As the industry continues pushing capital efficiency and chasing increasing lateral lengths, the odds of crossing subsurface faults or deformation zones rise. Some features can present different challenges than others. This study in the Midland Basin focuses on a strike-slip fault/deformation zone traversing a seven-well development. Although large-scale faulting is not as common in the Midland Basin as in other basins such as the Eagle Ford and Haynesville, they still present challenges that must be recognized and potentially mitigated. Deformation zones can lead to an unwanted connection to formations with higher water cuts or zones bearing H2S. From the completion perspective, deformation zones can also act as superconductive highways for frac fluids, leading to a loss of stimulation effectiveness and potentially less efficient capital deployment (Kerr et al., 2022). This study presents a possible mitigation technique to alleviate some of these economic, safety, and development concerns.
This study area is located in the northern part of the Midland basin (Figure 1a). Oil and gas development in this area includes wells in multiple targets within the Spraberry and Wolfcamp formations (Figure 1b). The San Andres, approximately one thousand feet below the surface, is a permeable dolomite enhanced by fracture permeability related to syndepositional margin collapse and reactivation of older faults during the Laramide Orogeny (Wilson et al., 2019). Over the last decade, the San Andres has been utilized as a salt-water injection formation. This injection of produced water into the San Andres has led to pressure gradient differences (Sanchez et al., 2019). These conditions are not only potential drilling hazards but can lead to vertical and lateral migration of the produced waters being injected in large quantities. Produced water injection promotes the growth of sulfate-reducing bacteria, which leads to the generation of hydrogen sulfide (H2S) as well as iron sulfides in producing wells. These can lead to serious safety concerns as well as implications for the optimized production of oil and gas reservoirs.