Abstract
Interwell interference has been widely observed in the development of unconventional reservoirs. It describes the phenomenon that legacy production of parent wells impact the completion quality of child wells, which in return changes production performance of both parent and child wells. This work models pressure and stress evolutions caused by parent well depletion and the corresponding asymmetric child well hydraulic fracture growth.
The study presents a 3D finite-element-based fully coupled flow and geomechanics model that simulates the poroelastic behaviors of pressure and in-situ stress evolutions, and a hydraulic fracture model. Based on the simulated pressure and stress heterogeneities at and around child wells, the complex and asymmetric fracture patterns for the child well can be quantified. In the study, with several candidate child-well locations placed away from the parent well, the stress and pressure evolutions along the child well are observed to be asymmetric. Numerical investigations show that production timing of parent wells, in-situ stress contrast, well spacing, parent well fracture geometry, and the design of perforation clusters along the child wellbore are key parameters affecting the asymmetric fracturing of child wells. Specifically, prolonged parent well production, small in-situ stress contrast and close parent-child well spacing lead to significant asymmetric stress and pressure evolutions along the child well, and consequently contribute to the asymmetric fracture wing growth during child well completion. Effects of the parent-well fracture geometry on asymmetric child-well fracture wing growth are only noticeable when the well spacing is small. This work identifies key parameters in a typical interwell interference case and studies their effects on asymmetric child well fracturing. The work serves as a reference for the avoidance of child-well underperformance, which is widely observed in many major shale plays.
