In order to streamline the CalGEM well review and data upload process associated with UIC project applications, CalGEM is requesting operators utilize the 'UIC Project Well List' template and upload it with your WellSTAR Application for Injection Approval form. This template utilizes the same format CalGEM uses to complete well reviews and moves data into WellSTAR through an internal Electronic Data Deliverable (EDD). A User Guide to populate the template is also available on the WellSTAR Training Page.
Application for Injection Approval
An operator requesting approval for an underground injection project must provide detailed data that, in CalGEM’s judgment, are pertinent and necessary for the evaluation of a proposed project. (14 CCR § 1724.7.) The application must include a detailed engineering study that includes a statement of the primary purpose of the project; the reservoir and fluid characteristics of each injection zone; and the planned well drilling and plugging and abandonment program to complete the project, including a flood-pattern map showing all injection, production, and plugged and abandoned wells, and unit boundaries. The engineering study must also include casing diagrams for all idle, plugged and abandoned, and deeper zone producing wells within the area affected by the project. The casing diagrams in the engineering study must evidence that plugged and abandoned wells in the area will not have an adverse effect on the project or cause damage to life, health, property, or natural resources. (14 CCR § 1724.7(a).)
Along with the engineering study, a geologic study and injection plan must also be submitted. At a minimum, the geologic study must include a structural and isopach map, at least two cross sections in the area of review through at least three wells including one injection well, and a representative electric log that identifies all geologic units, formations, freshwater aquifers, and oil or gas zones. (14 CCR § 1724.7(a)(2).) The injection plan must include a map showing all injection facilities; maximum anticipated injection pressure and volumes; monitoring system or method used to ensure that injection fluid is confined to the intended zone or zones of injection; method of injection; corrosion protective measures; the source, analysis, and treatment of the injection fluid; and the location and depth of water-source wells to be used in conjunction with the project. (14 CCR § 1724.7(a)(3).)
Additional information can be requested for projects that may be hazardous, large, unusual, or particularly complex. (14 CCR § 1724.7(e).) In instances where an operator desires to change or modify any of the originally approved operating methods or conditions of a project, such as expansion of the project, change of the injection interval, or an increase in the maximum allowable surface injection pressure, the operator must first obtain approval from CalGEM. (14 CCR § 1724.10(a).)
In order to expedite the application process, operators should evaluate the data being submitted to determine if the program requirements discussed below will be met. It is the operator’s responsibility to demonstrate to CalGEM’s satisfaction that the program requirements are met.
Area of Review
As explained above, every injection project must be supported by an engineering study that includes casing diagrams for all idle, plugged and abandoned, and deeper zone producing wells within the area affected by the project. The casing diagrams in the engineering study must evidence that plugged and abandoned wells in the area will not have an adverse effect on the project or cause damage to life, health, property, or natural resources. (14 CCR § 1724.7(a).) Additionally, CalGEM must evaluate casing diagrams for all wells within the area affected by the project including directionally drilled wells that intersect the injection zone or a deeper zone within the area affected.
Boundary Area of Review
In determining the “area affected by the project”, CalGEM’s definition of the Area of Review (AOR) is consistent with the federal Safe Drinking Water Act (SDWA) regulations. (14 CCR § 1720.1(a).) Under the federal regulations, the AOR is a minimum fixed radius of one-quarter-mile from the well bore, unless an approved mathematical model is used to determine the “zone of endangering influence.” (40 CFR § 146.6.) The federal regulation provides a modified “This equation” as an example of such a mathematical model. (40 CFR § 146.6(a)(2).) CalGEM’s regulations do not refer to the “zone of endangering influence” but rather describe this as the calculated distance that injected fluid may migrate. For an AOR using a fixed one-quarter-mile radius the following factors are to be taken into consideration: chemistry of the injected and formation fluids; hydrogeology; population; ground water use and dependence; and historical injection practices in the area. (40 CFR § 146.6(b).)
CalGEM nominally defines an AOR boundary for a proposed injection well as a fixed one-quarter-mile perimeter around the portion of the well’s path that lies within the approved zone of injection as projected on a horizontal plane at ground level. However, this definition is a starting point in determining an AOR boundary. The AOR boundary may be reduced or expanded based on pertinent information regarding the well’s completion, the local geology, and the injection parameters, including approved mathematical modeling.
