吐哈温西三油藏泡沫改善空气驱提高采收率实验研究
发布时间:2018-03-30 00:10
本文选题:空气驱 切入点:泡沫改善空气驱 出处:《成都理工大学》2015年硕士论文
【摘要】:吐哈油田温西三油藏属于低孔、中-低渗储层,原始地层压力23.78MPa,地层温度76℃,地层水矿化度20000mg/L以上,层间及平面非均质性严重[1]。油田进入高含水期后,井网及层系适应性逐步变差,自然递减增大[2];此外,吸水能力及注入能力下降,开发效果逐渐变差,采收率不高,开发形势严峻。目前,温西三先导试验区累积注水量109.12×104m3,累积产液量32.31×104t,累积产油量20.86×104t,剩余油量59.6×104t,综合含水率50%,标定采收率32%,而采出程度低,仅为25.93%。可见,仍然有70%以上的原油残留于地下。因此,大幅度提高温西三油藏的采收率,具有重要的生产实际意义。空气驱提高采收率技术,其优势不仅在于空气的可注性高,还可以作为驱油介质。此外,在油藏温度及压力条件下,空气中的氧气与原油中的某些组分发生氧化反应,释放大量热量,大幅度降低原油粘度,进而改善水油流度比[3];氧化反应过程产生的大量烟道气,扩大了空气在油层中的波及效率,因而提高了原油的采收率[4]。然而,由于低渗油层中的严重非均质性,包括平面及纵向的非均质性严重,注空气时,将产生气窜,使得空气驱油的效率降低。因此本文还重点开展了泡沫改善的空气驱油效果研究。本文将温西三区部分井组作为先导试验区,室内开展了空气驱提高采收率实验研究。给出了影响空气驱提高采收率的因素;采用具有理想封堵效果的泡沫,研究了不同发泡液段塞大小改善空气驱油效果及优化了发泡液与空气交替注入频率对提高采收率的影响[5];最后,通过数值模拟室内研究结果,预测了泡沫改善空气提高采收率效果。实验结果表明,空气驱较水驱能够有效降低注入压力,可解决注水开发注入困难的问题。空气注入段塞为0.3PV时,提高采收率为6.25%,注入压力较水驱降低0.03MPa;渗透率级差对空气驱提高采收率的影响较大,级差越大,最终提高采收率幅度越低,且当渗透率级差大到一定程度后,即使采用空气泡沫进行封堵,也不可能有效防止气窜。当渗透率级差由1.3:1增大至15.7:1时,提高采收率值降低6.66个百分点。此外,室内试验还发现,在双管驱替的过程中,相较于低渗层,空气较多地进入了高渗层中。可见,未采用泡沫调剖及防窜技术时,空气驱增采的原油主要来自于高渗层,低渗层的吸气能力较低,油层波及效率较低,其驱油效果亦相对较低。随着渗透率级差的增大,低渗层的含水率降低幅度通常比高渗层的含水率降低幅度大。说明低渗层的累积产液量随着级差的增大而降低;相应地,高渗层的累积产液量增大[6]。这表明随着非均质性严重程度的增大,由于气体流动性较强,高渗层中由于严重不利的流度比发生了严重的水窜及气窜,导致低渗层中的吸气量减小甚至不吸气,影响了驱油效果[7]。泡沫改善空气驱能够较空气驱明显提高驱油效率。起泡剂在高渗层运移过程中,尽管有大量气泡破灭,同时在孔隙介质中渗流时,也有大量气泡生成,由于有较高的视粘度及有效渗流粘度,能够有效封堵高渗层,降低高、低渗层的吸气及吸水剖面,甚至启动低渗层,扩大气驱时气体在地层中的波及体积,从而大幅度提高采收率[8]。结果表明,起泡液段塞越大,驱油效果越好,采收率越高。当起泡液段塞大小为0.04PV,空气段塞大小为0.3PV时,泡沫改善空气驱提高采收率幅度为12.10%,较空气驱0.3PV的6.25%提高5.85个百分点。空气/起泡液交替注入,可进一步提高或改善空气驱的驱油效果[9]。结果表明,随着交替频率增大,泡沫改善空气驱提高采收率的幅度也增大。当交替次数为8次时,提高采收率为15.33%。分析起来,主要原因是由于起泡液与空气的多次交替注入,空气与起泡液可以充分接触,有利于泡沫的生成[10]。此外,由于起泡液与空气总量一定,随着交替次数的增加,空气段塞与起泡液段塞在交替注入时相对减小,使得起泡液在孔隙中的发泡量增大,同时封堵大孔道、大孔隙,有效减少了气窜的发生,较空气驱过程改善了吸气剖面,充分启动了低渗层,使得低渗层的增油量较高渗层明显变大,提高了采收率[11]。数值模拟研究结果表明,空气段塞为0.25PV,起泡液段塞为0.05PV,交替次数为12次且注入速度与水驱相同(即160m3/d)时,先导试验区提高的采收率12.29%、空气增油量为68.11t/105m3,累积产气1.06×107m3,比气驱减少83.36%。
[Abstract]:Tuha oilfield reservoir belongs to the low temperature three hole in low permeability reservoir, the original formation pressure of 23.78MPa, the formation temperature of 76 DEG C above 20000mg/L, the salinity of formation water, interlayer and plane heterogeneity of [1]. oilfield in high water cut stage, wells and strata adaptability gradually becomes poor, the natural decrease of [2] increased; in addition water absorption capacity decreased, and the injection capability, development effect became worse, the recovery rate is not high, the development of the situation is grim. At present, the temperature three pilot test area of cumulative water injection of 109.12 * 104m3, 32.31 * 104t cumulative liquid production, cumulative production of 20.86 * 104t, the remaining oil quantity is 59.6 * 104t, comprehensive water content of 50% calibration, recovery 32%, and low recovery degree, only 25.93%. shows that there are still more than 70% of the crude oil remained underground. Therefore, greatly improve the recovery temperature three reservoir, has significance for practical production. Recovery technology to improve air drive, not only its advantages In the air can be injected high, also can be used as oil displacement medium. In addition, the reservoir temperature and pressure conditions, the oxygen in the air and oil in some components of the oxidation reaction occurs, releasing large amounts of heat, reduce the viscosity of crude oil greatly, and improve the water oil mobility ratio [3]; produce oxidation number the flue gas, expanding the sweep efficiency of air in the reservoir, thus improving the oil recovery rate of [4]., however, due to the low permeability reservoirs are in serious heterogeneity, including plane and vertical heterogeneity of air injection, the gas channeling, reduce the efficiency of the air displacement. So this paper studies the effect of oil also focus on the improvement of air foam flooding. The well group temperature three district as a pilot area, carried out indoor air injection experiments on EOR is given. The effect of air flooding to improve oil recovery factor; recovery With the ideal sealing effect of different foam, foaming liquid slug size improve flooding effect and optimization of air foam liquid and air injection alternately to improve [5] influence recovery frequency; finally, through numerical simulation, the results of laboratory studies, prediction of foam to improve air EOR effect. The