Injection Capacity and Hazard Analysis

Efforts to understand the injection capacity of systems in the Permian Basin and associated hazards

Injection for permanent disposal is the primary method used to manage the ~6 billion barrels of water produced annual from unconventional oil and gas wells in the Permian Basin region, with injection accounting for 80% of the volume of water produced in recent years. In the Midland and Delaware basins, injection occurs into two main subsurface stratigraphic levels: one below petroleum-producing shales and directly above the geologic basement (“deep”), and one above petroleum-producing shales and below evaporite-rich top seals (“shallow”). Geographically there are a total of five large-scale geologic systems utilized for injection Permian Basin: deep zones in the Delaware Basin, deep zones in the Midland Basin, shallow zones in the Delaware Basin, shallow zones in the Midland Basin, and all injection zones in the Central Basin Platform.

CISR research provides the requisite components to understand the capacity of each injection system in the basin, both at present day and with likely future development of the basin. Capacity assessments consider limits to injection such as permitted maximum surface injection pressures, fracture gradient of the injection strata, and containment by regional caprocks and seals. Assessments also provide insight into the occurrence of injection impacts such as ground surface deformation, earthquakes, surface flows of effluent, and drilling hazards. CISR’s pilot capacity assessment for the central Delaware Basin shallow injection system will be completed in 2024 and publicly available in 2025, and will be followed by capacity assessments of the other four injection systems in the Permian Basin region.

With funding from the Groundwater Protection Council, CISR developed a workflow to use uniform and comprehensive map-based products to help understand potential impacts and hazards of injection into shallow and deep strata in the Permian Basin. These maps span the required aspects of injection capacity assessment and earthquake hazard mitigation including:

Maps of wastewater co-produced with oil and gas production and wastewater injection
Maps of depth, thickness, porosity, and net pore volume for the principal injection target intervals
Maps of injection interval pore pressure evolution from comprehensive hydrogeologic models
Updated maps of fault systems in contact with the principal injection target intervals and indexed by relationship to recent seismicity
Maps of in situ stress including Sv, SHmax azimuth, stress ratio
Maps of fault slip potential indexed to the in situ condition prior to significant injection and also with consideration of pore pressure increase
Maps of ground surface heave from analysis of InSAR data

Through this effort, we aim to facilitate important discussions between stakeholders about water management and environmental risk. This framework can also shed light on methods and approaches to assess the capacity of the injection resource with constraints including environmental hazards.

Primary Contact: Katie Smye (katie.smye@beg.utexas.edu)

Figure: Components used as input for assessment of injection capacity and associated hazards, including operational data, geologic interpretations, modeled results, and impacts of injection.