The Lower Cambrian Longwangmiao Fm carbonatite gas reservoirs in the Leshan-Longnüsi Paleouplift in the Sichuan Basin feature strong heterogeneity,well-developed fractures and caverns,and a high content of H_(2)S...The Lower Cambrian Longwangmiao Fm carbonatite gas reservoirs in the Leshan-Longnüsi Paleouplift in the Sichuan Basin feature strong heterogeneity,well-developed fractures and caverns,and a high content of H_(2)S,so these reservoirs are prone to reservoir damages caused by the invasion of drilling fluid or the improper well completion,so to minimize the reservoir skin factor is key to achieving high yield of oil and gas in this study area.Therefore,based on the geological characteristics of the Longwangmiao reservoirs,the binomial productivity equation was applied to demonstrate the possibility and scientificity of minimizing the skin factor.According to the current status of reservoir stimulation,the overall skin factors of reservoir damage caused by drilling fluid invasion,improper drilling and completion modes etc were analyzed,which shows there is still potential for skin factor reduction.Analysis of reservoir damage factors indicates that the main skin factor of Longwangmiao Fm reservoirs consists of that caused by drilling fluid and by improper completion modes.Along with the minimization of skin factor caused by drilling and improper completion,a fracture-network acidizing process to achieve“non-radial&network-fracture”plug-removal by making good use of natural fractures was proposed according to the characteristics of Longwangmiao Fm carbonatite reservoirs.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
基金National science and technology major project“Complex Carbonate Gas Reservoir Development Technology Research”(No.2011ZX05015-003-005).
文摘The Lower Cambrian Longwangmiao Fm carbonatite gas reservoirs in the Leshan-Longnüsi Paleouplift in the Sichuan Basin feature strong heterogeneity,well-developed fractures and caverns,and a high content of H_(2)S,so these reservoirs are prone to reservoir damages caused by the invasion of drilling fluid or the improper well completion,so to minimize the reservoir skin factor is key to achieving high yield of oil and gas in this study area.Therefore,based on the geological characteristics of the Longwangmiao reservoirs,the binomial productivity equation was applied to demonstrate the possibility and scientificity of minimizing the skin factor.According to the current status of reservoir stimulation,the overall skin factors of reservoir damage caused by drilling fluid invasion,improper drilling and completion modes etc were analyzed,which shows there is still potential for skin factor reduction.Analysis of reservoir damage factors indicates that the main skin factor of Longwangmiao Fm reservoirs consists of that caused by drilling fluid and by improper completion modes.Along with the minimization of skin factor caused by drilling and improper completion,a fracture-network acidizing process to achieve“non-radial&network-fracture”plug-removal by making good use of natural fractures was proposed according to the characteristics of Longwangmiao Fm carbonatite reservoirs.
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.
