Development and Applications of the Solid Emulsifier Used to Improve the Performance of Oil-in-water Drilling Fluids

The oil-in-water emulsion drilling fluids, prepared by adding 5～12% (by volume) of mineral oil (or diesel) to water-based muds, have been widely used for stuck-pipe prevention in the Shengli Oilfield. In some cases, the emulsion stability of this kind of mud system is not strong enough to meet the requirements of drilling operations. To overcome this drawback, a solid emulsifier, which is characterized by its very small particle size and special wetting behavior (slightly water-wet), has been developed and successfully applied to improve the emulsion stability and other performances of these drilling fluids. Prior to the development of this technology, an extensive study was conducted to deal with the influence of various kinds of finely divided insoluble solid particles on oil/water emulsification. The substances used include bentonite, organophilic clay, kaolinite, barite, two kinds of calcium carbonate with different particle sizes, two kinds of silica with different wetting behaviors, and a newly developed solid emulsifier. Both the emulsion stability experiments and the drop coalescence experiments are performed to evaluate the contribution of these particles to emulsification. The measured final emulsion volume disappears after 12 hours and the half-life for water and oil drops are used as the measures of emulsion stability. The experimental data show that the type, size, concentration and wettability of the particles, and the presence of some surfactants control the type and stability of emulsions for a given oil/water system, and the fine particles of the solids emulsifier provide the most effective stabilization for water-continuous emulsions compared with other kinds of particles. Meanwhile, it can be observed that these particles also stabilize oil-continuous emulsions effectively in some cases since their wetting behavior is close to neutral. The O/W emulsion mud stabilized by the newly developed solid emulsifier has become one of the major mud systems used in directional and horizontal well drilling in the Shengli Oilfield. In addition to the improvement of emulsion stability, this solid emulsifier has the advantages of improving the lubricity of mud cake and is beneficial to the control of rheological properties and filtration.

Development and Performance Evaluation of a Deep Water Synthetic Based Drilling Fluid System

With the enhancement of environmental protection awareness, the requirements on drilling fluid are increasingly strict, and the use of ordinary oil-based drilling fluid has been strictly restricted. In order to solve the environmental protection and oil-gas reservoir protection problems of offshore oil drilling, a new synthetic basic drilling fluid system is developed. The basic formula is as follows: a basic fluid (80% Linear a-olefin + 20% Simulated seawater) + 2.5% nano organobentonite + 3.5% emulsifier RHJ-5# + 2.5% fluid loss agent SDJ-1 + 1.5% CaO + the right amount of oil wetting barite to adjust the density, and a multifunctional oil and gas formation protective agent YRZ has been developed. The performance was evaluated using a high-low-high-temperature rheometer, a high-temperature and high-pressure demulsification voltage tester, and a high-temperature and high-pressure dynamic fluid loss meter. The results show that the developed synthetic based drilling fluid has good rheological property, demulsification voltage ≥ 500 V, temperature resistance up to 160°C, high temperature and high pressure filtration loss < 3.5 mL. After adding 2% - 5% YRZ into the basic formula of synthetic based drilling fluid, the permeability recovery value exceeds 90% and the reservoir protection effect is excellent. The new synthetic deepwater drilling fluid is expected to have a good application prospect in offshore deepwater drilling.

Carbon dioxide/calcium oxide responsive behavior and application potential of amine emulsion

