低渗透砂岩油藏分子膜增注性能和机理研究

针对低渗透砂岩油藏储层低孔低渗导致注水压力高、欠注严重等问题,研制了带有酰胺基的阳离子双子表面活性剂BNFS（分子膜增注剂）。评价了BNFS的吸附性能、润湿性能、表界面活性及减阻性能,结果表明BNFS在砂岩表面吸附后形成分子膜层,岩心表面接触角从27.6°增至88.6°,由强亲水转为弱亲水。BNFS浓度为200mg/L时,溶液的表面张力为26.61mN/m,与煤油间的界面张力为0.06mN/m。岩心驱替实验表明,BNFS处理后,砂岩岩心的水相渗透率提高80%¹20%,注水压力降低12%¹8%。增注机理分析结果表明,在靠近孔壁处,分子膜增注剂、水与孔壁作用能级分别为10^-18、10²⁰J,分子膜增注剂与孔壁的综合作用能远大于水分子,在竞争吸附中占绝对优势,使有效渗流通道增加。BNFS处理岩心后,岩心-水的黏附功由136.5mN/m降至75.7mN/m,减阻作用明显。图5表1参7     

分子膜增注剂的分子模拟、合成及性能评价

分子膜增注技术有效期取决于分子膜增注剂在储层岩石表面的吸附性能。为了延长分子膜增注技术有效期,采用分子力学与蒙特卡洛相结合的方法研究了不同阳离子化合物在岩石表面的吸附性能,根据分子模拟结果设计了烷基脂肪胺聚氧乙烯醚三季铵盐(AFATQA)作为新型分子膜增注剂,对其吸附和减阻性能进行了预测,对合成产物的结构进行了表征,通过室内实验评价了AFATQA的性能,并在胜利油田实施分子膜复合措施。分子模拟结果表明,单分子吸附能随单分子电荷密度和分子疏水链长的增加而增加,酰胺基团和羟基可以提高单分子吸附能;预测AFATQA在岩石表面的吸附能高(-155.51 kcal/mol),吸附后减阻效果明显;按照分子结构模型合成的AFATQA可以吸附在岩石表面,随AFATQA浓度增加,岩石表面电位和接触角增加、AFATQA防膨率增大;室内岩心驱替实验结果表明,AFATQA能有效降低注水压力,临37-34井现场实施分子膜复合措施后降压增注效果明显,注水量增加,注水压力降低,对应油井产油量上升、含水量降低、动液面回升。     

聚硅纳米材料在纯梁中低渗透油田的增注试验研究

就聚硅材料产品对岩石润湿性的影响、处理效果与岩心渗透率的关系以及渗透率大小对岩心润湿性处理效果的影响进行了室内研究。通过室内及现场试验,证明了聚硅纳米增注剂对降低岩心注入压力、提高岩心的渗流能力具有一定的效果,可以使经过长期注水冲刷的岩心的润湿性从亲水转变为亲油,从而疏通注水通道,增加注水能力。现场试验取得了好的效果,水井注水量增加了且对应油井动液面也上升了。     

改性纳米二氧化硅流体的制备及其降压增注规律

为降低油藏注水压力，使用非离子表面活性剂吐温80分散改性纳米二氧化硅，通过室内实验研制了一种用于降压增注的纳米流体。研究了该体系的分散性，考察了体系的润湿反转性能；通过岩心驱替实验，研究了不同注入量、不同岩心渗透率下纳米流体的降压增注规律。实验结果表明，该纳米流体具有良好的分散性能，平均粒径约为15 nm，且润湿反转能力较好，可将岩心表面接触角从35°增大到130°；当注入量为1.0 PV时，减阻率达45.31%；对渗透率为1.00×10^-3～20.00×10^-3μm²的岩心，纳米流体的降压增注效果较好，减阻率达35.00%以上。     

