Stress Simulation of Vetical Hydraulic Fracture Propatation Mechanism in Tight Conglomorate Reseriors of Mahu Area

doi:10.7657/XJPG20200209

Abstract

Abstract:

In the light of the features of ultra-low porosity and permeability of the conglomerate reservoir in Mahu oilfield, the volume fracturing tests in horizontal wells are carried out to stimulate the reservoir. However, how to connect reservoirs at the extreme through hydraulic fracturing is a major difficulty in both theory and practice. Based on the theories of fluid-structure interaction and rock elastoplastic fracture and by means of finite element method, the paper discusses the stress evolution rules and fracture mechanism of mudstone layer, and analyzes the influencing factors such as mudstone interlayer thickness, rock mechanical parameter, dip angle and effective stress during volume fracturing in horizontal wells. The study results show that if the injection rate of fracturing fluid is constant, the effective thickness of the mudstone interlayer penetrated by hydraulic fractures is less than 5 m; the larger the differences of the mechanical parameters between conglomerate and mudstone, the larger the dip angle of mudstone layer and the worse the penetrating capability of the hydraulic fractures; the minimum horizontal principle stress plays a leading role in fracture propagation vertically. Additionally, the distance from a horizontal well to mudstone layer and well injection pressure have great influences on fracture propagation. Perforation at close range to mudstone interlayers should be avoided to improve fracturing effect.

Key words: Mahu sag, tight conglomerate, horizontal well volume fracturing, artificial fracture, in-situ stress, mudstone layer, numerical simulation

CLC Number:

TE357

WANG Shuo, QIN Jianhua, YANG Xinping, LI Xiaoshan, ZHANG Yi, WANG Yingwei. Stress Simulation of Vetical Hydraulic Fracture Propatation Mechanism in Tight Conglomorate Reseriors of Mahu Area[J]. Xinjiang Petroleum Geology, 2020, 41(2): 193-198.

Figures/Tables 7

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