基于Pickering乳状液的油基钻井液乳化稳定性能研究

将纳米材料形成的Pickering乳状液机理引入到油基钻井液中,形成了新型的油基钻井液。室内研究出了强亲油性的纳米材料CQ-NZC,对其形成的油基钻井液乳状液稳定性及影响因素进行了研究。实验表明,由该纳米材料CQ-NZC形成的乳状液极为稳定,破乳电压可达到2 000 V以上,有机土、润湿剂、降滤失剂及密度调节剂(重晶石和中空玻璃微珠)的加入后均会使乳状液稳定性降低,但在一定范围内乳状液还是具有一定的稳定性能,纳米材料形成Pickering乳状液的油基钻井液体系具有很深的研究价值。     

原油乳状液破乳机理及影响因素研究

由于原油乳状液的形成及稳定性的因素复杂,以及影响原油乳状液破乳的因素众多,因而研究原油乳状液的破乳机理各异,主要有顶替或置换、反相作用、絮凝-聚结、膜排液、膜击破、润湿增溶、反离子作用、褶皱变形机理.又由于原油乳状液的稳定与破乳是一对矛盾,影响乳状液稳定的因素也会影响乳状液的破乳;但从影响破乳剂对原油乳状液破乳的因素来看,主要有原油乳状液的性质、原油破乳剂的性质和外界脱水条件.研究原油乳状液的破乳机理及影响因素,目的是为不同的原油乳状液的破乳方法提供参考依据.     

有利于改进水包油钻井液性能的固体乳化剂的研制及应用

在水基泥浆中加入5—12%矿物油(或柴油)所形成的水包油钻井液已在胜利油田广泛应用于防止卡钻的发生。但在某些情况下,这种泥浆体系的乳化稳定性不能满足钻井作业的需要。为了克服这一缺点,研制出一种颗粒极细并具有特殊润湿性(弱亲水)的固体乳化剂,并已成功地应用于改进乳状液的稳定性和钻井液的其它性能。 在提出该项技术之前,对各种不溶于水的微细固体颗粒对水包油乳状液稳定性的影响进行了较深入的研究。这些颗粒状物质包括膨润土、有机土、高岭石粉、重晶石粉、两种颗粒尺寸不同的碳酸钙粉、两种具有不同润湿性的硅石粉以及新研制的固体乳化剂。为评价这些微粒对乳化稳定性的贡献,分别开展了乳状液稳定性实验和液滴聚并实验。使用静置12h后乳状液的体积和油/水滴的半衰期作为乳状液稳定性的评价指标。实验结果显示,对于给定的油/水体系,乳状液类型和稳定性取决于固体颗粒的类型、尺寸、浓度和润湿性,以及是否有表面活性剂存在。与其它类型的颗粒相比,固体乳化剂的微粒可为水包油乳状液提供最有效的稳定性。同时实验中发现,在某些情况下,固体乳化剂微粒还能有效地稳定油包水乳状液,因为其润湿性接近于中性。 目前,使用新研制的固体乳化剂稳定的水包油乳化泥浆已经成为胜利油田钻定向井和水平     

塔河油田重质油乳状液稳定性影响因素研究

通过电镜扫描和能谱分析发现,塔河油田重质乳化油中含胶质沥青质、Na Cl和黏土矿物等天然乳化剂。本文通过室内实验、理论分析以及现场油井数据研究了重质油的组成对其乳状液稳定性的影响,结果表明:1)胶质沥青质,含量越高乳化越稳定;2)重质油乳状液稳定性与水样矿化度成正比关系,矿化度越高,稳定性越好;3)固体颗粒含量越高,乳化油稳定性越好。     

