.2.1 Analysing Flow Chart For Oil Based Fluid Reports 80

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5.2 STATISTICAL DISTRIBUTION OF SOLIDS 84

5.3 EQUIPMENT PERFORMANCE 84

5.4 EQUIPMENT RECOMENDATIONS 85

5.4.1 Double Shale Shakers 86

5.4.2 Single Deck Shale Shakers 87

5.5 SCREEN SPECIFICATION 88 5.5.1 Nomenclature 88 5.6 CYCLONE SYSTEMS 89 5.7 CENTRIFUGE SYSTEMS 90 5.7.1 PrInciple Of Operation 90 5.7.2 Centrifuge Processing 91

6. TROUBLESHOOTING GUIDE

92

6.1 LOST CIRCULATION CONTROL TECHNIQUES 93

6.2 LOSSES IN VARIOUS FORMATION TYPES 94

6.3 CHOICE OF LCM SPOT PILLS 94

6.3.1 LCM Information 95

6.3.2 LCM Efficiency 95

6.4 TROUBLESHOOTING GUIDE 96

6.4.1 Loss Of Circulation With Water Based Fluids 96

6.4.2 Loss Of Circulation With Oil Based Fluids 98

7. STUCK PIPE TREATMENT/PREVENTITIVE ACTIONS

101

7.1 STUCK PIPE TREATMENT/PREVENTION 102

8. DRILLING FLUID TRADEMARK COMPARISONS

105

8.1 DRILLING FLUID PRODUCT TRADEMARKS 106

8.1.1 Weighting Materials 106 8.1.2 Viscosifiers 106 8.1.3 Thinners 106 8.1.4 Filtrate Reducers 107 8.1.5 Lubricants 107 8.1.6 Detergents/Emulsifiers/Surfactants 107 8.1.7 Stuckpipe Surfactants 108

8.1.8 Borehole Wall Coaters 108

8.1.9 Defoamers/Foamers 108

8.1.10 Corrosion Inhibitors 108

8.1.11 Bactericides 109

8.1.12 Lost Control Materials 109

8.1.13 Chemical Products 109

8.1.14 Oil Based Fluid Products 110

8.1.15 Base Liquids And Corrections 112

9. DRILLING FLUIDS APPLICATION GUIDE

113

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10.1.1 Density (Fluid Weight) 133

10.1.2 Marsh Viscosity 133

10.1.3 Viscosity, Yield Point, Gel Strength 134

10.1.4 API Filtrate 135

10.1.5 HPHT Filtrate 136

10.1.6 Oil, Water, Solids Measurement 137

10.2 WATER-BASED FLUIDS 138

10.2.1 Sand Content Estimate 138

10.2.2 pH Measurment 139

10.2.3 Methylene Blue Capacity Determination 140

10.2.4 Chloride Content Determination 141

10.2.5 Calcium Hardness Determination 142

10.2.6 Calcium And Magnesium Determination 143

10.2.7 Alcalinity, Excess Lime, Pf, Mf, Pm Measurment 144

10.2.8 Excess Gypsum Measurment 145

10.2.9 Semiquantitative Determination Of Sulphurs (Hatch Test) 146

10.2.10 Fluid Corrosivity Analysis 147

10.3 OIL BASED FLUIDS 148

10.3.1 Electrical Stability Determination 148

10.3.2 Fluid Alkalinity Determination 149

10.3.3 Fluid Chloride Determination 150

10.3.4 Calcium Determination 151

APPENDIX A - DRILLING FLUID CODING SYSTEM

152

A.1. CODE GROUPS 152

A.2. EXAMPLE CODING 153

APPENDIX B - ABBREVIATIONS

154

B.1. FLUID CODE ABBREVIATIONS 154

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1.1 INTRODUCTION

This manual is not a training document, but is intended to be instructional and aimed at engineers and technicians who are already familiar with drilling fluid technology. It is particularly intended to meet with Eni-Agip’s operational requirements.

This manual addresses the Company’s fluid operators, drilling engineers and all those involved in the supervision of the work carried out by contractor companies and in the planning or evaluation of the drilling fluids to be employed. However, it does not aim to be a comprehensive all encompassing document giving information on the entire subject, but aims to provide sufficient information to support the company’s technicians in better use of fluid technology.

Therefore, this manual does not instruct on how to prepare or maintain drilling fluids, but only to aid in these tasks by providing the information needed to evaluate the advantages and limitations of the various fluid systems, hence maximising drilling performance, reducing reservoir damage in an environmentally friendly and cost effective manner. This document does not describe the decision making process but summarises it through the use of flow charts and forms, organised in a logical sequence. The reader may select a single form or use the entire sequence in order to determine the best solution to their requirements. The method adopted herein, will be explained in the following ‘Guide to Using the Manual’. This document does not include standard industry calculations or charts relating to volumes and capacities or information relating to drilling fluids which are available in industry handbooks.

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1) Help in the choice of the most applicable drilling fluids necessary to meet with requirements for a well in a targeted area (Refer to section 2) and specifically it’s sub-sections relating to the different types of drilling fluids available. The flowchart below shows the selection process to be followed.

GATHER

INFORMATION AS PER THE FLOW CHART IN SECTION 2.1

IDENTIFY

THE TYPE(S) OF FLUID AS PER THE CHARTS IN SECTION 2.2

VERIFY

THE FEASIBLE CHARACTERISTICS OF THE SYSTEM IN SECTION 2.3

CHECK

THE CHOICE MADE FROM THE DESCRIPTION OF FLUIDS IN SECTIONS

3.1, 3.2, 3.3 and 3.4

DEFINE

THE CHARACTERISTICS OF FLUIDS AS THE PER CHARTS IN SECTIONS 2.6, 2.7

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These are described in sections 3.1, 3.2, 3.3, 3.4 and relate to the description of those drilling fluids which are considered the most applicable and economic for use in various operating conditions. Particular operating conditions may entail modification to these fluid formulations, hence their characteristics, specifically the densities.

• Fluid Maintenance:

This references the most important aspects of the specific fluid systems described and not any procedures relating to general maintenance common to all fluid systems.

• Contaminating Effects to Drilling Fluids:

Other information on contanminants can be found in sections 4.1 ‘Maintenance of Water Based Fluids’ and 4.2 ‘Maintenance of Oil Based Fluids’.

• Analysis of Daily Fluid Reports:

Use the flow charts relating to the fluids described in sections 4.1.1 and 4.1.2 where drilling fluid maintenance problems are identified. These charts follow the general rules in problem solving summarised as follows in the analysis of daily fluid reports.

IS THERE A PROBLEM ?

YES/NO

IF YES, WHAT IS THE PROBLEM ?

ANSWER

WHAT HAS BEEN DONE TO SOLVE IT ?

EVALUATE

WHAT ELSE CAN BE MADE TO SOLVE IT WHICH HAS NOT BEEN MADE YET ?

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fluid systems provides equipment recommend nations, see section 5.

4) Describe problems relating to lost circulation and stuck pipe, section 6. Regarding lost circulation, a troubleshooting guide describes remedial actions for various types of losses, in addition to some information concerning lost control materials. For stuck pipe, recommendations on preventive measures are included and treatment to be undertaken.

5) Provide information about drilling fluid products, section 8.1 ‘Comparable Charts of Competitive Drilling Fluid Product Trademark’ compares similar products and their functional performances and consequently the various products, at different concentrations. This indicates the different product concentrations and costs. Therefore technical and/or economical analysis of these different products should be carried out the concentrations necessary in similar operational conditions and results.

6) Provide analysis procedures in section 10 ‘Drilling Fluid Analysis’ provides analysis procedures which complies with API RP 13B-1 regulations dated June 1, 1990. The procedures with state listed on order to simplify the execution of various analysis showing the results achieved the conversion factors.

1.3 UPDATING, AMENDMENT, CONTROL & DEROGATION

This manual is a ‘live’ controlled document and, as such, it will only be amended and improved by the Corporate Company, in accordance with the development of Eni-Agip Division and Affiliates operational experience. Accordingly, it will be the responsibility of everyone concerned in the use and application of this manual to review the policies and related procedures on an ongoing basis.

Locally dictated derogations from the manual shall be approved solely in writing by the Manager of the local Drilling and Completion Department (D&C Dept.) after the District/Affiliate Manager and the Corporate Drilling & Completion Standards Department in Eni-Agip Division Head Office have been advised in writing.

The Corporate Drilling & Completion Standards Department will consider such approved derogations for future amendments and improvements of the manual, when the updating of the document will be advisable.

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This section is integrated with the following sub sections and covers all the various types of drilling fluids.

The Eni-Agip codes are fully described in Appendix A.

GATHER

INFORMATION AS PER FLOW CHART SECTION

IDENTIFY

THE TYPE(S) OF FLUID AS PER CHARTS AT SECTION

VERIFY

THE FEASIBILITY CHARACTERISTICS OF THE SYSTEM AT SECTION

CHECK

THE CHOICE MADE FROM THE DESCRIPTION OF FLUIDS IN DOCUMENTS

DEFINE

THE CHARACTERISTICS OF FLUIDS AS PER CHARTS

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MAIN IF REQUIRED AND/OR AVAILABLE FLOW LINES: GEOLOGICAL INFORMATION DEPH LITHOLOGY CHEMICAL PROPERTIES PHYSICAL PROPERTIES MINERALOHY GEOGRAPHICAL LOCATION ON/OFF SHORE ENVIROMENTAL PROTECTION DRILLING PROGRAMME GRADIENT DRILL TUBING PROFILES

DEVIATION PROGRAM HYDRAULIC PROGRAM

LENGTH

LEGISLATION

WASTE REMOVAL MODALITES

WASTE REMOVAL COSTS

TYPE OF PLANT LOGISTICS TYPE OF WATER TARGET WELL DATA CHARACTERISTICS REQUIRED PHYSICAL CHAR.

