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大型南Brae老油田位于英国北海。自1983年投入开发以来 ,其产油量已超过 2 6 5MMSTB ,主要采用水驱。本文介绍英国北海第一个混相驱工程在该油田的实施情况。在得到室内实验和油藏模拟的验证后 ,1994年实施了先导试验工程。第二次模拟考虑了油田的成功作业结果 ,目的是对全油田气驱进行评价 ,目前全油田气驱工程正在实施当中。由于该油田有较好的水油流度比 ,注水开发效果良好。即使这样 ,水驱后 ,目前平均剩余油饱和度仍达 4 0 %以上。室内岩心实验表明 ,注水后接着混相气驱和第二次注水 ,剩余油饱和度可降到 10 %以下。气驱先导试验工程在油藏已水驱过的部分区块进行。在转为再注水之前总共注入 2 2Bcf (10 9ft3 )的天然气。 4口生产井的产油量增加 4～ 10倍 ,同时伴随着气油比(GOR)上升 ,含水下降。在注气的头 5年内 ,先导试验工程得到 2 7MMSTB增油量的 80 %以上。全油田气驱油藏模拟表明 ,注入 2 0 0Bcf的天然气可增产原油 18～ 32MMSTB ,相当注入气的一半多被回采出来。由于天然气的出口受到限制 ,注入气的机会成本可以忽略不计。综合考虑这些因素 ,气驱工程具有较高的经济效益
Large South Brae old oil field is located in the British North Sea. Since it was put into development in 1983, its oil production has surpassed 26.5MMSTB, mainly using water flooding. This article describes the implementation of the first mixed phase flooding project in the North Sea in the field. After being verified by laboratory experiments and reservoir simulation, pilot pilot projects were carried out in 1994. The second simulation considered the successful operation results of the oilfield, with the purpose of evaluating the gas flooding in the whole oilfield. At present, the whole oilfield gas flooding project is under implementation. Because of the better ratio of water to oil in the field, waterflooding has worked well. Even so, after the water flooding, the average remaining oil saturation is still above 40%. Laboratory core experiments show that, after water injection followed by mixed gas drive and the second injection, the remaining oil saturation can be reduced to below 10%. Pilot pilot project of gas flooding is carried out in some blocks where the reservoir has been flooded. A total of 2 2Bcf (109ft3) of natural gas is injected before switching to refill. The oil production of 4 production wells increased 4 ~ 10 times, accompanied by the rise of GOR and the decrease of water content. In the first five years of gas injection, pilot pilot projects have achieved more than 80% of the oil volume increase of 27MMSTB. The simulations of gas-flooding reservoirs in the whole field show that the injection of natural gas at 200 Bcf can increase 18-32 MMSTB of crude oil, and the equivalent of more than half of the injected gas is recovered. Because natural gas exports are limited, the opportunity cost of injecting gas is negligible. Comprehensive consideration of these factors, gas flooding project has a higher economic efficiency