f Perched Hydrocarbon-Water Contacts - a Common but Poorly Understood Phenomenon

Most hydrocarbon accumulations have the same contacts throughout the reservoir formation provided that each fluid phase forms a continuum and correcting for capillary effects. Tilted contacts caused by dynamic aquifer conditions are rather rare expect in certain will known areas such as the Arabian Gulf. Nevertheless there exist many single reservoirs with more than one hydrocarbon-water contact. Some of these cases are the result of the presence of semi-sealing faults (Watts, 1987). However this paper is concerned with so-called perched hydrocarbon-water contacts which result from the presence of trapped water, a phenomenon on which there is very little literature (Johnson et al, 1986 & Weber, 1987).