SOLIDS REMOVAL EQUIPMENT MIXING FACILITIES STORING AREAS SUPPLY CHARACTERISTICS REQUIRED PHYSICAL/CHEMICAL CHARACTERISTICS LAB TESTING INTERACTIONS FORMATION/FLUID TYPE(S) OF FLUID

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Systems Agip Code AVA Bariod Dowell MI BH Inteq

Fresh Water

FW-GE-LI+FW

AVA Spud

Mud FW+Gel Pills FW+Gel Pills FW+Gel Pills FW+Gel Pills

Seawater FW-GE+SW SW Spud

Mud SW+H.VIS Pills SW+H.VIS Pills SW+H.VIS

Pills SW+H.VIS_Pills

SW-GG AVAGUM LO-LOSS SM(X) LO-LOSS LO-LOSS

2.2.2 Circulating, Start-Up Drilling Fluids

Fresh Water FW-GE AVAGEL Spud Mud Spud Mud Spud Mud Spud Mud

Seawater SW-GE AVAGEL Prehydrated

Gel Prehydrated Gel Prehydrated Gel Prehydrated Gel

2.2.3 Drilling Formations With Gradients Less Than 1.0kg/cm2/10m

Aerated FW/SW-AT Foam Base FW-SF Mixed AR-MM Air/Foam-Base AR-SF Air-Base AR-AR

2.2.4 Drilling Fluids For Non-Reactive Formations

With Gradient Between 1.03 - 1.5kg/cm2/10m

Bentonite-Base

FW/SW-GE-PO

AVAGEL-POL Gel/Polymer Gel/Polymer Gel/Polymer Gel/Polymer

FW/SW-LS AVAFLUID Q-BROXIN FCL Muds Spersene UNI-CAL

FW-LW AVABEX X-TEND II GELEX

Systems Low-Solid/ BENEX With Gradient > 1.5kg/ cm2/10m Bentonite-Base FW/SW-LS-_CL AVA Fluid/LIG Q-Broxin /CC16 FCL/CL Spersene /XP-20 UNICAL/ LIGCO

FW/SW-TA Desco Desco Desco Desco Desco

With Gradient >1.5 High Temperature (+/- 150-200 oC)

Bentonite-Base FW/SW-CL-RX AVAREX OC16/DUREN FCL/CL/HI-TEMP SPER/XP20/R ESINEX LIGCO/CHEM TRO-X FW/SW-CL-PC +POLICELL ACR

+THERMA-CHECK +POLYTEMP +POLY RX

+PYROTROL

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Systems Agip Code AVA Bariod Dowell MI BH Inteq With Gradient Between 1.03 - 1.5kg/cm2/10m

Encapsulators FW-PK

FW/SW-PA AVAPAC PAC Polymer FLR Polymer

Muds

Polypac Muds MIL-PAC Muds

FW/SW-PC Polivis EZMUD ID-Bond Polyplus New-Drill

Inhibitors

FW/SW-KC AVA-PC POT Chloride K Chloride K Chloride K Chloride

FW/SW-BR

FW/SW-SS AVA-Polysalt Salt Saturated Salt Saturated Salt Saturated Salt Saturated FW/SW-MR AVAKLM KLM KLM KLM KLM FW/SW-GY AVAFLUID/G YPS GYP/Q-BROXIN

Gypsum Mud GYP/SPERSE

NE

Gypsum Mud

FW/SW-LI AVAFLUID

/LIME Lime Muds Lime Muds Lime Muds Lime Muds

Oil-Base DS-IE AVOIL Invermul Interdril Versadril Carbodrill

With Gradient >1.5kg/cm2/10m

Encapsulators FW/SW-PC

POLVIS EZ-Mud ID-Bond Polyplus New-Drill

Inhibitors

FW/SW-KB-PC K/POLIVIS K/EZ-MUD K/ID-Bond K/ Polyplus K/ New-Drill

FW/SW-MR

AVAKLM KLM KLM KLM KLM

FW/SW-SS AVAPOLYSA

LT

Salt Saturated Salt Saturated Salt Saturated Salt Saturated

FW/SW-GY AVAFLUID/G

YS

GYP/Q BROXIN

Gypsum Mud Gyp/Spersene Gypsum Mud

FW/SW-LI AVAFLUID

/LIME

Lime Muds Lime Muds Lime Muds Lime Muds

Oil-Base DS-IE AVOIL Invermul Interdril Versadril Carbotec

With Gradient >1.5 And High Temperature (150-200 oC)

Oil-Base DS-IE AVOIL Invermul Interdril Versadril Carbotec

2.2.6 Drilling Fluids For Temperatures Greater Than 200oC

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Systems Agip Code AVA Baroid Dowell Mi B.H.Inteq Formations With Gradient Between 1.03 - 1.5kg/cm2/10m

Inhibitors FW/SW-K2 AVA-PC2 K Carbonate K Carbonate K Carbonate K Carbonate

FW/SW-KA AVA-PA K Acetate K Acetate K Acetate K Acetate

FW/SW-GL HF 100 Sansoil Biodrill

FW/SW-CT AVA-CAT CAT I M CAT

Oil-Base LT-IE AVOIL-LT Enviromul Interdril Nt Versaclean Carbodril Sea

LT-IE-50 Baroid 50/50 Interdril 50/50 Carb.Sea

50/50

EB-IE Petrofree

OF-IE Novadriill

UT-IE Ultidrill

Formations With Gradient>1.5kg/cm2/10m

Oil-Base LT-IE AVOIL-LT Enviromul Interdrill Nt Versaclean Carbotec Sea

OF-IE Novadrill

UT-IE Ultidrill

Formations With Gradient>1.5 AND HIGH TEMPERATURE (150-200 oC)

Oil-Base LT-IE AVOIL-LT Enviromul Interdrill Nt Versaclean Carbodril Sea

OF-IE Novadrill

UT-IE Ultidrill

Drilling Fluids For Temperature More Than 200 oC

Bentonite-Base

FW/SW-HT-GE

AVAGEL-TERM

Duratherm Pyro-Drill

Polymer-Base FW/SW-HT AVATEX Thermadril Polytemp Envirotherm Pyro-Drill

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AR PO ID E N TI FI CA TI O N CO DE PAG E 14 OF 155 R EVI SI ON ST A P -P -1 -M -6160 0 E R IST IC S OF T H E F L U ID SY ST EM of s o lid s r e m o v a l equi pm ent as i ndi c a ted i n the ‘ D e s c rip ti on of F lui d Sy s tem s ’ pm ent r e c o m m ended i n s e c tion 5. s ea wat e r di ese l fre s h w a te r LT o il al te rnat iv e oi l no n-di s per sed di spe rs e d c u tt ing i n hi bi ti on f o rm at ion i n hi bi L G S to le ra n c e m a in t. d iffe re n c l o gi s ti d if fe renc c onv er ti bl e re -u se t e m per at u re de nsi ty l u br ic ant pr o per s o lid s -re m o v a l e CUTTI NGS MUD AGIP CODE SYSTEM TEMPERATURE T1 T2 T3 T4 = 100 °C MAX = 150 °C MAX = 200 °C MAX = 250 °C MAX DENSITY' Kg/l D1 D2 D3 D4 D5 = 1.2 MAX = 1.5 MAX = 1.8 MAX = 2.1 MAX = 2.4 MAX COST S A M B ENV. = HIGH = MEDIUM = LOW = ENVIRONMENTALLY IMPACT FW SW-GE SW-GG FW SW-GE-PO FW SW-LS FW-LW FW SW-CL FW-PK FW SW-PA FW SW-PC FW SW-KC FW-K2 FW-KA FW SW-SS FW SW-GL FW SW-CT FW SW-MR FW SW-GY BENTONITE GUAR GUM SUSPENSION

BENTONITICO-CMC LIGNOSOLFONATE

LOW SOLIDS WITH BENT.EXTENDER CROMOLIGNIN AGIPAK (KCMC) PAC (DRISPAC) PHPA POTASSIUM CHLORIDE POTASSIUM CARBONATE POTASSIUM ACETATE SALT SATURATED CLYCOL CATIONIC MOR-EX (KLM) GYPSUM X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X (X) (X) (X) A B B B B B B T1 D1 B B B B B B B B B A M T1 D1 B B B B M B B M B A A T1 D1 B B B B B B A B B M B T2 D4 B B B M B B A B B B M T3 D4 B B B M M B B B M B B B B B B B B B B B B B M/B B M/B B B B B B B B B B B B B A A A A A A A A A A A A A A M A M A A A M A A A A A A A A A A A A A A A A A A A A A A A A A A A A M M M M M M M M M B M M M M M B B B B B B B B M T1 T2 T2 T2 T2 T2 T2 T2 T2 T2 D1 D1 D3 D3 D3 D3 D3 D3 D4 D4 D4 M M B A A A M M M B B B B B T3

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ID E N TI FI CA TI O N CO DE PAG E 15 OF 155 R EVI SI ON ST A P -P -1 -M -6160 0 r e m o v a l equi pm ent as i ndi c a ted i n the ‘ D e s c rip ti on of F lui d Sy s tem s ’ ent r e c o m m ended i n s e c tion 5. sea di e sel fre sh w L T oi al te no di sp cutti for m LG S to m a in lo gis con re -u tem de ns lu br sol id C U T MU D CODE TEMPERATURE T1 T2 T3 T4 = 100 °C MAX = 150 °C MAX = 200 °C MAX = 250 °C MAX DENSITY Kg/l D1 D2 D3 D4 D5 = 1.2 MAX = 1.5 MAX = 1.8 MAX = 2.1 MAX = 2.4 MAX CO ST A M B ENV. = HIGH = MEDIUM = LOW = ENVIRONMENTALLY IMPACT FW SW-LI FW SW-HT DS-IE LT-IE LT-IE-50 EB-IE OF-IE UT-IE DS-IE-100 LT-IE-100 . LIME

FOR T. MORE THAN 200 °C DIESEL INVERT EMULSION

LOW TOXICITY OIL I.E. E.I. 50/50 ESTER-BASE I.E. POLYOLEFINE I.E.

