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This paper addresses the petrophysical analysis issues related to the Securities and Exchange Commission definition of proved, proved developed, and proved undeveloped oil and gas reserves. It informs the practicing petrophysicist of the current SEC views concerning the relative merit of the various engineering and geological data typically utilized in reserve booking efforts so that he can be conversant with the important concepts and make the proper recommendations to ensure the appropriate data have been acquired and the applicable analyses performed. Current state of technology is addressed along with issues as they relate to the application of SEC definitions. There are numerous issues related to these definitions including the criteria for reasonable certainty; the weight given to the analysis of open-hole well log data; considerations for what constitutes representative fluid volumes from wireline and other well tests; and the role of core analysis, pilot studies, analogous reservoirs as well as other data sources such as seismic data to establish reservoir continuity. The strengths, limitations and use of these various data sets to establish proved developed reserves are presented along with areas requiring further industry clarification or development. For example, according to the SEC, "Reservoirs are considered proved if economic producibility is supported by either actual production or conclusive formation test."1 However, in the Gulf of Mexico, reserves are often classified as proved in the absence of production or flow tests when certain criteria are met. This occurs when the case for reasonable certainty is effectively made. In other cases, proved developed reserves such as thin bedded sections may require a flow test, cores and a more complete set of well logs and high resolution borehole information. Contractual, economic, and regulatory issues will not be addressed, nor will issues relating to drainage areas, recovery factors, enhanced recovery or other engineering-related issues be discussed. |