钻井液固体微粒在油/水/表面活性剂体系中的乳化作用

研究了钻井液、完井液中常见的固体微粒在不同条件下对表面活性剂存在的油水体系的乳化稳定作用,并对两种测定乳化稳定性的实验方法进行了对比。结果表明,油湿颗粒能稳定油包水乳状液,中性润湿的固体微粒既可以稳定油包水型又可以穗定水包油型乳状液,而水湿颗粒的乳化情况比较复杂。在一定条件下,某些固体微粒能够代替或部分代替表面活性剂而用于油包水或水包油乳化钻井液中。     

Pickering乳液在油基钻井液中的应用

Pickering乳液以其较高的聚并稳定性、多样性、可调控性、低成本、低毒性和生物兼容性等优势,广泛应用于生物医学、食品和化妆品等领域。近年来,Pickering乳液在石油行业的应用备受关注。分析了Pickering乳液的稳定机理与其相较于传统乳液的优势;探究了影响Pickering乳液稳定性的诸多因素及调控方式;最后综述了近年来国内外Pickering乳液在钻井和驱油方面的应用,并对Pickering乳液在石油行业中的发展前景进行了展望。      

固体颗粒对O／W乳状液稳定性的影响研究

采用界面张力仪、表面粘弹性仪和Zeta电位仪研究了部分水解聚丙烯酰胺(HPAM)溶液与大庆原油模拟油之间界面性质以及固体颗粒对这些界面性质的影响.结果表明,含100 ms/L的HPAM溶液中加入固体颗粒后,聚合物溶液与原油模拟油之间的界面张力上升,界面剪切粘度下降,但随着固体颗粒浓度的增加,聚合物溶液与原油模拟油间的界面张力和界面剪切粘度基本保持不变.在聚合物溶液中加入固体颗粒后,其与原油模拟油形成的O/W乳状液稳定性变差,乳状液内部油珠表面Zeta电位负值增加.O/W乳状液的稳定性取决于油水界面剪切粘度和Zeta电位的双重影响.     

龙岗礁滩气藏气井垢污分析及堵塞机理研究

针对四川盆地龙岗礁滩气藏在气井开发后期出现大量黑色固体和膏状垢污堵塞管串和储层,造成气井产量和压力急剧降低、酸化有效期缩短的现状,开展了堵塞机理分析。在堵塞物成分分析的基础上,结合XRD衍射仪分析,通过扫描电镜的微观形貌分析观察垢污组分之间的结合关系和组合状态,找出井下固体颗粒、残酸、油溶性外加剂和铁元素是影响堵塞物的主要因素。在模拟井况条件下对上述因素进行控制变量分析,以研究各因素对堵塞物形成的主要作用,探明该类气井的堵塞机理,即在高温高压条件下,入井液中油溶性组分与井下沉积的炭黑和硫等固体颗粒通过乳化、吸附作用形成高黏乳状液,同时残酸等入井液外加剂的高分子聚合物通过架桥吸附作用捕获井下固体颗粒形成凝胶体,二者综合作用使得井下出现大量黑色胶状堵塞物,并据此提出垢污防治建议。     

2-D智能纳米黑卡稳定乳状液的机理*

为揭示二维纳米片状材料(黑卡)对乳状液稳定性的影响,以扶余油田长春岭和三队区块原油为例,在水油体积比为7∶3的条件下,研究质量分数为0.005%的2-D智能纳米黑卡流体对原油乳状液稳定性的影响。通过稳定性分析仪和界面流变仪表征乳状液稳定性大小和界面膜强度,通过观察乳状液的微观形状和粒径分布分析黑卡增强乳状液稳定性的机理。研究结果表明,黑卡尺寸约为70×100(nm),厚度为0.65数1.2 nm。在原油和0.01%稳定剂十六烷基三甲基溴化铵(CTAB)组成的乳状液中加入黑卡后形成Pickering乳状液,乳状液的析水速度变慢,乳状液的稳定析水率从75.71%数78.57%降至65.71%数72.86%;乳状液稳定性提高,稳定性指数(TSI)值由4.73数5.64降至2.71数3.84;乳状液膜的强度增强,体系流变学特征由黏性转变为明显的弹性。黑卡作用的Pickering乳状液的背散射光曲线可分为乳状液破乳区、过渡区和乳状液聚并区3个区域。黑卡能改变稳定剂亲水-亲油平衡,将W/O型乳状液转变为O/W型乳状液,形成液滴尺寸为0.1数5μm大小的乳状液,大幅降低原油黏度。黑卡同时具有亲水-亲油两亲性质,可通过自吸附定向排布于液膜上,增加液膜强度,提高乳状液稳定性。图21表3参22。     