ULTRA LT OIL I.E. 100% DIESEL I.E. 100% LT OIL I.E. X X X X X M M B A M B M T2 D4 B B B M A A A M A A A T4 D5 A M M A A A M A B A T4 D5 B A A A A M A M M A T2 D2 A M M A A A A M A A A A A A A A A A A A A B B B A A M M A A A A A A A A A A A M M A A A A A A A A A T2 T3 T4 T4 T2 D3 D4 D5 D4 D5 A A B M M A A A A X X X X X X X B B B A M A A T4 D3 B A B B A A A A A A A A A A X X

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2.4.1 Concomitant Problems

High Deviation (>30o) X X X X X X X X

Very Reactive Formations X X X X X X X X X X X

High Differential Pressure X X X X X X X X

Risk Of Lost Circulation X X X X X X

High Density (>1.9 SG) X X X X X X X

High Temperature (>150 ) X X X X X

Risk Of Hydrated Gas X X X X

Order of preference: 1>2>3. Vertical reading, i.e., high density, high temperature; 1st OBM, 2nd LS.

2.4.2 Type Of Drilling Fluid Preferred

Oil-Base Fluid (DS, LT, EB, PO) 1 1 1 1 2 1 1

Lignosulfonate Fluid 1 2 1 2 2

Polymer-Base Fluids 2 3 2 3 1 3

Inhibitive Fluids 1 1 1 1 2 3 2

Order of preference: 1>2>3. Vertical reading, i.e., high density, high temperature; 1st OBM, 2nd LS.

2.5 CHOICE OF THE FLUID SYSTEM (Dependent On Its Main Variables)

Inhibition System Density Max. (kg/I)

Temperature Max. (oC)

Maintenance

Difficulty Cost

None FW-GE 1.2 100 Low Low

FW-LS 2.2 170 Low Low

Encapsulative FW-CMC 1.2 100 Low Low

FW-PA 1.6+ 150 Medium Medium

FW-PC 1.8+ 150 Medium Medium

Inhibitive FW-PK 1.2 100 Low Low

FW-LI 2.1 130 Medium Low

FW/SW-GY 2.1 170 Medium Low

FW/SW-KC-PC

1.8+ 150 High High

FW-MR 2.1+ 100 High High

DS-IE 2.4 >250 Medium Low/Medium

Note: The systems examined above are only a portion of that available.

Note: The high, medium, or low cost is evaluated with consideration of the inhibition grade. I N C R E A S E

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Characteristics Surface Phases Intermediate Phases Final Phases Main Problems • Hole Cleaning

• Losses

• Gradients

• Reactivity

• Formation Damage

Density Minimum to avoid losses.

More than pore and/or collapse gradients, less than fracture.

As low as possible compatibly with pore and/or collapse gradients, less than fracture gradient.

Plastic Viscosity This value depends upon density and fluid type. Maintain density as low as possible (in both technical and economic terms).

Yield Point Sufficiently high to clean the hole, but not so high to limit solids removal (+/- 10-15gr/100cmq). Same parameters as initial phases (+/-6-10gr/100cmq). Same parameters as initial phases (+/- 3-8gr/100cmq).

Gels Sufficiently high to

suspend cuttings and yield point.

Formulate them to well conditions.

Sufficient to avoid settling without

stressing the formation while tripping.

Sufficient to avoid settling without stressing the formation while tripping.

Api Filtrate HP/HT Filtrate

Particular controls are not generally required (15-20cc/30’), estimate for each case.

Carefully evaluate the formations and fluid density

(average values 4-10 cc/30’).

Commonly low to limit seepage formation and damage.

Cake Suitable to support

unconsolidated formations.

As low as possible. Less damaging as

possible.

Solids% Dependent on the system chosen,

optimise HGS, LGS and MBT. Each system has a different solids tolerance.

Dependent on the system chosen,

optimise HGS, LGS and MBT. Each system has a different solids tolerance.

Use of non damaging weighting agents ( which can be acidfield) or brine is preferred. Maintain LGS values at minimum.

MBT (kg/m3) Dependent on the minimum value and/or system tolerance to the drilling fluid chosen.

pH 8<pH<12+; Value 8 min. helps reduce corrosion. The other values depend

upon the fluid system chosen.

Chemical Characteristics

Dependent on the drilling fluid chosen.

Compatible to the fluids and shales of the reservoir.

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3.1 NON-INHIBITIVE WATER BASED FLUIDS

This section contains descriptions of the various water based drilling fluids, their applications and limitations.

The Eni-Agip codes, abbreviations and symbols used in this section are listed in Appendix A and Appendix B.

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Se a W a te r Di e s el Fr e s h W a te r LT Oi l A lt e rn a tiv e O il Non -di spers e d Di sp e rse d Cu tt in g I nhi b it io n F o rm at io n I n hi bi ti on LGS T o le ra nc e M a in te n . D iffe re n c e L ogi s ti c Di ff e re nc e C onv e rt ibl e Re -use T e m p erat ur e Den s it y L ubri c ant P rope rt ie s S o lids -re m o v a l E q . Cu tt in g s Mu d

BASE FLUID CHARACTERISTICS OF THE SYSTEM ENV.

Co

s

t

BENTONITE BASED FLUID FW-GE

X X B B B B B A B T1 D1 B B B B

- Drilling start-up;

- Viscose pills; A clay base should be provided to more complex polymer-base fluid; - After prehydrating, sea water can be added;

- Specific treatments may adapt characteristics to the needs; - Easily convertible to more complex systems.

BENTONITE (OCMA) CAUSTIC SODA FRESH WATER 40-70 1-2 MIXING TIME: +/- 25 m /hr F u nne l v is c . (s ec /q t) P la s tic vi sc. ( c p s ) De nsi ty ( S G ) Y ie ld po in t (gr /1 00c m ) G e l 1 0 " (gr/ 10 0c m ) Gel 10 '( g r/ 1 00 c m ) API F ilt ra te ( c c/ 3 0 ') A P I HT HP (cc/ 30' ) S o lid s ( % i n v o l. ) O il ( % in v o l. ) W a te r (% i n v o l. ) Sa n d ( % i n v o l) pH Pm Mf Na Cl (gr /l ) Ca ( g r/ l) Pf O/ W r a ti o E le c tr ic al s tabi lit y ( v o lt ) M B T (Kg /m e q u iv. )

CHARACTERISTICS OF THE DRILLING FLUID

1.3 1.15 40 60 6 10 5 10 1 3 6 15 12 20 8.5 320

- Highly sensitve to chemical contaminants; - Low solids tolerance;

- Unadequate characteristics for situations other than drilling start-up.

3 2 2 2 3 30 50 9.5 APPLICATION LIMITATIONS FORMULATION PRODUCTION kg-l/m3

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MAINTENANCE:

- Maintain an adequate solids percentage;

- Use water and bentonite to control viscosity and/or vary pH.

CONTAMINANTS _REMEDIALS Den s it y PV Yie ld Gel s Filt ra te pH Pf / Pm Mf So lid s MBT Ca Na Cl % S and

SAND GROUNDS + + - DESANDERS

SHALES + + + =/-- -- -- =/-- + + _{- CENTRIFUGE} - DILUTION - CONVERT TO FW-LS GYPSUM/ANHYDRITE =/+ =/+ = +/-- + + + =/-- -- + SALT =/+ +/-- + + + + CEMENT +/-- + + + + + -- + CO 2 -- + + -- -- + H S 2 + SO 4 -- DILUTION - Na CARBONATE - CONVERT TO FW-LS - CONVERT TO FW-GY - DILUTION, CMC - CONVERT TO FW -SS - DILUTION - Na BICARBONATE - DEGAS - ALTERNATE TREATMENT WITH NaOH and Ca(OH)2

- PREVENTIVE TREATMENT WITH SCAVENGER. - HYDROGEN PEROXIDE + NaOH. - DEGAS -- + + + + -- -- -- STINKING SMELL

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S e a W a te r Die s e l F res h W a te r LT Oi l A lte rn a ti v e O il N o n-d is per s e d D is pe rs ed C u tt ing Inh ib iti o n F o rm at ion Inhi b iti on LG S T o ll er an c e M a in t. Dif fe re n c e L o g ist ic Dif fe re n c e C o nv er ti bl e Re -u se T e m per atu re De n s it y L ubr ic ant P rop er ti es S o lid s -re mo v a l E q . Cu tt in g s Mu d

Co

st

DESCRIPTION AND APPLICATION

FORMULATION GUAR-GUM SUSPENSION SW-GG X T1 D1 B B B PRODUCT kg-l/m GUAR GUM BACTERICIDE SEA WATER 10 as needed MIXING TIME: +/- 30 m /hr F unn el V is c . ( s ec /qt ) P la s tic V isc. ( c p s ) De n s it y ( S G ) Gel 10" ( g r/ 100 c m ) Ge l 10 '( gr /10 0 cm ) A P I F ilt ra te ( c c /30 ') A P I HT HP ( c c/ 3 0 ') S o lid s (% in vo l. ) O il ( % in vo l. ) Wa te r ( % in vo l. ) S a n d ( % in vo l) pH Pm Mf Na Cl ( g r/ l) Ca ( g r/ l) Pf O/W R a ti o E le c tr ica l S ta b ilit y ( v o lt ) MB T (k g /m eq ui v .)

