低矿化度注水提高砂岩储集层采收率的微观机理

低矿化度注水是一项前沿技术,因在碳酸盐岩和砂岩储集层中能提高驱油效果,目前受到广泛关注。本文梳理了砂岩储层低矿化度注水提高采收率的主要微观机理,即润湿性的改变、黏土的膨胀与运移、双电层的扩散等。低矿化度水的质量浓度、离子类型能改变多种黏土内部力平衡及黏土与原油之间的力平衡,造成双电层扩散,最终使黏土出现润湿性的改变以及膨胀运移的现象。低矿化度注水能提高大部分砂岩油藏的采收率。国内大部分砂岩油藏开发已进入中后期,进行低矿化度注水的微观机理研究对砂岩油藏开发有极大的指导意义。     

致密气藏防水锁易返排滑溜水研究与应用

吉林油田致密气储层微纳米级孔隙发育,喉道窄小且连通性差,属低孔低渗储层。随着气藏的长期开发,地层压力、产能的逐渐降低,水锁伤害的影响逐渐显现,导致压后返排难度大,加之黏土的膨胀运移与堵塞,进一步降低了储层有效渗透率,严重制约了气藏采收率的提高。针对此问题,研发了防水锁易返排滑溜水压裂液体系,该体系主要由减阻剂XY-205、纳米微乳助排剂与黏土稳定剂XY-63组成。实验证明该体系具有速溶与低黏特性,能够满足快速连续混配要求,减阻率能够能达到70%以上,表面张力比常规气井滑溜水降低40%以上,利于致密气井压后助排,且能够较好地抑制黏土膨胀,对地层伤害小。该滑溜水对岩心的伤害率为9.45%,24 h岩心渗透恢复率接近90%,解除水锁伤害程度较高。该滑溜水体系在致密气区块现场应用4口井,压裂成功率100%,压后返排率提高2倍以上,试气效果显著,具有较好的大规模推广应用前景。     

致密气藏防水锁易返排滑溜水研究与应用

吉林油田致密气储层微纳米级孔隙发育,喉道窄小且连通性差,属低孔低渗储层。随着气藏的长期开发,地层压力、产能的逐渐降低,水锁伤害的影响逐渐显现,导致压后返排难度大,加之黏土的膨胀运移与堵塞,进一步降低了储层有效渗透率,严重制约了气藏采收率的提高。针对此问题,研发了防水锁易返排滑溜水压裂液体系,该体系主要由减阻剂XY-205、纳米微乳助排剂与黏土稳定剂XY-63组成。实验证明该体系具有速溶与低黏特性,能够满足快速连续混配要求,减阻率能够能达到70%以上,表面张力比常规气井滑溜水降低40%以上,利于致密气井压后助排,且能够较好地抑制黏土膨胀,对地层伤害小。该滑溜水对岩心的伤害率为9.45%,24 h岩心渗透恢复率接近90%,解除水锁伤害程度较高。该滑溜水体系在致密气区块现场应用4口井,压裂成功率100%,压后返排率提高2倍以上,试气效果显著,具有较好的大规模推广应用前景。      

Evaluation of enhanced oil recovery fromclay-rich sandstone formations

In the last few years, there has been a growing interest in smart water (SW) flooding as economically and environmentally friendly method to Enhanced Oil Recovery (EOR) in sandstone and carbonated reservoirs. Formation damage especially fines migration and clay swelling by lowering salinity and changing the ionic environment, causes the significant decrease in permeability of the sandstone reservoirs. In this study, an experimental study has been undertaken to illuminate the effect of formation damage during smart water injection as the function of clay types. The state of the art procedure has been established in direction of sandpack construction containing favorable clay content. Injection of smart water was performed in sandpacks with different clay types (montmorillonite and kaolinite). The results show that the presence of montmorillonite augments formation damage and enhances oil recovery. Analyzing Interfacial Tension (IFT) experimental data showed that interaction of oil/SW had no great influence on increasing oil recovery. The results have been achieved based on extensive experiments including Differential Pressure (DP) measurements, Zeta potential, and Recovery Factor (RF). Two mechanisms were proposed to interpret permeability reduction and amount of oil produced values which are clay swelling, and detachment/re-attachment for montmorillonite and kaolinite, respectively.     

