Engineers commonly expect symmetric fracture wings in multiple transverse fracture horizontal wells (MTFHWs). Microseismic surveys have shown asymmetric hydraulic fracture grow away from the recent fractured wells and grow towards previous produced wells. It might be caused by the elevated stress around the recently fractured well and the reduced stress near the depleted wells. This paper presents the asymmetric fracture growth observed by the microseismic events and develops a simple model to simulate the fracture propagation and its impact on the well productivity.
Motivated by the microseismic observations, we developed a simple fracture model to simulate asymmetric fracture wings that can capture the behavior of fracture hits between two adjacent horizontal fractured wells. Also, we developed a model to estimate the productivity of a well with asymmetric fractures.
The newly developed fracture model shows that the fracture can grow asymmetrically if the horizontal well is located where stress field is different between its two sides. The productivity model for asymmetric hydraulic fractures quantifies the penalty to the well performance. Results provide a reason why asymmetric fractures happen and that they do penalize well performance. Our models suggest the importance of fracturing under balanced stress distribution which benefits the long-term production. Use of the model suggested an optimized hydraulic fracturing treatment design will improve the overall performance of multiple parallel wells that minimizes or avoids asymmetric fracture wings.
The fracture propagation model and productivity model provide simple, but profound, guidelines for the well pad management, including well spacing, stage planning and spacing, completion and production order.