Oil-based drilling fluid suitable for high-water-sensitivity collapsible stratum as well as preparation method and application of oil-based drilling fluid

An oil-based drilling fluid, Minyi technology, applied in the direction of chemical instruments and methods, drilling compositions, etc., can solve problems such as rheological thickening, shale strength reduction, pore pressure increase, etc., and achieve strong electrical stability performance, inhibit hydration expansion, and reduce the effect of high temperature and high pressure filtration loss

Active Publication Date: 2022-05-03
CHINA PETROLEUM & CHEM CORP +2
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

But there are still some deficiencies. When drilling in shale formations with strong water sensitivity and easy collapse, the drilling fluid must have very good plugging ability, while the conventional plugging agent (calcium carbonate) used in conventional oil-based drilling fluids, but its Larger particle size (0.08-1000mm), it is difficult to form an effective tight seal for micro-cracks
Shale in strong water-sensitive formations is easily broken. Even when drilling with oil-based drilling fluid with strong inhibitory properties, the filtrate will destroy the cementation of shale after entering micro-fractures, causing hydration expansion and hydration of clay minerals. Dispersion increases pore pressure and reduces shale strength, leading to wellbore instability; at the same time, shale hydration expansion and hydration dispersion have a huge impact on the performance of drilling fluids, especially rheological properties thicken significantly

Method used

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  • Oil-based drilling fluid suitable for high-water-sensitivity collapsible stratum as well as preparation method and application of oil-based drilling fluid
  • Oil-based drilling fluid suitable for high-water-sensitivity collapsible stratum as well as preparation method and application of oil-based drilling fluid
  • Oil-based drilling fluid suitable for high-water-sensitivity collapsible stratum as well as preparation method and application of oil-based drilling fluid

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Effect test

preparation example Construction

[0067] The present invention also provides a method for preparing an oil-based drilling fluid suitable for highly water-sensitive and easily collapsed formations described in the above technical solution, comprising the following steps:

[0068] Add high-efficiency emulsifier, alkalinity regulator, fluid loss reducer, nano-blocking agent and organic soil to the oil phase in sequence to obtain the oil phase mixture;

[0069] The water phase is added to the oil-phase mixed liquid for emulsification, and then a weighting material is added to obtain the oil-based drilling fluid suitable for highly water-sensitive and easily collapsed formations.

[0070] In the invention, the high-efficiency emulsifier, the alkalinity regulator, the fluid loss reducer, the nano plugging agent and the organic soil are sequentially added into the oil phase to obtain the oil phase mixed liquid.

[0071] In the present invention, the high-efficiency emulsifier is preferably added to the oil phase for ...

Embodiment 1

[0079] (1) The preparation method of high-efficiency emulsifier is as follows:

[0080] Add 40 parts by weight of trimer acid, 30 parts of diethanolamine and 20 parts of NaOH catalyst into a three-necked flask, raise the temperature to 180°C for acylation reaction, keep the temperature down to 90°C after 8 hours of constant temperature reaction, and continue to add 10 parts of dimer acid, Stir for 30 minutes to mix evenly, add 20 parts of fatty alcohol polyoxyethylene ether dropwise, and react for 8 hours to obtain the high-efficiency emulsifier 1.

[0081] (2) The preparation method of nano-blocking agent is as follows:

[0082] Add 35 parts by weight of styrene, 15 parts of isobutyl acrylate, 10 parts of Span80, and 100 parts of water into a three-necked flask, pass in nitrogen gas, stir evenly, then raise the temperature to 80°C, and simultaneously add 1 part of initiator ammonium persulfate and 25 parts of methacrylic acid, stirred for 4 hours to cause emulsion aggregatio...

Embodiment 2

[0095] (1) The preparation method of high-efficiency emulsifier is as follows:

[0096] Add 30 parts by weight of trimer acid, 25 parts of diethanolamine and 18 parts of NaOH catalyst into a three-necked flask, raise the temperature to 200°C for acylation reaction, keep the temperature down to 120°C after 6 hours of constant temperature reaction, and continue to add 15 parts of dimer acid, Stir for 20 minutes to mix evenly, add 30 parts of fatty alcohol polyoxyethylene ether dropwise, and react for 7 hours to obtain the high-efficiency emulsifier 2.

[0097] (2) The preparation method of nano-blocking agent is as follows:

[0098] Add 45 parts by weight of styrene, 18 parts of isobutyl acrylate, 7 parts of Span80, and 100 parts of water into a three-necked flask, pass in nitrogen gas, stir evenly, and then raise the temperature to 60°C. At the same time, dropwise add 2 parts of initiator ammonium persulfate and 20 parts of methacrylic acid, stirred for 4 hours to cause emulsi...

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Abstract

The invention provides an oil-based drilling fluid suitable for a highly water-sensitive and easily collapsed stratum, and a preparation method and application thereof, and belongs to the field of petroleum and natural gas drilling. Comprising the following components: an oil phase, a water phase, a high-efficiency emulsifier, an alkalinity regulator, a filtrate reducer, a nano plugging agent, organic soil and a weighting material. The oil-based drilling fluid disclosed by the invention has the characteristics of strong inhibition, strong electrical stability, strong plugging performance, low filter loss and the like, can meet the requirement of strong water-sensitive collapsible stratum operation on the inhibition capability of the drilling fluid, effectively prevents underground complex conditions caused by water sensitivity, and improves the stability of a well wall, thereby preventing the collapse of the well wall.

Description

technical field [0001] The invention relates to the technical field of oil and gas drilling, in particular to an oil-based drilling fluid suitable for highly water-sensitive and easily collapsed formations, a preparation method and application thereof. Background technique [0002] With the large-scale exploitation of shale gas, the length of the horizontal section exceeds 800m. When drilling in easily collapsed and highly water-sensitive formations, due to the extremely developed nano-scale micropores and micro-fractures in the shale formation, it is easy to break, poor in stability, and complex in-situ stress. Due to the unique formation characteristics, complex accidents such as well wall collapse, reservoir water sensitivity damage and water lock damage are prone to occur, which seriously affect the development effect and process of shale gas. Due to the low fluid loss of oil-based drilling fluid, and the filtrate is oil instead of water, it has strong inhibitory perform...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C09K8/36C09K8/502C08F212/08C08F220/18C08F220/06
CPCC09K8/36C09K8/502C08F212/08C09K2208/10C09K2208/12C08F220/1804C08F220/06
Inventor 朱宝忠何淼李俊许明标雷佳萍
Owner CHINA PETROLEUM & CHEM CORP
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