ABSTRACT:

Low-permeability sandstone reservoirs have a large thickness and multi sandstone pay zones interbedded with thin mudstone layers in Shengli Oilfield. Staged fracturing in vertical wells is widely applied to stimulate sand-mudstone interbedded reservoir. To avoid hydraulic fracture propagating through the interface between sandstone and mudstone as well as control the fracture height, stress field interference study and accurate treatment parameters in different perforation clusters are of the essence. A fluid flow model coupled wellbore-perforations-fractures (WPF) is established to describe the flow distribution in different perforation clusters. The WPF model based on Kirchhoff’s law is coupled with the fractures flow. A coupled flow-stress-damage (FSD) nonlinear finite element model which consists of layers, interlayers, and weak planes is established. Studying on the changes of fracture vicinity stress field during propagation is to compare and analyze the parameters which influence the induced stresses. Meanwhile, the treatment parameters and the mudstone thickness are optimized.

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