葡南油田扶余油层注CO_2提高采收率技术研究
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摘要
我国低渗透油气田石油地质储量丰富,占陆地探明储量的26.9%。此类油藏开采难度大,目前油藏开发方式主要是注水和衰竭式开发。有些低渗透油藏由于注水困难,无法投入正常开发或无法动用。有的则采用衰竭式开发,由于没有能量补充,采收率特别低。如何经济高效开发低渗透油藏是当前油田开发中的一个难题。
国外开展低渗透油藏开发的实例较多,其中又以注气提高采收率方法为主。统计资料表明,国外提高采收率应用技术中,注气是第二位的。我国发展注气较慢,但随着低渗透油藏的比例和储量增大,国内已对一些油田进行可行性评价和现场试验。如我国吐哈葡北油田已开展注烃混相驱达3年多,运行效果良好;长庆靖安油田注天然气已获得成功,并取得了一定经验;富民油田已成功地开展了CO_2吞吐试验和注气驱现场试验,取得了明显经济效益;辽河油田注CO_2吞吐试验、大庆外围油田注CO_2驱现场试验正在进行中。因此,注气(尤其是CO_2)提高采收率作为低渗透油田三次采油提高采收率的关键技术,具有很大的应用潜力。
本文通过了解CO_2的物理化学性质,进行地层油膨胀实验,结果表明,注CO_2后地层油体积膨胀、粘度降低、CO_2与地层油之间界面张力降低;进行CO_2驱室内实验,研究注入压力与采收率、换油率、生产气油比之间的关系。实验表明,注入压力越高,最终采收率越高,与水驱相比,可提高22.90%～54.33%;进行CO_2吞吐室内实验,结合采收率、换油率、生产气油比等参数,认为浸泡时间、注入量、注入压力都存在最佳值,浸泡时间过短不利于CO_2的降粘、膨胀作用,过长会消耗地层能量;高压有利于CO_2侵入油层深部,但同时也会将注入端地层油驱到油层深部,影响吞吐效果。
It is abound of geologic reserves of low permeability fields in China, Which is about 26.9% of land proven reserves. It is difficult to exploit these reservoirs, and which are being mainly developed by flooding and depleting at present. Some low permeability oil fields are so difficult to develop that they can't be developed normally or produced simply. Those reservoirs developed by depletion type of drive are very low in recovery factor because of no energy supplement. Therefore, it is a puzzle how to develop low permeability reservoirs economically and efficiently.
There are many examples of development of low permeability reservoirs abroad, especially by gas injection. The statistical data shows that, gas injection is the second important method of EOR abroad. The technique of gas injection develops slowly in China, but with the proportion and reserves of low permeability reservoirs are becoming more and more, there are many oil fields have implemented feasibility assessments and field tests. For example, Pubei oil field in Tuha has been flooding by hydrocarbon gas for 3 years and obtained favorable results; Jing'an oil field in Changqing has been successful in natural gas flooding and acquired some experience; Fumin oil field has launched CO_2 Huff-Puff and gas drive tests successfully, and acquired obvious economic benefit; The CO_2 Huff-Puff tests in Liaohe oil field and CO_2 drive tests in Daqing periphery oil fields are being carried out. Therefore, Gas injection(especially CO_2) for EOR has the enormous applied potential as a gordian technique for tertiary oil recovery of low permeability oil fields.
In this paper, based on the comprehension of the physical and chemical properties of CO_2, a series of experiments were carried out including expansion experiment、CO_2 flooding and CO_2 Huff-Puff laboratory experiment. The results indicate that, CO_2 could make formation crude expanded、thined down and decrease the boundary tension between CO_2 with oil after injecting CO_2; The relationships of injection pressure with recovery ratio、oil exchange ratio and production gas-oil rate were researched, the higher injection pressure, the higher ultimate recovery, and it could be more than waterflooding's to 22.90%～54.33%; considering the recovery ratio、oil exchange ratio and production gas-oil rate etc, it is concluded that there are the best value of soak time、injection volume and injection pressure through CO_2 Huff-Puff, it is not benefit to visbreaking and expanding if the soak time too short, and deplete producing energy if too long; High pressure is benefit for CO_2 to intrude into reservoir deep, however, it could drive formation crude around the injection well to reservoir deep and affect Huff-Puff effect.
国外开展低渗透油藏开发的实例较多,其中又以注气提高采收率方法为主。统计资料表明,国外提高采收率应用技术中,注气是第二位的。我国发展注气较慢,但随着低渗透油藏的比例和储量增大,国内已对一些油田进行可行性评价和现场试验。如我国吐哈葡北油田已开展注烃混相驱达3年多,运行效果良好;长庆靖安油田注天然气已获得成功,并取得了一定经验;富民油田已成功地开展了CO_2吞吐试验和注气驱现场试验,取得了明显经济效益;辽河油田注CO_2吞吐试验、大庆外围油田注CO_2驱现场试验正在进行中。因此,注气(尤其是CO_2)提高采收率作为低渗透油田三次采油提高采收率的关键技术,具有很大的应用潜力。
本文通过了解CO_2的物理化学性质,进行地层油膨胀实验,结果表明,注CO_2后地层油体积膨胀、粘度降低、CO_2与地层油之间界面张力降低;进行CO_2驱室内实验,研究注入压力与采收率、换油率、生产气油比之间的关系。实验表明,注入压力越高,最终采收率越高,与水驱相比,可提高22.90%～54.33%;进行CO_2吞吐室内实验,结合采收率、换油率、生产气油比等参数,认为浸泡时间、注入量、注入压力都存在最佳值,浸泡时间过短不利于CO_2的降粘、膨胀作用,过长会消耗地层能量;高压有利于CO_2侵入油层深部,但同时也会将注入端地层油驱到油层深部,影响吞吐效果。
It is abound of geologic reserves of low permeability fields in China, Which is about 26.9% of land proven reserves. It is difficult to exploit these reservoirs, and which are being mainly developed by flooding and depleting at present. Some low permeability oil fields are so difficult to develop that they can't be developed normally or produced simply. Those reservoirs developed by depletion type of drive are very low in recovery factor because of no energy supplement. Therefore, it is a puzzle how to develop low permeability reservoirs economically and efficiently.
