Although high resolution can be provided by electrical logging, the measured electrical log range is narrow and is limited to near the well. Borehole-surface electric potential measurements are able to detect a wide e...Although high resolution can be provided by electrical logging, the measured electrical log range is narrow and is limited to near the well. Borehole-surface electric potential measurements are able to detect a wide enough range but its resolution is limited, particularly for reservoirs with complex oil and water distribution or complicated structure. In this study, we attempt to accurately locate the 3-D reservoir water and oil distribution by combining borehole-surface and crosswell electric potentials. First, the distributions of oil and water in both vertical and horizontal directions are detected by the borehole-surface and erosswell electric potential methods, respectively, and then the measured crosswell potential result is used to calibrate the measured borehole-surface electric potential data to improve vertical resolution so that the residual oil distribution is determined in a lower half-space with three dimensions. The evaluation of residual oil distribution is obtained by investigation of differences between the simulation results of the reservoir with and without water flooding. The finite difference numerical simulation results prove that the spatial residual oil distribution can be effectively determined by combining the crosswell and borehole-surface electric potentials.展开更多
3D inversion of borehole-surface electrical data for complex geo-electrical models is still a challenging problem in geophysical exploration. We have developed a program for 3D inversion to borehole-surface electrical...3D inversion of borehole-surface electrical data for complex geo-electrical models is still a challenging problem in geophysical exploration. We have developed a program for 3D inversion to borehole-surface electrical data based on the quasi-analytical approximation （QA） and re-weighted regularized conjugate gradient method （RRCG） algorithms using Visual Fortran 6.5. Application of the QA approximation to forward modeling and Frechet derivative computations speeds up the calculation dramatically. The trial calculation for synthetic data of theoretical model showed that the program is fast and highly precise.展开更多
The absorption and attenuation of seismic wave energy in complex loess plateaus has always been a challenging issue for geophysicists. The improvement of seismic data resolution and signal-to-noise ratio is particular...The absorption and attenuation of seismic wave energy in complex loess plateaus has always been a challenging issue for geophysicists. The improvement of seismic data resolution and signal-to-noise ratio is particularly difficult, making it hard to satisfy the requirements for describing reservoirs and exploring residual oil in mature oilfields. Based on the interpretation technology for conventional borehole seismic and surface seismic data, supporting interpretation technologies for fine reservoir description were developed by combining DAS 3D-VSP imaging data. These technologies included interpretation preprocessing based on boreholesurface joint exploration data, reservoir prediction, and fracture network characterization. In a certain block in the eastern part of the Ordos Basin, the post-stack adaptive spectrum broadening high-resolution processing technology based on borehole-surface joint exploration data has achieved a 5 Hz increase in main frequency and a 25 Hz bandwidth expansion. The waveform indication technology for thin reservoir inversion based on DAS 3D-VSP data could accurately identify single sand bodies with a thickness of 3~5 m, and the conformity rate of each horizon in the validation well reached 86.32%. The fracture-network identification technology based on dip-azimuth scanning constraint has achieved effective prediction of lower-order faults and fracture networks. Based on DAS borehole-surface joint exploration data, a set of fine reservoir description technologies integrating borehole surface data+borehole seismic data has been formed, and the accuracy of reservoir characterization has been improved by 15%. The application results show that the supporting technologies based on the DAS borehole-surface joint exploration have a significant promotional value.展开更多
文摘Although high resolution can be provided by electrical logging, the measured electrical log range is narrow and is limited to near the well. Borehole-surface electric potential measurements are able to detect a wide enough range but its resolution is limited, particularly for reservoirs with complex oil and water distribution or complicated structure. In this study, we attempt to accurately locate the 3-D reservoir water and oil distribution by combining borehole-surface and crosswell electric potentials. First, the distributions of oil and water in both vertical and horizontal directions are detected by the borehole-surface and erosswell electric potential methods, respectively, and then the measured crosswell potential result is used to calibrate the measured borehole-surface electric potential data to improve vertical resolution so that the residual oil distribution is determined in a lower half-space with three dimensions. The evaluation of residual oil distribution is obtained by investigation of differences between the simulation results of the reservoir with and without water flooding. The finite difference numerical simulation results prove that the spatial residual oil distribution can be effectively determined by combining the crosswell and borehole-surface electric potentials.
文摘3D inversion of borehole-surface electrical data for complex geo-electrical models is still a challenging problem in geophysical exploration. We have developed a program for 3D inversion to borehole-surface electrical data based on the quasi-analytical approximation （QA） and re-weighted regularized conjugate gradient method （RRCG） algorithms using Visual Fortran 6.5. Application of the QA approximation to forward modeling and Frechet derivative computations speeds up the calculation dramatically. The trial calculation for synthetic data of theoretical model showed that the program is fast and highly precise.
文摘The absorption and attenuation of seismic wave energy in complex loess plateaus has always been a challenging issue for geophysicists. The improvement of seismic data resolution and signal-to-noise ratio is particularly difficult, making it hard to satisfy the requirements for describing reservoirs and exploring residual oil in mature oilfields. Based on the interpretation technology for conventional borehole seismic and surface seismic data, supporting interpretation technologies for fine reservoir description were developed by combining DAS 3D-VSP imaging data. These technologies included interpretation preprocessing based on boreholesurface joint exploration data, reservoir prediction, and fracture network characterization. In a certain block in the eastern part of the Ordos Basin, the post-stack adaptive spectrum broadening high-resolution processing technology based on borehole-surface joint exploration data has achieved a 5 Hz increase in main frequency and a 25 Hz bandwidth expansion. The waveform indication technology for thin reservoir inversion based on DAS 3D-VSP data could accurately identify single sand bodies with a thickness of 3~5 m, and the conformity rate of each horizon in the validation well reached 86.32%. The fracture-network identification technology based on dip-azimuth scanning constraint has achieved effective prediction of lower-order faults and fracture networks. Based on DAS borehole-surface joint exploration data, a set of fine reservoir description technologies integrating borehole surface data+borehole seismic data has been formed, and the accuracy of reservoir characterization has been improved by 15%. The application results show that the supporting technologies based on the DAS borehole-surface joint exploration have a significant promotional value.