Green and low cost CO_(2) and CaO were used to stimulate amine emulsions to reveal the responsive behavior of amine emulsions.On this basis,oil-based drilling fluids responsive to CO_(2) and CaO were formulated and their properties were evaluated.The results showed that the amine emulsions inversed from water-in-oil state to oil-in-water state readily and their rheological behavior underwent transitions of decreasing,rising again and decreasing again via induction by CO_(2).These CO_(2) responsive behaviors could be reversed by CaO.Oil-based drilling fluids prepared based on the amine emulsions with oil-water volume ratios of 50:50 to 70:30,densities of 1.4-2.0 g/cm^(3) had good rheological and filtration properties at 160℃;and be readily cleaned up using CO_(2) bubbling.The useless solid phase with low density could be removed efficiently via reducing the viscosity of emulsion by CO_(2) and the residual liquid phase could be restored to the original state by CaO and reused to prepare drilling fluid.The mechanisms analysis indicated that CO_(2)/CaO induced the reversible conversion between amine emulsifiers and their salts,which enabled the reversible regulation of both the hydrophilic-lipophilic balance of amine emulsifiers and the emulsion particles’size and finally caused the controllable-reversion of the form and rheology of amine emulsion.

Micro/nano structured oleophobic agent improving the wellbore stability of shale gas wells

Through embedding modified nano-silica particles on the surface of polystyrene using the method of Pickering emulsion polymerization,a kind of nano/micro oleophobic agent named OL-1 was developed.The effects of OL-1 on the rock surface properties and its performance in inhibiting the oil phase imbibition into the rock were explored.The performance and mechanisms of OL-1 in improving the wellbore stability of shale gas wells were evaluated and analyzed.OL-1 could absorb on the surface of the shale core to form a membrane with a micro-nano two-stage roughness,making the surface energy of the core decrease to 0.13 mN/m and the contact angle of the white oil on the core surface increase from 16.39°to 153.03°.Compared with the untreated capillary tube,when immersed into 3#white oil,the capillary tube treated by OL-1 had a reversal of capillary pressure from 273.76 Pa to-297.71 Pa,and the oil imbibition height inside the capillary tube decreased from 31 mm above the external liquid level to 33 mm below the external liquid level.The amount of oil invading into the rock core modified by OL-1 decreased by 64.29%compared with the untreated one.The shale core immersed into the oil-based drilling fluids with 1%OL-1 had a porosity reduction rate of only 4.5%.Compared with the core immersed in the drilling fluids without OL-1,the inherent force of the core treated by 1%OL-1 increased by 24.9%,demonstrating that OL-1 could effectively improve the rock mechanical stability by inhibiting oil phase imbibition.

抗高温白油基钻井液体系构建及评价

油基钻井液是近年来在我国页岩气钻井现场广泛应用的一种作业流体,具有抗高温、抗盐钙侵、有利于井壁稳定、润滑性好和对油气层损害程度小等优点。本文通过对核心处理剂主乳化剂、辅乳化剂等进行优选及性能评价,同时对有机土、降滤失剂、润湿剂等白油基钻井液体系中的关键处理剂进行优选评价,得出一套体系,抗温度达200℃,长时间高温稳定性良好,72 h老化时间性能稳定,有良好的乳化稳定性能,可抗15%地层水污染。

低油水比油基钻井液体系研究

现阶段国内大量应用的油基钻井液体系油水比居高不下,且由于部分处理剂性能欠佳导致在钻井液体系中用量过大,两者叠加为降低油基钻井液体系综合成本带来极大困难。为此,提出了低油水比油基钻井液体系设计思路,并以此为指导研选了油基钻井液体系关键处理剂,通过配伍性实验构建了低油水比油基钻井液体系配方,并开展了现场应用。以保障在良好的乳化稳定性、流变性和较强的随钻封堵性基础上有效降低油水比为整体思路,研制了多活性点新型乳化剂,增加了分子内活性吸附基团的数量,在低油水比的情况下表现出良好的乳化稳定性和流变性;优选了具有良好增黏提切效果且可降低滤失量的有机土、具有良好降滤失效果的降滤失剂、具有改善流变性且提高乳化稳定性的流型调节剂,以3种处理剂为核心构建了低油水比油基钻井液体系;该体系在70/30的油水比条件下老化前后破乳电压>1000 V,在60/40的油水比条件下老化前后破乳电压>500 V,动塑比均>0.40,具有良好的乳化稳定性和流变性;低油水比油基钻井液体系在12口页岩水平井开展了现场应用,钻井液体系性能稳定、井眼净化效果良好,且乳化稳定性可控,大幅节约了基础油的用量,显著降低了油基钻井液体系的成本。

