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A method of improving oil recovery after polymer flooding

A polymer and oil recovery technology, applied in drilling compositions, chemical instruments and methods, production fluids, etc., can solve problems such as economic decline, high cost of oil displacement systems, and difficulty in large-scale application. Achieve the effects of increasing swept volume, enhancing oil recovery, and improving oil displacement efficiency

Active Publication Date: 2022-06-24
CHINA PETROLEUM & CHEM CORP +1
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

[0005] Shengli Oilfield (Cui Xiaohong, New Heterogeneous Composite Oil Flooding Method, Acta Petroleum Sinica, 2011) used polymers, PPG and surfactants as heterogeneous oil displacement agents in reservoirs after polymer flooding, and achieved relatively good results. Good displacement effect, but the heterogeneous composite flooding system (composed of polymer, PPG and surfactant) with a large slug volume, and the full use of PPG will lead to an increase in the cost of the flooding system, namely The economy is declining, and it is difficult to promote and apply on a large scale under low oil prices

Method used

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  • A method of improving oil recovery after polymer flooding
  • A method of improving oil recovery after polymer flooding
  • A method of improving oil recovery after polymer flooding

Examples

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Embodiment 1

[0028] The polymer used in this example is polyacrylamide with a number average molecular weight of 32 million, its degree of hydrolysis is 28.6%, the effective solid content of viscoelastic particles PPG is 86.5%, and the particle size is 300-900 μm. The mixed aqueous solution of polymer plus PPG is prepared from polymer, PPG and aging sewage, and the polymer aqueous solution is prepared from polymer and aging sewage.

[0029] The method for improving the oil reservoir recovery after polymer flooding of the present embodiment specifically includes:

[0030] (1) Inject the mixed aqueous solution of polymer plus PPG into the core at a flow rate of 50mL / h to form a 0.05PV pre-profile control slug, wherein the mass percentage of polyacrylamide is 0.15%, and the mass percentage of PPG is 0.15%. Then inject a polyacrylamide aqueous solution with a concentration of 1500 mg / L to form a 0.5PV intermediate body slug, wherein the mass percentage of polyacrylamide is 0.15%; finally injec...

Embodiment 2

[0033] For the method of improving the oil recovery after polymer flooding in this embodiment, refer to Embodiment 1, and the difference is only that the injection volume of the middle main slug in step (1) is 0.45PV, and the injection volume of the post profile control slug is 0.45PV. The volume is 0.10PV.

Embodiment 3

[0035] For the method of improving the oil recovery after polymer flooding in this embodiment, refer to Embodiment 2, and the difference is only in that the pre-profile control slug and the PPG mass percentage in the post-profile control slug in step (1) Both are 0.15%.

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Abstract

The invention belongs to the technical field of petroleum exploitation, and in particular relates to a method for improving the recovery rate of oil reservoirs after polymer flooding. The method includes the following steps: sequentially injecting a pre-profile control slug, an intermediate body slug, and a post-profile control slug into the reservoir, and the pre-profile control slug and the post-profile control slug both include a polymer and viscoelastic particles; the middle body slug includes at least one polymer body slug; the number average molecular weight of the polymer is 29 million to 35 million, and the particle diameter of the viscoelastic particles is 150 to 900 μm. Among them, the front profile control slug can adjust the water absorption profile of the formation and effectively block the water flooding channel, and the rear profile control slug can prevent fingering and channeling in the subsequent water flooding process, and improve the validity period and polymerization of chemical flooding. effective utilization of materials. The method of the invention combines profile control and oil displacement, can increase the swept volume and oil displacement efficiency of polymer flooding, and can realize the purpose of improving oil recovery under the premise of lower production cost.

Description

technical field [0001] The invention belongs to the technical field of petroleum exploitation, and in particular relates to a method for improving the recovery rate of oil reservoirs after polymer flooding. Background technique [0002] The research and application of chemical flooding technology in China has been extensive and in-depth, and the scale and annual oil increase of chemical flooding application ranks first in the world. Among them, polymer flooding technology has been popularized and applied in Daqing, Shengli, Henan and Dagang oilfields nationwide, and many units of these oilfields have been transferred to subsequent water flooding. The high water-cut old oilfields rely on polymer flooding technology to improve the recovery rate by about 6-10%. After polymer flooding, about 50-60% of the crude oil remains underground, which has a material basis for further tapping. It has become an urgent task for the stable development of oilfields to study the oil reservoirs...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): E21B33/13E21B43/22C09K8/508
CPCE21B33/13E21B43/16C09K8/5083C09K2208/18
Inventor 郭艳李岩陈磊孙林涛刘峥君刘艳华张卓束华东郝明耀朱义清盛海燕
Owner CHINA PETROLEUM & CHEM CORP
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