An Integrated Experimental Study of FoamyOil Flow During Solution Gas Drive

摘要

One of the important mechanisms in the primaryproduction of heavy oil reservoirs under solution gasdrive is the foamy oil flow effect. This form of flow occursonly under certain combinations of capillary, viscous andgravity forces. Several studies have been carried out toexamine this effect on the recovery process, but itremains poorly understood and difficult to model.The objective of this study was to examine the roles ofcapillary, viscous, and gravity forces in foamy oil flow.Primary depletion experiments were conducted in a twometerlong sand-pack holder to measure the oil and gasproduction at different depletion rates. The effect ofgravitational forces was investigated by comparing theexperiments conducted in horizontal and verticalorientations of the 2-meter long sand-pack. In the verticalorientation, the solution gas drive performance wasevaluated with the production from the bottom end of thesand-pack, as well as with production from the top end.The experimental results are presented in terms of theoil and gas production behavior affected by the capillarynumber and gravity forces. The results indicate that thegravity forces do not significantly influence the ultimateoil recovery when the oil is produced under foamy oilflow. Even at the lowest depletion rate used in these tests,when oil flow and gravity act in the same direction, gasgravity segregation did not improve the oil recoverysignificantly. Recovery efficiency and the critical gassaturation at which free gas flow starts are primarilydependent on the capillary number.