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| The prediction method of in-situ stress based on pre-stack anisotropic parameter inversion |
| Chao WANG1, Wei-Qi SONG1, Yu-Han LIN1, Yun-Yin ZHANG2, Qiu-Ju GAO2, Xin-Wei WEI2 |
1. College of Earth Science and Technology,China University of Petroleum(East China),Qingdao 266580,China
2. Institute of Geophysical Exploration,Shengli Oilfield Company,Sinopec,Dongying 257000,China |
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Abstract In the exploration and development of oil and gas reservoirs,the in-situ stress is closely related to the distribution of fractures,while fracture is an important channel for migration and accumulation of oil and gas,so the study of in-situ stress is of great significance for oil and gas development.In this paper,tight sandstone was taken as the research object.On the basis of the transverse isotropic rock layer model and in consideration of the complexity of sand and mud layer stress changes,the formation was assumed to be orthotropic,the elastic parameters of the inverse elastic impedance were taken as the background field of the working area,then the anisotropic parameters in orthotropic medium were obtained,and the ratio of differential stresses was calculated.The anisotropic impedance equation was used in this study,and the elastic parameters and fracture flexibility parameters were converted into anisotropic parameters,in order to verify the accuracy of the prediction method for the in-situ stress of tight sandstone;the ratio of differential stress calculated under the orthotropic model was compared with the results of the same log calculation and various characterization methods.It is shown that the results of geostress calculated under the assumption of orthogonal medium model are basically the same as those calculated by various control methods,thus proving that the orthotropic model stress prediction method is applicable in sand and mudstone formations,and has a good guiding significance for the exploration and development of low permeability oil and gas reservoirs in the future.
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Received: 29 March 2019
Published: 03 March 2020
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Flow chart of stress prediction
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Inversion results are processed
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Slice sections of elastic parameters and anisotropic parameters
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Slice of layers characterized by curvature (left) and curvature computed stress (right)
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Slice of the layers with the maximum (right) and minimum stresses (left)
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Comparison of horizontal slice of difference stress ratio under orthogonal anisotropy model (left) and calculation result of difference stress of well A logging curve (right)
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Fault interpretation diagram of the target layer(The black line is the fault line)
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