95-9 Injection Capacity of Shallow Reservoirs in the Permian Basin: Implications for Wastewater Management in the World’s Most Productive Oilfield

Session: Sustainable Subsurface Pore Space Utilization: Site Selection, Characterization, and Modeling

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Abstract:

Injection into subsurface reservoirs is the main strategy to handle the 20 million barrels of wastewater produced daily in the Permian Basin region, currently the most productive oilfield in the world. Understanding the capacity of the injection reservoirs to safely accommodate injected fluid is critical for future production in the region, and findings from this large-scale injection experiment have implications for other subsurface injection and storage operations.

Injection in the Permian Basin is into two subsurface levels: “deep” injection between shale producing strata and crystalline basement, and “shallow” injection between producing strata and the ground surface. Deep injection volumes have been curtailed in some areas of the basin due to induced earthquakes, increasing the demand for shallow injection. Shallow injection accounts for more than two-thirds of current injection, at rates of more than 250 million barrels per month in the Delaware Basin and 100 million barrels per month in the Midland Basin. To date, these reservoirs have received over 30 billion barrels of fluid. Challenges associated with this scale of injection are numerous, and include surface flows from older vertical wellbores, well control issues, and increased cost and hazard of drilling through the injection strata.

Here we show a quantitative analysis of the capacity of these shallow injection reservoirs to safely receive injected fluids. In both basins, injection reservoir stratigraphy, facies, and porosity and permeability distributions are characterized. Dynamic simulations of pore pressure change with injection show increases of hundreds of psi regionally in both basins, and up to 1000 psi in some areas of the Delaware Basin, increasing the native reservoir pressure by up to 40% locally. Remaining injection capacity is calculated per square-mile for a range of scenarios with varying pressure limits and compressibility values, and the remaining life of the injection resource is calculated based on extrapolation of present injection volumes. We show that in key areas of the Permian Basin, local injection capacity has already been exceeded by injection to-date. Areas of capacity exceedance show evidence of surface uplift of tens of centimeters and are spatially coincident with surface flows and other well incidents. Results provide critical data for mitigation of the most problematic areas of the basin and serve as a resource to optimize injection operations.

Geological Society of America Abstracts with Programs. Vol. 57, No. 6, 2025

doi: 10.1130/abs/2025AM-10699

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