Effects of Rock Permeability on Capillary Imbibition Oil Recovery from Carbonate Cores

Abstract

In order to investigate the feasibility and e ects of core permeability on capillary imbibition recoverable oil from carbonate cores, some laboratory tests were carried out at the EOR research laboratories of Sharif University, Iran. Outcrop rocks with di erent permeabilities were taken away from a recognized outcrop and used in these experiments. Special core analysis tests were run on two core samples to nd out relative permeability and end point saturations. Wellhead separator oil and gas samples were collected and recombined to a reservoir gas - oil ratio. A core ooding system with a capability of free and forced imbibition testing was designed and installed. A number of free and forced imbibition tests with di erent cores under reservoir conditions were conducted. The results of the tests revealed that capillary imbibition is an almost fast process at laboratory scale and the higher permeable cores will imbibe more easily. A good correlation could be obtained when the ratio of recovery factor to ultimate recovery factor versus a de nite function of time was plotted. From these experiments, it concluded that an up scaled relation can be perceived for very low permeable cores, the testing of which may take too long.