深水疏松砂岩储层微粒运移损害的控制方法

中国南海深水疏松砂岩油气层钻完井作业中，易发生微粒运移、堵塞，造成储层损害，需要探索微粒运移损害的控制方法。选用南海深水疏松砂岩储层岩样，通过微粒吸附和释放实验以及岩心动态损害评价实验，探讨了纳米材料控制微粒运移损害的作用效果；实验分析了纳米颗粒吸附对岩石表面形貌、粗糙度及电性的影响；利用微粒与吸附纳米颗粒的岩石孔壁之间的相互作用能计算模型，分析了不同离子强度下储层微粒与岩石孔壁之间的总相互作用势能及作用机制。结果表明，纳米颗粒能有效控制深水储层微粒的运移，将其吸附并固定在孔壁表面。随着流体离子强度增加，控制运移的作用效果增强。其中，纳米氧化铝NP-1的作用效果最好，可明显提高深水储层岩心的渗透率恢复值，并且与深水钻井完井液具有良好的配伍性。模型计算结果表明，吸附纳米颗粒后，岩石孔壁与储层微粒之间的总相互作用势能下降，有利于岩石孔壁吸附、固定微粒，原因是纳米颗粒的吸附增加了岩石表面粗糙度及黏附力矩，也影响了表面电荷分布，有利于降低排斥势垒，并使初级势阱加深，提高岩石表面固定微粒的能力。因此，深水钻完井中，可通过加入纳米颗粒、适当提高工作液矿化度来减少微粒运移引起的储层损害。     

PCT-系列地层处理剂在桥口油田的应用

PCT-系列地层处理剂是为了既能解除油层原有的污染堵塞，又能防止二次沉淀，以达到保护油层提高解堵效果而研制的一种系列地层处理剂。该地层处理剂可有效地解除近井地带、地层深部堵塞，预防粘土膨胀和运移，改善流体中微粘粒度以及在一定程度上收缩已膨胀的粘土之功能。经现场试验，取得了较理想的应用效果。     

高孔高渗储层保护修井液在海上油田的应用

渤海南部A油田明化镇储层岩性为含砾砂岩,平均孔隙度30.9%,渗透率1 551 mD,具有高孔高渗特征。随着地层能量的不断下降,油井在修井过程中出现了不同程度的修井工作液漏失现象,导致水敏、结垢等伤害。本文通过对X井储层伤害因素分析,开发了针对该高孔高渗储层保护的修井工作液。现场应用表明,使用该体系在投产后油井产能恢复周期短,产液含水下降快,具有良好的增油效果。表明该体系能有效减小黏土膨胀、微粒运移、原油乳化、水敏等伤害,增大油流通道,提高作业后油井产能。     

A laboratory investigation of carbon dioxide-enhanced oil recovery by focusing on CO2-oil physical properties

Carbon dioxide (CO₂) miscible flooding has become an important method in enhanced oil recovery (EOR) for recovering residual oil. In addition it may help in protection of the environment as (CO₂) is widely viewed as an important agent in global warming. Knowledge of the interactions between (CO₂) and reservoir crude oil is very critical for any (CO₂)-enhanced oil recovery (EOR) projects. This paper shows the effect of (CO₂) miscible flooding application for Egyptian oil fields by swelling studies. The swelling test is a laboratory simulation of the process of injecting gradually different percentage of (CO₂) gas into a reservoir containing under-saturated oil. The gas (injection solvent) can dissolve, causing the reservoir fluid to swell. This paper presents a summary of a wide range of laboratory tests conducted on ten different crude oils varying from 26.4 to 40.5 API. These were used to invested the use of (CO₂) and its effect on parameters such as viscosity, density, gas solubility and swelling factor as a function of pressure at temperature from 620.3 to 706.0?°R.     

