Post-fracturing productivity computation method of horizontal well with consideration to stress field variation: along the minimum principal stress in horizontal wellbore

The effect of reservoir stress variation on the fracture morphology is usually not considered in the simulation calculation on staged fracturing productivity of horizontal wells in low permeability and ultra-low permeability oil and gas reservoirs, leading to large calculation errors. In this paper, the 2D induced stress field computation model was combined with the estimated staged fracturing time interval in each stage to calculate the effect of the existing artificial fractures on the stress field variation and predict the artificial fracture morphology in subsequent fracturing. Then, based on the prediction results, a geologic model was established, and the 3D threephase black-oil model was used to calculate the post-fracturing productivity of horizontal wells. Finally, a staged fracturing productivity computation method of horizontal wells with consideration to the stress field variation in case of existence of artificial fractures was defined. According to the study results, when the stress field variation is considered, the artificial fracture morphology would change obviously, from the expected transverse fractures to T-like artificial fractures, and some transverse fractures would be far away from the planned perforation location. The field application in the JM reservoir shows that the five-year cumulative production of horizontal wells obtained with consideration to the existence of 8 transverse fractures is 5.6% different from that without consideration to the stress field variation. This verifies the necessity that the stress field variation should be considered in calculating the staged fracturing productivity of horizontal wells.