油基钻井液用超支化乳化剂的制备与评价

为了提高油基钻井液的乳化稳定性能,以妥尔油脂肪酸、二聚酸、椰油酸甲酯、二乙醇胺、二乙烯三胺、白油等为原料,将脂肪酸上的羧基与多胺的氨基通过脱水反应形成酰胺键,由此产生的多酰胺中心节点将多个脂肪酸分子连接起来,形成功能化的超支化酰胺聚合物,再与白油等复配形成具有“海葵”效应的超支化主乳化剂;以妥尔油脂肪酸、油酸、油酸甲酯、三乙醇胺为原料,制备了辅乳化剂。通过测定固定主辅乳质量比例为4∶1,总加质量为4%,油水体积比为80∶20时的乳状液的微观形态、粒径大小、界面张力、润湿性和稳定性,在4种乳化剂中优选出乳化稳定性能最好的乳化剂。进一步研究乳化剂加量、油水比、温度和密度对所配油基钻井液的影响。结果表明,具有超支化酰胺聚合物的主乳化剂和辅乳化剂复配的乳状液为球形形态,且分布均匀,互不聚集,平均粒径为≤4.5μm,界面张力为≤0.4 mN/m,接触角为≤40°,破乳电压≥400 V;配制的油基钻井液在90~180℃、油水体积比为75∶25~85∶15、密度1.1~1.9 g/cm 3的条件下,老化后流变性能稳定,破乳电压≥800 V,高温高压滤失量≤3 mL,可满足海上高温深井、大位移水平井等复杂井的作业需求。

反渗透钻井液体系的研究及其在东海的实践应用

东海地区存在大段砂泥岩互层,泥岩极易水化膨胀,伴随微裂缝发育,在钻井过程中极易发生起下钻遇阻和憋扭矩,甚至井壁失稳等复杂情况。考虑海上环保问题,油基钻井液使用受限,为解决东海钻井井壁失稳难题,通过借鉴油基钻井液活度平衡和半透膜理论,采用高浓度盐降低了体系的活度,同时增强体系的抑制性以及微纳米封堵技术,有效延缓压力和滤液的传递。通过性能对比评价,最终研发出一套与油基钻井液性能接近的反渗透钻井液体系,该体系现场应用结果表明,其在钻井过程中性能稳定,钻屑规则,井壁稳定,基本实现了直接起下钻,降低了东海地区泥岩地层的井壁失稳频次。

低密度水包原油钻井液的应用

介绍了一种新型高油水比(7:3)水包原油钻井液体系。对乳化剂及钻井液配方进行了优选,对水包原油钻井液的稳定性、抗温性、抗污染性进行了评价。结果表明,该钻井液具有密度低、滤失量低、润滑性好、抗温达120℃、流变性易调整等特性。在任平2井现场应用效果良好。

无土相油基钻井液的研究与应用

为解决无土相油基钻井液电稳定性差、油水极易分层的问题,研发出一种兼具润湿作用的新型复合型乳化剂G326-HEM,该剂以由高分子量脂肪酸、有机伯胺为主要原料合成的脂肪酸酰胺作主剂,该主剂具有亲油及亲水2个基团,可以在油水界面形成具有一定黏弹性的界面膜,显著降低界面张力;辅助增效剂为优选出的天然植物脂肪酸,可与体系中过量的石灰反应,生成的产物可在油水界面锲行排列,配合主剂形成油包水乳状液。以G326-HEM为乳化剂配制的无土相油基钻井液性能稳定,抗温可达180℃,密度可达2.50 g/cm3,可抗10%Na Cl盐水或15%岩屑的污染,乳化稳定性好,用矿物油或合成油均可配制。在ZT-21井获得了成功应用,解决了以往含土相油基钻井液在高密度条件下暴露出的流变性差、起下钻不畅、易发生压差卡钻、易诱发井漏等难题。指出,无土相油基钻井液由于当量循环密度低,在高密度条件下相对于含土相油基钻井液更具优势,尤其在高压易漏地层具有更好的应用效果。

