Production Induced Stress Change Impact on Infill Well Flowback Operations in Permian Basin
Authors: Zheng Wei , Xu Lili , Moncada Katharine , Xu Tao , Pankaj Piyush , Sinha Shekhar 
Published: October 2018

As many unconventional basins are maturing, infill well drilling and completion has taken the center stage in the development phase. Most operators now realize the importance of incorporating the geomechanical changes induced by stimulation and production of the parent wells while placing infill child wells. But after drilling and completion, post-stimulation flowback is also critical in maintaining well productivity and performance. To optimize field management strategy, a comprehensive understanding of the impact of production induced geomechanical property changes on infill well performance and its safe operating window for flowback operation is important. This paper investigates a well located in Permian basin and provides insights on flowback operation strategies for infill well using fully coupled finite element model and flowback simulator to help reduce fracture damage and maximize well deliverability.

First an integrated workflow coupling fracture, reservoir and geo-mechanic models is used in this paper to systematically investigate the depletion effects. Then a flowback simulator is utilized to robustly study the safe operating window for the infill well, implementing updated formation properties from previous model. A corresponding base model is created over wells completed in the Permian basin with geo-mechanical earth model generated from logs and field data. The integrated workflow with finite element computation was applied to predict the induced stress change after stimulation and production. To better understand the influence of geomechanical property changes over infill well performance and proppant flowback, a second model is also created, but without consideration of any production induced geomechanical property changes during flowback simulation. The differences of safe operating window simulated from these two models are compared and anaylized to reveal the impacts of stress change over the infill well in this area. Guidelines for adjusting choke settings and possible completion re-design are recommended to help reduce proppant flowback and improve the overall well productivity.

Based on the numerical results from above modeling study and comparison, flowback strategy is analyzed for infill well. In normal stress environment, due to the change in stress state from production and increase in differential stress around the wellbore, the choke management and possible completion design are adjusted accordingly as to reduce proppant flowback and optimize well performance. In addition, the capability of the workflow to model pressure depletion and associated stress conditions with respect to time enables us to optimize the field development for the area in long term.

The study presents a reference to strategic planning for operators and service companies to manage their infill well flowback operation on an existing pad with improved completion efficiency and stimulated volume in Permian basin. Intensive flowback operation management can help yield significant improvement in the well's long-term performance.