Technological parameter optimization for improving the complexity of hydraulic fractures in deep shale reservoirs

被引：0

作者：

Zhang F. ^{[1
,2
]}

Wu J. ^{[3
]}

Huang H. ^{[3
]}

Wang X. ^{[1
,2
]}

Luo H. ^{[3
]}

Yue W. ^{[3
]}

Hou B. ^{[4
,5
]}

机构：

[1] Key Laboratory of Geotechnical & Underground Engineering of Ministry of Education, Tongji University, Shanghai

[2] Department of Geotechnical Engineering, College of Civil Engineering, Tongji University, Shanghai

[3] Shale Gas Research Institute, PetroChina Southwest Oil & Gasfield Company, Chengdu

[4] State Key Laboratory of Petroleum Resources and Prospecting, China University of Petroleum, Beijing

[5] Key Laboratory of Petroleum Engineering Education Ministry, China University of Petroleum, Beijing

来源：

Natural Gas Industry | 2021年 / 41卷 / 01期

关键词：

Alternative injection of fracturing fluid; Bedding strength; Complexity of fracture propagation; Deep shale; Discrete lattice method; Displacement; Hydraulic fracturing; Physical simulation experiment;

D O I：

10.3787/j.issn.1000-0976.2021.01.011

中图分类号：

学科分类号：

摘要：

Deep shale reservoirs below 3 500 m are characterized by high horizontal principal stress difference, developed bedding fracture and low brittleness index, so it is difficult to form complex fractures during hydraulic fracturing. In order to better understand the propagation laws of hydraulic fractures in deep shale reservoirs, this paper applies the 3D discrete lattice method to carry out discrete element numerical simulation and analysis on the true triaxial fracturing physical simulation experiment results of Lower Silurian Longmaxi Formation deep bedding shale in the Sichuan Basin under the horizontal principal stress difference of 12 MPa. And the numerical simulation results are consistent with fracture propagation laws clarified in the laboratory fracturing physical simulation of shale outcrop with single bedding. Then, the propagation laws of the fractures in deep shale reservoirs with multiple beddings under the influence of displacement, fracturing fluid viscosity, bedding strength and alternative fracturing fluid injection were numerically simulated. And the following research results were obtained. First, high-displacement injection and increasing fracturing fluid viscosity can enhance the deep-penetration stimulation capacity of deep shale reservoirs. Hydraulic fractures can continuously pass through four beddings and penetrate the entire sample when the displacement reaches 90 mL/min or the fracturing fluid viscosity is increased to 60 mPa•s. Second, under high horizontal principal stress difference, low-viscosity fracturing fluid tends to activate horizontal bedding while high-viscosity fracturing fluid tends to pass through the bedding directly to form vertical main fractures. In conclusion, the fracturing technology based on the alternative injection with high-viscosity fracturing fluid in the early stage and low-viscosity fracturing fluid in the later stage can maximize the complexity of hydraulic fractures in deep shale reservoirs. In addition, when there is weak bedding near the wellbore, it is necessary to adjust fracturing technologies and parameters (such as to increase the construction displacement as much as possible and to adopt guar fracturing fluid), so that hydraulic fractures can break through the inhibition of the weak bedding near the wellbore and achieve deep-penetration stimulation. © 2021, Natural Gas Industry Journal Agency. All right reserved.

引用

页码：125 / 135

页数：10

共 37 条

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