Rebirth of a Mature Carbonate Gas Pool

Abstract

This article, written by Assistant Technology Editor Karen Bybee, contains highlights of paper SPE 88773, "Rebirth of a Mature Carbonate Gas Pool," by K.C. Carr, SPE, and M. Fiori, BP Canada Energy Co., prepared for the 2004 Abu Dhabi International Petroleum Exhibition and Conference, Abu Dhabi, UAE, 10-13 October. Operation of a mature pool requires increasing cost control and infrastructure optimization and consolidation to maintain profitability. The decision to initiate this type of reservoir-management plan, sometimes described as “harvest,” is driven in part by reservoir-performance analysis and in part by commodity prices. The full-length paper presents the account of a 3.7-Tcf sour-gas pool in Alberta, Canada, and the technical impact of harvest on field operations, reservoir performance, and ultimate recovery. The combination of new production-decline analysis and a well workover with surprising results led to a complete change in reservoir interpretation. Introduction Management of mature pools is not a new challenge. In the Western Canadian basin, the surge of exploration and development activity in the 1950s and 1960s has left a legacy of very mature pools, with many of these 40- to 50-year-old pools still producing. Records show that of the 30,000 gas pools discovered in Alberta, 2,000 were discovered before 1970. In the aggregate, these pools represent 15 Tcf of remaining recoverable reserves. Each of these pools was at some point declared mature on the basis of the science of the day and treated as a harvest candidate (i.e., a pool with very limited upside where the best strategy is to control cost and produce what is left without further investment).