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A kind of low-density water-based drilling fluid for drilling shale

A water-based drilling fluid and low-density technology, which is applied in the direction of drilling compositions, chemical instruments and methods, can solve problems such as well wall instability, and achieve the effects of less environmental pollution, less rheology, and low cost

Active Publication Date: 2017-09-05
SOUTHWEST PETROLEUM UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0004] The purpose of the present invention is: in order to overcome the problem of wellbore instability when using water-based drilling fluid to drill into shale formations, to suppress the hydration and collapse of shale formations, and to effectively plug the micro-nano pores and fractures of shale formations. Low-density water-based drilling fluid for drilling shale

Method used

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  • A kind of low-density water-based drilling fluid for drilling shale
  • A kind of low-density water-based drilling fluid for drilling shale
  • A kind of low-density water-based drilling fluid for drilling shale

Examples

Experimental program
Comparison scheme
Effect test

example 1

[0014] Example 1: A preparation method for drilling shale with low-density water-based drilling fluid.

[0015] First measure 1000 grams of tap water and raise the water temperature to 70°C, add 30 grams of bentonite for drilling fluid under electric stirring at a low speed of 500r / min, stir for 10 minutes and add 1.5 grams of Na 2 CO 3 Stir for another 30 minutes, after prehydration at normal temperature and pressure for 24 hours, add 15 grams of SZT under high-speed 8000r / min electric stirring and stir for 6 minutes, then add 2 grams of zwitterionic polymer coating agent FA367 under low-speed 500r / min electric stirring and stir Add 10 grams of fluid loss reducer CG810S-T and stir for 5 minutes, add 0.2 grams of drilling fluid rheology regulator JHRM and stir for 5 minutes, add 40 grams of high-gloss calcium carbonate C-L501 and stir for 15 minutes, add 10 grams of lubricant R-16 and stir for 5 minutes , add 40 grams of drilling fluid with solid polymeric alcohol JHGC and st...

example 2

[0016] Example 2: The rolling recovery rate of the drilling fluid system of the present invention was measured by using an XGRL-2 type roller heating furnace.

[0017] Table 2 Experimental results of rolling recovery rate of this low-density water-based drilling fluid system

[0018] Drilling Fluid Formula Experimental conditions Recovery mass (g) Recovery rate(%) Clear water + 50g red bed soil 105℃ / 16h 5.64 11.28 Low-density water-based drilling fluid system + 50g red bed soil 105℃ / 16h 47.67 95.34

[0019] Note: 1) The red layer soil is Sichuan red layer soil debris, and the shale outcrop is Chang 7 shale outcrop, all of which are 6-10 mesh, and the recovery rate is over 40 mesh; 2) The results in the table are all 2 times The mean of the experimental data.

[0020] Table 3 Experimental results of linear expansion of this low-density water-based drilling fluid system

[0021]

[0022] Note: 1) The core is formed by pressing bentonite (m...

example 3

[0024] Example 3: The thermal stability effect of the shale water-based drilling fluid was tested by using the XGRL-2 type roller heating furnace for continuous hot rolling.

[0025] Table 4 Thermal stability evaluation of the low-density shale water-based drilling fluid system

[0026]

[0027] Table 5 Evaluation of the temperature resistance of the low-density shale water-based drilling fluid system

[0028]

[0029] From the thermal stability results in Table 4, it can be seen that the viscosity, shear and fluid loss of the system change little with the increase of rolling time, and the system has good thermal stability. From the temperature resistance test in Table 5, it can be seen that the viscosity of the low-density water-based drilling fluid is greatly reduced at 150°C, and the water loss of HTHP is greatly increased. Water, can resist temperature 120 ℃.

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Abstract

The invention relates to low density water-based drilling fluid for drilling into shale. The fluid overcomes the problem of wellbore instability when the water-based drilling fluid is used. The drilling fluid adopts the technical scheme that the drilling fluid comprises the following raw materials: 30-50g bentonite for the drilling fluid, 1.5-2.5g sodium carbonate, 5-10g sodium hydroxide, 15-20g shear strength improving agent SZT, 2-5g zwitterionic polymer coating agent FA367, 10-15g fluid loss agent CG810S-T, 0.2-1g drilling fluid rheological regulator JHRM, 40-60g highlight calcium carbonate C-L501, 10-30g lubricant R-16, 25-35g emulsified paraffin, 40-60g solid polymerization alcohol JHGC for the drilling fluid and 1000g tap water. The tap water, the bentonite for the drilling fluid and soda are added for prehydration for 24h first, the shear strength improving agent SZT is added under the mixing condition at 8000r / min, then the treatment agents are sequentially added under the mixing condition at 500r / min, pH (potential of hydrogen) of a system is regulated to 8.5, and barite is added finally. The drilling fluid system has good rejection capability and blocking performance and is used for drilling of a long horizontal section of a shale bed.

Description

technical field [0001] The invention relates to a low-density water-based drilling fluid for drilling shale, which is especially suitable for drilling long horizontal well sections of shale with developed micro-fractures. Background technique [0002] At present, oil-based drilling fluids are commonly used in shale gas wells at home and abroad. Because oil-based drilling fluids can increase the capillary pressure of water-wet shale and prevent drilling fluids from invading shale, oil-based drilling fluids and synthetic-based drilling fluids can be used. Effectively solve the problem of well wall instability. In dealing with the wellbore stability of shale gas horizontal wells, the use of oil-based drilling fluid system is currently the most effective measure abroad. But even if oil-based drilling fluid is used, for shale formations with developed fractures or beddings, it is necessary to strengthen the plugging to reduce the pressure transmission caused by the liquid enteri...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): C09K8/24
CPCC09K8/24C09K8/426C09K2208/34
Inventor 白杨王平全王波杜敬国时海涛余冰洋
Owner SOUTHWEST PETROLEUM UNIV
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