Division and resources evaluation of hydrocarbon plays in the Amu Darya basin, central Asia

Based on the newest geological data and exploration achievements and the analysis of hydrocarbon accumulation elements and distribution rules of oil and gas fields, hydrocarbon plays are divided according to the reservoirs in the Amu Darya basin, central Asia. The hydrocarbon plays are evaluated in terms of resources potential and geologic risk, and the favorable hydrocarbon plays are selected using the double factors method of resources-geological risks. Ten hydrocarbon plays have been divided into in the major reservoirs, including the Cenomanian to Turonian sandstones of the Upper Cretaceous, the Hauterivian to Albian sandstones of the Lower Cretaceous, the Callovian to Oxfordian carbonates of the Upper Jurassic, and the Middle-Lower Jurassic sandstones. The undiscovered petroleum resources of the plays, evaluated by the Monte Carlo method, are about 3 308 million tons, in which gas accounts for more than 98%. Considering the geological risks evaluation of the key hydrocarbon elements of reservoirs, traps, migration and preservation, the favorable plays are evaluated and selected using the double factors method of resources-geological risks: two plays of class I, one play of class IIa, two plays of class IIb, three plays of class III, one play of class IVa, and one play of class IVc. The most favorable exploration objectives are the carbonate reservoirs of the Upper Jurassic Callovian-Oxfordian in the Murgab depression.