Present-day in situ stress prediction in Bozi 3 deep sandstone reservoir, Kuqa Depression: implications for gas development

Resources, including petroleum and natural gas, from deep and ultra-deep reservoirs have become an important contributor to global reserve growth and deliverability construction. Knowledge of the present-day in situ stress field has significant applications for efficient exploration and development. The Bozi 3 deep sandstone reservoir is important for increasing natural gas production in the Kuqa Depression. However, little attention has been given to the present-day in situ stress state of the Bozi 3 Block. In this study, the in situ stress orientation and magnitudes were investigated based on stress indicator interpretation, well log calculation, and geomechanical modeling. Drilling-induced tensile fractures and borehole breakouts indicated a dominant NW-SE direction for the horizontal maximum principal stress (SHmax) in the Bozi 3 deep sandstone reservoir. The stress regime for the Bozi 3 Block indicates a dominant strike-slip faulting type (SHmax≥Sv≥Shmin). Numerical simulation of the present-day in situ stresses showed that the SHmax and horizontal minimum principal stress (Shmin) magnitudes were − 150~− 178 MPa and − 121~− 157 MPa in the Cretaceous, respectively. Natural fractures are generally stable in the present-day stress field. When the specific gravity reaches 2.15, approximately 75% of all natural fractures are reactivated. Under the present-day stress state in the Bozi 3 Block, new horizontal wells should be drilled with ENE-WSW-trending. The results for the present-day in situ stress state are expected to provide geological and engineering references for deep gas production in the Bozi 3 Block of Kuqa Depression.