The Jurassic Lianggaoshan Formation in eastern Sichuan Basin is a key target for shale oil exploration.It faces challenges in three-pressure prediction due to complex structural and sedimentary interactions,as well as...The Jurassic Lianggaoshan Formation in eastern Sichuan Basin is a key target for shale oil exploration.It faces challenges in three-pressure prediction due to complex structural and sedimentary interactions,as well as strong reservoir anisotropy.These issues often lead to wellbore instability and gas logging anomalies during drilling.This study presents an integrated workflow that combines residual moveout correction using correlation-based dynamic time warping(CDTW),high-resolution seismic waveform indication inversion,and three-pressure prediction of jointing well-seismic data.Applied to the LT1 well block,the workflow effectively corrects anisotropic residual moveout in image gathers,leading to a signal strength increase of over 10%in frequency bands above 30 Hz and enhancing event continuity.High-resolution rock mechanical parameters are obtained through seismic waveform inversion and regional calibration,enabling the prediction of three-dimensional pore pressure,collapse pressure and fracture pressure.The results are consistent with actual drilling gas shows and core data,confirming the method's accuracy and supporting mud weight planning and wellbore stability efforts.This cost-effective and technically robust approach proves highly reliable in complex environments with significant heterogeneity and anisotropy,assisting drilling decisions and risk management in eastern Sichuan and similar challenging geological settings.展开更多
Taiyuan formation is the main exploration strata in Ordos Basin, and coals are widely developed. Due to the interference of strong reflection of coals, we cannot completely identify the effective reservoir information...Taiyuan formation is the main exploration strata in Ordos Basin, and coals are widely developed. Due to the interference of strong reflection of coals, we cannot completely identify the effective reservoir information of coal-bearing reservoir on seismic data. Previous researchers have studied the reservoir by stripping or weakening the strong reflection, but it is difficult to determine the effectiveness of the remaining reflection seismic data. In this paper, through the establishment of 2D forward model of coal-bearing strata, the corresponding geophysical characteristics of different reflection types of coal-bearing strata are analyzed, and then the favorable sedimentary facies zones for reservoir development are predicted. On this basis, combined with seismic properties, the coal-bearing reservoir is quantitatively characterized by seismic inversion. The above research shows that the Taiyuan formation in LS block of Ordos Basin is affected by coals and forms three or two peaks in different locations. The reservoir plane sedimentary facies zone is effectively characterized by seismic reflection structure. Based on the characteristics of sedimentary facies belt and petrophysical analysis, the reservoir is semi quantitatively characterized by attribute analysis and waveform indication, and quantitatively characterized by pre stack geostatistical inversion. Based on the forward analysis of coal measure strata, this technology characterizes the reservoir facies belt through seismic reflection characteristics, and describes coal measure reservoirs step by step. It effectively guides the exploration of LS block in Ordos Basin, and has achieved good practical application effect.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supported by Science and Technology Cooperation Project of the CNPC-SWPU Innovation Alliance(No.2020CX010202).
文摘The Jurassic Lianggaoshan Formation in eastern Sichuan Basin is a key target for shale oil exploration.It faces challenges in three-pressure prediction due to complex structural and sedimentary interactions,as well as strong reservoir anisotropy.These issues often lead to wellbore instability and gas logging anomalies during drilling.This study presents an integrated workflow that combines residual moveout correction using correlation-based dynamic time warping(CDTW),high-resolution seismic waveform indication inversion,and three-pressure prediction of jointing well-seismic data.Applied to the LT1 well block,the workflow effectively corrects anisotropic residual moveout in image gathers,leading to a signal strength increase of over 10%in frequency bands above 30 Hz and enhancing event continuity.High-resolution rock mechanical parameters are obtained through seismic waveform inversion and regional calibration,enabling the prediction of three-dimensional pore pressure,collapse pressure and fracture pressure.The results are consistent with actual drilling gas shows and core data,confirming the method's accuracy and supporting mud weight planning and wellbore stability efforts.This cost-effective and technically robust approach proves highly reliable in complex environments with significant heterogeneity and anisotropy,assisting drilling decisions and risk management in eastern Sichuan and similar challenging geological settings.
文摘Taiyuan formation is the main exploration strata in Ordos Basin, and coals are widely developed. Due to the interference of strong reflection of coals, we cannot completely identify the effective reservoir information of coal-bearing reservoir on seismic data. Previous researchers have studied the reservoir by stripping or weakening the strong reflection, but it is difficult to determine the effectiveness of the remaining reflection seismic data. In this paper, through the establishment of 2D forward model of coal-bearing strata, the corresponding geophysical characteristics of different reflection types of coal-bearing strata are analyzed, and then the favorable sedimentary facies zones for reservoir development are predicted. On this basis, combined with seismic properties, the coal-bearing reservoir is quantitatively characterized by seismic inversion. The above research shows that the Taiyuan formation in LS block of Ordos Basin is affected by coals and forms three or two peaks in different locations. The reservoir plane sedimentary facies zone is effectively characterized by seismic reflection structure. Based on the characteristics of sedimentary facies belt and petrophysical analysis, the reservoir is semi quantitatively characterized by attribute analysis and waveform indication, and quantitatively characterized by pre stack geostatistical inversion. Based on the forward analysis of coal measure strata, this technology characterizes the reservoir facies belt through seismic reflection characteristics, and describes coal measure reservoirs step by step. It effectively guides the exploration of LS block in Ordos Basin, and has achieved good practical application effect.
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.
