BIOGEOCHEMICAL CHANGES IN PERMIAN BASIN RESERVOIRS DUE TO WELL-TO-WELL COMMUNICATION IMPACT WELLBORE INTEGRITY

High producing oil and gas regions, such as the Permian Basin, have a high occurrence of unconventional wells horizontally drilled and fractured in close geographical proximity. This results in frac hits, or interwell communication events where an established well is impacted by the pumping of fracture fluid into a new well. Although this well-to-well communication has been observed in industry, the extent to which these events impact produced fluid migration and the associated biogeochemistry has not yet been documented.

We completed three sampling events spanning from 2018 to 2022 in the Permian Basin. During our initial sampling events, we identified a unique geochemical signature which allows for the detection of frac hits. We returned in 2022 to explicitly measure the impact of well-to-well communication on the geochemistry and microbial community in adjacent wells. To do so, we collected produced water samples from 30 unique unconventional wells, including 14 wells adjacent to an active fracture job site, over a 2.5-week period in the Permian Basin. We also collected samples from both a nearby groundwater pond and a nearby pond of treated produced water.

We found that Permian Basin produced water is characterized by higher sulfate and lower total dissolved solids (TDS) concentrations compared to other regions. Interestingly, wells impacted by frac hits have a geochemical profile that resembles that of fracture fluid, with both lowered sulfate and lowered TDS concentrations compared to unaffected wells in this region. This unique frac hit geochemical signature results in an altered microbial community with presence of anaerobic, halophilic, and sulfur reducing taxa that demonstrate a high potential for deleterious microbial activity associated with souring and corrosion. These results demonstrate how well-to-well communication can result in unpredicted corrosion hazards for wellbore integrity.