固体微粒对油水体系的乳化稳定作用

采用静置（或离心）沉降法和乳滴稳定性测试法，研究了与钻井液、完井液有关的若干种固体微粒对油、水体系乳化稳定性的影响。研究结果表明，在一定条件下，钻井液中的某些固体微粒能完全或部分替代表面活性剂，对油、水体系起乳化稳定作用。一般情况下，亲油的固体微粒（如有机土）倾向于稳定Ｗ／Ｏ乳状液；亲水的固体微粒倾向于稳定Ｏ／Ｗ乳状液；接近中性润湿的固体微粒（如ＳＮ－１）对两类乳状液均具有一定的稳定作用。固体微粒     

基于Pickering乳液的油基钻井液

Pickering乳液通过颗粒在油水界面吸附,形成稳定界面膜防止水滴聚并,能够提高油基钻井液的稳定性。然而,关于Pickering乳液油基钻井液的研究,忽略了油相中水滴和无机亲水颗粒间相互作用,均未考虑配浆时加入的氢氧化钙、加重剂以及地层中进入的劣质固相等无机颗粒对乳液中水滴存在形式的影响。因此,向W/O型Pickering乳液中加入氢氧化钙、重晶石和不同水化程度高岭土颗粒,通过宏观沉降实验和显微镜图像证明水滴与颗粒结合,以结合水形式存在,导致颗粒聚集;通过激光共聚焦显微镜和低温差示扫描量热对结合水进行表征。通过添加分散剂可以促进结合水颗粒的分散,提高钻井液体系的稳定性。基于W/O型Pickering乳液的油基钻井液不是油包水乳液,而是结合水颗粒在油相中适度分散的体系。此外,配制低密度油基钻井液模型体系,并调控体系的流变性能,实现低温恒流变。     

CTAB诱导膨润土乳液转相机理及其在可逆乳化油基钻井液中的应用

针对目前油基钻井液对油井完井损害问题，结合Pickering乳液高稳定性的特点，通过改变表面活性剂CTAB的浓度，采用原位活化工艺制备了具有不同表面润湿性的膨润土固体颗粒，研究了CTAB诱导膨润土乳液转相机理。Zeta电位及接触角的变化表征膨润土颗粒亲水、亲油性及表面润湿性的变化；膨润土乳液体系电导率及微观形貌的变化表征乳液转相行为。实验结果表明，通过改变CTAB浓度可实现对膨润土颗粒表面润湿性的改变，进而诱导膨润土乳液发生两次相转变行为。应用性能研究表明，该可逆乳化油基钻井液体系热稳定性良好，滤失量小，解决了传统油基钻井液对油井完井的损害问题。     

Stability of Water-in-Crude Oil Emulsions: Effect of Oil Aromaticity,Resins to Asphaltene Ratio,and pH of Water

Abstract

The formation of tight water-in-oil emulsions during production and transport of crude oils is a great problem challenging the petroleum industry. Tremendous research works are directed to understanding the mechanism of formation, stabilization, and controlling of oil field emulsions. This article presents experimental results of some of the factors controlling the formation and stabilization of water-in-crude oil emulsions. In this study, asphaltenes and resins separated from emulsion samples collected from Burgan oil field in Kuwait have been used to study emulsion stability. Model oils of resin to asphaltene ratio of 5:1 and toluene-heptane mixtures have been used to study the effect of oil aromaticity on emulsion stability. Results indicate that at low toluene content (below 20%) or high content (above 40%) less stable emulsions are formed. At a threshold value of 30% toluene, a very tight model oil emulsion is formed. The effect of resins to asphaltene (R/A) ratio on stability of model oil has also been investigated. Results reported in this paper show that as the R/A increases the emulsions become less stable. The effect of pH on stability of model oil emulsion made of 50/50 heptane-toluene mixture having R/A ratio of 5:1 have been studied. Experimental results revealed that as the pH of the aqueous phase of model oil increased from 2 to 10, the emulsion became less stable. At high pH, the asphaltene particles are subjected to complete ionization leading to destruction of the water-oil interface and eventually breakdown of the emulsion.     

