Identification, classification and regulation of newly discovered gas condensate and volatile oil reservoirs

Volatile oil and gas condensate reservoirs are special reservoirs because of their potential for improved hydrocarbon liquid recovery through some form of pressure maintenance operation. These reservoirs are difficult to identify from surface production characteristics. Many times, the correct determination of the reservoir fluid type requires laboratory analysis of the reservoir fluid. Current regulations enforced by the Texas Railroad Commission do not specifically recognize volatile oil or gas condensate reservoirs. Single phase reservoirs are classified as being either oil or gas reservoirs, based on initial produced gas-oil ratios. As a consequence of the state's reservoir classification and the regulations associated with the classifications, many opportunities for improved hydrocarbon liquid recovery from newly discovered volatile oil and gas condensate reservoirs are lost. This research examines issues related to the identification, classification and regulation of newly discovered gas condensate and volatile oil reservoirs in Texas. A method for simulating surface production characteristics of different reservoir fluid types is developed and used to analyze the production differences attributed to the fluid type. Recommendations are made to change some existing regulations so that the chances are improved for increased hydrocarbon liquid recovery from newly discovered gas condensate and volatile oil reservoirs.