There are many examples of development of low permeability reservoirs abroad, especially by gas injection. The statistical data shows that, gas injection is the second important method of EOR abroad. The technique of gas injection develops slowly in China, but with the proportion and reserves of low permeability reservoirs are becoming more and more, there are many oil fields have implemented feasibility assessments and field tests. For example, Pubei oil field in Tuha has been flooding by hydrocarbon gas for 3 years and obtained favorable results; Jing'an oil field in Changqing has been successful in natural gas flooding and acquired some experience; Fumin oil field has launched CO_2 Huff-Puff and gas drive tests successfully, and acquired obvious economic benefit; The CO_2 Huff-Puff tests in Liaohe oil field and CO_2 drive tests in Daqing periphery oil fields are being carried out. Therefore, Gas injection(especially CO_2) for EOR has the enormous applied potential as a gordian technique for tertiary oil recovery of low permeability oil fields.
In this paper, based on the comprehension of the physical and chemical properties of CO_2, a series of experiments were carried out including expansion experiment、CO_2 flooding and CO_2 Huff-Puff laboratory experiment. The results indicate that, CO_2 could make formation crude expanded、thined down and decrease the boundary tension between CO_2 with oil after injecting CO_2; The relationships of injection pressure with recovery ratio、oil exchange ratio and production gas-oil rate were researched, the higher injection pressure, the higher ultimate recovery, and it could be more than waterflooding's to 22.90%～54.33%; considering the recovery ratio、oil exchange ratio and production gas-oil rate etc, it is concluded that there are the best value of soak time、injection volume and injection pressure through CO_2 Huff-Puff, it is not benefit to visbreaking and expanding if the soak time too short, and deplete producing energy if too long; High pressure is benefit for CO_2 to intrude into reservoir deep, however, it could drive formation crude around the injection well to reservoir deep and affect Huff-Puff effect.
引文
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[4]李士伦,张正卿,冉新权,等著.注气提高采收率技术[M].成都:四川科学技术出版社,2001.
[5]曹学良,郭平,杨学峰,等.低渗透油藏注气提高采收率前景分析[J].天然气工业,2006,26(3):100-102.
[6]江怀友,沈平平,陈立滇,等.北美石油工业二氧化碳提高采收率现状研究[J].中国能源,2007,29(7):30-33.
[7]何艳青,张焕芝.CO_2提高石油采收率技术的应用与发展[J].环球石油,2008,3:24-26.
[8]Special report EOR/heavy oil survey[J].Oil & Gas,2006(4).
[9]NECMETTIN MUNGAN,et al.Enhance oil recovery with high pressure N_2 injection[J].SPE 62547.
[10]DENOYELLE L,et al.Interpretation of a CO_2/N_2 injection field test in a moderately fractured carbonate reservoir[J].SPE,1988(2).
[11]SARA SHAVEGI,et al.Improved cyclic stimulation using gas mixtures[J].SPE36687.
[12]TERAMOTO T,et al.Air-injection EOR in high water_saturated light-oil reservoir[J].SPE 100215.
[13]AWAN R,et al.EOR survey in the north sea[J].SPE 99546.
[14]Issever K.非混相CO_2驱提高重油采收率[J].国外油田工程,2001,1:7-11.
[15]EOR Weathers low oil prices.EOR SURVEYOGJ special.Mar.20.2000.
[16]李士伦,周守信,杜建芬,等.国内外注气提高石油采收率技术回顾与展望[J].油气地质与采收率,2002,9(2):1-5.
[17]才汝成,李晓清.低渗透油藏开发新技术[M].北京:中国石化出版社,2004.
[18]李士伦,孙雷,郭平,等.再论我国发展注气提高采收率技术[J].天然气工业,2006,26(12):30-34.
[19]马涛,汤达祯,蒋平,等.注CO_2提高采收率技术现状[J].油田化学,2007,24(4):379-382.
[20]张亮.CO_2EOR及其在油藏中的储存[J].国外油田工程,2007,23(3):9-12,35.
[21]罗平亚,孟英峰,舒适洪,等.我国低渗透油气资源勘探和开发中的若干问题[J].世界石油工业,1998.
[22]马翠.注气法开采难采储量[J].大庆石油地质与开发,2000(6).
[23]李向良,李振泉,郭平,等.二氧化碳后续驱的长岩心物理模拟[J].石油勘探与开发,2004,31(5):102-104.
[24]李孟涛,单文文,刘先贵,等.超临界二氧化碳混相驱油机理实验研究[J].石油学报,2006,27(3):80-83.
[25]谈士海,张文正.非混相CO_2在油田增产中的应用[J].石油钻探技术,2001,29(2):58-60.
[26]李孟涛,张英芝,杨志宏,等.低渗透油藏CO_2混相驱提高采收率试验[J].石油钻采工艺,2005,27(6):43-47.
[27]蒋明,赫恩杰.二连低渗透砂岩油藏开发中的几点认识[J].石油学报,2000,21(4):58-64.
[28]刘炳官,朱平,雍志强.江苏油田CO_2混相驱现场试验研究[J].石油学报,2002,23(4):56-60.
[29]谢尚贤,韩培慧,钱昱.大庆油田萨南东部过渡带注CO_2驱油先导性矿场试验研究[J].油气采收率技术,1997,4(3):13-19.
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