注水阻力分析及功能型减阻增注剂的性能评价

为了提高低渗透油藏注水井的降压增注效率,本文研究了岩石表面润湿性、界面张力等因素对低渗透油藏注水阻力的影响规律,并在此基础上研究了一种多功能型减阻增注剂CNG,评价了CNG溶液改变油水界面张力、改变岩石表面电性和润湿性和改变岩心降压增注效果的能力。研究结果表明:CNG既能降低油水界面张力至10~(-3)mN/m数量级、消除岩心毛管阻力;又能吸附在岩石表面消除岩石表面负电荷、改善岩石表面润湿性至弱水湿。CNG即适用于含有残余油的岩心降压增注,又适用于强水湿油藏的减阻增注,还适用于即有残余油又强水湿油藏的降压减阻增注。对于胜利油田某区块天然岩心,CNG用于不洗油的原始岩心时,渗透率提高48.49%,驱替压差降低31.25%;CNG用于没有残余油、呈现水润湿状态的岩心时,渗透率提高36.32%,驱替压差降低27.66%。图10表1参10     

海拉尔油田分子膜增注技术研究与实践

针对海拉尔油田在注水开发过程中存在注水井注入压力长期居高不下、注水量低的问题,提出通过注入一种带有阳离子基团的物质（在此称为分子膜剂）溶液可以缓解这一问题。该分子膜剂与带有负电荷的岩石表面具有极强的吸附能力,被注入地层后会取代水膜而吸附在岩石孔隙内表面,并形成一层纳米级分子膜,使岩石由原来的强水润变为中间湿或弱水湿,从而提高了水相渗透率,达到降压增注目的。通过室内试验研究及现场应用实践表明,该技术可以降低该油田注水井的注水压力,提高油藏的吸水能力。     

注水井化学降压增注技术应用

针对低渗透注水井研制的降压增注剂FYR-ZZ能增加水相渗透率,降低注入压力;降低油水界面张力,减少贾敏效应,增加油流动能力;改变岩石表面润湿性,使油藏变得更加亲水,发挥毛管力作用;抑制细菌生长,减少对井底及地层堵塞;抑制粘土膨胀,减少对地层伤害;同时还具有一定的驱油作用.现场采用连续注入与注水井两种方式进行试验,结果表明:应用注水井降压增注剂后,增加了注水量,降低注水压力,减轻了注水泵负荷,提高了注水管线安全系数,同时具有一定的增油效果.注水井注入压力的降低,节省了电能.     

低渗油藏纳米膜增注技术研究与应用

针对低渗油藏物性差,在注水开发过程中存在注水井注入压力高、注水量不能满足配注要求的突出问题,提出酸化处理后通过注入一种带有阳离子基团的纳米膜剂溶液来改善储层的润湿性,提高储层吸水能力,进一步提高水驱采收率的技术。纳米膜以水溶液为介质,依靠静电作用成为膜动力,吸附到呈负电性的岩石表面,改变储层表面的润湿性,降低注入水在孔隙中的流动阻力,避免粘土颗粒的膨胀与运移,从而提高水相渗透率,降低注水压力,达到降压增注的目的。室内实验研究及现场应用表明,该纳米膜可以改善低渗油藏注水井的注水开发效果。     

活性纳米材料增注技术的研究与应用

为了降低注水压力，改善文东油田的注水开发效果，将纳米技术引入油田开发领域，使用纳米材料降低注水压力，提高吸水能力。活性纳米材料以SiO2为主要成分，具有极强憎水亲油能力，在砂岩颗粒表面产生物理吸附作用，改变砂岩表面的润湿性，提高水相渗透率，从而降低注入水的流动阻力，起到降压增注作用，开发出成本低廉的水基携带液。经岩心驱替试验与现场应用证明，纳米材料增注技术能够降低低渗透油田的注水压力，提高吸水能力。从而改善油田注水开发效果。     

降压增注剂界面修饰对岩心孔隙水膜厚度的影响

为改善文33块沙三上油藏开发中采用酸化解堵时低无效井所占比例较高,且普遍存在措施有效期较短、注水压力较快恢复至措施前的问题,室内将低浓度(0.05％)的降压增注剂XH207B(非离子表面活性剂)注入天然岩心,研究孔隙水膜厚度和相对渗透率的变化规律,揭示降压增注剂对注入压力和渗透率变化的影响.结果表明,降压增注剂处理后,...     