Thermal Resistance and Application of Nanoclay on Polymer Flooding in Heavy Oil Recovery

High molecular weight and water-soluble synthetic organic polymers are currently being used in the field with the hope of enhancing the recovery of oil by water flooding. Nanotechnology has been used in many applications and new possibilities are discovered constantly. Recently, a renewed interest arises in the application of nanotechnology for the upstream petroleum industry. The author focuses on roles of clay nanoparticles on polymer viscosity. Polymer-flooding schemes for recovering residual oil have been in general less than satisfactory due to loss of chemical components by adsorption on reservoir rocks, precipitation, and resultant changes in rheological properties. Rheological properties changes are mainly determined by the chemical structure and mix of the polymers, surface properties of the rock, composition of the oil and reservoir fluids, nature of the added polymers, and solution conditions such as salinity and temperature. On the other hand, the author's focus is on viscosity, temperature, and salinity of solutions polyacrylamide polymer solutions with different nanoparticles. Results show that ultimate oil recovery by nanoclay polymer flooding enhances by a factor of 5.8% in comparison to polymer flooding high salinity and temperature.     

宝浪油田储层渗流参数特征及油层伤害机理研究

宝浪油田自1996年开始试注开采以来,到目前已初步形成规模,但由于其特殊的储集条件,开采难度非常大,油层伤害严重。通过开展对开发初期宝浪油田储层渗流参数特征的研究,更好地认识了现阶段储层的物性、微观孔隙结构、润湿性、相对渗透率、水驱油效率、储层敏感性、油气水性质等特征,并对油层潜在损害的地质因素进行综合分析。建议新井投注开发前进行近井地带的粘土稳定剂预处理,预防粘土矿物膨胀及微粒运移,注水速度小于4.5m/d;入井流体矿化度应控制在13250～40410mg/L;钻井时应利用屏蔽暂堵技术;在开发中后期宜进行调剖不宜进行聚合物驱。     

中高渗透稠油油藏新型防膨抑砂剂的研制及应用

胜利油田中、高渗透稠油油藏大部分以原油胶结为主,这类油藏原油黏度高,黏土含量高,出砂严重且地层砂粒度中值相对较小,储层非均质性严重。新型防膨抑砂剂——FS-FYJ防膨抑砂剂是一种网状多羟基阳离子聚合物,能够非常有效而永久地防止黏土膨胀,控制砂粒运移,既有效地保护了油层又明显地改善了中、高渗透稠油油藏的开发效果。通过室内泥岩颗粒稳定、抑砂等评价、伤害实验测试了FS-FYJ防膨抑砂刺的防膨抑砂效果及对地层的伤害率,并在郑家、王庄等多个地区现场推广应用了10余口井,取得了显著的防砂效果,解决了胜利油田中、高渗透稠油油藏的防砂难题。     

粘土矿物及流体对低渗透岩心渗流特性的影响

通过室内填砂管渗流实验，研究了不同粘土类型、不同粘土比例的低渗透岩心在不同流体注入方式下的渗流特性，并根据实验结果分析了其渗流机理。分析认为，膨胀性牯土的存在是影响低渗透油藏渗流特性的关键因素；注入流体矿化度的差异和注入方式的变化，对粘土膨胀和抑制膨胀作用亦有影响。研究结果为进一步研究低渗透油葳渗流特性，有效开发低渗透油藏奠定了一定的实验基础。     

应用核磁共振技术研究压裂液伤害机理

核磁共振岩心分析技术能够快速、无损地检测出岩心含油饱和度和含水饱和度、束缚流体和可动流体饱和度的大小.通过测量压裂液侵入岩心引起的束缚水增加量、油相反排后的滞留量,能够分别判断出粘土吸水膨胀、水锁效应引起的岩心渗透率伤害程度,由此获得了压裂液对致密岩心伤害程度和机理的新认识.研究结果表明,压裂液对岩心的伤害机理和伤害程度不同,粘土吸水后引起的粘土膨胀和粘土颗粒分散运移对岩心渗透率有伤害,但由于粘土吸水量较少,岩心渗透率的损害率也较小,约为10%.反排后可动压裂液滤液或可动活性水在岩心孔隙内的滞留量均很少,因此水锁效应对油相有效渗透率的损害率较小,约为10%.压裂液滤液对岩心有效渗透率损害率比活性水高出约30%,这说明压裂液中的大分子物质在岩心孔隙内的吸附滞留是引起岩心渗透率伤害的主要原因.     

