生物酶改变岩石表面润湿性实验研究

根据岩石润湿性的衡量标准,用光学投影法测定岩石接触角,对生物酶改变岩石表面润湿性进行了实验研究,包括生物酶与岩石作用后岩石润湿性的变化、毛管力的变化以及粘附功的变化。实验结果表明,生物酶与岩石作用后,可以明显改变水驱油毛营力的大小,可以加速剩余油的流动,从而提高油藏的采收率。     

活性水驱微观驱油机理的探索

润湿性是油藏岩石、原油和水三者相互作用的综合表现形式,了解油藏润湿性对提高原油采收率有重要意义。文章讨论了润湿角、界面张力、粘附功之间的关系和润湿角、界面张力、毛管力之间的关系,从本质上分析粘附功、毛管力对提高采收率的影响,详细解释了低界面张力机理、润湿反转机理、降低亲油油层的毛管阻力机理。     

空气辅助微生物改变地层岩石与流体性质的能力研究

为了提高微生物采油的应用效果,研究了空气辅助对微生物改变地层岩石与流体性质作用机理。通过实验研究空气辅助微生物改变岩石表面润湿性、油水界面张力及微生物降解原油机理,以岩石润湿性和油水界面张力改变为基础,探讨了空气中氧对微生物改变岩石表面和黏附功的影响。实验结果表明,空气中氧可提高微生物菌液改变石英表面润湿角速度,溶氧4.5～5.5mg/L菌液中润湿角降低50.14%～56.94%。4.5 mg/L溶氧条件下,菌液作用后原油界面张力下降80%。与含溶氧5.5mg/L培养的微生物作用后,油质组分增加8.414%,蜡质组分降低7.728%,胶质组分降低5.538%。实验表明,空气辅助可增强微生物改变地层岩石与流体性质的能力,进一步提高原油采收率。     

声波振动与岩石表面润湿性

通过水与岩石表面接触角的测定、声被驱油实验和理论分析,研究考察了声波振动对原油─岩石、水─岩石界面特性的影响,从界面化学角度对岩石表面的润湿性和声波驱油机理进行了探索。结果表明:经原油浸泡后,由于原油中极性化合物(胶质、沥青质等)在岩石表面的吸附,岩石表面由水相润湿为主转变为油相润湿为主;无论岩石表面以水相润湿为主还是油相润湿为主,在水浸泡过程中,声波振动可促进其表面亲油性减弱和亲水性增强,毛细管阻力降低;伴随着岩石表面润湿性的改变,原油对岩石表面的粘附功明显降低;减弱了原油与岩石表面间的粘滞力,使原油更易于从岩石表面上剥离,提高原油采收率;岩石的渗透率越低,声波振动作用越显着。     

油田注水吞吐采油的可行性分析

Graham.J．W．的自吸理论公式揭示了裂缝性油藏自吸水驱油量与基质的物性、润湿性、油水界面张力、原油粘度以及油水接触面积的关系。根据这一理论公式，阐明了注水吞吐采油井应选择地层能量不足、原油粘度低、剩余可采储量高、油层亲水并具有1～2个物性好的主力油层，最好是反韵律所组成的裂缝发育的油组。亲油岩心、高粘度原油的全模拟实验证明，在注入水中加入表面活性剂和粘土防膨胀剂，可有效地保护储层、降低油水界面张力、改变岩石润湿性．可大幅度提高原油采出程度。     

低渗透砂岩润湿性对水驱和复合驱采收率的影响

在砂岩岩心渗透率小于50×10-3μm2条件下,考察驱替相润湿接触角分别为37,86,126和167°的驱油效果,对应水驱采收率平均值依次为16.18%,15.47%,13.94%和9.02%,复合驱采收率依次为21.12%,17.33%,13.53%和5.26%。结果表明,除强亲油性外,其他润湿性对岩心水驱采收率的影响不显著。复合驱提高采收率幅度随润湿性由亲油到亲水变化逐渐提高,其平均值与润湿接触角呈二阶线性负相关关系,即润湿接触角越小,采收率越高,接触角为37°时提高采收率最大。低渗透孔隙微毛细管对原油的捕集作用是制约驱油效率的关键因素,应用复合驱应重点从降低油水界面张力和改变岩石润湿性2方面考虑克服毛管对原油的捕集束缚。     

