Methods for high-precision tectonic stress field simulation and multi-parameter prediction of fracture distribution for carbonate reservoirs and their application
Tectonic fractures serve as primary reservoir spaces of carbonate rocks,and local stress-induced tectonic fracturing acts as a prominent factor influencing their development.Simulating tectonic stress fields using the finite element method has become an important method for tectonic fracture prediction.However,this method faces challenges such as large discrepancies between model setting and actual geologic condition,low efficiency in obtaining optimal boundary conditions,and undefined factors governing the development of tectonic fractures.To address these issues,a method for constructing a heterogeneous rock mechanics model and a self-adaptive boundary constraint algorithm are introduced to enhance the precision of stress field simulations,and quantitatively characterize fracture development in reservoirs using parameters such as reservoir rupture rate and fault activity.Then,by quantitatively exploring the impacts of differences in strike-slip fault deformations and stress perturbations on tectonic fractures,the most significant factors controlling fracture development are selected to construct a development index for fractured carbonate reservoirs,and quantitatively investigate its dominant controlling factors.Lastly,based on reservoir scale prediction,as well as single-well fracture logs and core interpretations,we build a geologic model of fractured carbonate reservoirs at different levels.This method has been applied to the Ordovician carbonate reservoirs in the No.18 fault zone and adjacent regions in Shunbei area,Tarim Basin.The application results indicate that the degree of fracture development decreases in the order of transtensional,translational,and transpressional fault segments of the fault zone and that higher deformation amplitude of strata is associated with a higher developmental degree of fractures.In addition,the development index of fractured reservoirs is constructed using the rock mechanical parameters,distances from faults,horizontal bidirectional stress differences,stress heterogeneity coefficient,and comprehensive rupture rate of reservoirs.The reservoir classification results based on this index align closely with actual geologic conditions.
dominant factor controlling fracture developmenttectonic stress field simulationquantitative prediction of fracture distributionquantitative assessment of reservoircarbonate reservoirOrdovicianShunbei areaTarim Basin
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