海上油田注水井降压增注用表面活性剂优选及性能评价

针对海上某油田注水井注水压力升高过快以及注水量下降等问题,通过大量室内实验评价,优选出了适合海上油田注水井降压增注用的复配表面活性剂,并对其界面活性、润湿性能和降压增注性能进行了评价.结果表明:表面活性剂A-2和C-1按1:1进行复配,当其加量为0.6％时,可以使油水界面张力值降低至10-3 mN·m-1范围,达到超低界面张力水平;使用复配表面活性剂浸泡处理亲油玻片后,其表面接触角可以由106°降低至51°,由亲油性转变为亲水性,表现出良好的润湿性能;岩心水驱压力稳定后注入复配表面活性剂体系可以有效降低后续驱替压力,当复配表面活性剂注入1.0 PV时,岩心驱替压力降低率可以达到35％左右,起到了良好的降压增注效果,能够满足海上油田注水井降压增注的需求.     

海上油田注水井降压增注用表面活性剂优选及性能评价

针对海上某油田注水井注水压力升高过快以及注水量下降等问题,通过大量室内实验评价,优选出了适合海上油田注水井降压增注用的复配表面活性剂,并对其界面活性、润湿性能和降压增注性能进行了评价.结果表明:表面活性剂A-2和C-1按1:1进行复配,当其加量为0.6％时,可以使油水界面张力值降低至10-3 mN·m-1范围,达到超低界面张力水平;使用复配表面活性剂浸泡处理亲油玻片后,其表面接触角可以由106°降低至51°,由亲油性转变为亲水性,表现出良好的润湿性能;岩心水驱压力稳定后注入复配表面活性剂体系可以有效降低后续驱替压力,当复配表面活性剂注入1.0 PV时,岩心驱替压力降低率可以达到35％左右,起到了良好的降压增注效果,能够满足海上油田注水井降压增注的需求.     

低渗透油藏注水井表面活性剂降压增注体系研究

低渗透油藏注水井经过长时间注水开发后容易出现注入压力升高以及注水量减少的现象。通过表面活性剂、防膨剂以及防垢剂的优选评价实验,研制了一套适合低渗透油藏注水井的表面活性剂降压增注体系,室内评价了其降低界面张力性能、润湿性能以及降压增注性能。结果表明:该体系与储层原油之间的界面张力随着时间的延长逐渐降低,20 min后即可稳定在10~(-2) mN·m~(-1)数量级,具有良好的降低界面张力性能;亲油岩心切片在该体系中浸泡10 h后的表面接触角可以减小到60°以下,具有良好的润湿性能;岩心水驱压力稳定后注入该体系可以有效降低后续水驱压力,注入0.5 PV后的降压率可以达到26.18%,具有良好的降压增注性能。该表面活性剂降压增注体系能够满足低渗透油藏注水井降压增注现场施工的要求。     

稠油油藏注水井降压增注用表面活性剂的研制及性能评价

稠油油藏注水井注水过程中普遍存在压力上升过快、欠注现象严重等问题。室内通过一步法合成出一种适合于稠油油藏注水井降压增注用季铵盐阳离子双子表面活性剂HYX-1,评价了其与地层水的配伍性、CMC值、界面张力以及降低稠油黏度性能,并通过岩心驱替模拟实验评价了其降压增注效果。结果表明,不同浓度表面活性剂HYX-1与地层水均具有良好的配伍性,且具有较低的CMC值;当其浓度为50~300mg·L-1时,瞬时界面张力最低值可以达到10-3 mN·m-1数量级;当其体积分数为0.05%~0.5%时,目标区块稠油黏度降低率达到90%以上;注入3PV浓度为300~500mg·L-1的HYX-1溶液后,第二次水驱压力比第一次水驱压力降低30%以上。表明,表面活性剂HYX-1具有较好的降压增注效果,可以作为稠油油藏注水井降压增注用表面活性剂。     

用于降压增注的双子表面活性剂合成及性能评价研究

针对低渗油田注水井注入压力高的问题,研发出一种新型表面活性剂MT-01,并且通过室内实验考察了双子表面活性剂的性能及降压增注的效果。研究表明：当双子表面活性剂在较低质量浓度为800 mg/L时,表面张力达到最低,且能有效防止粘土膨胀,能够有效降低油水界面张力,其良好的润湿能力使储层砂岩表面从亲水性向中间润湿转变。岩心驱替实验结果表明,当其质量浓度在400~1000 mg/L浓度范围下,注入2 PV双子表面活性剂降压增注效果显著,降压幅度最高可达29％,提高水相渗透率幅度最高达40％。该新型双子表面活性剂对于提高渗透油田注水井吸水能力、降低注入压力具有较好应用潜力。     

