SAGD油井产出液热能利用工艺技术研究

Technology for Recovering Heat from Liquids Produced by SAGD Oil Wells

直井(水平井)与水平井组合重力泄油(SAGD)开发方式,其原理是:蒸汽经过直井被注入油层,并在油层中形成连续的蒸汽腔,蒸汽冷凝放出热量,地下原油经加热后,与冷凝水一同依靠重力作用流入水平井被大排量采出,采收率可达50%。该工艺目前处于工业化应用阶段。在SAGD开发方式下,油井产出液携带大量的可利用热能,其热能能否有效利用,直接制约着SAGD技术的工业化应用。为此,开展油井产出液热能利用工艺技术研究,将油井产出液携带的可利用热能,用于该区块注汽锅炉使用的软化水升温,其工艺流程为:产出液从井口进入计量接转站脱气,脱气后进入集中换热站换热,温度从155℃降到90℃后,进入联合站脱水;软化水从软化水站进入集中换热站,换热升温后(温度从20℃提到64℃,进注汽站温度为57.6℃),为该区块注汽锅炉供水。产出液热能利用工艺技术实施后,每年可节约燃料油14814t,使超稠油区块采收率从21.6%提高到50%。

Steam assisted gravity drainage（SAGD） is an enhanced oil recovery technology in which both vertical and horizontal boreholes are used.Steam is injected through vertical boreholes into the oil reservoir and forms a ＂steam chamber＂ that grows vertically and horizontally in the formation.The heat from the steam reduces the viscosity of the crude oil which allows it to flow together with condensate water down into the horizontal segments of the wellbore,where it is pumped out.The oil recovery rate of this method can reach up to 50%.This technology is being commercialized.In the oil production using SAGD,liquids produced from wellbores carry significant amounts of recoverable heat.The efficient recovery of heat from these liquids has a direct influence on the commercialization of SAGD technology.Researchers conducted a study on the technology for recovering heat from liquids produced by oil wells.In the study,heat is recovered from the liquids produced by oil wells to raise the temperature of the softened water used in steam injection boilers in a block.The procedures are：liquids produced from the wellhead enter a metering and transfer station for degasification and then enter a centralized heat exchanger station to undergo heat exchange.When its temperature is reduced to 90℃ from 155℃,the liquids enter a multipurpose station and is dehydrated.The softened water enters the centralized heat exchanger station from the softened water station and after the temperature rises through heat exchange（from 20℃ to 64℃,and its temperature when it enters the steam injection station is 57.6℃）,water supply to the steam injection boiler starts.After the liquids heat recovery technology is introduced,the block′s fuel oil consumption will drop by 14814t annually and the block′s heavy oil recovery rate will rise to 50% from 21.6%.