NATURAL FLOW AND ARTIFICIAL LIFT FOR A SOLUTION GAS DRIVE RESERVOIR
ABSTRACT
Solution gas drive reservoirs are characterized by rapid and continuous decline of reservoir pressure. This rapid and continuous decline of reservoir pressure causes direct decline of reservoir performance at early stages of the life of the reservoir. The principal source of energy which is gas liberation from the crude oil and the subsequent expansion of the solution gas as the reservoir pressure is reduced are inadequate to produce such reservoirs to their full capacities. Ultimate oil recovery from natural flow of a solution – gas drive reservoir makes it one of the least efficient primary recovery mechanisms. This leaves a substantial amount of remaining oil residing in the reservoir which must be produced.
Artificial lift technologies such as continuous gas lift, gas lift with velocity strings and positive displacement pumping is therefore employed at later phases of the reservoir’s life to increase the ultimate recovery which is what this project sort to do. Synthetic data based on material balance for a solution – gas drive reservoir is analyzed to predict its primary oil recovery based on which gas lifting, velocity strings technology and positive displacement pumping are suggested to be employed with respect to time at different stages of reservoir’s life.
Chapter 1
1.0 Introduction
1.1 Problem Statement
Solution gas drive also known as Dissolved gas drive or Internal gas drive reservoirs are characterised by a rapid and continuous decline of reservoir pressure. This reservoir pressure behaviour is attributed to the fact that no extraneous fluids or gas caps are available to provide a replacement of the gas and oil withdrawals (Tarek, 2001). This rapid and continuous decline of reservoir pressure causes a direct decline of reservoir performance at early stages of the life of the reservoir. Moreover, the principal source of energy which is gas liberation from the crude oil and the subsequent expansion of the solution gas as the reservoir pressure is reduced are inadequate to produce such reservoirs to their full capacities (Tarek, 2001). Ultimate oil recovery from natural flow of a solution gas drive reservoir (less than 5% to about 30%) makes it one of the least efficient primary recovery mechanisms (Tarek, 2001). The low recovery from this type of reservoir suggests that large quantities of oil remain in the reservoir and, therefore, solution gas drive reservoirs are considered the best candidates for secondary recovery applications
