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Water-based drilling fluid system for deepwater operation and preparation method thereof

A water-based drilling fluid and water-based fluid technology, applied in the direction of chemical instruments and methods, drilling compositions, etc., can solve the problems of poor thermal stability, unfavorable pressure control, increased viscosity, etc., and achieve excellent rheology and enhanced inhibition Good rheological effect

Active Publication Date: 2012-06-20
CHINA NAT OFFSHORE OIL CORP +1
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0003] (1) The system contains a small amount of bentonite, which increases the solid content of the system, which is not conducive to the realization of low solid phase control and reservoir protection
[0004] (2) The system uses large molecular weight partially hydrolyzed polyacrylamide and KCl as shale inhibitors to inhibit the hydration and dispersion of shale through synergistic effect, but the inhibitory performance is still insufficient when drilling into shale formations; On the one hand, polyacrylamide with large molecular weight is easy to increase the viscosity of the system, and the phenomenon of paste sieving is easy to occur at low temperature;
[0005] (3) The thermal stability of the system is poor, the filtration loss of HTHP is large, and the mud cake is thick and loose;
[0006] (4) The rheology of the system is greatly affected by temperature, especially the dynamic shear force YP at low temperature changes significantly, and pressure control is not used

Method used

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  • Water-based drilling fluid system for deepwater operation and preparation method thereof
  • Water-based drilling fluid system for deepwater operation and preparation method thereof
  • Water-based drilling fluid system for deepwater operation and preparation method thereof

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0038] Use barite as a weighting agent, and the configuration density is 1.2g / cm 3 Seawater-based deepwater water-based drilling fluid: Measure 400ml of seawater with a measuring cylinder and place it in the slurry cup, add 0.8g of anhydrous sodium carbonate, 60g of NaCl, and 12g of inhibitors (purchased from CNOOC PF-HAB), 2g cationic polyacrylamide with a weight-average molecular weight of 600,000 (purchased from COSL PF-LV60), 2g low-viscosity polyanionic cellulose, 8g modified starch, 12g polymeric alcohol lubricant, 0.8g Xanthan gum, 12g oily lubricant, 12g KCl, stir at high speed for 20min, add 35g barite, stir at high speed for 40min.

Embodiment 2

[0040] Limestone is used as a weighting agent, and the configuration density is 1.15g / cm 3 Seawater-based deepwater water-based drilling fluid: Measure 400ml of seawater with a measuring cylinder and place it in the slurry cup, add 0.8g of anhydrous sodium carbonate, 60g of NaCl, and 12g of inhibitors (purchased from CNOOC PF-HAB), 2g cationic polyacrylamide with a weight-average molecular weight of 600,000 (purchased from COSL PF-LV60), 2g low-viscosity polyanionic cellulose, 8g modified starch, 12g oily lubricant, 0.8g xanthan Glue, 12g oily lubricant, 12g KCl, stir at high speed for 20min, add 25g of limestone, stir at high speed for 40min.

Embodiment 3

[0041] Embodiment 3 (field configuration)

[0042] The preparation density is 1.12g / cm 350 cubic meters of seawater-based deepwater water-based drilling fluid: pour 40 cubic meters of seawater into the mud tank, add 0.1 tons of anhydrous sodium carbonate, 7.5 tons of sodium chloride, and 1.5 tons of inhibitors through the mixing pump (purchase COSL PF-HAB) , 0.25 tons of cationic polyacrylamide with a weight average molecular weight of 600,000 (purchased from COSL PF-LV60), 0.25 tons of low-viscosity polyanionic cellulose (purchased from COSL PF-PAC-LV), 1 ton of modified starch ( Purchased from COSL PF-FLOCAT), 1.5 tons of oil-based lubricant (purchased from COSL PF-LUBE), circulated with a mixing pump for 20 minutes, and then added 0.1 tons of xanthan gum (purchased from COSL PF-XC-H) Then change the shear pump to shear for 1 hour. Finally, add seawater to a volume of 50 cubic meters and keep stirring.

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Abstract

The invention relates to a water-based drilling fluid system for deepwater operation, which is prepared from (by weight): 100 parts of water-based fluids, 3-4 parts of inhibitors, 0.4-0.8 parts of low molecular-weight coating inhibitors, 2.5-5.5 parts of filtrate loss reducer, 0.2-0.3 parts of alkalinity regulators, 10-20 parts of NaCl, 2-3 parts of lubricants, 0.2-0.4 parts of flow regulators, 3-5 parts of KCl and 5-80 parts of weighting agent. The invention further relates to a preparation method for the water-based drilling fluid system for deepwater operation.

Description

technical field [0001] The invention relates to a water-based drilling fluid system and a preparation method thereof, and in particular to a water-based drilling fluid system for deepwater operations and a preparation method thereof. Background technique [0002] Compared with land and shallow sea drilling, drilling fluids in deepwater oceans face technical challenges such as low temperature and high pressure, large amount of drilling fluid, gas hydrates, and narrow safe density window. In the past, water-based drilling fluids used in deepwater operations still have the following deficiencies: [0003] (1) The system contains a small amount of bentonite, which increases the solid content of the system, which is not conducive to the realization of low solid phase control and reservoir protection. [0004] (2) The system uses large molecular weight partially hydrolyzed polyacrylamide and KCl as shale inhibitors to inhibit the hydration and dispersion of shale through synergis...

Claims

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Application Information

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IPC IPC(8): C09K8/12
Inventor 李怀科田荣剑罗健生李自立耿铁苗海龙王楠
Owner CHINA NAT OFFSHORE OIL CORP
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