Present in-situ stress distribution characteristics of strike-slip in SH Oilfield, Tarim Basin

Present in situ stress field is the basis of petroleum engineering, and its distribution characteristics are the key to reservoir reconstruction. The target reservoir in SH Oilfield is a fractured-vuggy reservoir controlled by strike-slip fault, which needs fracturing. However, the present in situ stress field distribution characteristics of the main faults in SH Oilfield are still unclear, which needs to be solved. Taking SB1, SB5, and SB7 faults as research targets, the magnitude and direction of present in situ stress field in the study area are calculated by using logging data and oil well dynamic data. The single well in situ stress profile is established, and then the difference of present in situ stress distribution in different strain segments of strike-slip fault is discussed. On this basis, the boundary element numerical simulation method is used to study the influence of the fault on the present in situ stress distribution. The trend of fracture sliding friction is introduced to measure reservoir quality qualitatively. The results show that the maximum principal stress in SH area is 180~1220MPa, and the direction is NE39 °~ 46°; the middle principal stress is 178~187MPa, and the direction is vertical; the minimum principal stress is 131~135MPa, and the direction is SE129°~136°. The whole SH area is in the state of strike-slip stress. The strike-slip fault disturbs the direction of the horizontal principal stress. The maximum horizontal principal stress near the fault twists obviously and tends to be parallel to the fault. The present in situ stress field state of different strain segments in strike-slip fault is different, and the difference is mainly reflected in the maximum horizontal principal stress. The horizontal compression of uplift segment is the strongest, up to 227MPa, followed by the translation segment, and the horizontal compression of pull-apart segment is obviously weakened, only 197MPa. Using the fracture sliding trend as the qualitative evaluation standard of reservoir quality, it is found that the permeability of pull-apart segment has the best permeability, the translation segment takes the second place, and the uplift section is the worst. The results are consistent with the actual oil production. © 2021, Saudi Society for Geosciences.