非均相复合驱油体系设计与性能评价

为进一步提高聚驱后油藏采收率,针对聚驱后油藏非均质性强、剩余油普遍分布的特点,提出了非均相复合驱油体系。非均相复合驱油体系包括黏弹性颗粒驱油剂（PPG）、表面活性剂和聚合物。通过研究黏弹性颗粒驱油剂的溶胀能力、黏弹性、滤过能力和在岩心中运移性能,及其与表面活性剂、聚合物之间相互作用,得到了适合于胜利高温高盐油藏和聚合物驱后油藏的非均相复合驱油体系1000 mg/L PPG＋1000 mg/L聚合物＋0.3％胜利石油磺酸盐＋0.1％非离子表面活性剂1709。结果表明,PPG可遇水溶胀,耐盐性能好,在油藏中具有封堵和运移性能,较单一聚合物能够更好地提高波及体积。在含水98％条件下注入0.3倍孔隙体积的非均相复合驱油体系,聚合物驱后提高采收率13.6%(OOIP)。该体系可应用于高温高盐油藏或聚合物驱后油藏大幅度提高采收率。     

Effect of Nanoclay on Heavy Oil Recovery During Polymer Flooding

Polymer flooding for improving sweep efficiency has been studied extensively in laboratory and tested in fields for conventional oils. A novel nanofluid based on polyacrylamide clay has been developed and its properties have been experimentally tested as a suitable candidate in polymer flooding for oil field projects. This authors review the polymer flood fundamentals as they are applied to heavy oil recovery. In this study, they focus on roles of clay nanoparticles on polymer viscosity and improve recovery in heavy oil recovery. The theory is supported with coreflood and physical model results for several oils ranging in viscosity from 200 to 4200 mPa.sec. For some of these coreflood tests the nanopolymer flood was able to increase the oil recovery in comparison to a baseline polymer flood. These laboratory results will be helpful for the planning of nanoclay polymer flooding for heavy oil reservoirs. Also flooding test showed a 5% increase in oil recovery for nanoclay polymer solution in comparison with polymer solution after one pore volume fluid injection.     

水驱后油藏CO2驱提高采收率评价研究

我国注水提高采收率技术已成熟,但注水开发到后期仍有大量的剩余油无法开采出来。详细分析了油藏水驱后的储层变化特征,长期水驱后粘土矿物膨胀、渗透率降低、注入压力过高,无法进一步提高采收率。介绍了CO2驱驱油方式混相驱与非混相驱,对比分析了连续注CO2、重力稳定驱和水气交替注入三种CO2注入方式各自的优缺点及油藏适应性,优选了适合油藏水驱后CO2的最优注入方式为水气交替注入方式。水气交替注入方式不仅具有降低原油粘度、使原油膨胀、降低油水界面张力、改善油层渗透率及抽提和萃取原油中轻质组分等作用,还可以降低黏性指进,防止气体早期突破等作用,能很好的提高水驱油藏采收率。并进行了现场应用的可行性分析,研究表明注CO2提高我国水驱后开发后的油藏具有很好的应用前景。     

稠油自乳化降黏技术在临盘油田的应用

针对目前临盘油田稠油油藏开发中存在的采出液含水率高、产油量低、普通水驱采收率低等问题,开展了稠油自乳化降黏吞吐技术研究。通过室内实验优选了最佳配方,然后进行了温度、 质量分数、矿化度和反应时间等因素对驱油效果影响的评价及物模驱替评价,得出了适合临盘油田稠油低温高矿化度地层条件的降黏剂的使用条件。现场小型试验表明,NB-5034A降黏剂能有效提高临盘稠油井采收率。     