Use of Oil-in-water Pickering Emulsion Stabilized by Nanoparticles in Combination With Polymer Flood for Enhanced Oil Recovery

Efficient flooding agents are required to produce additional oil from mature reservoir. In this work, oil-in-water Pickering emulsion systems stabilized using nanoparticles, surfactant, and polymer have been developed and tested for enhanced oil recovery with and without a conventional polymer flood. Stability of nanoparticles in the dispersion of surfactant-polymer solution was tested using zeta-potential before use. Several flooding experiments have been conducted using Berea core samples at 13.6 MPa and temperatures of 313 and 353 K. It has been observed that a combination of 0.5 PV polymer flood with 0.5 PV Pickering emulsion was efficient and have resulted in 1–6% additional oil recovery as compared to 0.5 PV Pickering emulsion flooding alone. The injection of polymer flood have shown to enhance the pressure drop in the core sample after emulsion flooding and considered as an important factor for an additional recovery of oil. The effect of temperature on the viscosity of flooding agents in relation to pressure drop and oil recovery have also been investigated. Viscosity and pressure drop of emulsion flood systems have shown to marginally decrease with increase in temperature. Studies on nanoparticle retention using SEM have shown that nanoparticles were retained in the core sample during emulsion flooding which may be detrimental for permeability of core sample. It is observed that Pickering emulsion flood with polymer flood would be effective for the enhanced oil recovery suitable for matured reservoirs.     

丙烯酸酯-醋酸乙烯乳液共聚合的研究

本文通过测定乳液的稳定性、固含量及聚合过程的 pH 变化,从7种类型的乳化剂中选用了 MES-9乳化剂。当乳化剂、引发剂用量分别为单体含量的3%、0.2%,聚合温度为60℃时,可制备高固含量(55-60%)的丙烯酸酯-醋酸乙烯乳液。在聚合过程中 pH 基本保持不变,乳液的稳定性优于其他类型的乳化剂。考察了工艺条件对收率、特性粘度、乳液粘度、胶粒粒径的影响。并测定了丙烯酸乙酯-醋酸乙烯(EA-VAc)共聚的竞聚率:r_(EA)=6.54,r_(VA)c=0.0225。     

DESTABILIZATION OF WATER IN BITUMEN EMULSION BY WASHING WITH WATER

In order to get more information about the mechanism of stabilization of water-in-diluted-bitumen emulsion, bitumen diluted with toluene (10%, 25%, and 50% in volume) was “washed” using different amounts of water (0.20% in volume). The washing water was emulsified and then separated by high-speed ultra-centrifugation. The supernatant was then used to create a second w/o emulsion with the addition of new water. Stability of the new emulsion was measured in terms of the water separation rate under a low centrifugal force

It has been found that a very stable w/o emulsion was obtained in original diluted bitumen. However, after the diluted bitumen was pre-washed with a few per cent of water, the second emulsion became unstable. This indicates a significant effect of pre-washing with water on emulsion stability, possibly through the removal of emulsion stabilizing agents. Based on analytical results such as surface tension, and FTIR spectra, it appears that a small fraction of bitumen, mostly polar compounds such as carbonic acids and other oxygen-containing compounds, are responsible for the emulsion stabilization. Emulsion stability decreases with increasing volume of washing water but increases with the bitumen concentration.