Low-permeability reservoir bed starting pressure testing method

Abstract

The invention relates to a low-permeability reservoir bed starting pressure testing method which comprises the following steps of: placing a core with 0.8-1.5m in length in a core holder with multiple pressure testing points, and applying a confining pressure by simulating oil deposit conditions; vacuumizing the core, and filling the core with formation water until the original oil deposit pore pressure is achieved; setting the pressure of a return pressure valve to be with the pressure value of a designated testing pore fluid; setting the velocity of the formation water passing across a core chamber to be 0.1-1mL / min, gradually reducing the velocity to 0, and recording the pressure difference value between each pressure testing point and a fluid inlet; calculating the starting pressure gradient of the core by using the pressure difference data values between different pressure testing points and the fluid inlet. The calculation formula is GradP=(PAB / LAB+PAC / LAC+......) / n, wherein PAB, PAC ...... represent the pressure differences of section AB, section AC ...... of the core, and n represents the quantity of the pressure testing points. The low-permeability reservoir bed starting pressure testing method has small testing error and can be used for accurately testing the starting pressure under low-permeability reservoir bed oil deposit conditions by simulating oil deposit pressure conditions.

Description

technical field [0001] The invention relates to a low-permeability reservoir start-up pressure testing method. Background technique [0002] The development of low-permeability reservoirs is a worldwide problem. For my country, the challenge faced by the development of low-permeability reservoirs is even more difficult. By the end of 2004, the geological reserves of proven low-permeability reservoir oilfields in my country were about 6.3 billion tons. It accounts for more than 30% of all proven geological reserves, and most of the newly proven reserves in recent years are low-permeability and ultra-low-permeability reservoirs. With the development of my country's petroleum industry, more low-permeability oilfields will be put into development. The special seepage characteristics and laws in low-permeability rock reservoirs have attracted people's attention. Sandstone reservoirs are very different, and low-permeability reservoirs are not well understood. The pore structure an...

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Problems solved by technology

Although the capillary pressure measurement at both ends of the core holder can accurately and sensitively reflect the change of the liquid level, the experimental plan of this method is limited. The fluids are all under high-pressure conditions, and the experimental conditions are quite different from the reservoir conditions, which cannot more realistically simulate the actual high-pressure conditions of the reservoir

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