Tests of Conversion into Steam Stimulation Following Water Flooding in Karamay Conglomerate Oilfield

摘要

It is estimated that the ultimate oil recovery by waterflooding is not more than 25percent in conglomerate III reservoir in Karamay oilfield due to high crude oil viscosity and poor development effect. Therefore, it is found that the development effect and oil recovery can be significantly improved by steam injection because this kind of conglomerate reservoir is charactrerized by shallow burial, relatively concentrated oil layers and good connectivity. Based on the thermal drive experiments in laboratory and numerical simulation, about 24percent and 20percent incremental oil recovery can be achieved by conversion into stemaflood respectively. Excellent development effect has been gained with an average production of 951t/well within a stimulation cycle, daily production of 4.2t/d per well, cumulative OSR of 0.355, production rate of 3.5percent, all of which have reached the designed indexes. It is proved that, for conglomerate reservoirs like type III in Karamay oilfield, conversion into steam stimulation at the late waterflooding stage is an effective way to improve its development effect.