用于降压增注的双子表面活性剂合成及性能评价研究

针对低渗油田注水井注入压力高的问题,研发出一种新型表面活性剂MT-01,并且通过室内实验考察了双子表面活性剂的性能及降压增注的效果。研究表明：当双子表面活性剂在较低质量浓度为800 mg/L时,表面张力达到最低,且能有效防止粘土膨胀,能够有效降低油水界面张力,其良好的润湿能力使储层砂岩表面从亲水性向中间润湿转变。岩心驱替实验结果表明,当其质量浓度在400~1000 mg/L浓度范围下,注入2 PV双子表面活性剂降压增注效果显著,降压幅度最高可达29％,提高水相渗透率幅度最高达40％。该新型双子表面活性剂对于提高渗透油田注水井吸水能力、降低注入压力具有较好应用潜力。     

表面活性剂降压增注提高采收率机理研究

针对低渗透油田注水压力高的问题,开展了表面活性剂降压增注机理研究。通过表面活性剂的油水界面张力测试及岩心驱替实验,考察了表面活性剂的油水界面张力与降压效果的关系。实验结果表明,表面活性剂的油水界面张力越低,降压和提高采收率效果越好。     

表面活性剂乳化性能对低渗油藏采收率影响研究

为同时解决低渗透油藏面临注入困难和储层非均质性强的问题,基于表面活性剂的降压增注原理和乳化调驱机理,探讨了表面活性剂驱油体系在低渗透油藏的应用可行性。实验选取乳化能力不同,其余性能(降低油水界面张力能力、改变润湿性能力、吸附性能)相同的两种表面活性剂,通过室内洗油实验、岩心注入实验和驱油实验,评价了表面活性剂降压增注性能和低渗透条件下乳状液深部调驱性能,探讨了表面活性剂在低渗透油藏中的提高采收率机理。研究结果表明:乳化能力不同的两种表面活性剂具有相近的洗油能力;乳化能力强的表面活性剂在岩心中驱替原油的过程中会形成稳定的乳状液体系,这会降低表面活性剂的降压增注效果,但却可以起到深部调驱作用,可有效提升驱油剂的波及范围,提升低渗透油藏原油采收率。低渗透油藏表面活性剂驱油体系的筛选,需综合考虑提高采收率效果及降压增注性能,根据油藏实际情况选取性能不同的表面活性剂驱油体系。     

海上油田注水井降压增注新工艺的研究与应用

针对低孔低渗储层常规酸化作业难度大、有效期短、经济效益差等治理难题，以X-01井现场工况和治理要求，提出酸化解堵与表面活性剂组合应用的降压增注工艺。在对储层伤害机理分析的基础上，通过正交试验、配伍性、溶蚀性和动态驱替评价实验等手段，确定酸液体系配方组分的质量分数为9%盐酸、6%改性硅酸和4%缓速酸。针对筛选的表面活性剂，通过不同条件下界面张力测试、润湿性测试、段塞组合测试实验说明表面活性剂的特点，并确定段塞组合的浓度梯度为0.8%、0.5%和0.3%。现场采用先酸化解堵、后在线泵注表活性剂的工艺完成施工。应用结果表明，措施后注水压力由16.2MPa降至0,日注水量由180m³增加至570m³,措施有效期超过200d,措施效果显著。该研究成果可为延长海上低孔低渗区块注水井降压增注提供一定的技术支持。     

陕北M油田长8油藏注水井欠注原因及治理措施

针对陕北M油田长8油藏注水井高压欠注的问题,通过对储层特征、注入水和地层水的配伍性、井筒及地面注水系统的分析,找出陕北M油田长8油藏注水井的欠注原因并提出相应的治理措施,对该区块合理实施降压增注措施和保持长期稳定注水高效开发具有重要意义,为下步治理同类油藏提供了借鉴。     

Surfactant Enhanced Oil Recovery in a High Temperature and High Salinity Carbonate Reservoir

The goal of this work was to find an effective surfactant system for enhanced oil recovery after water injection substituting for oil at a vuggy fractured reservoir with a high temperature and high salinity (220,000 mg/L). Four types of surfactants with concentrations (less than 0.2 %) were screened. Washing oil experiments were conducted in Amott cells. A surfactant system was established by mixing a surfactant with best ultimate recovery and one with best recovery rate. The optimized surfactant system could recover 50 % of remaining oil. To study the mechanism of enhanced oil recovery after water injection substituting oil, interfacial tension (IFT) and contact angle were measured. Experimental results showed that surfactants with good washing ability had low IFT, but surfactants with low IFT may not have a good washing ability. IFT had no obvious relationship with the increased oil recovery or washing ability. The optimized system could not alter carbonate to decrease the oil‐wetting capability. Though octadecyl trimethyl ammonium chloride had a good ability wet the carbonate with water, it could not recover much oil. Therefore, except for interfacial tension and wettability alteration, there must be other parameters dominating oil recovery after water injection substituting for oil.     

