A method for optimizing soaking time of shale gas wells after volume fracturing

Abstract

The invention discloses a method for optimizing the soaking time of a shale gas well after volume fracturing, comprising the steps of: preparing a rock sample according to the rock in a shale reservoir section and drying it to a constant weight; obtaining the physical property index of the rock sample; and obtaining the brittleness of the rock sample Index; obtain the hydrophilic index of the rock sample; fit the clay mineral content and hydrophilic index curve to determine the critical value of the clay mineral content; determine the comprehensive index of rock sample hydration through the physical property index, brittleness index, and hydrophilic index of the rock sample ; Establish a two-dimensional coordinate system and a four-region optimization chart based on the clay mineral content of the rock sample and the comprehensive index of hydration of the rock sample, and optimize the boring time of the gas well according to the optimization chart. This method establishes a shale gas well soaking time optimization chart, and mine engineers can quickly optimize the soaking time through the chart, which saves the cost of long-term production testing in the mine.

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...

AI Technical Summary

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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