羧甲基酸性压裂液在安塞油田的应用

普通胍胶压裂液,由于它低廉的价格和较好的流变控制特性,多年来一直用于油气井的储层改造,尤其是羟丙基瓜尔胶-硼所形成的水基冻胶压裂液携砂性能较好、具有抗剪切性好、热稳定性好、控制滤失能力强,成本低等诸多优点,是长庆油田低渗透储层压裂改造较为成熟的压裂液体系。然而,安塞油田长_(10)储层绝大部分粘土矿物均能与碱发生反应,致使粘土水化,膨胀,运移,生产沉淀而堵塞地层,所以各类粘土矿物都存在碱敏损害问题,而普通胍胶压裂液利用的是有机硼交联,交联的环境要求为弱碱性。羧甲基酸性压裂液是在酸性条件下交联的冻胶压裂液体系,避免常规水基压裂液的以上不足,从而更加有效地改造储层特别是碱敏地层,该压裂液体系在长_(10)储层的现场应用中,压裂施工过程平稳,增产效果明显。     

缝洞型碳酸盐岩油藏覆膜型体膨颗粒堵剂卡封机理微观可视化研究及注入参数优化

塔河油田属于典型的缝洞型碳酸盐岩油藏,油藏温度高达120~150 ℃,地层水总矿化度(20~25)×104 mg/L。对筛选出的耐温抗盐型体膨颗粒XN-T进行了物理覆膜,并对其膨胀性能、封堵性能进行了评价。实验结果表明,覆膜型体膨颗粒具有较好的延缓膨胀性能,24 h达到最大膨胀倍数约5倍,130 ℃下240 h的膨胀倍数仍有3.6倍;体膨颗粒在130 ℃下的封堵率达到98.4%,推荐现场使用覆薄膜的XN-T体膨颗粒。借助玻璃刻蚀微观可视化模型,研究了覆膜型体膨颗粒缝洞中的堵水机理及卡封运移的规律,并对颗粒注入参数及注入方式进行了优化。研究结果从微观尺度上证实了覆膜型体膨颗粒能在缝洞油藏的高渗孔缝中形成有效的“堆积”、“桥接”、“附着驻留”,迫使流体进入低渗小孔缝中,增大波及系数,提高采收率;体膨颗粒在储层中运移、封堵的次数越多,在多次挤压、剪切、变形作用下,封堵性能越差,第1次突破压力为0.48 MPa,后面逐渐降低,最终突破压力降为0.03 MPa。对覆膜型体膨颗粒进行注入参数优化:颗粒粒径为0.4~0.6 mm,颗粒浓度取固液比10%,推荐塔河油田现场试验采用有机覆膜型体膨颗粒+耐高温抗高盐型萘酚凝胶二元复合型深部调堵技术。现场试验采用凝胶与颗粒混注工艺,达到了增产目的。     

Experimental investigation into Fe3O4/SiO2 nanoparticle performance and comparison with other nanofluids in enhanced oil recovery

Nanofluids because of their surface characteristics improve the oil production from reservoirs by enabling different enhanced recovery mechanisms such as wettability alteration, interfacial tension (IFT) reduction, oil viscosity reduction, formation and stabilization of colloidal systems and the decrease in the asphaltene precipitation. To the best of the authors’ knowledge, the synthesis of a new nanocomposite has been studied in this paper for the first time. It consists of nanoparticles of both SiO₂ and Fe₃O₄. Each nanoparticle has its individual surface property and has its distinct effect on the oil production of reservoirs. According to the previous studies, Fe₃O₄ has been used in the prevention or reduction of asphaltene precipitation and SiO₂ has been considered for wettability alteration and/or reducing IFTs in enhanced oil recovery. According to the experimental results, the novel synthesized nanoparticles have increased the oil recovery by the synergistic effects of the formed particles markedly by activating the various mechanisms relative to the use of each of the nanoparticles in the micromodel individually. According to the results obtained for the use of this nanocomposite, understanding reservoir conditions plays an important role in the ultimate goal of enhancing oil recovery and the formation of stable emulsions plays an important role in oil recovery using this method.