渗透率级差对油层实际气液比的影响
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摘要
为揭示低渗透非均质油藏实际气液比的变化规律,提高气液交替泡沫驱措施成功率,室内进行填砂管物理模拟试验,按气/液体积流量1∶1的比例交替注入空气及质量分数为0.1%的起泡剂溶液(0.1 PV起泡剂+0.1 PV氮气交替注入),注采达到平衡后(压力恒定或注入速度等于产出速度),观察不同渗透率级差的高、低渗管的产气量、产液量以及气液比变化规律,研究渗透率级差对泡沫驱油层气液比的影响规律。研究结果表明:当渗透率级差在1.0数14.6的范围内,随着级差的增大,高渗管的载气速率和载液速率逐渐增高,而低渗管逐渐降低,但变化幅度不大,泡沫驱能有效改善地层非均质性。当渗透率级差在14.6数38.4的范围内,随着级差的增大,高渗管的载气速率和载液速率急剧上升,而低渗管的载液速率和载气速率急剧下降,其中高渗管气液比稳定在1∶1,能理想发泡,低渗管实际气液比开始偏离此数值,起泡效果不理想,低渗管主要降低油水界面张力来提高单管采收率。当渗透率级差在38.4数88.3的范围内,大量的气、液沿着高渗层流动,气液比稳定在1∶1左右,而低渗管载气速率仅为1.68 m L/h,载液速率仅为0.04 m L/h,实际气液比严重偏离1∶1。此时,低渗管处于泡沫驱启动极限,产生严重的所谓"气走气路、水走水路"的现象。图9表3参10。
In order to reveal the change law of the actual gas-liquid ratio of low-permeability heterogeneous reservoirs,and improve the success rate of gas-liquid alternating foam flooding measures,the indoor physical simulation test of sand filling pipe was carried out by alternately injecting air and a foaming agent solution with 0.1% mass fraction(0.1 PV foaming agent + 0.1 PV nitrogen alternately)according to the ratio of gas/liquid volume flow 1∶1. After the equilibrium was reached,the pressure being constant or the injection speed being equal to the output speed,the gas production,liquid production and gas-liquid ratio change of high and low permeability pipes with different permeability grades was observed,and the effect of the permeability difference on gas-liquid ratio of the foam flooding was probed. The experimental results showed that when the permeability difference was in the range of 1.0—14.6,the carrier gas velocity and carrier fluid velocity of the high-permeability pipe gradually increased with the increase of the grade difference,while the low-permeability pipe gradually decreased,but the change was not distinct,and the foam drive could effectively improve the formation heterogeneity. When the permeability difference was in the range of 14.6—38.4,the carrier gas velocity and the carrier fluid velocity of the high-permeability pipe rose sharply with the increase of the permeability difference,while the carrier liquid velocity and the carrier gas velocity of the low-permeability pipe decreased sharply,at the same time,the gas-liquid ratio of the high-permeability pipe was stable at 1∶1,which was ideal for foaming,while that of the low-permeability pipe deviated from this value,the foaming effect being not ideal,the enhanced oil recovery of the low-permeability pipe mainly realized by decreasing the oil-water interfacial tension. When the permeability difference was in the range of 38.4—88.3,a large amount of gas and liquid flowed along the high permeability pipe,and the gas-liquid ratio of the high-permeability pipe was stable at about1∶1,while the carrier gas velocity of the low permeability pipe was only 1.68 mL/h,and the carrier liquid velocity was only 0.04 m L/h,and the actual gas-liquid ratio deviated significantly from 1∶1,at this time,the low-permeability pipe was at the limit of the foam drive,resulting in a serious phenomenon of so-called "air-moving gas path,water walking water path".
In order to reveal the change law of the actual gas-liquid ratio of low-permeability heterogeneous reservoirs,and improve the success rate of gas-liquid alternating foam flooding measures,the indoor physical simulation test of sand filling pipe was carried out by alternately injecting air and a foaming agent solution with 0.1% mass fraction(0.1 PV foaming agent + 0.1 PV nitrogen alternately)according to the ratio of gas/liquid volume flow 1∶1. After the equilibrium was reached,the pressure being constant or the injection speed being equal to the output speed,the gas production,liquid production and gas-liquid ratio change of high and low permeability pipes with different permeability grades was observed,and the effect of the permeability difference on gas-liquid ratio of the foam flooding was probed. The experimental results showed that when the permeability difference was in the range of 1.0—14.6,the carrier gas velocity and carrier fluid velocity of the high-permeability pipe gradually increased with the increase of the grade difference,while the low-permeability pipe gradually decreased,but the change was not distinct,and the foam drive could effectively improve the formation heterogeneity. When the permeability difference was in the range of 14.6—38.4,the carrier gas velocity and the carrier fluid velocity of the high-permeability pipe rose sharply with the increase of the permeability difference,while the carrier liquid velocity and the carrier gas velocity of the low-permeability pipe decreased sharply,at the same time,the gas-liquid ratio of the high-permeability pipe was stable at 1∶1,which was ideal for foaming,while that of the low-permeability pipe deviated from this value,the foaming effect being not ideal,the enhanced oil recovery of the low-permeability pipe mainly realized by decreasing the oil-water interfacial tension. When the permeability difference was in the range of 38.4—88.3,a large amount of gas and liquid flowed along the high permeability pipe,and the gas-liquid ratio of the high-permeability pipe was stable at about1∶1,while the carrier gas velocity of the low permeability pipe was only 1.68 mL/h,and the carrier liquid velocity was only 0.04 m L/h,and the actual gas-liquid ratio deviated significantly from 1∶1,at this time,the low-permeability pipe was at the limit of the foam drive,resulting in a serious phenomenon of so-called "air-moving gas path,water walking water path".
引文
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[3]李敬,李兆敏,刘伟.多相泡沫体系调剖优化实验研究[J].油田化学,2012,29(4):427-430.
[4]姜颜波,元福卿,赵方剑.反韵律油藏泡沫驱提高采收率研究[J].石油天然气学报,2014,36(1):109-113.
[5]PRUESS K.TOUGH2:A general-purpose numerical simulator for multiphase fluid and heat flow[J].Nasa Sti/recon Technical Report N,2017,92.
[6]OLDENBURG C M,PRUESS K.Mixing with first-order decay in variable-velocity porous media flow[J].Transport Porous Med,2015,22(2):161-180.
[7]WU Y S,PRUESS K.Numerical simulation of non-isothermal multiphase tracer transport in heterogeneous fractured porous media[J].Adv Water Res,2009,23(7):699-723.
[8]CLASS H,HELMIG R.Numerical simulation of non-isothermal multiphase multicomponent processes in porous media[J].Adv Water Res,2012,25(5):551-564.
[9]SKj?LAAEN I,EBIGBO A,ESPEDAL M,et al.A model for transport of hydrogen sulfide in oil-and water-saturated porous media[J].Comput Visual Sci,2010,13(6):265-273.
[10]WEISHAUPT K,BORDENAVE A,ATTEIA O,et al.Numerical investigation on the benefits of preheating for an increased thermal radius of influence during steam injection in saturated soil[J].Transport Porous Med,2016,114(2):601-621.