1. Eastern Hemisphere Technology Center Novel Water-Based Systems Development and Field Application of a 3rd Generation Silicate Drilling Fluid Steve Young, Sandy Milne and Jan Erik Hanssen M-I Drilling Fluids International Technology Center Eastern Hemisphere

2. Technology Center SILICATES Available in Liquid Form: Water Glass Viscosity dependant on Solids content Na, K, or mixed silicates available K > mixed > Na, inhibition without salt K > mixed > Na, costs Solids content determined by SiO 2 : M 2 O ratio pH determined by type and SiO 2 : M 2 O ratio

3. Eastern Hemisphere Technology Center Silicate: Structures Some silicate species in Na-silicate solutions.

4. Eastern Hemisphere Technology Center Silicate Drilling Fluids Silicates gel with reducing pH Silicates precipitate with divalent cations Silicates bridge shales by FW/pH-induced gelation/precipitation near the borehole wall, reducing pressure communication in shale. Silicate fluids made from commodity materials, typically 40-50% active. Good engineering key to successful use.

5. Eastern Hemisphere Technology Center Typical Lab Formulation and Properties – AncoSil PRODUCTCONCENTRATION Freshwater0.842m3/m3 Sodium Silicate30ltr/m3 KCl30kg/m3 Starch12kg/m3 Xanthan Gum3kg/m3 Barite504kg/m3 Density1.4SG PV13cps YP11.5Pa 3 rpm6cps API FL5.6mls pH11.2

6. Eastern Hemisphere Technology Center Linear Swelling Tests London Clay 0 1 2 3 4 KCl/PHPA KCl/POL./ GLYCOL NaCl OBM REACT. SILICATE % Shale Deformation

7. Eastern Hemisphere Technology Center North Sea Shales vs. Foss- Eikeland clay

8. Eastern Hemisphere Technology Center Shale Dispersion (API RP 13i) Hot rolling 350 ml mud with 100 g clay at 70 ° C 8.9 8.4 98.3 0 10 20 30 40 50 60 70 80 90 100 KLA-CUREANCO 4000SILICATE % RECOVERY Hot rolling 350 ml mud with 100 g clay at 70 °C Foss-Eikeland clay

9. Eastern Hemisphere Technology Center Dispersion test: Effect on rheology 0 2 4 6 8 10 12 14 16 18 PV, BHRPV, AHRYP, BHRYP, AHR KLA-CURE ANCO 4000 SILICATE Foss-Eikeland clay

10. Eastern Hemisphere Technology Center Shale recovery tests: Effect of Silicate Concentration Foss-Eikeland clay SiO 2 : Na 2 O = 2.8

11. Eastern Hemisphere Technology Center Shale recovery tests: Effect of Salt Type & Concentration Foss-Eikeland clay SiO 2 : Na 2 O = 2.8

12. Eastern Hemisphere Technology Center Recovery of dispersive clay as a function of SiO 2 : M 2 O Recovery (%) 0 10 20 30 40 50 60 70 80 90 100 3,42,82,52,061,65 SiO 2 :Na 2 O 0 10 20 30 40 50 60 70 80 90 100 3,02,52,01,8 SiO 2 :(Na/K) 2 O Recovery (%) 0 10 20 30 40 50 60 70 80 90 100 3,93,32,92,2 SiO 2 :K 2 O Recovery (%)

13. Eastern Hemisphere Technology Center Silicate System pH Effect of Silicate Concentration and SiO 2 : Na 2 O Ratio 10 11 12 13 0,010,1110 % Na Silicate Solids pH 2.0 : 1 2.6 : 1 3.3 : 1 SiO 2 : Na 2 O

14. Eastern Hemisphere Technology Center Solids Tolerance: 3% KCl – NaSilicate Solids Tolerance: 3% KCl – NaSilicate 2.0:1 0 100 200 300 YP (Pa) - OCMA PV - OCMA YP (Pa) - Wyoming PV - Wyoming 0 5 10 15 20 25 30 35 Kg/m3 Clay added

15. Eastern Hemisphere Technology Center Solids Tolerance: 3% KCl – NaSilicate Solids Tolerance: 3% KCl – NaSilicate 2.8:1 0 100 200 300 YP (Pa) - OCMA PV - OCMA YP (Pa) - Wyoming PV - Wyoming 0 5 10 15 20 25 30 35 40 Kg/m3 Clay added

