Method for determining stress sensitivity of fractured low-permeability reservoir based on scale model

Abstract

The invention relates to a method for determining stress sensitivity of a fractured low-permeability reservoir based on a scale model. According to the method, the scale model of the stress sensitivity of the fractured compact reservoir is obtained by using a rock mechanics analysis method and a medium series-parallel model. Factors such as core size, underground flowing size, fracture density, fracture occurrence and ground stress are taken into account in the scale model. A pore type core and a fractured core are tested in a stress sensitivity experiment respectively, and the stress sensitivity experimental law of the small-sized pore type core and of the fractured core is obtained by the scale model, so that the actual reservoir large-range flowing law is deduced. Besides, the method shows that effective stress in a stress sensitivity model cannot be simply equal to effective stress of a reservoir (burden pressure-pore pressure), but is equal to normal effective stress of a fractured surface. The stress sensitivity scale model provided by the invention can be used for predicting capacity, and the method is a novel method for researching capacity calculation for fractured compact reservoir horizontal wells, multi-branch horizontal wells and staged fracturing horizontal wells.

Description

technical field [0001] The invention relates to a method for determining the stress sensitivity of fractured low-permeability reservoirs, to predict the influence of factors such as stress change, fracture density, and fracture occurrence on the permeability of fractured low-permeability reservoirs, so as to determine the stress sensitivity of tight and low-permeability fractures. Provide technical guidance for productivity prediction of permissive reservoirs. Background technique [0002] my country is very rich in low-permeability oil and gas resources. As of 2009, low-permeability oil and gas reserves accounted for 27.5% of the onshore developed geological reserves, and 70.8% of the proven unproduced reserves. With the increasing demand for oil, the recoverable reserves of the easy-to-exploit medium and high-permeability oilfields will gradually decrease, and the contribution of low-permeability oilfields, including tight oilfields, to oil and gas production will increase...

AI Technical Summary

Problems solved by technology

[0003] Fractured tight reservoirs have heterogeneity, stress sensitivity and anisotropy, and the core size (usually 25mm) of the stress sensitivity evaluation experiment is limited by the coring conditions and experimental conditions, so it is impossible to enlarge infinitely, so the experimental test The flow scale is far smaller than the actual downhole flow scale, so the experimental data cannot directly describe the actual reservoir flow law

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