FremgangsmÕte og system for Õ bedre utnyttelse av oljeforekomster fra en undervannsbr°nn ved lavt reservoartrykk

摘要

An account has been given of a method and a system for increasing the petroleum recovery rate in at least one (14) of two or more adjacent underwater wells (12, 14), in which the reservoir pressure has become so low that it within short is expected to be unsatisfactory for bringing petroleum from the formation up to the surface. To this end, it is known per se to inject gas into the first-mentioned underwater well (14), causing, however, a substantial, undesired reduction of the cross-sectional through flow area in the well (14) upon gas supply through coilable tubing. Therefore, it is intended to provide a rational petroleum recovery rate increase without any reduction of respective well's (14) cross-sectional through flow area, utilizing a preferably adjacent well (12), which is plugged (at 16) close to the reservoir. Above the plugged well portion (16), an injection well (18) is drilled to the first-mentioned well (14), whereafter gaseous fluid under pressure is supplied through said adjacent well (12) to the injection well (18, 18') and, from there, to the well whose petroleum recovery rate is to be favoured through the gas lift established within the well (14).