16. Eastern Hemisphere Technology Center Fluid Loss – AncoSil Common FL Additives PAC LV1 Pac LV2 PAC LV2 Pot Starch Corn starch HP Starch Hp Starch PAC/Starch Before Aging After HR at 95 °C 0 2 4 6 8 10 12 14 16 API Fluid Loss (ml) at 14 kg/m 3 Note: API/HPHT FL less relevant for silicate

17. Eastern Hemisphere Technology Center Metal/Metal Lubricity 13 ppg Fluids KCl/Glycol Mod Glycol Silicate Oil Mud 0 0,1 0,2 0,3 0,4 Coefficient of friction KCl/Glycol Mod Glycol Silicate Oil Mud 250# 500#

18. Eastern Hemisphere Technology Center Summary - Laboratory Experience Excellent Shale Inhibition Solids Tolerance Compromise Viscosifier – Xanthan Gum optimal Fluid Loss – best with Starch/PAC Seawater – best treated with excess Silicate Lubricity – searching for efficient lubricant

19. Eastern Hemisphere Technology Center System Optimization Salts improve stability Optimum inhibition at 5% silicate alone Optimum inhibition at 4% silicate with KCl Lower SiO 2 :M 2 O – Better solids tolerance – Higher pH (11.5 – 12.5)

20. Eastern Hemisphere Technology Center Typical Field Mud Formulation Freshwater KCl20 ppb NaSilicate (­ 2.7)8% Volume (4% Silicate) Caustic Soda0.25 ppb Starch3 ppb PAC LV1 ppb Xanthan Gum1.5 ppb BariteAs Required

21. Eastern Hemisphere Technology Center AncoSil Field Experience 8 wells drilled – North Sea 26”, 24”, 17 1/2”, 16” Hole Reactive Clays, Sandstone, Limestone High levels of Wellbore Stability Control over reactive shale and dispersive chalk Low costs/low dilutions Seawater and FL polymers deplete silicate Silicate depletion through young shales Optimum 5 - 7% silicate – lower can give problems

22. Eastern Hemisphere Technology Center Cost comparison 100 % 87 % 75 % 0 % 10 % 20 % 30 % 40 % 50 % 60 % 70 % 80 % 90 % 100 % KLA-CUREANCO 4000SILICATE

23. Eastern Hemisphere Technology Center Typical Cost Breakdown

24. Eastern Hemisphere Technology Center Ongoing Development Better Lubricity Better with Extremely Dispersive Clays Storage (1-3 months; preservatives?) K-Silicates, Blends Molar Ratio Re-Optimization Lubricant Polyglycol (won’t hydrolyse) Alternate Viscosifier, FL-controller New Applications Seepage/Leaky Formations; CWD Reservoir Drilling ???

25. Eastern Hemisphere Technology Center Shale inhibition Swelling clays High levels of Na-montmorillonite e.g., Wyoming bentonite Silicate optimal stabiliser Dispersive chalks Highly dispersive clays High levels of Ca-montmorillonite e.g., Shetland group, Foss-Eikeland Silicates precipitated by Ca, Mg…

26. Eastern Hemisphere Technology Center Summary Statoil/Anchor Lubricity project Systematic product screening More than 60 candidate lubricants All major suppliers (and many minor…) Four drilling fluids KCl/Polymer, KCl/Polymer/Glycol LAO-base, Ester-base Comparative testing OFI tester vs. LEM Lab vs. Field data

27. Eastern Hemisphere Technology Center Presentation of results Comparison scans Performance (friction change) relative to current (Anchor) product line, or to unlubricated mud, or... All data for each mud at one glance; flexible. Method comparison Evaluation of lubricity test methods LEM vs. OFI vs. (a few) field data Application Where is the improvement need and potential?

28. Eastern Hemisphere Technology Center Main findings Performance scans WBM’s: most “recommended” candidate lubricants give poorer lubricity results than currently marketed products Olefin: Few tested products give much improvement on product line while remaining environmentally acceptable Ester: Small improvements possible… and required? Method comparison LEM tester not completely validated... No commonly used lab tests are representative Field data suggest OFI test usable in (rough) screening