1.03 100+ 20 30 15 15 NC 7

ADVANTAGES AND LIMITATIONS

3 3 Y iel d P o in t (gr /10 0c m )2 2 ₂ 3 X - Drilling start-up

- Viscose pills in sea water or in presence of electorlytes; - Can be used as Bentonite extender (in low concentrations); - Reduced logistical problems in drlling start-up.

- Fresh water is needed for hydration; - Low cost;

- Low concentration usage; - Fermention;

- Non resistant to high temperatures; - Suitable for viscose pills only.f

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PREPARATION

- Avoid adding NaOH to the system; - Use a bactericideif not used immediately; - For hydrations, stir at high speed for approx. 1hr; - 'Fish eyes' can be easily observed.

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S ea W a te r D ies el F res h W a te r LT Oi l A lt e rn a tive O il N o n -di s per s e d Disp e rs e d C u tt in g Inh ibi ti on F o rm ati on Inhi bi ti on LG S T o le ra nc e M a in t. D iffe rence L ogi s ti c D if feren c e C o n v er ti bl e Re -u se T e m p er a tur e De n s it y L ubri c ant P roper ti es S o lid s-re m o va l E q . C u tti n g s Mu d

Co

st

FORMULATION

BENTONITE-AND CMC-BASE FLUID FW-GE-PO

X X B B B B B A B T1 D1 B B B B PRODUCT kg-l/m BENTONITE CAUSTIC SODA FRESH/SALT WATER 20 - 60 1 - 3 MIXING TIME: +/- 25 m /hr F unnel V is c . (s ec /qt) P la s tic V isc. ( c p s ) De n s it y ( S G ) Y iel d P o in t ( g r/10 0c m ) Gel 10" ( g r/1 00c m ) Ge l 10' (gr /100 c m ) A P I F ilt ra te ( cc/30' ) API H T H P ( c c /3 0 ') S o lid s ( % in vo l. ) O il ( % in vo l. ) W a ter ( % i n vol .) S and (% i n v o l) pH Pm Mf Na Cl ( g r/ l) Ca lciu m ( g r/ l) Pf Ex ce ss L im e ( k g /m 3 ) E le c tr ica l S ta b ilit y ( v o lt ) M B T (k g /m equi v .)

1.03 1.15 40 80 5 15 4 15 2 4 8 15 10 2 8.5 9.5 ADVANTAGES AND LIMITATIONS

3 3 2 2 ₂ 3 X 20 60 CMC HV CMC LV 0 - 6 2 - 10 - Drilling start-up when FW-GE characteristics are not sufficient;

- Drilling non reactive formations with gradient <1.1 kg/cm2.

- Easy maintenance and low cost;

- Highly sensitive to chemical contaminants; - Low solids tolerance.

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SAND GROUNDS CONTAMINANTS REMEDIALS D ens it y PV Yie ld Ge ls F ilt ra te pH Pf / Pm Mf So lid s MB T Ca Na C l % S and + + - DESANDERS SHALES + + + =/-- -- -- =/-- + + - CENTRIFUGE - DILUTION - CONVERT TO FW LS GYPSUM/ANHYDRITE =/+ =/+ = +/-- + + + + + =/-- -- _SO4- - - DILUTION - Na CARBONATE - CONVERT TO FW-LS - CONVERT TO FW-GY SALT - DILUTION, CMC - CONVERTIRE IN FW SS =/+ +/-- + + + + CEMENT - DILUTION - Na BICARBONATE +/-- + + + + + -- + CO2 -- + + -- -- + - DEGAS H S₂ -- + + + + -- -- -- _{STINCKING SMELL} GREEN OR BLACK COLOUR MAINTENANCE:

To control RHEOLOGY: - Increase: Bentonite, CMC HV;

- Decrease: Solids-Removal, Dilution, Lignosulfonates. To control FILTRATE: - CMC LV and/or Bentonite. - PREVENTIVE TREATMENT WITH SCAVENGER. - HYDROGEN PEROXIDE + NaOH - DEGAS

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S ea W a te r D ies el F res h W a te r L T Oi l A lt e rnat iv e O il N o n-di s pers e d D isp e rse d C u tt ing I nhi bi ti on F o rmat ion I nhi bi ti on LG S T o le ranc e M a in t. D ife re n c e Log is ti c D if fe renc e C o nv e rt ibl e Re -u se T e mpe rat ure De n s it y Lub ri c a nt P rop ert ies S o lid s -remov a l E q . C u tti n g s Mud

Co

st

FORMULATION PRODUCT kg-l/m MIXING TIME: F u nnel V is c . (s ec /q t) Pl a s ti c Vi s c . (c p s ) D ens it y ( S G) Y iel d P o in t (g r/ 100c m ) G e l 1 0 " (gr/ 10 0c m ) G e l 1 0 '( gr/ 100c m ) A P I F ilt ra te (c c /3 0 ') A P I H T HP ( cc/ 3 0 ') S o lid s (% in v o l. ) O il ( % i n vo l. ) W a te r ( % i n v o l. ) S a nd ( % i n v o l) pH Pm Mf Na Cl ( g r/ l) Ca ( g r/ l) Pf O/W R a ti o E lec tr ic al S tab ili ty . (v ol t) MB T (k g /m equi v .)

CHARACTERISTICS OF THE DRILLING FLUID ADVANTAGES AND LIMITATIONS

3

2

2 ₂

m /h

LOW-SOLIDS FLUID WITH BENTONITE EXTENDER FW-LW

X XX M B B M B A A T1 D1 B B B B

- Low density and high viscocity with a reduced solids-contents; - Reduced transportation problems;

- Optimum for drilling start-up or when high mixing time is required.

- Sensitive to chemical contaminants; - Sensitive to chlorides;

- Low solids tolerance.

1.03 45 5 8 2 5 15 3 6 9.5 8 MAX 0.1 MAX FRESH WATER BENT. EXTENDER BENTONITE NaOH/KOH (CMC LV) 30 50 2-10 1-1,2 3 _: 0,12

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MAINTENANCE CONTAMINANTS REMEDIAL De n s it y PV Yie ld Gel s F ilt ra te pH Pf / Pm Mf So lid s MB T Ca Na Cl % S a nd SALT, SALT WATER CaSO4 SOLIDS EXCESS POLYMER +/- + + + + + + + + + + + + + = = = = - - - =/-+ - - - - -CONVERT TO SW-PO

SODA ASH + EXTENDER

ADD EXTENDER, DILUTE

ADD. BENTONITE - Prehydrate bentonite before adding extencer;

- Extender should be prehydrated before adding to the active system; - Addition ratio is1 kg of extender every 250 kg of bentonite;

- Control solids as per range indicated;

- Efficiency of shale shakers and cyclones is important; - High quantity of extender is an energic encapsulating agent.

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S ea W a ter Die se l F res h W a ter LT Oi l A lte rnati v e Oi l N on-di s pers e d Disp e rse d C u tti ng In hi bi ti o n F o rmati on Inhi bi ti on LGS T o le ranc e M a in t. T o le ra nce Log is ti c T o le ranc e C onv er ti bl e Re -u se T e m per ature D ens it y Lub ri c ant P rope rti e s S o li ds -r em ov al Eq . C u tti ngs Mud

Co st DESCRIPTION FORMULATION LIGNOSULPHONATE-BASE FLUIDS FW/SW-LS X B B A B B M B T2 D4 B B B M PRODUCT kg-l/m BENTONITE FCL

FRESH (SALT) WATER

20 - 70

MIXING TIME: +/- 20 m /hr + weighting time

F u n nel V is c . (s ec /q t) P la s tic V isc. ( c p s ) D ens it y (S G) Y iel d P o in t ( g r/1 00c m ) Gel 10 " ( g r/10 0c m ) Gel 10 '( gr /100c m ) A P I F ilt ra te ( cc/30' ) A P I HT HP ( cc/ 3 0 ') S o li d s ( % in vo l. ) O il ( % in vo l. ) W a ter ( % i n vol .) S and ( % i n v o l) pH Pm Mf Na Cl ( g r/ l) C a (g r/ l) Pf O/W R a ti o E le c tr ic a l S ta b ilit y ( v o lt ) MB T (k g /m equi v .)

1.1 2.1 38 60 5 45 2 12 1 2 5 15 10 2 9.5 10.5 ADVANTAGES AND LIMITATIONS

- Environmental impact concerns;

- Lignosulphonates are uneffective in salt saturated fluids; - Optimum pH is 10, this value helps shale dispersion;

- Lignosulphonate stabilises the collidal dispersion of shale in water reducing the effectiveness of any encapsulators.

