Simulation of reservoir seismic response in the northern slope of the middle Tarim Basin with random fracture-cavern media model
Ma Lingwei1,2, Yang Qinyong1, Gu Hanming3, Liu Jun4, Lin Zheng-liang1, Lü Shanshan5
1. Geophysical Research Institute, SINOPEC, Nanjing, Jiangsu 211103, China;
2. School of Earth Sciences and Engineering, Nanjing University, Nanjing, Jiangsu 210046, China;
3. Institute of Geophysics and Geomatics, China University of Geosciences(Wuhan), Wuhan, Hubei 430074, China;
4. Research Institute of Exploration and Development, Northwest Oilfield Branch Co., SINOPEC, Urumqi, Xinjiang 830011, China;
5. East China 814 Geophysics Survey Company Limited, Nanjing, Jiangsu 210007, China
Abstract：In fractured carbonate reservoirs,rocks show discontinuous changes in physical properties and reservoir bodies vary significantly in shape.For this reason,existing random media models are incapable to simulate fractured carbonate reservoirs.Moreover,as random media exhibit heterogeneity only in horizontal and vertical directions,these models cannot describe heterogeneous characteristics of underground rocks in arbitrary directions.In this view,a new autocorrelation function is constructed by introducing a directionality factor into a mixed autocorrelation function,and the resulted random media will be directional.Based on this,fractured media models with different statistical characteristics are created by thresholding and designating the lengths of semi-major and semi-minor axes of fractures as well as local fracture density.These models can be used to effectively describe complex fractures of varying sizes,density,orientations,and filling rates.Then a random fractured media model is developed for the northern slope in the Tazhong Uplift using borehole data and results of well logging interpretation.After that,wave equation modeling for heterogeneous media is performed to investigate the kinematic and dynamic characteristics of a reservoir located at the top of Yijianfang Formation with different parameter values.The outcome of forward modeling suggests that as the fracture size and density increased,the fracture filling rate decreased,and the peak corresponding to the T74 interface shows a weaker reflected energy at low-frequency.This result provides a basis for analyzing wave field and characterizing fractured reservoirs at the top of the Yijianfang Formation.Furthermore,the most sensitive attributes to fractured reservoir variations such as root mean square amplitude and instantaneous frequency are extracted to improve fractured reservoir prediction in the presence of strong reflection interference from interfaces.
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Ma Lingwei, Yang Qinyong, Gu Hanming, Liu Jun, Lin Zheng-liang, Lü Shanshan. Simulation of reservoir seismic response in the northern slope of the middle Tarim Basin with random fracture-cavern media model. OGP, 2016, 51(6): 1119-1127.
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