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Coal seam liquid CO2 phase change oriented perforation fracturing dominant direction judgment method

A technology of directional perforation and direction judgment, which is used in earth-moving drilling, design optimization/simulation, wellbore/well components, etc. question

Active Publication Date: 2018-10-26
CHONGQING UNIV
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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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  • Coal seam liquid CO2 phase change oriented perforation fracturing dominant direction judgment method
  • Coal seam liquid CO2 phase change oriented perforation fracturing dominant direction judgment method
  • Coal seam liquid CO2 phase change oriented perforation fracturing dominant direction judgment method

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Embodiment Construction

[0065] Below in conjunction with accompanying drawing and embodiment the present invention will be further described:

[0066] as attached figure 1 Coal seam liquid CO shown 2 The method for judging the dominant direction of phase change directional perforation fracturing specifically includes the following steps: (1) Calculating the theoretical correspondence between the hole wall rupture pressure P and the drilling azimuth angle α, dip angle β and perforation angle θ,

[0067] Specifically, the elastic mechanics theory is used to establish a calculation model for the fracture pressure of the perforation-fractured hole wall under the action of in-situ stress, and formula (1) is used to convert the three-dimensional in-situ stress into the Cartesian coordinate system of the borehole,

[0068]

[0069] Where: σ H , σ h , σ v are the stress components in the X, Y, and Z directions of the borehole Cartesian coordinate system, and the unit is MPa; τ xy , τ xz , τ yz is t...

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Abstract

The invention discloses a coal seam liquid CO2 phase change oriented perforation fracturing dominant direction judgment method. The method comprises the steps that first, the theoretical correspondingrelation among hole wall fracture pressure P, a drilling azimuth alpha, a dip angle beta and a perforation angle theta is inferred; second, a three-dimensional ground stress test is performed; third,a rock Poisson's ratio and hole wall tensile strength parameter test is performed; fourth, hole wall fracture pressure values under different drilling azimuths, dip angles and perforation angles arecalculated; fifth, minimum hole wall fracture pressure under different drilling azimuths and dip angles is determined; sixth, a distribution cloud chart and a relation curve graph of the minimum holewall fracture pressure under different drilling azimuths and dip angles are drawn; and seventh, the liquid CO2 phase change oriented perforation fracturing dominant direction is determined through analysis. Through the method, theoretical support can be provided for optimizing a drilling layout in the application process of the liquid CO2 phase change fracturing permeability increase technology, the influence radius of coal seam liquid CO2 phase change oriented perforation fracturing is effectively increased, the drilling work amount is reduced, and construction efficiency is improved.

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. According to the analysis of coal mine accidents from 2000 to 2009, the number of fatalities in gas accidents accounted for 36.4% of the total number of deaths in coal mine accidents, 63.1% of which were 3-9 deaths (major accidents), and more than 10 deaths (extraordinary accidents). Accounted for 79.9%. At the same time, coalbed methane is a potential clean energy source. Under the current energy shortage situation, accelerating the development and utilization of ...

Claims

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Application Information

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IPC IPC(8): G06F17/50E21B43/16E21B43/26
CPCE21B43/164E21B43/26G06F2119/06G06F30/20
Inventor 白鑫张东明尹光志王浩李树建李铭辉何庆兵楚亚培叶辰杨邦友
Owner CHONGQING UNIV
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