Method for optimizing soaking time after volume fracturing of shale gas well

Abstract

The invention discloses a method for optimizing soaking time after volume fracturing of a shale gas well. The method comprises the steps that a rock sample is prepared according to rock of a shale reservoir section and dried to constant weight; a physical property index of the rock sample is obtained; a brittleness index of the rock sample is obtained; a hydrophilicity index of the rock sample isobtained; a clay mineral content and hydrophilicity index curve is fitted, and a clay mineral content critical value is determined; a rock sample hydration effect comprehensive index is determined according to the physical property index, the brittleness index and the hydrophilicity index of the rock sample; and a two-dimensional coordinate system and a four-region optimization plate are established according to the rock sample clay mineral content and the rock sample hydration effect comprehensive index, and the gas well soaking time is optimized according to the optimization plate. Accordingto the method, the shale gas well soaking time optimization plate is established, mine field engineers can quickly optimize the soaking time through the plate, and the cost of a long-time productiontest of a mine field is saved.

Description

technical field [0001] The invention relates to the field of petroleum and natural gas engineering, in particular to a method for optimizing the brine time of a shale gas well after volume fracturing. Background technique [0002] Large-scale volume fracturing of horizontal wells is a key technology for efficient development of shale gas. Different from conventional sandstone, due to differences in geological characteristics and fracturing techniques, shale gas wells show special flowback characteristics after volume fracturing: Low flowback rate, high productivity, reduced water production after brine well, increased gas production, large difference in flowback rate, etc. The hydration of shale clay minerals induces micro-cracks, improves the flow capacity of shale reservoirs, and the continuous transformation of shale reservoirs is an important reason for the above special flowback characteristics. Statistics from a large number of mines show that braising wells is benefic...

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Problems solved by technology

However, there are many factors affecting the dialysis and diffusion of shale salt ions, and the differences between different shale gas wells are large, which requires special treatment for wells and cannot provide reliable reference for other wells

[0004] (2) Han Huifen et al. (Han Huifen, Yang Bin, Peng Junliang, et al. Research on shale water absorption and crack initiation and expansion during brine after fracturing [J]. Natural Gas Industry, 2019, 39(1): 74-80.) through rock triaxial Combined with the uniaxial rock anti-pressure experiment and the micro-fracture initiation model, the fracture initiation threshold pressure was obtained, and the reasonable soaking time of the Silurian Longmaxi Formation shale gas wells was discussed. This method combines theory and experiment The reasonable soaking time is determined by the method, but the theoretical model has many simplification factors, which cannot reflect the law of microfracture initiation under real shale reservoir conditions

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