Laboratory Studies to Determine Suitable Chemicals to Improve Oil Recovery from Garzan Oil Field

Garzan oil field is located at the south east of Turkey. It is a mature oil field and the reservoir is fractured carbonate reservoir. After producing about 1% original oil in place (OOIP) reservoir pressure started to decline. Waterflooding was started in order to support reservoir pressure and also to enhance oil production in 1960. Waterflooding improved the oil recovery but after years of flooding water breakthrough at the production wells was observed. This increased the water/oil ratio at the production wells. In order to enhance oil recovery again different techniques were investigated. Chemical enhanced oil recovery (EOR) methods are gaining attention all over the world for oil recovery. Surfactant injection is an effective way for interfacial tension (IFT) reduction and wettability reversal. In this study, 31 different types of chemicals were studied to specify the effects on oil production. This paper presents solubility of surfactants in brine, IFT and contact angle measurements, imbibition tests, and lastly core flooding experiments. Most of the chemicals were incompatible with Garzan formation water, which has high divalent ion concentration. In this case, the usage of 2-propanol as co-surfactant yielded successful results for stability of the selected chemical solutions. The results of the wettability test indicated that both tested cationic and anionic surfactants altered the wettability of the carbonate rock from oil-wet to intermediate-wet. The maximum oil recovery by imbibition test was reached when core was exposed 1-ethly ionic liquid after imbibition in formation water. Also, after core flooding test, it is concluded that considerable amount of oil can be recovered from Garzan reservoir by waterflooding alone if adverse effects of natural fractures could be eliminated.     

The use of inorganic sacrificial agents in combination with surfactants in enhanced oil recovery

Current literature on optimization of surfactants in enhanced oil recovery is summarized. Effectiveness of the use of surfactants in chemical EOR processes is dependent on many factors. Uncontrollable factors such as reservoir parameters, minerology, and the nature of the crude oil influence the choice of a chemical process. Each reservoir offers a different set of problems to be solved. When the use of a surfactant is warranted, one attempts to optimize further the activity of this surfactant by modifying the chemistry of the reservoir system. Cost aside, maintenance of optimal surfactant activity is essential to minimize the oil/water interfacial tension. Also, loss of surfactant activity due to adsorption on substrate material is particularly disadvantageous because the water wet nature of the rock may be decreased. The use of alkaline, weak acid anions, such as sodium silicate, phosphate and carbonate to enhance surfactant effectiveness has been studied. These sacrificial agents can reduce the hardness (divalent cation) activity of the solution and compete with surfactant for active sites on the reservoir rock surface. Core flood results show that there is an inverse correlation between surfactant retention in the core and residual oil recovery. They also suggest that surfactants may be recovered for reinjection by the optimal use of sacrifical agents-in particular, the sodium silicates.     

花土沟油田精细注水开发实践及认识

花土沟油田为典型的长井段薄互层复杂断块油藏,非均质性严重,油水关系复杂,注采对应差,注水单层突进,地层压力下降快,产量递减幅度较大。为了改善该油藏的水驱开发效果,在精细油藏描述的基础上,通过实施改善水质、井网完善、层系细分、水井分注、剩余油挖潜等精细注采调整工作,达到“注好水、注够水、精细注水、有效注水”目的,注采井数比由1：2.7提高到1：1.7,水驱控制程度和动用程度明显提高,地层压力稳中有升,自然递减率由14.37%降低到8.7%,综合开发效果得到了明显提高。     

高盐油藏提高采收率的室内研究

高盐油藏在水驱采油之后仍有相当一部分原油滞留在地层中,很难将其采出,因此可选用化学方法动用,但高盐油藏地层水矿化度相对较高,温度相对较高,普通表面活性剂很难满足如此苛刻条件下的油藏环境。因此需要将表面活性剂进行复配,充分发挥各种活性剂的优势,进而达到提高采收率的目的。针对玉门油田鸭儿峡L油藏地层水矿化度的特点,采用阴离子-两性表面活性剂复配,通过测定不同复配比和活性剂浓度下的油水界面张力,最终确定了适用于L油藏的表面活性剂驱油复配体系。实验表明在石油磺酸盐A与C14BE复配比为1:4、1:3,总浓度为0.6%、0.1%时,油水界面张力达到了10-3 m N/m级别。此驱油配方适用于L油藏提高采收率的要求。     

Surfactant-Induced Wettability Alteration of Oil-Wet Sandstone Surface: Mechanisms and Its Effect on Oil Recovery

