Experimental study on invasion law of oil rim in condensate gas reservoir with bottom water and oil rim

Abstract

The condensate gas reservoir with bottom water and oil-rim faces the invasion of oil-rim and bottom water in the process of depleted gas production. In order to explore the invasion mechanism and distribution of oil-rim for a better coping strategy, the long-core displacement apparatus was modified for X-CT scan withstanding high temperature and high pressure (HTHP). From 56.58 to 47 MPa, the oil-gas contact rose fast and gradually slowed down, and the corresponding invasion volume accounted for 82.98% of the total invasion volume. From 47 to 8.8 MPa, the watercut soared to 98% and the invasion rate tended to stagnate. Finally, oil-rim oil was left completely in the reservoir pores and the recovery of condensate oil was only 30.27%. The paper revealed the damage of excessive pressure drop to condensate and oil-rim, and discussed its influencing factors and various pressure control methods. The modified apparatus filled the gap of obtaining oil saturation by X-CT scan under stable HTHP, which had a general application prospect in subsequent optimization and core displacement experiments where oil distribution needed to be observed under HTHP.