Geomechanical Studies on Fractured Basement Oil/Gas Reservoir in Yufutsu, Japan

摘要

Geomechanical information is of crucial importance for optimizing development of fracturedrnoil/gas reservoirs. Forming and re-activating fractures in a reservoir are strongly affected by stressrnenvironment; consequently the most of fractures contributing fluid flow are showing preferentialrnorientations. This paper summarizes recent studies relating to the characterization and modeling forrnthe fractured basement reservoir in Yufutsu oil/gas field. The studies include multi-scale fracturernsurveys using cores, borehole images, microseismic monitoring, and 3D seismic survey. Thoserndata-sets are analyzed independently and interpreted in the context of stress environment andrnintegrated to characterize field scale fracture distribution. The flowing fractures confirmed in thernproduction wells show orientations preferential to shear failure. The major fracture systemsrninterpreted from microseismic distribution also have similar orientations and additionally provide us arncharacteristic spacing. The ant-track outputs from 3D seismic survey provide potential sub-seismicrnfaults and can extrapolate the knowledge extracted from microseismic data to all over the field. Wernconclude that an integrated interpretation combining stress and fractures is of most importantrnapproach to delineate the major flow pathways in the reservoir and optimize the development.