Different analytical methods were utilized to investigate the mechanisms for wettability alteration of oil-wet sandstone surfaces induced by different surfactants and the effect of reservoir wettability on oil recovery. The cationic surfactant cetyltrimethylammonium bromide (CTAB) is more effective than the nonionic surfactant octylphenol ethoxylate (TX-100) and the anionic surfactant sodium laureth sulfate (POE(1)) in altering the wettability of oil-wet sandstone surfaces. The cationic surfactant CTAB was able to desorb negatively charged carboxylates of crude oil from the solid surface in an irreversible way by the formation of ion pairs. For the nonionic surfactant TX-100 and the anionic surfactant POE(1), the wettability of oil-wet sandstone surfaces is changed by the adsorption of surfactants on the solid surface. The different surfactants were added into water to vary the core surface wettability, while maintaining a constant interfacial tension. The more water-wet core showed a higher oil recovery by spontaneous imbibition. The neutral wetting micromodel showed the highest oil recovery by waterflooding and the oil-wet model showed the maximum residual oil saturation among all the models.     

低渗透油田注水井深部调剖技术完善与推广

陇东油区油层属低产、低渗、低压三低油田,区块较多。各区块平面上、纵向上渗透率分布差异大,导致注入水或边底水沿高渗带、大孔道、裂缝指进或锥进,使油井过早见水,并很快水淹,降低了油田采收率。为了遏制油井含水上升过快的势头,提高水驱动用程度和采收率,研究适应陇东油区的堵水调剖技术,满足封堵大孔道、驱替小孔道残余油、剥离岩石孔隙中的油膜的目的,从而提高中高含水期的水驱效率,达到提高采收率的目的。本次研究综合运用示踪剂分析、脉冲试井、PI决策、水驱前缘测试4种方法,开展对储层的见水类型、见水方向、窜流程度研究与分析;对于三叠系裂缝油藏堵剂进行了优选与评价并且提出了堵水调剖方案优化设计方法。     

表面活性剂对特低渗油藏的适用性及应用

为评价表面活性剂WLW对特低渗油藏的适用性,研究了WLW的渗吸特性、乳化性能和界面张力及其在特低渗油藏物理模拟岩心驱油实验和现场中的应用。室内实验结果表明,WLW对注入水的渗吸效率有促进作用;注入质量分数0.2%的WLW溶液,可在水驱基础上提高驱油效率5%左右;WLW在特低渗岩心中提高驱油效率的幅度明显高于中低渗岩心。2011—2013年在长庆靖安油田A1和A2井组开展注WLW现场试验,累计增油4 781 t,WLW对于特低渗油藏提高采收率效果明显。     

驱油阴/两性表面活性剂复配体系协同效应研究

针对某油藏A区块,利用阴离子/两性表面活性剂的协同作用,进而达到油水超低界面张力,且两性表面活性剂十二烷基甜菜碱在浓度为0.1%~0.5%的范围内,降低油水界面张力的效果达到10~(-2) mN/m数量级,在加入阴离子表面活性剂的条件下,复配体系可以使油水界面张力达到超低界面张力。通过探讨表面活性剂的总浓度以及复配比对油水界面张力的影响,最终得到阴离子/两性表面活性剂复配体系可在较高矿化度和较低的浓度(0.4%)范围内达到10~(-3) mN/m的超低界面张力,并在此基础上对两者的协同作用进行分析。     

Synergistic Effects between Anionic and Sulfobetaine Surfactants for Stabilization of Foams Tolerant to Crude Oil in Foam Flooding

In foam flooding, foams stabilized by conventional surfactants are usually unstable in contacting with crude oil, which behaves as a strong defoaming agent. In this article, synergistic effects between different surfactants were utilized to improve foam stability against crude oil. Targeted to reservoir conditions of Daqing crude oil field, China (45 °C, salinity of 6778 mg L⁻¹, pH = 8–9), foams stabilized by typical anionic surfactants fatty alcohol polyoxyethylene ether sulfate (AES) and sodium dodecyl sulfate (SDS) show low composite foam index (200–500 L s) and low oil tolerance index (0.1–0.2). However, the foam stability can be significantly improved by mixing the anionic surfactant with a sulfobetaine surfactant, which behaves as a foam stabilizer increasing the half-life of foams, and those with longer alkyl chain behave better. As an example, by mixing AES and SDS with hexadecyl dimethyl hydroxypropyl sulfobetaine (C₁₆HSB) at a molar fraction of 0.2 (referring to total surfactant, not including water), the maximum composite foaming index and oil tolerance index can be increased to 3000/5000 L s and 1.0/4.0, respectively, at a total concentration between 3 and 5 mM. The attractive interaction between the different surfactants in a mixed monolayer as reflected by the negative β^s parameter is responsible for the enhancement of the foam stabilization, which resulted in lower interfacial tensions and therefore negative enter (E), spreading (S), and bridging (B) coefficients of the oil. The oil is then emulsified as tiny droplets dispersed in lamellae, giving very stable pseudoemulsion films inhibiting rupture of the bubble films. This made it possible to utilize typical conventional anionic surfactants as foaming agents in foam flooding.