Produced water disposal is a necessary component of development plans for Wyoming Operators. Not all existing wells will make acceptable disposal wells according to the Wyoming Oil & Gas Conservation Commission (WOGCC) or the Wyoming Department of Environmental Quality (WDEQ). The following checklist provides a comprehensive screening criterion for disposal well selection.
Disposal or Injection?
- Is the well completed in a formation that has been unitized for secondary recovery (waterflood)?
- If a waterflood unit has been approved with an aquifer exemption, the injection application may be approved administratively which should take 15 days or less and would not require a hearing. (Chapter 3 Section 7)
- If the well is not within a unitized waterflood area and the purpose of the disposal is not to displace oil or gas, a disposal application is appropriate. (Chapter 3 Section 5)
Aquifer Exemption Criterion
Source Water (fluid expected for disposal)
- What type of fluid do you expect to disposal of? (This will help identify the type of application required and the regulating agency to report to.)
- Hazardous, Industrial, or Municipal waste – considered Class I disposal which is regulated by the WDEQ.
- Oil field waste from your wells- considered Class II Non-commercial disposal which is regulated by the WOGCC.
- Oil field waste from your wells and wells operated by others – considered Class II Commercial disposal which may be regulated by the WOGCC (as of 2021) or the WDEQ.
- CO2 Sequestration – considered Class VI Disposal which is regulated by the WDEQ.
- Has a water sample from the well been analyzed for Total Dissolved Solids (TDS)?
- If TDS > 10,000 ppm, the application process will typically remain under the jurisdiction of the WOGCC.
- If TDS 5,000-10,000 ppm, the application will be reviewed by the EPA for concurrence which will add at least another 45 days to the approval process.
- If TDS < 5,000 ppm, expect rigorous involvement from EPA.
- If a sample has not been collected, how difficult will it be to collect a representative sample from the receiving formation? The WOGCC typically requires a water sample analysis prior to disposal approval. It may also be beneficial to test for the presence of hydrocarbons especially if low TDS is anticipated.
- Did laboratory testing of the water sample include QA/QC?
- The WOGCC requires that all water sample testing include appropriate QAQC documentation. If the lab did not document these procedures, another water sample will likely need to be collected and tested.
- The following questions may need to be addressed with a Wyoming-licensed Professional Geologist:
- Are there adequate geologic aquitards that will confine the injected fluid to the approved disposal formation?
- Is there seismic activity in the area?
- Are there nearby faults?
Well Construction & Mechanical Integrity
- Is the well cased and cemented adequately? Will the well pass a pressure test or require remedial cementing?
- Such activities may delay approval.
- Is a cement evaluation log available?
- A CBL is generally required to document isolation of the receiving interval in the wellbore.
Migratory Pathway Wells
- Are there other wells within 1/4-mile of the proposed disposal well?
- Do any of the wells within 1/4-mile of the proposed disposal well penetrate the disposal formation or the overlying confining unit?
- All wells within 1/4-mile of the proposed disposal well that penetrate the disposal formation or overlying confining unit, including P&A’d wells, will need to be evaluated to determine if the wellbore(s) could serve as a migratory pathway to other formations.
- Producing rates of nearby wells may be impacted by the disposal operations.
- Does an existing disposal well exist within 1/4-mile of the proposed disposal well?
- If yes, a closer inspection will be required to determine if the two plumes of injectate will overlap and to what degree.
Land & Mineral Ownership
- Who owns the surface and mineral rights within 1/2-mile of the proposed disposal well?
- Wyoming has unique laws that grant the surface estate the ownership of non-hydrocarbon-bearing pore space.
The formations in Wyoming that are typically available for disposal tend to exhibit much lower reservoir quality than disposal formations in the Gulf Coast Region; this can make disposal solutions a challenge for Wyoming Operators. Unfortunately, the Wilcox Formation does not exist in Wyoming.