Influence of hydraulic fracturing on casing deformation of deep shale gas reservoir
In order to further study the main factors of casing deformation and casing failure mechanism during hydraulic fracturing of deep shale gas reservoir in Sichuan Basin,this paper established a three-dimensional finite element numerical analysis model under formation-cement sheath-casing coupling for deep shale hydraulic fracturing as well as a model for inducing slip of fault or natural fractures based on the idea of integration of geological engineering.Taking Well Lu 203 as an example,the evolution process of in-situ stress during hydraulic fracture propagation is systematically analyzed,and the main controlling factors of deep shale casing deformation under the influence of multiple factors in fracturing process are identified.The results show that:(1)During hydraulic fracturing,the three-dimensional in-situ stress changes affects the propagation law and distribution characteristics of hydraulic fractures;(2)The defects of cementing quality have a weak impact on casing deformation,and the slip of faults or natural fractures caused by hydraulic fracturing is the main cause of casing deformation;(3)In the early stage of fracturing,there is a rapid sliding phenomenon in faults or natural fractures.When the fluid pressure within the fault is sufficient to overcome the vertical stress,the shear stress on the fault surface is completely released and the slip stops.The research results can provide reference for the efficient development of hydraulic fracturing in deep shale gas reservoirs.
deep shale gashydraulic fracturingevolution of geostressnumerical simulationcasing deformation
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