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Water plugging method of unconventional oil and gas reservoir oil well

An oil and gas reservoir, unconventional technology, applied in chemical instruments and methods, earthwork drilling and production, wellbore/well components, etc., can solve the problems of less remaining oil, unreasonable technology, short effective time after plugging, etc.

Inactive Publication Date: 2019-01-18
CHINA NAT OFFSHORE OIL CORP +1
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

Now, the water plugging of oil wells, especially in special oil reservoir wells, often has the following problems: 1. The effective time after plugging is short, the reason is that the plugging radius is small, and the method of large-dose injection is used in the process, and the over-displacement method is used; 2. Plugging The reason is that the performance of the plugging agent is not good, and the well cannot be plugged, or the well is blocked. The solution is a high-quality plugging agent, non-cross-linked gel. So far, no effective solution has been found for the above problems.
[0006] However, at present, oil well plugging, especially in unconventional reservoir wells, often has the following problems: poor plugging agent performance leads to short effective time after plugging, no effect after plugging, and low productivity; Unreasonable (only focus on plugging function and not other functions such as oil displacement); special geological conditions of special reservoirs such as bottom water reservoirs, active bottom water reservoirs require stronger plugging performance of plugging agents; horizontal wells require plugging agents with more Good selective plugging ability, stronger thixotropy, and less negative impact of gravity operation; conglomerate oil layer requires plugging agent to have good selective plugging ability and good injectability; low permeability fractured oil and gas reservoirs require plugging agent to have selective plugging ability Strong, only seals big cracks but not small cracks

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0061] A well was opened three times, which is a horizontal well with a depth of 2434m, a horizontal open hole section of 520m, a reservoir temperature of 65°C, a salinity of injected water of 4550mg / L, Ca 2+ , Mg 2+ The content is 3043mg / L, the formation is micro-fractured, and drilling shows a small amount of leakage. After the fracturing in 2008, the initial daily oil production was 15t, and the water cut was 3.56%. In June 2012, the water cut rose from 30% to 70%. %, the analysis shows that fracturing man-made fractures communicate with natural fractures, and water injection opens and scours, causing the injected water to enter the oil well along the fractures.

[0062] Prepare 10,000 mg / L and 3,000 mg / L non-crosslinked gel aqueous solutions respectively, and mature them in a liquid storage tank for 4 hours before use. Under the conditions of simulating on-site liquid distribution, a horizontal well model is adopted, and four slug combinations are adopted indoors: (1) plu...

Embodiment 2

[0065] A well was opened for the third time, which belongs to the bottom water oil and gas reservoir, the well depth is 4354m, the reservoir temperature is 85℃, the injected water salinity is 12589mg / L, Ca 2+ , Mg 2+ Content 356mg / L, bottom water reservoir, put into production in 2004, initial daily oil production 28t, no water cut, annual growth rate of water cut 28.72% from 2014 to 2016, water cut 99% in September 2016, shut down 4 times from 2014 to 2016 The pressure cone is invalid, and the water plugging of conventional oil wells is effective for less than two months. The original formation pressure of this well is 48.2MPa, and the static pressure measured in 2016 is 45.6MPa. This leads to high water cut in this well.

[0066] Prepare 10,000 mg / L and 3,000 mg / L non-crosslinked gel aqueous solutions respectively, and mature them in a liquid storage tank for 4 hours before use. Under the conditions of simulating on-site liquid distribution, the bottom water model is adopt...

Embodiment 3

[0069] A well was opened for the second time, belonging to a low-permeability fractured oil and gas reservoir, the well depth is 2214m, the reservoir temperature is 65°C, the salinity of injected water is 9873mg / L, Ca 2+ , Mg 2+ Content 349mg / L, low permeability fractured reservoir, put into production in 2006, the initial daily oil production was 4.6t, no water cut, the annual growth rate of water cut was 6.72% from 2010 to 2014, and the water cut suddenly rose from 56% to 100% in September 2015. Chloride ions show that the incoming water of the well is injection water. Under the long-term water injection opening, the injected water rushes into the well along the micro-fractures, forming a dominant water flow channel, leading to violent flooding of the oil well.

[0070] Configure 5000mg / L, 800mg / L, and 8000mg / L non-crosslinked gel aqueous solutions respectively, add the shielding agent betaine, and the dosage is 0.8% of the quality of the non-crosslinked gel aqueous solution...

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Abstract

The invention discloses a water plugging method of an unconventional oil and gas reservoir oil well. According to the method of the invention, a multi-sectional-plugging combination way is adopted, and each section plug adopts a non-cross-linked gel polymer aqueous solution of different concentrations as a plugging agent. The water plugging method of the invention only utilizes one non-cross-linked gel plugging agent, so that compared with the prior art of adopting a way of combining multiple chemicals, the cost can be effectively saved, the control is facilitated, and multiple functions of regulation, plugging and driving can be simultaneously realized.

Description

technical field [0001] The invention relates to the technical field of oil and gas field development, in particular to a water plugging method for oil wells in unconventional oil and gas reservoirs. Background technique [0002] The oil and gas resources in the world are divided into two parts, conventional oil and gas resources and unconventional oil and gas resources. The ratio of the reserves of the two resources is about 2:8. Conventional oil and gas resources, such as structural, lithologic and stratigraphic oil and gas reservoirs, are increasingly difficult to explore and develop over time. Therefore, the focus of the world's attention has gradually shifted to unconventional oil and gas resources, and even unconventional oil and gas resources have been regarded as new resources to replace conventional oil and gas resources. According to the history of exploration and development of oil and gas resources, now we have quietly entered a new oil and gas era of simultaneou...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C09K8/508E21B33/13
CPCC09K8/5083E21B33/13
Inventor 胡科张健康晓东郭拥军赵文森李先杰石爻曾杨冯茹森王捷张新民周明源
Owner CHINA NAT OFFSHORE OIL CORP