Numerical simulation study on creep characteristics and fracture closure of deep shale

Shale oil and gas resources are currently an important replacement resource for oil and gas in China and have huge potential development. During the mining process, the reservoir shale has creep characteristics due to its own physical properties and mineral composition, which causes the artificial fracturing network to produce a closure effect, which affects the production capacity of the reservoir. This work mainly studies the creep characteristics of reservoir shale and its influence on reservoir productivity. The shale in Chang-7 block of Yanchang formation in the Ordos Basin is selected as the research object. The triaxial creep experiment is used to determine that the shale creep law conforms to the power order. The Abaqus finite element analysis software is used to simulate the creep of the shale sample under the creep time of 1 year, 5 years, and 10 years to observe the changes of reservoir fractures under the action, evaluate the degree of fracture closure, and analyze the effect of creep on reservoir conductivity. The research results show that shale reservoir creep will cause proppant embedment and fracture closure, non-linear reduction of reservoir conductivity, and the growth rate of production gradually slowed down by the effect of time.