超低渗油藏CO_2吞吐室内评价及参数优化
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摘要
针对鄂尔多斯盆地某超低渗透油藏注水开发矛盾突出、水驱动用程度差和原油采收率低等问题,基于超低渗透油藏特征及国外CO_2驱的成功案例,提出了CO_2吞吐提高采收率的开发思路。通过长岩心驱替实验,结合换油率和驱油效率来综合评价CO_2吞吐在超低渗透油藏的开发效果,并进行了CO_2吞吐注采参数的优化。研究结果表明,当油藏压力大于最小混相压力(20.78 MPa)时CO_2吞吐能获得较高的采收率;当CO_2吞吐段塞大小为0.1 PV、焖井时间为24 h,吞吐3轮次时的CO_2吞吐的开发效果最佳,驱油效率为56.39%,平均换油率为0.454。
The ultra-low permeability reservoirs in Ordos Basin face serious problems of water injection difficulty,poor flooding results and low oil recovery. In order to improve the oil recovery of ultra-low permeability reservoir,the development idea of CO_2 huff-n-puff was proposed based on the characteristics of ultra-low permeability reservoirs and the successful cases of CO_2 flooding in abroad. Long core flooding experiment were done in laboratory,and the effect of CO_2 huff-n-puff were evaluated combining the oil change rate and displacement efficiency,meanwhile,the injection parameters were optimized. The experiment result showed that CO_2 huff-n-puff had higher oil recovery when reservoirs pressure was greater than the minimum miscible pressure(MMP),being of20.78 MPa. The optimum operation strategy was 0.1 PV for slug size,the soaking time of 24 h and three-cycle huff-n-puff. CO_2 huff-n-puff provided an effective method for ultra-low permeability reservoir,the oil displacement efficiency was 56.39%,the average oil exchange ratio was 0.454.
The ultra-low permeability reservoirs in Ordos Basin face serious problems of water injection difficulty,poor flooding results and low oil recovery. In order to improve the oil recovery of ultra-low permeability reservoir,the development idea of CO_2 huff-n-puff was proposed based on the characteristics of ultra-low permeability reservoirs and the successful cases of CO_2 flooding in abroad. Long core flooding experiment were done in laboratory,and the effect of CO_2 huff-n-puff were evaluated combining the oil change rate and displacement efficiency,meanwhile,the injection parameters were optimized. The experiment result showed that CO_2 huff-n-puff had higher oil recovery when reservoirs pressure was greater than the minimum miscible pressure(MMP),being of20.78 MPa. The optimum operation strategy was 0.1 PV for slug size,the soaking time of 24 h and three-cycle huff-n-puff. CO_2 huff-n-puff provided an effective method for ultra-low permeability reservoir,the oil displacement efficiency was 56.39%,the average oil exchange ratio was 0.454.
引文
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[2]高云丛,赵密福,王建波,等.特低渗油藏CO2非混相驱生产特征与气窜规律[J].石油勘探与开发,2014,41(1):79-85.
[3]郝永卯,薄启炜,陈月明.CO2驱油实验研究[J].石油勘探与开发,2005,32(2):110-112.
[4]MALCOM D M,SCOTT M F.New approach to CO2flood:soakalternating gas[R],SPE 70023,2001.
[5]MEHDI M S,MOHAMMAD A S,EGHBAL S,et al.Comparisonof oil removal in surfactant alternating gas with water alternatinggas,water flooding and gas flooding in secondary oil recoveryprocess[J].J Pet Sci Technol,2014,120:86-93.
[6]李莉,庞彦明,雷友忠,等.特低渗透油藏合理注气能力和开发效果分析[J].天然气工业,2006,26(9):118-121.
[7]何应付,周锡生,李敏,等.特低渗透油藏注CO2驱油注入方式研究[J].石油天然气学报,2010,32(6):131-134.
[8]LIU P C,ZHANG X K,HAO MQ,et al.Parameter optimization ofgas alternative water for CO2flooding in low permeabilityhydrocarbon reservoirs[J],J Renew Sustain Ener,2016(8):1-12.
[9]TORABI F,ASGHARI K.Effect of operating pressure,matrixpermeability and connate water saturation on performance of CO2huff-n-puff process in matrixfracture experimental model[J].Fuel,2010,89(10):2985-2990.
[10]TORABI F,FIROUZ A Q,KAROUSI A,et al.Comparativeevaluation of immiscible,near miscible,and miscible CO2huff-n-puff to enhance oil recovery from a single matrix-fracturesystem[J].Fuel,2012(93):443-453.
[11]SAVEGH S G,MAINI B B.Laboratory evaluation of the CO2huff-n-puff process for heavy oil reservoirs[J].J Can PetrolTechnol[J].1984,23(3):29-36.
[12]SONG C Y,YANG D Y.Experimental and numerical evaluationof CO2huff-n-puff processes in Bakken formation[J].Fuel,2017(190):145-162.
[13]任大忠,孙卫,田辉,等.鄂尔多斯盆地姬塬油田长6储层成岩作用特征及孔隙度演化研究[J].西北大学学报(自然科学版),2016,46(1):105-112.
[14]THOMAS G A,MONGER T G.The feasibility of cyclic CO2injection for light oil recovery.SPE Res Eng,1991,6(2):179-184.
[15]PATTON J T,SIGMUND P,EVANS B.Carbon dioxide wellstimulation:part 2—design of Aminoil’s North Bolsa Stripproject[J].J Petrol Technol,1982,34(8):1798–1804.
[16]SIMPSON M R.The CO2huff‘n’puff process in a bottomwaterdrive reservoir[J].J Petrol Technol,1988,40(7):887-893.