润湿性反转剂的微观渗流机理

为了研究润湿性反转剂对渗流过程的影响,对润湿性反转剂的微观渗流机理进行了研究。用接触角法和W ashburn法测定了固体表面的接触角,研究了润湿性反转剂对润湿性的影响;用界面张力仪测定了润湿性反转剂的油水界面张力,分析其降低油水界面张力的能力;并用微观刻蚀模型驱油试验研究了润湿性反转剂的微观渗流机理。试验结果表明:润湿性反转剂能改变表面的润湿性,使亲油表面变为亲水表面;润湿性反转剂有降低油水界面张力的能力,能使油水界面张力降低至10-1mN/m;润湿性反转剂使油膜剥离并形成油桥,使润湿性反转。该研究说明油水界面张力和润湿性都影响油水渗流特征,为进一步研究如何改善油水渗流过程奠定了基础。     

张店油田储层注水影响因素探讨

张店油田在注水开发过程中，出现注水难和注不进去的现象，通过岩心试验评价不同毛管力，不同润湿性，不同温度下模拟注水以及注表面活性剂的岩心驱替试验，并结合张店油田储层有关特征，对影响张店油田注水驱油效果的因素做出分析评价。研究结果表明，毛细管力是影响注水的重要因素之一，随着样品水润湿性程度的增加，注水压力升高，驱油效率减小。注水温度越低高含蜡原油结蜡严重，影响注水。表面活性荆能降低油水界面张力，从而降低注入压力，提高原油采收率。     

不同润湿性砂岩中聚合物吸附滞留对渗流过程的影响

为了研究不同润湿性孔隙中发生聚合物吸附滞留后的流体渗流机制,首先用非稳态法实验研究了亲水岩心和亲油岩心中聚合物吸附前后的油水两相流动过程,然后改进了半渗透隔板法测试油水毛管力实验方法,用常规驱替流程直接测试了聚合物吸附前后油水毛管力.研究表明,聚合物在岩心中吸附能选择性地降低水相相对渗透率;改变孔隙与渗流流体的相互作用,使亲水岩心束缚水饱和度增加,残余油饱和度降低,亲水程度增强,油水毛管力增加,毛管力曲线变陡;使亲油岩心润湿性反转,油水毛管力由负值变为正值;深化了高含水油藏聚合物驱降水增油机理.     

张店油田储层注水影响因素探讨

张店油田在注水开发过程中 ,出现注水难和注不进去的现象 ,通过岩心试验评价不同毛管力 ,不同润湿性 ,不同温度下模拟注水以及注表面活性剂的岩心驱替试验 ,并结合张店油田储层有关特征 ,对影响张店油田注水驱油效果的因素做出分析评价。研究结果表明 ,毛细管力是影响注水的重要因素之一 ,随着样品水润湿性程度的增加 ,注水压力升高 ,驱油效率减小。注水温度越低高含蜡原油结蜡严重 ,影响注水。表面活性剂能降低油水界面张力 ,从而降低注入压力 ,提高原油采收率。     

癸烷在二氧化硅表面的油膜形成与表面润湿性

用二氧化硅片作为模拟岩石，以椭圆偏振法测量癸烷在其表面形成的油膜厚度，通过长度测量法测定水在二氧化硅表面的接触角来判断润湿性及润湿性的变化。亲水的二氧化硅表面难以形成油膜，而疏水的二氧化硅表面能形成较厚而稳定的油膜。疏水或近中性的二氧化硅表面在经碱水作用或吸附表面活性剂后，在特定的条件下能变成弱亲水或亲水，从而将油膜破坏。     

