Application of time-frequency electromagnetic method in predicting favorable areas for deep shale gas
Based on the exploration principle of integrating time-frequency domain and electricmagnetic fields,time-frequency electromagnetic(TFEM)exploration compensates for the shortcomings of traditional electro-magnetic methods in terms of insufficient anti-interference capability,and boasts advantages of controlled source electromagnetic methods such as multi-information integration and high precision.Guided by petrophysi-cal and well logging data,we conduct a time-frequency electromagnetic data within the Silurian Wufeng Forma-tion to Ordovician Longmaxi Formation shale series of the Baozang-Yunjin syncline in Luzhou to predict favora-ble areas for shale gas.Field outcrop measurements and resistivity logging data statistics indicate that high-re-sistivity shale formations generally exhibit better gas-bearing properties,providing the electric exploration with physical bases.Distinct electrical differences exist between different formations in the study area,which can be vertically divided into six alternating high-low resistivity layers.Notably,the Wufeng-Longmaxi formation,the primary shale gas production layer,exhibits significant resistivity differences from the host.Starting from the principles of time-frequency electromagnetic prospecting,we conduct numerical simulations using one-dimensional finite element and finite difference methods to validate the feasibility of the approach,and de-sign optimal acquisition parameters based on the forward modeling results.After specifically collecting data on the targeted formation,we use the independently-developed system GeoGME to process and explain the data and clarify the distribution characteristics of the resistivity and polarization of small layers of Long 1,submem-ber with the help of weak information extraction,well-seismic dual control constrained inversion,and other techniques.Comprehensively considering the resistivity anomalies and polarization anomalies of the targeted shale gas formation,we predict four favorable areas for shale gas prospecting,providing technical support for further deployment of shale gas drilling wells in this region.This study shows that the time-frequency electro-magnetic method is effective for predicting favorable areas for deep shale gas.
electromagnetic explorationWufeng-Longmaxi formationweak information extractionwell-seis-mic dual controlresistivitypolarization
万方数据
维普