3 3 2 2 ₂ 3 X 20 70 NaOH CMC LV / LIGNIN 1 - 4 2-10 / 10 - 20 X

- Most versatile fluid. Ideal for exploration wells; - High solids-tolerance. Easy maintenance; - High tolerance to chemical contaminants; - Convertible to Lime or Gypsum-based fluids.

10 7 40 60 1 3 0.5 0.7 BARITE as needed 10 - 30

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MAINTENANCE: CONTAMINANTS REMEDIAL De n s it y PV Yie ld Ge ls F ilt ra te pH Pf / Pm Mf So lid s MB T Ca Na Cl % Sa n d

- Dependent on the solids percentage;

- Thanks to the system flexibility characteristics may be adapted according to the needs by simply adding additives;

- For high temperature and/or high density, use lignin as an alternative to CMC to control filtrate.

SHALE GYPSUM/ANHYDRITE SALT CO2 CEMENT + + + + + + + + + + + + + + + + + + + + =/-=/- =/-=/- =/-= -+/- +/= + + +/-=/+ -- -=/+ -= - SOLIDS CONTROL

- TREATMENT WITH FCL+SODA

- FCL + SODA ASH - ADD CMC LV - CONVERT TO FW-GY -FCL + SODA ASH -CMC LV -CONVERT TO SS

- FCL + C.SODA and/or LIME

-PRETR. WITH NaHCO3 - FCL+CMC

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Se a W a te r Die s e l F res h W a te r LT Oi l A lt e rnat iv e Oi l N on-di s p e rs e d Dis p e rse d C u tt ing I nhi bi ti on F o rm at ion I nhi bi ti on LGS T o le ranc e M a in t. D iff er enc e L ogi s ti c D if fer enc e C onv e rt ibl e Re -u s e T e mperat ur e D ens it y Lubri c a n t P roper ti es S o lid s -remov a l E q . C u tti n g s Mud

BASE FLUID CHARACTERISTICS OF THE SYSTEM ENV.

Co

s

t

FORMULATION _PRODUCT kg-l/m MIXING TIME: F unnel V is c . (s ec /q t) P la s ti c V is c . ( c ps ) D ens it y ( S G ) Y iel d P o in t (gr /1 0 0 c m ) Gel 10" (gr/ 100c m ) Gel 10' (gr/ 100c m ) A P I F ilt ra te ( c c /3 0 ') A P I HT HP ( c c/ 3 0 ') S o lid s ( % in vo l. ) O il ( % i n vo l. ) W a te r (% i n v o l. ) S and (% i n v o l) pH Pm Mf Na Cl ( g r/ l) C a (gr/ l) Pf O/ W R a ti o E le c tr ic a l S ta b ilit y ( v o lt ) MB T (k g /m equi v .)

CHARACTERISTICS OF DRILLING FLUIDS ADVANTAGES AND LIMITATIONS

3 3 2 2 ₂ m / h3 (CHROME)-LIGNIN-BASE FLUIDS FW/SW-CL

- Development of Lignosulphonate-based fluids at high temperatures:

To aid filtrate control add chrome Lignin which integrates the thinning effect of Lignosulphonate. X (X) X B B A B B B M B B B M 1.08 2.1 40 60 8 40 5 8 1 1 4 10 10 2 30 10 8 40 9.5 11 1 3 0.3 0.7 0.5 1.5 0.2 MAX 60 10 FRESH WATER BENTONITE FCL CL NaOH POLYMERS (CMC, PAC) BARITE 20 + WEIGHTING TIME 20-70 10-30 10-30 0.5-5 0-10 as needed - Versatile and economical system;

- High solids tolerance;

- Cr-Lignin is a less effective scavenger than lignosulphonate. Its effectivness is further reduced in sea water and becomes completely uneffective in presence of calcium;

- Environmental impact concerns.

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MAINTENANCE CONTAMINANTS REMEDIAL D ens it y PV Yie ld Gel s F ilt ra te pH Pf / P m Mf So lid s MB T Ca Na Cl % S a nd

- High solids tolerance;

- Up to 150°C, deflocculant effect is due to FCL; over this temperature CL is most commonly employed; - Alkalinity control is highly important to guarantee Cr-Lignin solubility;

- Dump if contamination from carbonates or bicarbonates is present.

SHALE + + + + - - - =/- + + - CENTRIFUGE

CEMENT = +/- + + + + + =/+ - + NaHCO3 O Na2CO3

- +FCL + CL + NaOH - DILUTION

- + FCL + CL

CaSO4 = +/- + + + +/- = =/+ + - + Na2SO4 E/0 NaOH

- + FCL + CL - CONVER.IN FW-GY SALT =/+ +/- + + + - - - ₊ - + FCL + CL - CONVER.IN FW-SS - FOR T. >150° C UTILIZZARE DS-IE

= + + + =/- +/- + +/- - + LIME AND/OR C. SODA

CARBONATES/ BICARBONATES

TEMPERATURE + + + + - + FCL + CL

- + DEFLOC. AT HT - RHEOLOGY

- Decrease: add FCL/CL/ Soda, dilute only in case of excess solids;

- Increase: add prehydrated and FCL protected Bentonite carefully. Evaluate the addition of polyacrylates.

- FILTRATE

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S e a W a ter Die se l F res h W a ter LT Oi l A lter nati v e Oi l N o n -di s p er s e d Di sp e rse d C u tti ng Inh ib iti on F o rm ati on Inhi bi ti on LGS T o le ra nc e M a in t. D iffr en c e Logi s ti c D iffer enc e C onv erti bl e Re -u se T e mp eratu re D ens it y Lubr ic a n t P roper ti e s S o lid s-re m o va l Eq . C u tti ngs Mud

Co

st

FORMULATION PRODUCT kg-l/m MIXING TIME: F u n nel V isc. ( s ec/qt) P la s tic V isc. (c p s ) D ens it y (S G) Y iel d P o in t (g r/100 c m ) Gel 10" (gr /100c m ) Gel 10' (g r/10 0c m ) A P I F ilt ra te ( c c /3 0 ') A P I HT HP ( c c /3 0 ') S o lid s ( % in vo l. ) Oi l ( % i n vol .) W a ter ( % i n vol .) Sa n d ( % i n v o l) pH Pm Mf Na Cl ( g r/ l) C a (g r/ l) Pf O/W R a ti o E lec tr ic al S tabi li ty ( v ol t) M B T (kg/m e qui v.) CHARACTERISTICS OF THE DRILLING FLUIDS

3 3 2 2 2 m /h3

P.A.C.- BASE FLUIDS (DRISPAC) FW/SW-PA

X X M B B M A A T2 D4 B M B B

- Encapsulating system, optimum base for inhibitive polymer systems; - High concentrations may limit cutting dispersion;

- Same application as FW-PO, but has a better efficiency at high concentrations of monovalent salts.

- Encapsulating system which needs the addition of an inhibitive salt for inhibition; - High sensitvity to contaminations from polyvalent salts;

- Low solids tolerance.

1.05 45 ₁₀ ₆ ₃ ₁₀ ₈ 6 8.5 20 1.5 60 20 10 5 15 2 16 9.5 20 FRESH/SALT WATER BENTONITE P.A.C.(REGULAR) P.A.C.LV NaOH 25 + WEIGHTING TIME X 0.4 MAX BARITE 20-40 2-5 0-5 1,0-1,5 as needed

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MAINTENANCE CONTAMINANTS REMEDIAL D ens it y PV Yie ld Gel s F ilt ra te pH Pf / P m Mf So lid s MB T Ca Na Cl % S a nd

- Mainly encapsulating, this system needs an adequate concentration of polymer (>3 kg/m3) to limit cutting dispersion and high increase of viscosity;

- Easily convertible to a Potassium-base system, both Polymer-base and dispersed;

- If a density increase above optimum range is desired, convert the system to a more solids-tolerant one.

SHALE + + + + - - - + +

CEMENT = +/- + + + + + + - PRETREAT WITH SODIUM

BICARBONATE - DILUTION

- CONV. TO A MORE INHIBITIVE SYSTEM

CaSO4 = +/- + + + - = =/+ + - ADD. SODA ASH.

- CONV IN FW/SW GY - ADD FCL SALT =/+ +/- + + + - - - + - CONTAMINANT IS DEPENDENT ON OBM - CONV. TO FW/SW-SS - RHEOLOGY

- Decrease: Deflocculate using a short chain polymer (i.e.: short chain CMC LV, PHPA); Dilute; add CL and/or FCL.

- FILTRATE

- Use PAC Regular/LV and/or CMC LV dependent on rheology desired. High salt content fluids can result economical if employed with starches.

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Se a Wa te r D ies el F res h W a ter LT Oi l A lt e rnat iv e Oi l N on-di s p er s e d Dis p e rs e d C u tt ing I n hi bi ti on F o rm at io n I n hi bi ti o n L G S T o le ranc e M a in t. D iffe re n c e Lo g is ti c D iffer e nc e C onv er ti b le Re -u se T e m p er at ur e D ens it y L ubri c a n t P rop ert ie s S o lid s-re m o va l E q . C u tti n g s Mu d

Co

st

FORMULATION _PRODUCT kg-l/m MIXING TIME: F unne l V is c . (s ec /q t) P la s tic V isc. ( c p s ) De n s it y ( S G ) Y iel d P o in t ( g r/1 0 0 c m ) G e l 10 " (gr /100 c m ) G e l 10 '( gr/ 100c m ) A P I F ilt ra te ( cc/3 0 ') A P I HT HP ( cc/ 3 0 ') S o lid s ( % in vo l. ) O il ( % in v o l. ) W a te r (% i n v o l. ) S a nd ( % i n v o l) pH Pm Mf Na Cl ( g r/ l) C a (g r/ l) Pf O/W R a ti o E le c tr ic a l S ta b ilit y ( v o lt ) M B T (kg /m e q u iv.)