油包水乳状液稳定性影响因素分析

油基钻井液优良的抑制性能及耐高温性能,使其成为钻复杂井的重要解决手段,特别是在钻高温深井和水敏性地层中优势更明显。影响油基钻井液稳定性的因素有很多,其中乳状液的稳定性是油基钻井液的决定性因素。文章介绍了油水比、配制条件、内外相种类等因素对油包水乳状液稳定性的影响机理,重点分析了乳化剂种类和加量对油包水钻井液的影响规律,通过钻屑污染实验分析了固相颗粒进入油基钻井液体系后由于大量吸附了体系中的表面活性剂,导致了钻井液中有效乳化剂质量浓度降低造成的电稳定性下降。

抗220℃高温油包水钻井液研究与应用

介绍了抗 2 2 0℃高温油包水钻井液的室内试验与现场应用情况。在葡深 1井的现场应用表明 ,该油包水钻井液具有流变性优异、稳定性好、滤失量低等特点 ,顺利地完成了松辽盆地最深 ( 5 5 0 0 m)、国内井温最高井 (井底温度 2 2 0℃ )的钻探任务 ,达到预期目的 ,解决了国内钻井液的一大技术难题。

低切力高密度无土相油基钻井液的研制

传统的油基钻井液采用有机土作为增黏剂来增加悬浮重晶石的能力,是一种含土相的油基钻井液,高密度条件下含土相油基钻井液流变性控制困难限制了其应用的范围。为此,以新研制的复合型乳化剂(G326-HEM)为核心,构建了无土相油基钻井液体系,并对该配方进行了优选和性能实验。结果表明:1无土相油基钻井液体系无须使用辅乳化剂、润湿剂,具有配方简单,高密度条件下流变性好等特性;2与含土相钻井液相比,高密度条件下塑性黏度、终切力低,降低了高密度钻井液因黏切高诱发井漏的风险,可节省10%的基础油;3塑性黏度和动切力随着油水比的降低而升高,不同密度下的油基钻井液选用不同的油水比;4无土相油基体系配方对基础油的适应性较广,可广泛应用于合成基、矿物油基钻井液。结论认为,该成果较好地解决了无土相体系在高密度条件下的电稳定性弱、悬浮稳定性差的难题,为页岩气及其他非常规气藏规模开发提供了技术保障。

鄂尔多斯盆地延长组页岩气井壁稳定钻井液

针对鄂尔多斯盆地延长组页岩气水平井钻井过程中存在的裸眼井壁失稳问题,对该组地层进行理化性能分析,明确了导致页岩井壁失稳的主要因素,即钻井液滤液沿地层微裂缝进入地层引起伊蒙混层膨胀,岩石强度降低,为此提出了采用油包水乳化钻井液的技术对策。在此基础上,通过室内实验优选了一套页岩水平井油包水乳化钻井液。室内性能评价实验表明:该体系可加重至1.60 g/cm3,破乳电压高于800 V,抗温120℃,封堵突破压力为7.28 MPa,浸泡后对页岩强度影响较小,能够有效抑制页岩膨胀和封堵裂缝性地层,对于解决该区页岩气钻井过程中的井壁失稳问题具有指导意义。

油包水型乳状液高温稳定性

研究了2种乳化剂RHJ-Ⅰ和RHJ-Ⅱ的油/水界面活性及温度的影响。以国产合成油为基础油,25%CaCl_(2)水溶液为水相,并添加Ca(OH)_(2)制备了油包水(W/O)型乳状液,考察了体系组成、老化处理温度和静置温度等对其稳定性的影响,探讨了稳定机理。结果表明,所研究的乳化剂可显著降低合成油/水界面张力,在油/水界面形成黏弹性界面膜。所制备的W/O型乳状液具良好的分散稳定性,RHJ-Ⅰ和RHJ-Ⅱ复配具协同增稳效应。乳状液经高温(180和232℃)老化处理后,其稳定性明显增强,缘于乳化剂与Ca(OH)_(2)作用形成“有机Ca(OH)_(2)”,从而增强乳状液的高温稳定性。水/油比在1∶9~5∶5范围内增大,稳定性明显增强。