Characterization of reservoir systems at elevated pressure

The efficiency in enhanced oil recovery strongly depends on interphase behaviour of the participating fluids and solids. Analysis is carried out using experimental techniques for recording contact angles and interfacial tension at elevated pressure and relating these data by use of known approaches from literature. Even in fairly incompressible liquid–liquid–solid systems the solid–liquid interfacial energies are shown to change at rising pressure. Combination of measured contact angles of a ternary water–n–alkane–dolomite system with those of the respective binary systems enables estimation of surface and interfacial energies of rock surfaces. In the presence of gases, especially methane, the water–n-alkane interfacial tension as well as the contact angle of a (non-wetting) water drop on dolomite in n-alkane is decreased which is only possible if the interfacial energy of n-alkane–dolomite rises based on Young's law. In a water-wet system, wetting by water was also observed to improve under pressure which is attributed to a decreasing water–rock interfacial energy since the water–oil interfacial tension is increased at the same time.     

Experimental Investigation of Contact Angles Under Oil-Microbial Solution on Carbonate Rocks

Abstract

Contact angles are used to measure the wetting behavior of two immiscible fluids on a solid surface. Fluids are considered wettings if their contact angles with surface are less than 90°, and they are considered nonwetting, if their contact angles are greater than 90°. Because of its influence on other petrophysical properties of reservoir rocks, such as relative permeability, capillary pressure, and the residual oil saturation after a flood, wettability and its direct measure, the contact angle, play a significant role in affecting the recovery from both primary and improved recovery processes. In this work, contact angle alteration occurring in microbial enhanced oil recovery processes (MEOR) are quantified and described, along with a study of the factors that would enhance such contact angle alteration. An experimental method for the measurement of contact angles has been developed in which the contact angle is measured as a function of time. Measurements of contact angle and interfacial tension for four different types of UAE crude oil and four different mineralogical rock composition over a range of microbial concentration, salinity, and temperature are reported. Results showed that contact angles for the studied systems increased with temperature, crude oil sulfur concentration and microbial concentration up to a certain concentration, beyond which the bacteria concentration exhibited no effect on the contact angle. Crude oils containing low asphaltene concentration produced a stable contact angle and oils containing high asphaltene concentration produced surfaces with unstable wettability. The mineralogical composition of limestone rocks had no effect on the contact angle of microbial-oil system.     

Experimental Investigation of Contact Angles Under Oil-Microbial Solution on Carbonate Rocks

Contact angles are used to measure the wetting behavior of two immiscible fluids on a solid surface. Fluids are considered wettings if their contact angles with surface are less than 90°, and they are considered nonwetting, if their contact angles are greater than 90°. Because of its influence on other petrophysical properties of reservoir rocks, such as relative permeability, capillary pressure, and the residual oil saturation after a flood, wettability and its direct measure, the contact angle, play a significant role in affecting the recovery from both primary and improved recovery processes. In this work, contact angle alteration occurring in microbial enhanced oil recovery processes (MEOR) are quantified and described, along with a study of the factors that would enhance such contact angle alteration. An experimental method for the measurement of contact angles has been developed in which the contact angle is measured as a function of time. Measurements of contact angle and interfacial tension for four different types of UAE crude oil and four different mineralogical rock composition over a range of microbial concentration, salinity, and temperature are reported. Results showed that contact angles for the studied systems increased with temperature, crude oil sulfur concentration and microbial concentration up to a certain concentration, beyond which the bacteria concentration exhibited no effect on the contact angle. Crude oils containing low asphaltene concentration produced a stable contact angle and oils containing high asphaltene concentration produced surfaces with unstable wettability. The mineralogical composition of limestone rocks had no effect on the contact angle of microbial-oil system.     

