A New Stimulation Method to Significantly Improve Hydrocarbon Recovery Using Temporary Beneficial Changes in Stress Anisotropy

摘要

As a result of the creation of a hydraulic fracture, transient geomechanics forces are exerted on the formation, which modify the stress landscape near the wellbore and the fracture plane. It has been observed that the potential exists for temporary reversal in the minimum stress direction, enabling a brief time interval in which a second hydraulic fracture can be created in a completely different direction. This provides hydraulic fracturing connectivity to previously unattainable locations in the formation, which can significantly improve initial hydrocarbon production and economic ultimate recovery from the formation. This paper presents a computational validation of this multioriented hydraulic fracturing (MOHF) process. A unique transient 3D computational geomechanic fracture simulator was developed to perform this study, as traditional hydraulic fracture simulations are derived using static formation properties and steady-state assumptions. The new model incorporates cohesive zone elements to represent the fracture plane and friction elements to account for plastic energy storage of the multiple formation rock layers in the model. Time lapse stress fields show distinct windows of opportunity wherein new fractures can be influenced to extend in alternate directions. This new stimulation method enhances the state-of-the-art in hydraulic fracturing. However, a deeper understanding of the transient geomechanic response in the treatment area is necessary to successfully design and perform the stimulation operation. Unfortunately, it also creates new complications with respect to industry standard hydraulic fracture models being incapable of modeling the transient response of the system. Furthermore, the availability of data related to the dynamic behavior of rocks is limited, and unique testing equipment and procedures must be developed to obtain such data.