A gas generation system for improving seepage capacity of tight oil reservoirs and its application

A tight oil reservoir and seepage technology, which is applied in the direction of production fluid, drilling composition, wellbore/well components, etc., can solve problems such as safety risks, formation throat and fracture blockage, and gel breaking difficulties, and achieve increased Residual fluid flowback rate, increase formation energy, and reduce formation pollution effects

Active Publication Date: 2018-08-17
CHINA PETROLEUM & CHEM CORP +1
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0004] 1. The corrosion problem caused by the presence of acid in the operation process brings troubles to subsequent production
In addition, for oil reservoirs with low formation pressure, it is difficult to flow back the residual acid of the acidizing fluid, and if it stays in the formation, it will easily cause secondary pollution to the reservoir, reduce the acidizing effect of the acidizing fluid, and even make the acidizing ineffective
[0005] 2. The fracturing fluid causes damage to the reservoir: (1) The fracturing fluid causes problems such as expansion, dispersion, migration, and blockage of the formation clay; Phase permeability becomes smaller; (2) After the fracturing fluid is broken and hydrated, residual solid particles or incomplete gel breaking will block formation throats and fractures; (3) Filtration results in the formation of dense filter cakes on the surface of fractures
At the same time, the filtrate enters the formation fractures to form concentrated fracturing fluid, which makes it difficult to break the gel, resulting in greatly reduced seepage channels
CO 2 Although foam fracturing can avoid the damage of fracturing fluid to the reservoir, the unevenness of the foam in the reservoir affects the fracturing effect. In addition, the technical requirements for equipment are high, the cost of measures is high, and there are safety risks
[0006] 3. After carrying out acidizing, fracturing and acid fracturing measures, the extent to which seepage capacity can be improved is limited
[0007] 4. The cost is high, the effect of single fracturing is limited, and the cost of multi-stage fracturing is too high
This increases the difficulty and workload of construction

Method used

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  • A gas generation system for improving seepage capacity of tight oil reservoirs and its application
  • A gas generation system for improving seepage capacity of tight oil reservoirs and its application
  • A gas generation system for improving seepage capacity of tight oil reservoirs and its application

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Experimental program
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Effect test

Embodiment Construction

[0036] 1. Preparation of gas system:

[0037] 1. Preparation of microcapsules (gas agent A): urea and sodium nitrite are mixed to form a core material, and a mixture of azobisisobutyronitrile, styrene, methyl methacrylate and methacrylic acid is used as a capsule coat, and the Appropriate coatings are sprayed on the granules several times while drying to obtain microcapsules.

[0038] 2. Hydrochloric acid (gas generating agent B).

[0039] 2. Construction application:

[0040] 1. Measure process:

[0041] 1) Injection method: oil pipe positive injection; the string structure is an acidizing string.

[0042] 2) Construction displacement: The displacement ensures that when the gas generating agent and gas generating agent system are injected, the construction pressure can crush the formation.

[0043] 3) Construction pressure: according to the stratum fracture pressure gradient and stratum fracture pressure, the theoretical calculation shows that when the ground construction...

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Abstract

The invention provides a gas-producing system capable of improving permeability of a tight oil reservoir and application thereof, belonging to the technical field of oilfield development. The gas-producing system comprises a microcapsule and hydrochloric acid; the microcapsule uses a mixture of urea and sodium nitrite as a core material and a mixture of azodiisobutyronitrile, styrene, methyl methacrylate and methacrylic acid as a capsule dressing. In operation, nitrite and the microcapsule are injected into a stratum to a predetermined depth; and the microcapsule undergoes corrosion under stratum conditions and chemically reacts with hydrochloric acid to produce a great amount of gas and release a great amount of heat, so local high pressure is formed in a predetermined part. According to the invention, effective seepage channels of difficult-to-produce reserves such as an ultralow-permeability oil reservoir and the tight oil reservoir are increased so as to improve permeability, increase local energy of reservoirs and the flowback rate of raffinate, and reduce reservoir contamination, so the purpose of improving the recovery efficiency of the difficult-to-produce reserves is achieved.

Description

technical field [0001] The invention relates to the technical field of oilfield development. Background technique [0002] As the developed oilfields enter the high water cut period and the development of new proven reserves becomes more and more difficult, and the proportion of hard-to-produce reserves such as ultra-low permeability reservoirs and tight oil reservoirs in the newly discovered reserves is increasing, so the difficult-to-produce reserves The extraction of reserves is becoming more and more important. However, the reservoir characteristics of tight oil reservoirs bring great challenges to the development. The main problems faced by the development of such reservoirs are low formation porosity and permeability, low natural energy of the oil field, and low formation water absorption capacity. How to effectively improve the seepage capacity of this kind of reservoir is particularly important for its exploitation. [0003] At present, the main ways to improve the...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): C09K8/74C09K8/70E21B43/26
CPCC09K8/70C09K8/74E21B43/26
Inventor 杨付林吕红梅李汉周汤元春崔永亮李安
Owner CHINA PETROLEUM & CHEM CORP
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