3 3 2 2 ₂ m /h3 PHPA-BASE FLUIDS FW/SW-PC X X M B M M M A A T2 D3 B M B B

- Pre-soluble polymers are required to viscosify and encapsulating cuttings; - High solids-tolerance;

- Optimum base for a KCI-base fluid;

1.03 45 10 5 2 15 8 8.5 50 1.8 60 30 15 5 20 2 27 10.5 20 FRESH/SALT WATER BENTONITE PHPA CMC LV (CL) NaOH/KOH 25 + WEIGHTING TIME X 0.4 MAX BARITE 30 5 0-7 (10) 0.1-0.5 as nedeed

- Encapsulating system which needs the addition of an inhibitive salt for inhibition; - High sensitivity to contaminations from polyvalent salts;

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CONTAMINANTS REMEDIAL De n s it y PV Yie ld Ge ls F ilt ra te pH Pf / Pm Mf So lid s MB T Ca Na C l % S and SHALE + + + + +/- - - + + CEMENT = +/- + + + + + + CaSO4 = +/- + + + - = =/+ + SALT =/+ +/- + + + - - - + - ADD PHPA - PRETREAT WITH - ADD. PHPA LMW. -INCREASE INHIBITION NaHCO3 - ADD. Na2CO3 - CONV IN FW/SW GY - ADD FCL - CONTAMINANT IS DEPENDENT ON MBT - CONV. TO FW/SW-SS

- Encapsulating system: An adequate concentration of polymer (3>kg/M3) is needed to limit cutting dispersion and high increase of viscosity;

- Easily convertible to a potassium-base system;

- Polymer may be added wherever but not through the hopper to avoid foam formation; - Can tolerate up to 170°C by using additives.

- RHEOLOGY

- Decrease: Deflocculate using a short chain polymer (i.e.: short chain CMC LV, PHPA); Dilute; If a more energic action is needed, them add CL and/or FCL.

FILTRATE

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•

their applications and limitations.

• Fluid formation herein described, relating to drilling fluids, are the most simple and economical. Particular operating conditions may greatly modify them, so characteristics are reffered to the density indicated.

• Suggestions relating to fluid maintenance only refer to the most important aspect of the system described and do not include those relating to the general maintenance which are common to all systems.

• Containment effects refer to the fluid type. Other information on contamination can be found in section 4.1 ’Water Based Fluid Maintenance’.

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S ea W a te r D ies el F res h W a ter LT Oi l A lt e rn a tive O il N on-D is p ers e d D is p e rse d C u tti ng In hi b it io n Format ion In hi bi ti on LGS T o le ranc e M a in t. D iffe re n c e Logi s ti c D if fe renc e C onv ert ibl e Re -u se T e mper atu re D ens it y Lubr ic ant P rope rt ie s S o lid-remov a l eq. CU T T ING S MU D

BASE FLUID CHARACTERISTICS OF THE FLUID ENV.

CO

S

T

O

FORMULATION PRODUCT Kg-l/m MIXING TIME: F u n n e l vi s c . (s e c /q t) P la s ti c vi s c . ( c p s ) De n s it y ( S G ) Y ie ld poi nt ( g r/ 100c m ) Gel 10" (gr /1 00c m ) Gel 10' (g r/ 100c m ) A P I fi lt ra te ( c c /3 0 ') A P I HT HP ( c c/ 3 0 ') S o lid s ( % i n vo l. ) O il ( % in v o l. ) W a te r ( % i n vo l. ) S and (% i n v o l) pH Pm Mf Na Cl ( g r/ l) Ca ( g r/ l) Pf O/ W r a ti o E lec tr ic al s tabi lit y (v ol t) MB T (K g /m e qui v .)

3

2

2 ₂

m /h3

SALT SATURATED FLUID FW/SW-SS

X X A M B A A B A T2 B M A A

1.2 2.1

15 +WEIGHTING TIME X

- Lower cost and east availability of NaCl;

- Na+ has an inhibition effect only in high concentrations. In low concentrations it helps shale dispersion;

- Salt saturated fluid is a special discarding fluid;

- High salt content will affect the product performance. Dispersants, i.e. FCL, are low-effective. Dilution is required tp maintain the system.

- Conditioned with NaCl, generally saturated;

- Mainly used to drill salt formations. More rarely as an inhibitive fluid in shale formations.; - Viscosified salt solutions are employed as W.O. fluid.

38 80 10 50 4 10 0 2 10 15 5 1 2 38 _8.5 9.5 320 320 10 10 BENTONITE PREIDRATATA SODA CAUSTICA AMIDO SALE

(PAC REG, LOVIS) BARITE 40-60 3-6 10-20 350 (3-6) as needed D4

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CONTAMINANTS REMEDIAL De n s it y PV Yie ld Gel s Fi lt ra te pH Pf / Pm Mf So lid s MB T Ca Cl _{% Sa} n d SHALE + + + + =/- - - + + CEMENT = +/- +/- +/- + + + + Ca++ = +/- +/= +/= +/= -/= + Mg++ = + + + - - - HIGH TEMPERATURES + + + - - + MAINTENANCE RHEOLOGY FILTRATE

- Up to approx. 100 °C Temperature, use starch; For hgiher temperatures, PAC and/or CMC; for temperatures more than 140 °C, estimate the use of oil-based fluid.

- CENTRIFUGE

- PRETREAT WITH - DILUTE

NaHCO3

- USE PRODUCT TOLERANT TO Ca ++

- AVOID DIRECT ADDITION OF ALKALINE AGENTS

- USE PAC

- SUBSTITUTE WITH OBM. - IF DUE TO COMPLEX SALTS pH 8 IS MAX WITH MgO. DO NOT ADD ALKALINE AGENTS IN CIRCULATION.

- Prior to dilution, try to use small concentrations of short chain polymer (i.e. CMC LV), or FCL (prehydrated in fresh water) ;

- Rheology is generally maintained by adding prehydrated protected Bentonite (with a polymer or Lignosulphate) and starch; If needed use a Bio-polymer.

- Traditionally maintained with dilution; - In absence of Mg++ salts, keep Pf>1;

- System maintenance may result more complex in drilling complex salt formations (i.e. zechstein). In this case contact expert technicians.

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Se a W a te r Di es el F res h W a te r LT O il A lt e rn at iv e Oi l Non-Di s p e rs e d Di s pers e d C u tti n g In h ib it io n F o rm at io n Inhi bi ti o n LGS T o le ran c e M a in t. D if fe re n c e Logi s ti c Di ff eren c e Con vert ibl e Re-use Te m p e rat ur e De nsi ty Lubri c an t P rope rt ie s S o li d -r e mo va l e q . CU T T ING S MU D

CO

S

T

O

FORMULATION PRODUCT Kg-l/m MIXING TIME: F u n n e l v isc . ( s e c /q t) P la s ti c v isc . (c p s ) Den s it y (S G ) Y iel d poi n t (gr/ 10 0c m ) Gel 10 " ( g r/ 10 0c m ) Gel 1 0 '( gr/ 1 00c m ) API F il tr a te ( c c /3 0 ') A P I HT HP (c c /3 0 ') S o li d s ( % i n v o l. ) O il ( % i n v o l. ) W a te r (% i n v o l. ) S a n d ( % in v o l) pH Pm Mf NaC l (gr/ l) C a (g r/ l) Pf O/ W r a ti o E lec tr ic al s tabi li ty . ( vol t) M B T (K g /m eq ui v. )

3

2

2 ₂

m /h

AGIPAK (KCMC)-BASE FLUID

FW-PK

X X M B B B M A A T1 D1 B B B B

- A certain inhibition grade is given to the system by replacing the sodium base with the potassium one; - Same applications as FW-PO;

- May be used as a dispersed polymer and potassium-base system.

- Slightly encapsulating and inhibitive system;

- Can only be used in fresh water, as salt water affects the potassium-base effect; - Low-solid tolerance. 1.03 ₄₀ ₅ ₄ 2 8 10 5 8.5 20 1.15 80 15 15 3 15 2 15 9.5 60 FRESH WATER BENTONITE KCMC / AGIPAC HV KCMC / AGIPAK LV KOH 20-60 2-6 2-10 2-4 25 . . _ 3

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CONTAMINANTS REMEDIAL D ens it y PV Yie ld Gel s F ilt ra te pH Pf / Pm Mf _Soli d s MB T Ca Na Cl % S and SHALE + + + + - - - =/- + + CEMENT = +/- + + + + + + CaSO4 = +/- + + + - = =/+ + SALT =/+ +/- + + + - - - + - Dilute

-Pretreat with KHCO3 - Add K+ - Add FCL E/O CL - Add K2CO3 - + KCMC-LV - Convert to FW-GY - Convert to SW-PO - Convert to FW-SS MAINTENANCE - Low-solids tolerance;

- Good operating performance of the solids-removal equipment is needed to limit dilutions; - Easily convertible to a dispersed potassium and polymer base system.

RHEOLOGY

- Decrease: dilution, KCMC-LV has a light deflocculating effect; - Increase: addition of KCMC-HV.