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油田污水经处理后回注,既避免了环境污染,又达到了注水保压的目的。但注水过程中,注入水必然要与储层岩石、流体接触,并发生各种物理化学作用,从而导致储层渗透率恶化,使地层受到伤害。此外,不合格的注水入还会引起集输系统和井筒的腐蚀和结垢,从而大大降低注水效果。为了避免和减少这些不利因素,必须对注入水的水质进行评定,确定合理可行的水质指标,从而达到保护油气层、提高彩收率的目的。文章立足于多年来轮南油田注入     

Investigating wettability contact angle measurement in Kuwaiti heavy oil reservoir and modeling using 2D imaging technologies

Wettability contact angle characterization will be investigated by 2D technologies and a deterministic model is developed. Deterministic approach is a robust technique using 2D image capturing and image analyses that are applied on a Kuwaiti silty sandstone reservoir to accurately quantify wetting contact angle trends in the rock sample. And, then, generate all possible pore contact angles. In this study, heavy oil recovery prediction model is also developed by constructing mathematical model based on statistical grouping and averaging for all measured pore-walls available and quantifying wetting contact angle follows morphological approach that has greater confidence.     

Variations in Wettability Caused by Nanoparticles

Recently, polysilicon nanoparticles were used to enhancing water injection capacity of injection wells and also enhanced oil recovery of production wells. Polysilicon nanoparticles can be adsorbed on rock surface, and then they can change rock wettability. Predicting the amount of contact angle variations is important for these purposes. The objective of this work is to study the effects of polysilicon nanoparticles on wettability. To assess this, contact angle changes of oil droplet on carbonate cores were measured. In the next stage, an empirical model for predicting wettability variation is presented and curve fitting was conducted. The results show that as increasing nanoparticle concentration, the contact angle decreases in a homographic manner.     

渝东南地区页岩润湿性的定量表征研究

以渝东南地区五口井页岩为研究对象,采用光学接触角测试方法测试其润湿性,并对比分析页岩润湿性特性与地层压力系数、解析速率、黏土含量、TOC之间的相关性,找出不同页岩储层间润湿性变化特点,总结影响页岩润湿性变化的可能因素。最终得出研究结果:①常压井的白油/岩石的平均接触角相对较低,即更具有亲油性;超压井的水/岩石的接触角较低,即更具有亲水性;②在解析速率方面,发现高解析速率的页岩气井的亲水、亲油的程度均高于低解析速率的页岩气井;③页岩TOC越高,其亲油程度越高,但亲水性影响不大,表明有机质含量与亲油性存在直接联系。最后,利用杨氏方程,通过界面张力来定量表征岩石的润湿性特点,可用于接触角法评价页岩润湿性的应用研究。     

An evaluation of modified silica nanoparticles’ efficiency in enhancing oil recovery of light and intermediate oil reservoirs

The role of nanoparticles in enhancing oil recovery from oil reservoirs is an increasingly important topic of research. Nanoparticles have the properties that are potentially useful for enhanced oil recovery processes, as they are solid and two orders of magnitude smaller than colloidal particles. This paper presents a comparison between the efficiency of modified silica nanoparticles in enhancing oil recovery from two different Iranian light and intermediate oil reservoirs. The mechanisms used to recover additional oil would be oil–water interfacial tension reduction and wettability alteration. Oil phase contact angles and oil–water interfacial tensions were measured in the absence and the presence of nano fluids’ different concentrations (1–4 g/L). Results showed that the interfacial tension reduces dramatically in the presence of nanoparticles for both light and intermediate oil. In addition oil phase contact angle results showed a transformation of rock wettability from water-wet toward oil-wet condition. However, these nanoparticles are more capable in the reduction of the interfacial tension and the alteration of wettability in the case of light oil reservoir. A comparison between recovery results indicated that these nanoparticles are more efficient in light oil reservoirs and produce more incremental amount of oil after primary and secondary processes.