coal seam liquid co 2 Judgment method for dominant direction of phase change directional perforation fracturing

Abstract

The invention discloses a coal seam liquid CO 2 The method for judging the dominant direction of phase change directional perforation fracturing includes the following steps: (1) Calculating the theoretical correspondence between the fracture pressure P of the hole wall and the drilling azimuth angle α, dip angle β, and perforation angle θ; (2) Application of three-dimensional geostress parameter testing; (3) Rock Poisson’s ratio and hole wall tensile strength parameter testing; (4) Calculation of hole wall rupture pressure values ​​under different drilling azimuth angles, inclination angles, and perforation angles; (5) Different drilling Determine the minimum hole wall fracture pressure under the conditions of hole azimuth and inclination; (6) Draw the distribution cloud map and relationship curve of the minimum hole wall fracture pressure under different drilling azimuths and inclination angles; (7) Analyze and determine the liquid CO 2 Predominant direction of phase change directional perforation fracturing. The present invention can be liquid CO 2 In the application process of phase change fracturing and anti-permeability technology, the optimization of drilling layout provides theoretical support, effectively increasing the coal seam liquid CO 2 Phase change directional perforation fracturing affects the radius, reduces the amount of drilling work, and improves construction efficiency.

Description

technical field [0001] The invention belongs to the technical field of coal mine drilling and fracturing construction, and in particular relates to a coal seam liquid CO 2 A method for judging the dominant direction of phase change directional perforation fracturing. Background technique [0002] Mine gas is the main factor affecting the safe production of coal mines in my country. Among the deaths caused by coal mine accidents in China, gas accidents account for a large proportion, especially serious accidents. At the same time, coalbed methane is a potential clean energy source. Under the current energy shortage situation, accelerating the development and utilization of coalbed methane has important practical significance for improving my country's energy structure, fully utilizing energy and reducing environmental pollution. Studies have shown that more than 50% of coal seams in my country are high-gas coal seams, and the geological resources of shallow coalbed methane b...

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Problems solved by technology

"Due to the poor geological conditions of coal seams in my country and the low permeability of coal seams, the mine gas extraction rate is low and the gas drainage efficiency is low. Therefore, it is necessary to artificially strengthen the coal seam and increase permeability. Relevant scholars have proposed the use of hydraulic fracturing and deep hole pre-fracturing. Measures such as anti-reflection have achieved certain results, but there are still various deficiencies in the application process

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