FILTRATE

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Se a W a te r D ies el F res h W a te r LT Oi l A lt e rn a tive O il N on-D is p e rs ed d isp e rse d C u tti n g In hi bi ti o n F o rm ati o n In hi bi ti o n LGS T o le ra nc e M a in t. D iffe re nce Log is ti c D iffe re nce C o nv e rt ibl e Re -U se T e m p era tur e De n s it y Lub ri c a nt P rop ert ie s S o lid -R em ov a l E q . C u tti n g s Mud

Co

st

FORMULATION _PRODUCT kg-l/m MIXING TIME: F u n n e l V isc. (s ec/ q t) P la s tic V isc. (c p s ) D ens it y (S G) Y iel d P o in t (g r/ 1 0 0 c m ) G e l 1 0 " (g r/ 100 c m ) G e l 10 ' (g r/ 1 0 0 c m ) A P I F ilt ra te ( cc/30 ') A P I HT HP ( cc/ 3 0 ') S o li d s ( % in vo l. ) O il ( % in vo l. ) W a te r ( % in vo l. ) S a n d ( % in vo l. ) pH Pm Mf Na Cl ( g r/ l) C a lciu m ( g r/ l) Pf O/ W R a ti o E le c tr ica l S ta b ilit y (v o lt ) M B T (kg/m e qui v.)

3

2

2 2

m /h3

POTASSIUM CHLORIDE- BASE FLUID FW/SW-KC

X X A M B/M A M M A T2 D3 B A B M

- Conditioned with KCI, which is added preferably to polymer and non-dispersed; - Mainly employed in drilling shales like gumbo;

- Drilling formations which, when hydrated have swelling and sloughing tendencies.

1.05 1.8

25 + WEIGHTING TIME

X (X)

- KCl is an available and low-cost salt;

- Inhibitive ion concentrations can be easily adapted to the formation reactivity; - K+concentration should be constantly monitored ;

- High salt concentration may create disposal problems; - K+destabilises high caolinitecontent formations.

THE CHARACTERISTICS ARE THOSE TYPICAL OF THE BASE SYSTEM EMPLOYED.

- The formulations are those typical of the base systems employed. - Product concentrations are traditionally higher.

- A biopolymer is used as a base viscosifier to provide the system with adequate suspending characteristics.

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MAINTENANCE CONTAMINANTS REMEDIAL De n s it y PV Yie ld Ge ls Fi lt ra te pH Pf / P m Mf _So lid s MB T Ca Cl % S a nd Shale + + + + +/- - - + + _ Cement = +/- + + + + + + CaSO4 = +/- +/= +/= +/= -/= + Salt =/+ +/- +/- +/- = - - - +

- Adequate concentration of KCI must be maintained and monitored through laboratory tests, as well as by observing the cuttings over the shale shakers;

- Fluid maintenance is that of the system to which KCI is added;

- System may be optimised by replacing the soda-base products with potassium-base ones; - In sea water higher concentrations of KCI are required.

RHEOLOGY AND FILTRATE - Refer to the base-system used.

NOTE: KCl-BASE SYSTEM, ESPECIALLY IF POLYMERIC, TRADITIONALLY HAS HIGH RATES OF CORROSION.

- Add. K+

- Pretreat with

- Increase concentration (K+)

KHCO3

- Use products tolerant Ca++

- Generally minimum contamination - Increase K+ - Convert to SS

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Se a w a te r Di e s e l F res h w a te r LT o il A lt e rn a tiv e o il N o n-di s p e rs e d D isp e rse d C u tt in g i nhi bi ti on F o rm at io n i n hi bi ti on L G S tol e ra nce M a in t. d iffe re nc e Ll ogi s ti c di ff e re n c e C o n v ert ibl e Re -u s e T e mp er at ur e De n s it y Lub ri c ant pr op ert ies S o lid -r e m o va l e q . CUT T ING MU D

CO

S

T

O

FORMULATION PRODUCT kg-l/m MIXING TIME F u nn e l V is c . ( s e c /q t) Pl a s ti c Vi s c . ( c p s ) De n s it y ( S G ) Y iel d P o in t ( g r/ 1 0 0 c m ) Ge l 10 " (gr /100 c m ) G e l 10 '( gr /1 00 c m ) A P I F ilt ra te ( cc/3 0 ') A P I HT HP ( cc/ 3 0 ') S o lid s ( % i n v o l. ) O il ( % in vo l. ) W a te r (% i n v o l. ) S a n d ( % in vo l) pH Pm Mf Na Cl ( g r/ l) Ca ( g r/ l) Pf Ex ce ss l im e ( k g /m 3 ) E le c tr ica l S ta b ili ty ( v o lt ) M B T (kg /m e q u iv .)

CHARACTERISTICS OF THE DRILLING FLUID ADAVANTAGES AND LIMITATIONS

3

2

2 ₂

m /h3

GYPSUM-BASE FLUIDS FW/SW-GY

X A B A M B B M T3 B B B M

1.1 2.1

20 + WEIGHTING TIME

(X) X D4

- High solids and good cutting inhibition; - Can be weighted up to elevated values; - Can also be used at high temperatures; - Low cost;

- Effectiveness can be enhanced by using KOH or Ca(OH)2 as alkaline agent; - Gelation problems may occur to high solids content fluid at high temperatures.

50 4 6-12 10-20 3-7 as needed 40 60 10 45 3 8 1 1 5 15 8 2 5 35 9.5 10.5 15 0.2 0.5 1.2 0.6 30 70 10 20

- Used for drilling reactive shales and massive formations of CaSO4: - Gypsum is used as a Ca++ source;

- Dispersed, Lignosulphonate base system;

- The system may be more inhibitive if used in fresh water.

FRESH/SALT WATER BENTONITE ALCALINE AGENT FC-LIGNOSOLFONATE GYPSUM CMC-LV/LIGNITE BARITE

(45)

CONTAMINANTS REMEDIAL De n s it y PV Yie ld Ge ls Fi lt ra te pH Pf / Pm Mf So lid s MB T Ca Cl _% S a nd SHALE + + + + =/- - - + + CEMENT = +/- +/- + + +

-- INCREASE CaSO4 EXCESS - DECREASE MBT SALT/SALTED WATER HIGH TEMPERATURE + + + - - MAINTENANCE

- Maintain excess Gypsum ranging from 10 to 20 kg/m3, regulate soluble Ca++ by varying pH from 9 to 10.5. When pH is low, Ca++ is more soluble, and inhibition and maintenance difficulty become higher.

RHEOLOGY

FILTRATE

- CMC LV is an optimum filtrate reducer. The concentration of soluble Ca++ affects the quantity of filtrate reducer needed;

- For elevated temperatures use lignite to control the filtrate.

- Use FCL as a thinning agent. If Ca++ is high, gelation problems may occur, especially with high-solids content and temperatures near the system limit (150 °C).

- DECREASE MBT. - DECREASE EXCESS GYPSUM - ADD LIGNIN +/- +/- +/- + - - =/+ + - ADD. FCL - DECREASE pH WITH NaHCO3 - MODERATE CONTAMINATION - ADD FCL E CMC-LV - CONVERT TO FW-SS

(46)

Se a Wa te r Die se l F res h W a te r LT O il A lt e rn a tiv e O il No n -d isp e rse d Di sp e rse d C u tti ng I n h ib iti o n F o rm at ion I nhi bi ti on LG S T o le ra nc e M a in t. Dif fe re n c e L ogi s ti c D if fe renc e C onv er ti b le Re -u s e T e mpe rat ur e D ens it y L ubri c ant P ro per ti es S o lid s-re m o va l E q . C u tti ng Mud

Co

st

FORMULATION PRODUCT kg-l/m MIXING TIME: F unn el V is c . ( s e c /q t) Pl a s ti c Vi s c . ( c p s ) D ens it y ( S G) Y iel d P o in t ( g r/ 100c m ) G e l 10" ( g r/ 1 00c m ) G e l 10' (g r/ 10 0c m ) API F ilt ra te ( c c /3 0 ') API H T H P ( c c /3 0 ') S o lid s ( % in v o l. ) O il ( % i n vo l. ) W a te r ( % i n v o l. ) S a n d ( % in v o l) pH Pm Mf Na Cl ( g r/ l) C a (g r/ l) Pf Ex c e s s Li me (k g/ m3) E lec tr ic al S ta b ili ty (v ol t) M B T (kg /m e q u iv .)

CHARACTERISTICS OF THE DRILLING FLUIDS ADVANTAGES AND LIMITATIONS

3

2

2 ₂

m /h3

LIME-BASE FLUIDS FW/SW-LI

X M B A M B M M T2 B B B M

1.1 2.15

20 + WEIGHTING TIME

X X D4

- High-solids tolerance and medium cutting inhibition; - Can be weighted up to high values;

- Fairly good resistance to chemical contaminants; - Low cost;

- Reduced calcium inhibitive effect due to the pH dispersing action; - Gelation problems may occur near temperature limit (130 °C).

38 65 8 55 4 10 1 1 3 15 10 2 5 40 12 12.5 8 20 2 5 70 20 5 23

- Used for drilling reactive shale formations, even at high temperatures; - Lime is used as the source of Ca++;

- Dispersed, lignosulphonate-base system;

- Two basic formulations: Low-Lime content and high-Lime content, varying from 5 to 20 kg/m3 of excess Lime respectively.