后续水驱油藏堵聚防窜剂性能研究与应用

介绍了防窜剂FCP堵聚防窜机理,分别考察了防窜剂表面活性、对非均质地层封堵性、热稳定性、耐水冲刷性能及驱油能力。结果表明,防窜剂含量达0．1％时,油水界面张力可达3．127×10^-3mN／m,显示良好的表面活性;在不同渗透率岩芯中堵塞率均达90％以上;与HPAM聚合物反应生成的沉淀物有较好的热稳定性;经50PV注入水冲刷后,岩芯堵塞率保持在97％以上,具有很强的防窜能力;对非均质较高并联岩芯驱油效果更明显,其采收率较单一水驱平均提高10％以上,因此,渗透率级差较大油藏可采用“水驱-HPAM-FCP-水驱”方式提高原油采收率。     

SZX调剖剂的研制及应用

SZX调剖剂是将油田污水回注处理过程中产生的水处理淤泥作主剂，加入一定量添加剂组成。室内研究从水处理淤泥的物化性能入手，分析添加剂、主剂、水质对SZX调剖剂悬浮性的影响；岩芯试验结果表明，SZX调剖剂对不同渗透率岩芯均具有较强的封堵能力，能调整并联岩芯的产液比。在胜利滨南油田进行了现场试验并获得较好的增油降水效果，同时解决了环境污染问题。     

基于压力传递的钻井液纳米封堵剂研究与应用

针对南堡油田泥页岩地层孔隙尺寸为纳微米级,传统的微米级以上的固相颗粒难以实现有效封堵这一问题,选用纳米级钻井液封堵剂FT-3000、HLFD-1及环境友好型可变形聚合物封堵剂Green seal,在室内展开研究,评价其对高温高压滤失、砂盘滤失及泥饼承压能力的影响,并针对南堡油田所选岩心进行孔隙/裂缝封堵前后渗透率变化情况、压力传递及膜效率测试分析。结果表明用Green seal作封堵剂的钻井液,高温高压滤失量为17 mL,砂盘滤失量为13.8 mL,均为最小值,且其能有效提高泥饼承压能力至大于8 MPa,孔隙/裂缝封堵前后渗透率分析显示其封堵效果最佳,有效减缓了压力传递,膜效率为0.099 0,最大。该封堵剂在NP36-3652和NP36-3701井进行了应用,应用井井壁稳定、井径规则、渗透率恢复值高、滤液侵入量低,实现了泥页岩地层井壁稳定、储层保护的多重目的。      

表面活性剂对超低渗透油藏渗流特征的影响

针对超低渗透岩心,通过宏观驱替实验研究不同界面张力的表面活性剂对单相启动压力、油水两相启动压力、相对渗透率曲线、降压效果及提高采收率效果的影响,分析表面活性剂对超低渗透油藏渗流规律的影响。研究结果表明,随驱替液界面张力的降低,单相启动压力明显降低。油水两相启动压力实验中,在油水两相相同流速比下,随界面张力的降低,油水两相启动压力梯度逐渐降低,含水饱和度逐渐增大。从束缚水饱和度到残余油饱和度,随含水饱和度的增加,油水两相启动压力梯度先缓慢下降,后迅速下降。相渗曲线实验中,随表面活性剂质量分数的增加,油水两相渗流区增大,油相相对渗透率增大,残余油下水相相对渗透率增加,残余油饱和度降低,油气采收率升高,水相(端点以内)渗透率基本没有变化。表面活性剂段塞驱替实验中,岩心一次水驱后,注入表面活性剂可明显降低超低渗透岩心的注入压力、提高岩心采收率,且油水界面张力越低,降压效果越好,提高采收率幅度越大。     

Physical simulation of fluid flow and production performance in extra-low permeability porous media

For extra-low permeability reservoirs, with a permeability of about 0.3x 10-3 μm2, fluid flow and production performance in cores were studied. A long core holder with a multi-location piezometrie measurement was specially designed. An artificial long core, about 700 mm long and with a cross section of 45mmx45mm, was used. In the experiment, pressure distribution along the core can be measured in real time. Single phase flow in the core was investigated. Different modes of production in long cores were also simulated including natural depletion, water flooding, and advanced water flooding. Through physical simulation, flow parameters were collected and production characteristics in extra-low permeability cores were studied. From experimental results, it can be seen that fluid flow in extra-low permeability cores is different from that in high permeability cores. Transmission of pressure in extra-low permeability cores is very slow, and it needs a long time for the pressure to become stable. The distribution curve of pressure along the core is nonlinear and the production rate in extra-low permeability reservoirs decreases sharply.The development effects of different production modes in extra-low permeability cores were compared with one another. Among the production modes, advanced water flooding has much potential for effective development of extra-low permeability reservoirs. Natural depletion and conventional water flooding can also be used in early production periods. In addition, the countermeasures and some ideas especially for the potential development of extra-low permeability reservoirs are suggested.     

