Stress sensitivity test method and device

Abstract

The embodiment of the invention provides a stress sensitivity testing method and device. The method comprises the steps: obtaining effective stress borne by a rock framework according to overlying stratum pressure and initial pore pressure when a rock core to be measured is located in an original stratum; increasing the confining pressure and the back pressure borne by the rock core to be measuredstep by step according to a preset confining pressure rising step length and a preset rising back pressure step length until the confining pressure is equal to the overlying strata pressure and the back pressure is equal to the initial pore pressure; keeping the confining pressure constant, reducing the return pressure step by step according to a preset return pressure reduction step length, andcalculating the permeability of the rock core to be measured under different return pressures; and when the return pressure borne by the rock core to be tested is reduced to a preset pressure value, determining the stress sensitivity of the rock core to be tested according to the permeability of the rock core to be tested under different return pressures and the effective stress borne by the rockframework. Therefore, the accuracy of stress sensitivity testing is improved.

Description

technical field [0001] The embodiments of this specification relate to the field of petroleum and natural gas engineering, in particular to a stress sensitivity testing method and device. Background technique [0002] During the effective development of low-permeability reservoirs, permeability is one of the important petrophysical parameters affecting the development of oil and gas fields. As the effective stress gradually increases, the pore space of the reservoir decreases continuously, and the permeability decreases accordingly. This phenomenon is called reservoir stress sensitivity. Due to the very low permeability of tight / shale oil and gas reservoirs and the extremely narrow pore throats, during the process of oil and gas depletion and production, the pressure of the reservoir is reduced, which shows a significant stress sensitivity characteristic, resulting in a further decrease in reservoir permeability and a large increase in production capacity. reduce. Accurate...

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Problems solved by technology

[0004] However, when the stress sensitivity is tested by the above two methods, the state of the core is quite different from the stress of the rock skeleton or particles under the original reservoir conditions, especially for the case of high plastic mineral content, so the stress sensitivity is high. The error of working system optimization and productivity prediction is relatively large, especially for deep tight / shale oil and gas reservoirs, where the initial effective stress under in-situ conditions is higher, and the deformation of rock skeleton or particle contact is more complicated

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