70-120 3-8 6-12 8-30 20/7 as needed WATER BENTONITE ALCALE FC-LIGNOSOLFONATE LIME STARCH/CMC-LV BARITE 0,1 0,4

(47)

CONTAMINANTS REMEDIAL D ens it y PV Yie ld Gel s F ilt ra te pH Pf / Pm Mf So lid s MB T Ca Cl % S a nd SHALE + + + + =/- = - + + CEMENT = = = = +/= + -/=

- INCREASE EXCESS Ca(OH)2 - REDUCE MBT SALT/SALT WATER HIGH TEMPERATURE + + + - - MAINTENANCE

- Excess lime to be used depends on the formation reactivity;

- The relationship betwen Pm/Pf with Pm>3Pf is vital as it provides exact indication of excess lime.

RHEOLOGY

FILTRATE

- CMC LV is an optimum filtrate reducer. The concentration of soluble Ca++ affects the quantity of filtrate reducer needed;

- For elevated temperatures use lignite to control the filtrate. - Increase: Prehydrated, lignosulphonate protected bentonite;

- Decrease: Maintain excess lime within optimum values, add lignosulphonate, dilute.

+/- +/- +/- + - - =/+ +

GYPSUM = + + + - -/+ +

- MODERATE CONTAM.

- REDUCE MBT. - RED. Pm AND Pf. - ADD. CMC LV AND LIGNIN

- MODERATE CONTAM. - ADD FCL AND STARCH - CONVERT TO FW-SS

- ADD. NaOH - COVERT TO FW-GY

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Se a W a te r D ies el F res h W a te r LT oi l A lt e rn at iv e O il N on-di s per s e d Dis p e rse d C u tt ing I nhi bi ti o n F o rmat ion I nhi bi ti o n LGS T o le ranc e M a in t. D iffe re nc e Logi s ti c D iff er enc e C onv ert ibl e Re -u se T e mper at ure D ens it y Lubri c ant P rope rt ie s S o lid s-re m o va l E q . C u tti ng s Mu d

Co

st

FORMULATION PRODUCT kg-l/m MIXING TIME: F unnel V is c . ( s e c /q t) P la s ti c V isc . ( c p s ) D ens it y (S G ) Y iel d P o in t (gr /1 00c m ) G e l 10" ( g r/ 100c m ) G e l 10' (gr /100c m ) A P I F ilt ra te ( c c /3 0 ') A P I HT HP ( c c/ 3 0 ') S o lid s ( % in v o l. ) O il (% in v o l. ) W a te r (% i n v o l. ) S and (% i n v o l) pH Pm Mf Na C l (g r/ l) Ca ( g r/ l) Pf Ex c e s s Li me (k g/ m3) E le c tr ica l S ta b ilit y ( v o lt ) M B T (kg /m eq u iv .)

3 3 2 2 ₂ m /h3 MOR-REX-BASE FLUID (KLM) FW/SW-MR X X A B A A A B A T1 B A B M 1.1 2.1 15 + WEIGHTING TIME (X) D4

- High solids tolerance and ;ood cutting inhibition; - Can be weighted up to high values;

- Complex system, expert technicians are needed for maintenance; - Several products are needed for its formulation and maintenance, this may create supply problems;

- Gelation problems may occur in high solids content fluids near temperature limit (130 °C). 40 (1-3) 6-12 3 12-17 10-15 40 55 15 50 4 8 1 3 2 15 10 6 5 35 12.5 12.5 15 15 2-3 2-3 2-4 2-4 0.4 0.8 60 MAX 10 15

- Used for drilling reactive shale formations, even at high temperatures;

- Calcium and Potassium are added as KOH and Ca(OH)2, while Morex as a deflocculant and calcium chelant polymer;

- Optimum application is in freshwater fluids with high ROP and density, but not too high temperatures. as needed FRESH/SALT WATER PREHYDRATED BENTONITE (BIOPOLYMER) MOR-REX KOH LIME MOD. STARCHES/LIGNITE BARITE

(49)

CONTAMINANT REMEDIAL De n s it y PV Yie ld Ge ls F ilt ra te pH Pf / Pm Mf So lid s MB T Ca Cl % S and SHALE + + + + =/- - - + + CEMENT = + + + + + + CaSO4 + + + - -/+ + SALT HIGH TEMPERATURE + + + - -

- System with floculation controlled by the balance between two salts and a polymer: Highly important to maintain the balance between Pf, Pm and Morex;

- Always add Lime and Morex simultaneously in a ratio of 4/2 and 3/2 dependent on the characteristics desired and temperature.

RHEOLOGY

- Flocculation control is due to the ratio Lime/Morex. Do not use dispersers;

- Keep MBT below 10%; For high densities and temperatures > 135 °C, do not exceed 4-6%.

FILTRATE

- Use starch as main filtrate reducer up to a temperature of 100 °C, for higher temperatures use starch and lignite in a ratio of 2/1 and 1/1;

- Do not add alkaline agent to starch simultaneously as it may cause an increase of viscosity. Pre-solubilised lignite may be convienvent.

+/- + + + - - + +

- Ca++ AND MOR-REX

- ADD. LIME + MOR-REX - DECREASE MBT + WATER + LIGNITE + - IF Ca++ > 1200 ppm ADD. K2CO3 - CONV. TO FW-GY - DECREASE MBT. - ADD. LIGNITE FOR FILTRATE.

- CONV. TO FW-SS

(50)

(51)

S e a W a ter Die se l F res h W a te r LT Oi l A lt e rn a tive O il No n -d isp e rse d Disp e rs e d C u tti n g In hi b iti on F o rm ati o n In hi bi ti o n LGS T o le ran c e M a in t. D iffe re nce Log is ti c D iffe re n c e C o nv e rti bl e Re -u se T e mpe ratur e De n s it y L u b ri c a n t P rop er ti es S o li d s -r em ov a l E q . C u tti n g s Mu d

Co st FORMULAtion MIXING TIME: F u nne l V is c . ( s e c /qt) P la s ti c V isc. ( c p s ) De n s it y ( S G ) Y iel d P o in t ( g r/ 10 0 c m ) G e l 10 " ( g r/ 10 0c m ) Gel 1 0 '( gr /100 c m ) A P I F ilt ra te ( cc/30 ') A P I HT HP ( cc/ 3 0 ') S o lid s ( % in vo l. ) O il ( % in vo l. ) W a te r ( % i n vol .) S a n d ( % in vo l) pH Po m ( cc H2 S O 4 N/ 1 0 ) Mf Ca Cl2 ( % ) Pf Exce ss L im e ( k g /m 3 ) E le c tr ica l S ta b ilit y ( v o lt ) O/W R a ti o

CHARACTERISTICS OF THE DRILLING FLUID @ 120 °F

2

2 ₂

m /h

DIESEL INVERT EMULSION FLUID DS-IE

A A A M A B M T4 A M A A

1.2

15 + WEIGHTING TIME

X X A D3

40 15 5 2 5 0 10 8 64 28 3 30 70/30 6 600

- Water emulsion in Oil with Oil as the filtrate;

- Used for drilling shales, high temperatures, salt formations, deviated wells, water-damaging reservoir, completion fluid;

- High density drilling fluids used when fluid recovery and re-use is advantageous.

- The emulsion has a nonionic continuous phase and does not interact with shale layers and the most common chemical contaminants;

- Due to high environmental restrictions, the zero charge is needed;

- Compared to other drilling fluids or zero discharge areas, it has the advantage of a low dilution ratio and the possibility to be re-used;

- Lost circulation control, and Gas kick detection and maintenance may create some problems.

2.2 60 42 8 1.5 6 0 3 40 54 6 8 30 90/10 13 2000 PRODUCT kg-l/m 3 3 DIESEL EMULSIFIER/S LIME

FILTRATE REDUCER (IF REQUIRED) BRINE (20-30% CaCl2)

VISCOSIFIER

WETTING AGENT (IF REQUIRED) BARITE

FORMULATIONS AND QUANTITIES DEPEND ON DENSITY, OIL/WATER RATIO AND SERVICE COMPANY'S FORMULATIONS.

FOLLOW THE INSTRUCTION IN THE SPECIFIC MANUAL.

(52)

REMEDIALS D ens it y PV Yie ld Gel s F . HP HT PO M 0/ W EL . ST AB . Ca Cl2 Wa te r W e tti n g A s pec t C u tt in gs SOLIDS + + + ++ =/- = (?) (PLASTIC) WATER -/+ + + + + - - - - (+) (PLAST.) - ADD.WETTING AGENT - DILUTE

- IF O/W OK, + EMULSION. IF O/W K.O., + OLIO X OK MAINTENANCE

- An Oil-base fluid is traditionally easy to maintain. Pay attention to record dilutions and product quantities required in order to keep correct concentrations;

- To avoid problems, constantly monitor any modifications of the characteristics, especially the electrical stability and HPHT filtrate. If any modifications, determine the possible causes and take prompt remedial actions.

RHEOLOGY

- Should be determined at a temperature of 120 or 150oF. Do not use marsh viscosity for maintenance;

- Water is the principle viscosifier of Oil-base fluids. Its percent will vary depending on the characteristics required. Other viscosifiers enhance yield point and Gels. Viscosity is also given by solids, thus it is essential to decrease the water content in the fluid by increasing density.

FILTRATE

-The main filtrate reducer is given by the quality of emulsion. Other filtrate reducers may be needed for high temperatures or for very low HPHT filtrate values.

CONTAMINANTS

CaCl2 > 35% +/- +/- + - =/+ (PLAST.) - LIGHT CONTAM.