1. (a) The following definitions are applicable to this article:

   1. (1) “Area of review” means the three-dimensional extent of the reservoir used for underground gas storage and surrounding areas that may be subject to its influence. The area of review is delineated by the geologic extent of the reservoir such as confining strata, structural closure, decrease or loss of porosity and permeability, or hydrodynamic forces in a three-dimensional image.
   2. (2) “Confining strata” means the rock layer or layers at the boundaries of the storage reservoir acting as the primary barriers preventing migration of fluids.
   3. (3) “Fluid” means liquid or gas.
   4. (4) “Gas storage well” means an active or idle well used primarily to inject or withdraw gas from an underground gas storage project.
   5. (5) “Reservoir” means the portion of the geologic stratum that is being used to store natural gas in an underground gas storage project. The entire depth interval of a reservoir from the shallowest to the deepest depth can be subdivided into one or more depth intervals, which are referred to in this article as “zones”.
   6. (6) “Underground gas storage project” means a project for the injection and withdrawal of natural gas into an underground reservoir for the purpose of storage. An underground gas storage project includes the reservoir used for storage, the confining strata, gas storage wells, observation wells, and any other wells approved for use in the project. An underground gas storage project also includes the wellheads and, to the extent that they are subject to regulation by the Division, attendant facilities, and other appurtenances.
   7. (7) “Gas Storage Well Chemical Inventory” means a list of all chemical constituents that may be emitted from a gas storage well in the event of a reportable leak as defined in Section 1726.9, subdivision (a), and related data as required in Section 1726.4.3.
   8. (8) “Inflow Performance Relationship” or “IPR” means a mathematical tool used to assess well performance and estimate the absolute open flow potential of a well by comparing the well's flow rate to the flowing bottom hole pressure. The data required to create the IPR are obtained by measuring the flow rates under various pressure regimes. The absolute open flow potential is the theoretical rate at which the well would flow against a theoretical atmospheric backpressure at surface. The reservoir fluid composition and behavior of the fluid phases under flowing conditions determine the shape of the curve.

Note: Authority cited: Sections 3013, 3106 and 3180, Public Resources Code. Reference: Sections 3011, 3106, 3180, 3181.5, 3183, 3186.3, 3220 and 3403.5, Public Resources Code.

History

1. New section filed 6-28-2018; operative 10-1-2018 (Register 2018, No. 26).

2. Amendment of subsection (a)(1), new subsections (a)(7)-(8) and amendment of Note filed 5-1-2025; operative 7-1-2025 (Register 2025, No. 18).