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。固体微粒的种类、加量、粒径和形状也是决定其乳化稳定作用的重要因素。

抗高温水包柴油乳状液研究

针对欠平衡钻井对低密度钻井液的要求,以水包柴油乳状液为研究对象,通过实验优选乳化剂,研究了2种和多种乳化剂协同作用下水包柴油乳状液的稳定性,优选出了抗温性能好、乳化能力强的复合乳化剂,配制出了抗180℃高温的水包油乳状液。

加盐超浓反相乳液的合成、表征及性能研究

采用超浓反相乳液聚合法对AA/AM/AMPS三元单体共聚合,合成出了钻井液用降滤失剂,研究了加盐对产物降滤失性能和稳定性的影响,并通过热重分析法和差示扫描量热法对合成聚合物进行了表征。结果表明,盐的存在一定程度上提高了聚合物乳液的降滤失性能及稳定性,但对聚合物的耐热性能没有显著的影响。

油水比对油基钻井液性能的影响研究

为获得适合页岩气水平井的低油水比下性能优良的油基钻井液,利用Turbiscan Lab型分散稳定性分析仪研究了油水比对油包水乳状液的粒径及稳定性的影响,考察了油水比对油基钻井液性能的影响。研究结果表明,油水比由90∶10降至60∶40时,油包水乳状液的平均粒径由5.65μm增至8.21μm;随着油水比降低,乳状液的背散射光强度值变化幅度逐渐增大,油包水乳状液稳定性变差。在处理剂加量不变的条件下,油水比由90∶10降至60∶40,热滚后的油基钻井液的塑性黏度由16 m Pa·s增至55 m Pa·s,动切力由7 Pa增至30 Pa,破乳电压由1211 V降至303 V。通过提高乳化剂加量、降低有机土加量在低油水比条件下获得了性能优良的油基钻井液,并成功用于焦页54-3HF、焦页25-2HF、焦页54-1HF等多口井的现场施工。

用作延缓交联剂的多重乳液热稳定性研究

拟用作聚合物水基凝胶延缓交联剂的多重乳液按下述方法制备:1.5%醋酸铬水溶液与加入3%油包水乳化剂的柴油按体积比70∶30混合,制成W1/O乳液,后者与加有1%水包油乳化剂的矿化度32 g/L的模拟地层水按体积比70∶30混合,制成(W1/O)/W2多重乳液。用电导率法测定乳液静置30天析出水相中醋酸铬含量并计算乳液破裂率,结果表明多重乳液的稳定性远小于相应的W1/O乳液,使用油包水乳化剂T161(HLB值3.8)和水包油乳化剂Tween20(16.7)的多重乳液的稳定性好于使用Span80(4.3)和Tween20的多重乳液,30℃、50℃、70℃破裂率分别为11.5%,17.8%,28.0%和21.0%,56.0%,67.3%。加入T161的柴油与模拟地层水之间的界面剪切粘度ηs大于加入Span80时的相应值,表面活性剂加量0.3%时,30℃,50℃,70℃下60 minηs值(mN.s/m)分别为0.112,0.100,0.096和0.0442,0.0349,0.0257。在水相中加入0.02%和0.10%Tween20使加入3.0%T161的柴油与模拟地层水之间30℃、60 minηs值降低14.3%和27.3%,油包水乳化剂为Span80时则降低34.9%和65.4%。用T161/Tween20制备的多重乳液稳定性较好的原因,是油水界面的T161分子不易被Tween20分子顶替。图9表3参9。