Water-based drilling fluid for stabilizing shale gas stratum borehole wall and application thereof

A technology of water-based drilling fluid and waterproofing agent, which is applied in wellbore/well components, earthwork drilling, flushing wellbore, etc. It can solve the problems of shale gas safety, efficient development, poor environmental acceptability, and wellbore collapse, etc. problems, to achieve the effects of maintaining wellbore stability, inhibiting shale hydration, and slowing down the reduction of compressive strength

Inactive Publication Date: 2018-09-14
CHINA UNIV OF PETROLEUM (EAST CHINA)
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0004] At home and abroad, the industrial development of shale gas has been realized on the basis of medium and long-section horizontal wells. Strong plugging and strong inhibition oil-based drilling fluid can basically meet the needs of shale gas drilling, but the environmental acceptability is poor and the cost is high. Water-based drilling fluid replacing oil-based drilling fluid is the future development trend
Wellbore collapse is very serious during the drilling of long horizontal shale gas wells with water-based drilling fluids, which has become a technical bottleneck restricting the safe and efficient development of shale gas

Method used

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  • Water-based drilling fluid for stabilizing shale gas stratum borehole wall and application thereof
  • Water-based drilling fluid for stabilizing shale gas stratum borehole wall and application thereof
  • Water-based drilling fluid for stabilizing shale gas stratum borehole wall and application thereof

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Embodiment

[0042] The present invention will be described in detail through examples below, but the present invention is not limited thereby. In the following preparation examples, examples and comparative examples, unless otherwise specified, the materials used are all commercially available, and the methods used are all conventional methods in the art.

[0043] The structural formula of waterproofing agent is C 8 f 17 SO 2 NHCH 2 CH 2 CH 2 Si(OCH 2 CH 3 ) 3 , purchased from Chengdu Chunfeng Petroleum Technology Co., Ltd.;

[0044] The surface hydration inhibitor is a mixture containing sorbitan laurate and polyoxyethylene sorbitan stearate, which is purchased from Chengdu Chunfeng Petroleum Technology Co., Ltd.;

[0045] Polymerized alcohol and sulfonated lignite resin were provided by the Engineering Technology Research Institute of China Petroleum Corporation.

[0046] The nano-membrane structure plugging agent was prepared according to the following preparation examples 1-...

preparation example 1

[0054] 1. Preparation of organic montmorillonite

[0055] Put 5g of sodium montmorillonite, 3g of cetyltrimethylammonium chloride and 100ml of distilled water in a 250ml flask, stir at 120rpm in a water bath at 80°C for 4h, let stand overnight, remove the upper solution, filter, and wash with deionized water to no Cl - (with a concentration of 0.01mol / L AgNO 3 solution test), dried in a vacuum oven at 70°C, and crushed through a 300-mesh sieve to obtain organic montmorillonite (O-MMT).

[0056] 2. Preparation of nano-membrane structure plugging agent

[0057] (1) In a three-necked flask equipped with a thermometer and a mechanical stirrer, add styrene, benzyl dithiobenzoate and azobisisobutyronitrile at a molar ratio of 400:1:0.4, and add styrene 5% by weight of organic montmorillonite, after sealing the reaction device, the air in the system was removed by freezing and vacuuming, filled with nitrogen, and circulated for 3 times, fully stirred under the protection of nitrog...

preparation example 2

[0060] Prepare organic montmorillonite according to the method of preparation example 1, and the preparation method of nano-membrane structure sealing agent is as follows:

[0061] (1) In a three-necked flask equipped with a thermometer and a mechanical stirrer, add p-methylstyrene, cumyl dithiobenzoate and azobisisoheptanonitrile at a molar ratio of 200:1:0.3, And add organic montmorillonite accounting for 3% by weight of p-methylstyrene, seal the reaction device, remove the air in the system by freezing and evacuating, fill with nitrogen, cycle 3 times, fully stir under the protection of nitrogen, and heat at 130 ° C The reaction was carried out in an oil bath. After reacting for 2.5 hours, the reaction system was cooled with an ice-water bath, and the product was precipitated in methanol, filtered, and then dried in vacuum at 70° C. to obtain poly-p-methylstyrene / montmorillonite nanocomposite macromolecular chain transfer agent.

[0062] (2) In the there-necked flask equip...

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Abstract

Relating to the technical field of shale gas drilling, the invention discloses a water-based drilling fluid for stabilizing a shale gas stratum borehole wall and application thereof. The water-based drilling fluid comprises a nanofilm structure plugging agent, a waterproofing agent, a surface hydration inhibitor, polymeric alcohol, bentonite, polyanionic cellulose, a sulfonated lignite resin and water, wherein the waterproofing agent is N-perfluoroalkyl sulfonyl propyl triethoxysilane, and the nanofilm structure plugging agent includes a montmorillonite sheet, a structural unit shown as formula (1) and a structural unit shown as formula (2). The water-based drilling fluid provided by the invention shows good performance of inhibition, rheology and retarding of the shale compressive strength reduction when applied to stabilization of the shale gas stratum borehole wall.

Description

technical field [0001] The invention relates to the technical field of shale gas drilling, in particular to a water-based drilling fluid for stabilizing the well wall of a shale gas formation and its application. Background technique [0002] my country's shale gas geological resource reserves are 80×10 12 m 3 , the reserves of technically recoverable resources are (10~25)×10 12 m 3 , has a good prospect for exploration and development. Once the large-scale exploration and development is successful, it can effectively alleviate the contradiction between oil and gas supply and demand in my country. Therefore, shale gas exploration and development has become a major national strategy. [0003] The main difficulty in shale gas drilling lies in the problems of wellbore collapse, leakage, underpressure and pipe sticking caused by the strong water sensitivity of shale, the development of micro-fractures and fractures, long soaking time and large well inclination angle. The wel...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C09K8/035C09K8/24C09K8/22C09K8/508E21B21/00
CPCC09K8/035C09K8/22C09K8/24C09K8/5083C09K8/5086C09K8/514C09K2208/12E21B21/00
Inventor 刘敬平孙金声吕开河黄贤斌
Owner CHINA UNIV OF PETROLEUM (EAST CHINA)
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