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Method for improving recovery rate of oil reservoir after polymer flooding

A technology of polymer and recovery factor, applied in drilling compositions, chemical instruments and methods, and production fluids, etc., can solve the problems of declining economy, difficulty in large-scale popularization and application, and increasing cost of oil displacement system, and achieve The effect of increasing swept volume, enhancing oil recovery, increasing swept volume and oil displacement efficiency

Active Publication Date: 2020-09-08
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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  • Method for improving recovery rate of oil reservoir after polymer flooding
  • Method for improving recovery rate of oil reservoir after polymer flooding
  • Method for improving recovery rate of oil reservoir 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 aged sewage, and the polymer aqueous solution is prepared from polymer and aged sewage.

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

[0030] (1) Inject the mixed aqueous solution of polymer and PPG into the rock 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 0.05%; then inject a polyacrylamide aqueous solution with a concentration of 1500mg / L to form a 0.5PV intermediate body slug, wherein the mass percentage of polyacrylamide is 0.15%; finally inject ...

Embodiment 2

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

Embodiment 3

[0035] The method for improving the recovery of oil reservoirs after polymer flooding in this embodiment refers to Example 2, the only difference is: the mass percentage content of PPG in the pre-profile control slug and 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 particularly relates to a method for improving the recovery rate of an oil reservoir after a polymer flooding. The method comprises the following steps that 1, a front profile control slug, a middle main body slug and a rear profile control slug are sequentially injected into a reservoir stratum, wherein the front profilecontrol slug and the rear profile control slug each comprise a polymer and viscoelastic particles; 2, the middle main body slug comprises at least one polymer main body slug; and 3, the number averagemolecular weight of the polymer is 29 million to 35 million, and the particle size of the viscoelastic particles is 150 [mu]m to 900 [mu]m. The front profile control slug can adjust a stratum layer water injection profile and effectively block a water flooding fluid channeling channel, and the rear profile control slug can prevent the fingering and fluid channeling in the subsequent water flooding process and improve the validity period of the chemical flooding and the effective utilization rate of the polymer. According to the method, profile control and oil displacement are combined, so that the swept volume and the oil displacement efficiency of the polymer flooding can be improved, and the purpose of improving the crude oil recovery ratio can be achieved on 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 quite extensive and in-depth, and the scale of chemical flooding application and annual oil increment rank first in the world. Among them, the polymer flooding technology has been promoted and applied nationwide in Daqing, Shengli, Henan, and Dagang oilfields, and many units in these oilfields have been transferred to follow-up water flooding. Old oilfields with high water cut rely on polymer flooding technology to increase 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 the potential. It has become an urgent task for the stable development of oilfields to s...

Claims

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Application Information

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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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