Well downspacing and in-fill drilling programs are in full swing for many unconventional reservoir plays in the transition to full field development. However, production or completion activities in offset wells can result in significant variations in pressure and stress within the reservoir, sometimes making it difficult to effectively stimulate the new wells. Pressure and stress imbalances can lead to highly asymmetrical fracture growth toward the low stress region. When this happens, hydraulic fracture width is significantly reduced at the junction of the fracture and wellbore.
This presentation is a case study of an in-fill Barnett Shale well exhibiting anomalous treatment behavior, which included proppant bridging (i.e., screen-out or pressure-out) as 100-mesh sand entered the fractures. Persistent pressure-out behavior led to terminating the fracturing program and suspending the well after attempting only two fracturing stages. The root cause of the adverse behavior was diagnosed as extremely variable reservoir pressure and stress, and a field-wide plan was implemented to reduce the pressure and stress imbalance in the vicinity of the problem well. Then, a remedial treatment plan was implemented, including using viscous fracturing fluid to enhance fracture width at the wellbore in order to facilitate proppant entry. A large volume of slick water was incorporated as well to enhance far-field fracture complexity. All nine fracturing stages were pumped to completion as per job design, including restimulation of one of the two previously screened-out treatment stages. Post-stimulation productivity of the treatment and offset wells was excellent.