Method for calculating apparent permeability of porous media of shale reservoir

Abstract

The present invention belongs to the technical field of unconventional oil and gas development, and relates to a method for calculating apparent permeability of porous media of shale reservoir. The method includes the steps of: S1, collecting basic parameters of shale gas reservoir, calculating to obtain a Knudsen coefficient and a contribution coefficient; S2, utilizing the Knudsen coefficient tojudge the flow state of the gas in the capillary tube, and establishing the corresponding gas mass transport equation; S3, according to the water saturation of the reservoir rock sample, determiningthe effective flow radius corresponding to the capillaries of different sizes; S4, establishing unified mass transport equation of gas in different flow states in capillary tubes; S5. according to theunified mass transport equation, calculating the apparent permeability of the capillary tube, and superposing the apparent permeabilities of the capillary tubes with different sizes to obtain the apparent permeability of the whole shale core. The method of the invention takes into account the influence of different capillary sizes, distribution frequencies and water saturation of shale, and the method provided by the invention is closer to the real situation of the reservoir and obtains more accurate data.

Description

technical field [0001] The invention relates to a calculation method for the apparent permeability of porous media in shale reservoirs, and belongs to the technical field of unconventional oil and gas development. Background technique [0002] With the rapid economic development in the 21st century, the demand for energy continues to rise, and the consumption of traditional energy such as coal, oil, and natural gas is also gradually increasing, and the energy pressure is increasing day by day. Under the new situation of huge demand for energy, as an effective supplement to conventional oil and gas energy, shale gas has entered people's field of vision in the form of unconventional natural gas. [0003] The development of shale gas reservoirs is mainly based on horizontal well staged fracturing. In order to accurately simulate the productivity of shale gas fracturing, one of the important aspects is to accurately calculate the apparent permeability of shale matrix. Shale has...

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Problems solved by technology

Most of the current methods for calculating the permeability of shale matrix can only solve the permeability of a single capillary. The apparent permeability of a single capillary is extended to the apparent permeability of shale through the theory of equivalent hydraulic radius or fractal. This approximation The processing method cannot reflect the influence of various flow states of shale gas in the shale matrix and the influence of different capillary diameters on the apparent permeability, and ignores the influence of the water film thickness on the apparent permeability of the shale capillary, resulting in The calculation result has a large error, which will affect the subsequent production capacity calculation

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