The entire volume of natural gas contained and trapped in the earth, before any is extracted and produced. Essentially, the total resource base includes estimations of all of the natural gas that is, or was (before production), trapped in the earth. Most of this natural gas is in forms that are technically non-recoverable. For instance, there is a great deal of natural gas located in very low concentrations throughout the earth’s crust. The technology does not exist, nor is it expected to come about in the near future, to effectively extract this gas. The remainder of the total resource base is natural gas that is obtainable using current or foreseeable technology. It is this portion of the resource base that is of most interest, and is included in estimates of the amount of natural gas.