泡沫封堵及选择性分流实验研究

采用岩心分流驱替实验装置,研究了泡沫对单一含油岩心、含水岩心的封堵能力以及对不同渗透率级差含油、含水并联岩心的分流能力。结果表明,在单一泡沫驱替岩心实验条件下,泡沫具有封堵叠加的作用;而在并联岩心驱替实验条件下,泡沫不仅对含油、含水岩心具有选择性,而且对高、低渗透率岩心也具有选择性。泡沫具有较好的选择性暂堵分流效果,适用于非均质地层。     

Effect of wettability on oil recovery and breakthrough time for immiscible gas flooding

The effect of wettability on oil recovery at higher water saturation is still not fully understood, especially in the case of mixed wettability. This study was conducted to examine the effects of wettability on oil recovery and breakthrough time through experiments for two wettability conditions (water-wet and mixed-wet) and three water saturations (20%, 40%, and 60%). Clashach sandstone core with a porosity of 12.8% and a permeability of 75 md was utilized as the porous media. Immiscible gas flooding was performed by injecting nitrogen gas into the core at room temperature and pressure. The results showed 54.3% and 48.8% of the initial oil in place (IOIP) as the ultimate oil recovery at 40% water saturation from mixed-wet core and water-wet core respectively. In contrast, the water-wet core displayed better results (32.6% of the IOIP) in terms of breakthrough time compared to the results of water-wet core (10.6% of the IOIP) at the same water saturation. In conclusion, oil recovery was found highly dependent on water saturation while breakthrough time was mainly affected by the wettability of the cores.     

Physical simulation of fluid low and production performance in extra-low permeability porous media

For extra-low permeability reservoirs,with a permeability of about 0.3×10-3 μm2,fluid flow and production performance in cores were studied.A long core holder with a multi-location piezometric measurement was specially designed.An artificial long core,about 700 mm long and with a cross section of 45mm×45mm,was used.In the experiment,pressure distribution along the core can be measured in real time.Single phase flow in the core was investigated.Different modes of production in long cores were also simulated including natural depletion,water flooding,and advanced water flooding.Through physical simulation,flow parameters were collected and production characteristics in extra-low permeability cores were studied.From experimental results,it can be seen that fluid flow in extra-low permeability cores is different from that in high permeability cores.Transmission of pressure in extra-low permeability cores is very slow,and it needs a long time for the pressure to become stable.The distribution curve of pressure along the core is nonlinear and the production rate in extra-low permeability reservoirs decreases sharply.The development effects of different production modes in extra-low permeability cores were compared with one another.Among the production modes,advanced water flooding has much potential for effective development of extra-low permeability reservoirs.Natural depletion and conventional water flooding can also be used in early production periods.In addition,the countermeasures and some ideas especially for the potential development of extra-low permeability reservoirs are suggested.     

低渗透砂岩油藏水锁伤害研究

针对低渗透砂岩油藏受低孔、低渗的制约,在开发过程中储层极易受到水锁伤害的特点,对低渗透砂岩岩心进行了水锁伤害研究。分析了产生油井水锁伤害的机理,建立了水锁试验评价方法,研究了水锁伤害的规律和程度。试验结果表明,低渗透岩心经外来水侵入后,油相渗透率将产生比较严重的伤害,渗透率下降范围在7%~60%之间,流动压力升高1~3倍。针对这一情况,研制开发了解除水锁伤害的化学剂。室内岩心物模试验证明,研制的化学剂水锁伤害解除率达85%,经现场应用取得了显著效果。     

张店油田注水井粘土稳定剂配方的室内筛选

张店油田属强水敏地层，注水开发的关键是防止储层发生粘土膨胀，对一系列粘土稳定剂进行粘土防膨和岩芯流动试验，筛选出适合张店油田注水井的最佳粘土稳定剂配方为2％JJA＋2％NH4Cl。用该配方处理后的岩芯，注张店注入水50PV后，渗透率保持率达94．74％。