A set of fine exploration technologies had been developed and applied to improve exploration success rate in the tight sandstone gas reservoirs in the Upper Triassic Xujiahe Formation in Hexingchang-Fenggu area

western Sichuan Basin.Guided by geological understandings and based on seismic data

the technologies are employed to study the tight sand gas reservoirs through fine division and correlation of sand groups as well as integration of dynamic performance with static geological features.The gas reservoir characteristics were described and the main controlling factors were identified.Sweet spot prediction and well emplacement were carried out through strengthening seismic prediction

drilling tracing

testing layer selection as well as comprehensive geologi-cal study during stimulation.The success rate of exploratory drilling has been greatly improved through real-time modification of drilling program during drilling operation.Fine exploration of the Hexingchang-Fenggu area reveals that the gas reservoir has the characteristics of water-soluble gas.It can be classified as paleo-structural-lithological trap

with paleo-structural high controlling gas accumulations.Four play fairways were identified:the wellblocks of CH148-CH137-GM3 and GM2-CG561 with the second member of Xujiahe Fm as the target

and the wellblocks of GM2-CG561-GM4 and CF563-CF175 with the fourth member of the Formation as the target.