experimental results show that the air. Compared with water flooding can reduce the injection pressure, injection water injection development can solve the difficult problem. The air injection slug of 0.3PV, improve the recovery rate of 6.25%, lower than the water flooding pressure 0.03MPa injection; permeability of air flooding improve recovery is larger, the greater the difference, and ultimately improve the oil recovery rate is low and, when the permeability ratio reaches to a certain degree, even if the use of air foam sealing, could not effectively prevent gas channeling. When the permeability ratio increased from 1.3:1 to 15.7:1, high recovery value A decrease of 6.66 percentage points. In addition, the indoor tests also found that, in the process for the double drive, compared to the low permeability layer, more air into the high permeability layer. Obviously, the foam profile control and anti channeling technology, air flooding enhanced oil recovery of crude oil mainly from the high permeability layer, low permeability and inspiratory capacity the lower layer, reservoir sweep efficiency is low, the flooding effect is also relatively low. With the increase of permeability, the water content decreased rate is usually higher than the rate of reduction of water in high permeability layer in low permeability layer. It shows the cumulative liquid production with differential increases reduced correspondingly low permeability; the cumulative, high permeability layer liquid yield increased [6]. this shows that with increasing heterogeneity in the severity of gas due to strong liquidity, high mobility layer due to serious adverse than serious water channeling and channeling, resulting in reduced intake layer do not inhale low permeability. Rang the oil displacement effect of [7]. foam flooding can improve air air injection significantly improve oil displacement efficiency. Agent in high permeability layer during migration of foaming, despite the large number of bubble burst, and seepage in porous medium, there are a lot of bubble formation, the apparent viscosity and viscosity of high effective flow, can effectively block high to reduce the high layer, low permeability layer and suction profile, even starting in low permeability reservoir, gas drive sweep volume expansion of gas in strata, and thus greatly improve the recovery rate of [8].. The results show that the foaming liquid slug flooding is bigger, better, the recovery rate is high. When the foaming liquid slug the size of 0.04PV, the air slug size is 0.3PV, the improvement of air foam flooding to improve oil recovery rate of 12.10%, compared with the air injection 0.3PV 6.25% increased by 5.85 percentage points. The air / foam alternative injection, can further improve the efficiency of oil displacement or improve air flooding Results [9]. results showed that with the alternating frequency increases, improve the air foam flooding to improve oil recovery rate increases. When the time is 8 times the turn, improve the recovery rate of up to 15.33%., the main reason is because the foaming liquid and air repeatedly alternating injection, air and foaming liquid can be fully contacted, beneficial to the formation of [10]. foam in addition, the foaming liquid and air amount, with the increase of the number of alternate, air plug and bubbly liquid slug in alternating injection is relatively reduced, increasing the amount of foaming foaming liquid in the pores, large pores and large pores, blocking, and effectively reduce the occurrence of gas channeling, improve the suction section is the air drive process, fully launched the low permeability layer, the oil layer quantity of higher layer was significantly larger in low permeability, improve the recovery rate of [11]. simulation results show that the air slug 0.25PV, foaming liquid slug 0.05P V, the number of alternation times is 12 times and the injection rate is the same as that of the water flooding (i.e. 160m3/d). The pilot test area improves the recovery factor 12.29%, the air oil increment is 68.11t/105m3, the cumulative gas production is 1.06 x 107m3, which is less than the gas drive 83.36%..
【学位授予单位】:成都理工大学
【学位级别】:硕士
【学位授予年份】:2015
【分类号】:TE357.46
【参考文献】
相关期刊论文 前3条
1 蒋有伟;张义堂;刘尚奇;关文龙;陈亚平;刘双卯;;低渗透油藏注空气开发驱油机理[J];石油勘探与开发;2010年04期
2 贾虎;赵金洲;杨怀军;李sパ,
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