Confinement to the Intended Zone
Every injection project must include an injection plan that ensures that the injection fluid will be confined to the intended zone or zones of injection. (14 CCR § 1724.7(e)(3).) To confirm that injection fluid is confined to the approved zone or zones, mechanical integrity testing must be performed on each injection well upon commencement of injection and periodically thereafter. (14 CCR § 1724.10(i).)
In order to determine whether abandoned wells within the AOR could act as a conduit for injection fluid, well data must be examined to ascertain the condition of the wells. Consistent with the requirements discussed below, it is safe to assume that a well will not act as a conduit if it has a verified 100 linear feet of cement above the approved zone of injection, or a calculated 150 linear feet of cement above the approved zone of injection. (When the top of cement is determined by calculation a substantial margin of safety is needed to allow for variations in hole size, cementing procedures, pre-flush conditions and displacement of fluids.) For abandoned wells, consideration must be given to the cement both inside and outside all casing strings, but for active and idle wells, only the cement outside of all casing strings is relevant.
The specific requirements to be considered when examining the data for wells within the AOR include the following:
- Plugged and abandoned wells are required to have oil-bearing or gas-bearing strata isolated. Operators are required to use every effort and endeavor to protect any underground or surface water suitable for irrigation or domestic purposes from the infiltration of detrimental substances. (Pub. Resources Code, § 3228.) State Water Resources Control Board Resolution No. 88-63 (Appendix A) states that water with total dissolved solids (TDS) of 3,000 mg/L or less is suitable, or potentially suitable, for municipal or domestic use. An aquifer exemption may be required for water with TDS between 3,000 and 10,000 mg/L. (40 CFR 146.4.)
- Current regulation requires operators to fill the annular space to at least 500 feet above oil and gas zones and anomalous pressure intervals. However, prior to 1978, operators were only required to have 100 feet of cement in the annular space above oil and gas zones and anomalous pressure intervals. CalGEM may provide a variance to the current requirement if supported by known geological conditions. (14 CCR § 1722.4.)
- Plugged and abandoned wells are required to have cement across all perforations and the plug shall extend at least 100 feet above the top of a landed liner, the uppermost perforations, the casing cementing point, the water shutoff holes, or the oil and gas zone, whichever is highest. (14 CCR § 1723.1(b).)
- In an open hole, a minimum 200-foot plug is required across all fresh-saltwater interfaces. An interface plug may be placed wholly within a thick shale if the shale separates the freshwater from the brackish or saltwater sands. If there is cement behind the casing across the fresh-saltwater interface, then a 100-foot plug is required inside the casing across the interface. Squeeze-cementing, a cavity shot, or other special plugging procedures may be required in certain circumstances. (14 CCR § 1723.2.)
Submission of Area of Review Data
CalGEM recommends that operators provide the information and data detailed below when submitting AOR data in support of active or proposed injection operations. This information and data will generally facilitate CalGEM’s review and expedite a determination of whether it has been satisfactorily demonstrated that wells within the AOR will not have an adverse impact on the injection project or cause damage to life, health, property or natural resources.
It is CalGEM’s preference to receive all data in electronic format. If spreadsheets are provided electronically, only Microsoft Excel format can be accessed by CalGEM.
- Supporting data used in determining the AOR boundary (i.e. a directional survey or a well bore plat map of the subject well). (Follow link for examples via file request Appendix B.)
- Well bore plat map with AOR boundary and well bore paths of all wells within and near the AOR boundary. (Follow link for examples via file request Example.)
- Vertical sub-sea structure map of the top of the approved zone of injection over the entire AOR, superimposed over the well bore plat map. It is helpful if a mark is placed on all well bore paths where the well bore path penetrates the top of the zone of injection. It is also helpful if indication is provided next to the mark of the true vertical depth (sub-sea level) in feet of the top of the zone of injection for that particular well bore path.
- List of all wells within the AOR boundary.
- Since CalGEM staff must review casing diagrams for all wells within the area affected by the project, submitting all diagrams will expedite the project application review. (Follow link for examples and discussion via file request Appendix C.)
- To speed up CalGEM’s internal evaluation, include with the application the results of the operator’s own consideration of its AOR, identifying the following:
- Wells that clearly would not act as a conduit for injection fluid.
- Wells that do not have ample cement above the zone of injection that, in the operator’s opinion, will not act as a conduit for injection fluid. CalGEM encourages operators to provide explanation of why such a well will not have an adverse impact on the injection project or cause damage to life, heath, property or natural resources.
- Wells in need of remediation. CalGEM encourages operators to lay out the plan for remediating problem wells within the AOR.
