A method and system for large-scale pressure gradient displacement in medium-high permeability oil reservoirs

By optimizing formation energy parameters and employing a pressure gradient displacement method that integrates water injection and production in medium-to-high permeability reservoirs, the problems of formation energy replenishment and differential gradient displacement in medium-to-high permeability reservoirs have been solved, resulting in a significant improvement in pressure gradient and recovery rate.

CN122707804APending Publication Date: 2026-09-08CHINA PETROLEUM & CHEMICAL CORP +1
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Patent Information

Application Number
CN202510256570.5
Authority / Receiving Office
CN · China
Patent Type
Applications(China)
Current Assignee / Owner
Filing Date
2025-03-05
Publication Date
2026-09-08

AI Technical Summary

Technical Problem

In existing technologies, large-scale, rapid, and balanced replenishment of formation energy and differential displacement methods with large pressure gradients have not been systematically applied to medium- and high-permeability reservoirs, resulting in limited improvement in oil recovery.

Method used

This paper presents a method for large-scale displacement under high pressure gradient in medium-to-high permeability reservoirs. By optimizing formation energy parameters, differentiating water injection, and injection-production linkage, it achieves formation pressure equilibrium recovery and large pressure gradient displacement. The method includes the following steps: Step 1: Optimizing formation energy parameters for large-scale rapid recovery in medium-to-high permeability reservoirs; Step 2: Determining the formation pressure recovery level and the average daily injection level per well; Step 3: Injecting water based on the differences in formation energy deficit volume in the well area; Step 4: Differentiated fluid extraction from oil wells to utilize the widely distributed remaining oil under a large pressure gradient.

Benefits of technology

It achieved rapid and balanced recovery of formation energy in medium- and high-permeability oil reservoirs, increased the pressure gradient by 94%, effectively utilized the widely distributed remaining oil, and increased the recovery rate by 3.8 percentage points.

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Abstract

This invention discloses a large-scale pressure gradient displacement method and system for medium-to-high permeability reservoirs. It fully considers the availability of oil and water wells, utilizing techniques such as radial drilling to improve the injection-production well network in layers. Combined with field analysis, numerical simulation is used to optimize the formation pressure recovery level and average daily injection level per well, determining the total injection volume during the formation pressure recovery period. Water injection per well is optimized based on energy distribution and allocated to smaller layers according to water absorption capacity, with oil wells acting as actuators to quickly and evenly restore formation pressure. The combination of reservoir, geology, process, and numerical simulation optimizes the average daily fluid level per well during the displacement period, determining the total daily fluid for the block. Well zones are divided around oil wells, and fluid allocation is differentiated based on the proportion of remaining movable reserves in each zone. The seepage resistance coefficient method is applied to distribute the fluid production from oil wells to corresponding water wells in each injection-production direction, with the sum of water volumes in each direction used for injection into the corresponding water wells. This invention is mainly applicable to relatively closed and independent integrated medium-to-high permeability and ultra-high water-cut late-stage reservoirs, and can improve oil recovery.
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