Characteristics of Present-day In-situ Stress in the Wufeng-Longmaxi Formation of Luzhou Block,Southern Sichuan Basin:Implications for Shale Gas Development
The Luzhou Block in southern Sichuan Basin is an important shale gas production area in China,where the Wufeng-Longmaxi Formation shale gas resources are abundant,indicating a high exploration and development potential.The present-day in-situ stress has important applications in the analysis of shale gas migration and enrichment,drilling and completion engineering,reservoir fracturing and well pattern deployment,etc.The present-day in-situ stress state of Wufeng-Longmaxi Formation deep shale gas reservoirs in the Luzhou block was analyzed,and natural fracture activity and hydraulic fracture propagation under the effect of present-day in-situ stresses were discussed.The research results show that the dominant present-day in-situ stress orientation in the Wufeng-Longmaxi Formation shale gas reservoir is WNW-ESE-trending.The magnitude of horizontal maximum principal stress is the largest,magnitude of horizontal minimum principal stress is the lowest,indicating a strike-slip stress regime.The stress difference in the Wufeng Formation and S1 l1-1-1 layer is 11.90～15.76 MPa and 11.80～16.75 MPa,respectively,which is beneficial for generating complex fracture networks.Under the present-day in-situ stress conditions,natural fracture activity in the Wufeng-Longmaxi Formation shale gas reservoirs of Luzhou Block is relatively weak.With fluid injection during shale gas development,natural fractures are gradually activated,and their critical pressure increase is 15～23 MPa.Hydraulic fractures vertically propagate under the strike-slip stress regime.The results can provide present-day in-situ stress analysis basis for further beneficial development of deep shale gas in the Luzhou Block of southern Sichuan Basin.
the present-day in-situ stressin-situ stress sectionfracture activitydeep shale gasLuzhou block
万方数据
维普
