Automatic History Matching Study Of Shale Gas Reservoir Based On Microseismic Events And Production Data

Numerical simulation has been effectively applied to oil-gas reservoir prediction and dynamic analysis.History matching can increase reservoir engineers’ understanding for reservoir geological structure and fluid flow characteristics by parameters inversion,so as to improve the prediction accuracy of future reservoir dynamics.The assistant history matching technique,especially the data assimilation method based on the Ensemble Kalman Filter algorithm(EnKF),is applied to the reservoir parameters estimation,which greatly improves the efficiency and accuracy of the history matching.Hydraulic fracturing is one of the most economic and effective stimulation measures for shale gas reservoir.However,the failure of automatic history matching might be caused by the unclear grasp of reservoir geological information such as fracture distribution.Therefore,fracture diagnosis technology is crucial for accurate description of shale gas reservoirs.Finally,this paper proposed a new fracture identification and tracking technology based on microseismic events to characterize complex hydraulic fractures.And Embedded Discrete Fracture Model(EDFM)is used to accurately modeled complex fractures in order to ensure the efficiency and accuracy of EnKF automatic history matching.In this paper,a cluster-tracking algorithm based on space-time and energy parameters of microseismic events is firstly proposed to characterize the fracture geometry and distribution in order to clearly understand the geological model and to effectively ensure reservoir parameters inversion.The cluster–tracking algorithm was validated by acoustic emission(AE)monitoring and digital image correlation(DIC)laboratory experiments.The Ensemble Kalman Filter algorithm(EnKF)was used to further estimate gas reservoir flow parameters integrated with historical production data after obtaining a more accurate geological model of fractured shale gas reservoir by using the fracture tracking algorithm.The Embedded Discrete Fracture Model(EDFM)with high computational efficiency and accurate simulation results is applied to complex hydraulic fracture simulation to ensure the effective implementation of automatic history matching.The method proposed in this paper is applied to a typical fractured shale gas reservoir and a field shale gas reservoir block in Zhaotong.The results show that the new fracture tracking method can accurately interpret complex hydraulic fractures based on microseismic events.The prior information i.e.microseismic data,used to characterize fracture geometry,can provide a reasonable geological model for EnKF parameter inversion and improve the final parameter estimation,which is of great significance to the development and production prediction for shale gas reservoirs under uncertain conditions.Embedded Discrete Fracture model(EDFM)can simulate complex fractures accurately and efficiently,and ensure the effective implementation o f EnKF automatic history matching.By assimilating dynamic observations,the Ensemble Kalman Filter(EnKF)method can improve history matching efficiency,reduce the inversion parameters uncertainty and make an accurate production prediction.