摘要
Marine carbonate reservoirs in China are of a distinctive heterogeneity and complex formation mechanism,which have been all along a focus concerned by oil and gas exploration of China.We examined reservoir characteristics of the Yingmai-2 well field by applying various data of 3D seismic attributes,cores,imaging loggings and thin sections.It was concluded that reservoirs in the Yingmai-2 well field are not typical weathering-crust karst but faulted or fault-controlled karst.The reservoir space includes mainly fractures unfilled or semi-filled with calcite,small corroded vugs and cracks,and its distribution is strongly controlled by faults.Based on comprehensive analyses of structural activity background and fluid inclusion salinity,we thought that faulted karst in the study area experienced successively two corroded processes,one is surface water corrosion downward along faults and the other is hydrothermal fluid corrosion upward along faults.The former is predominantly constructive to the formation of reservoirs,while the latter is mainly destructive.The study result showed that it is not enough to search only for weathering-crust karst reservoirs in oil and gas exploration of the Tabei area,thus,more attentions should be paid to other types of reservoirs,among which fault-controlled karst is very promising to be the next significant exploration target in this area.