Gas-hydrate formation,agglomeration and inhibition in oil-based drilling fluids for deep-water drilling

One of the main challenges in deep-water drilling is gas-hydrate plugs,which make the drilling unsafe.Some oil-based drilling fluids（OBDF） that would be used for deep-water drilling in the South China Sea were tested to investigate the characteristics of gas-hydrate formation,agglomeration and inhibition by an experimental system under the temperature of 4 ？C and pressure of 20 MPa,which would be similar to the case of 2000 m water depth.The results validate the hydrate shell formation model and show that the water cut can greatly influence hydrate formation and agglomeration behaviors in the OBDF.The oleophobic effect enhanced by hydrate shell formation which weakens or destroys the interfacial films effect and the hydrophilic effect are the dominant agglomeration mechanism of hydrate particles.The formation of gas hydrates in OBDF is easier and quicker than in water-based drilling fluids in deep-water conditions of low temperature and high pressure because the former is a W/O dispersive emulsion which means much more gas-water interfaces and nucleation sites than the later.Higher ethylene glycol concentrations can inhibit the formation of gas hydrates and to some extent also act as an anti-agglomerant to inhibit hydrates agglomeration in the OBDF.

High temperature and high pressure rheological properties of high-density water-based drilling fluids for deep wells

To maintain tight control over rheological properties of high-density water-based drilling fluids, it is essential to understand the factors influencing the theology of water-based drilling fluids. This paper examines temperature effects on the rheological properties of two types of high-density water-based drilling fluids （fresh water-based and brine-based） under high temperature and high pressure （HTHP） with a Fann 50SL rheometer. On the basis of the water-based drilling fluid systems formulated in laboratory, this paper mainly describes the influences of different types and concentration of clay, the content of a colloid stabilizer named GHJ-1 and fluid density on the rheological parameters such as viscosity and shear stress. In addition, the effects of aging temperature and aging time of the drilling fluid on these parameters were also examined. Clay content and proportions for different densities of brine-based fluids were recommended to effectively regulate the rheological properties. Four theological models, the Bingham, power law, Casson and H-B models, were employed to fit the rheological parameters. It turns out that the H-B model was the best one to describe the rheological properties of the high-density drilling fluid under HTHP conditions and power law model produced the worst fit. In addition, a new mathematical model that describes the apparent viscosity as a function of temperature and pressure was established and has been applied on site.

Influence of monoethanolamine on thermal stability of starch in water based drilling fluid system

To improve the thermal stability of starch in water-based drilling fluid,monoethanolamine(MEA)was added,and the effect was investigated by laboratory experiment.The experimental results show that the addition of monoethanolamine(MEA)increases the apparent viscosity,plastic viscosity,dynamic shear force,and static shear force of the drilling fluid,and reduces the filtration rate of drilling fluid and thickness of mud cake apparently.By creating hydrogen bonds with starch polymer,the monoethanolamine can prevent hydrolysis of starch at high temperature.Starch,as a natural polymer,is able to improve the rheological properties and reduce filtration of drilling fluid,but it works only below 121℃.The MEA will increase the thermal stability of starch up to 160℃.There is a optimum concentration of MEA,when higher than this concentration,its effect declines.

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.

Preparation and Performance of the Hyperbranched Polyamine as an Effective Shale Inhibitor for Water-Based Drilling Fluid

Seeking effective solutions to control and mitigate the interaction between drilling fluids and clay formations has been a challenge for many years, and various shale inhibitors have shown excellent results in problematic shale formations around the world. Herein, the hyperbranched polyamine (HBPA) inhibitor with a higher ratio of amine groups and obvious tendentiousness in protonation was successfully synthesized from ethylenediamine, acryloyl chloride and aziridine by five steps, in which the metal-organic framework (MOF) was employed as a catalyst for ring-open polycondensation (ROP). The structure and purity were confirmed by nuclear magnetic resonance hydrogen spectroscopy and high-performance liquid chromatography (HPLC) respectively. The HBPA displays more excellent performance than EDA and KCl widely applied in the oil field. After aging at 80°C and 180°C, the YP of a slurry system containing 25 wt.% bentonite and 2 wt.% HBPA are just 8.5 Pa and 5.5 Pa (wt.%: percentage of mass), respectively. The swelling lengths of 2 wt.% HBPA are estimated to be 1.78 mm, which falls by 70% compared with that of freshwater. Under a hot rolling aging temperature of 180°C, the HBPA system demonstrates a significant inhibition with more than 85% shale cuttings recovery rate and is superior to conventional EDA and KCl. Mechanism analysis further validates that the HBPA can help to increase the zeta potential.

Study on a Polyamine-Based Anti-Collapse Drilling Fluid System

In complex strata, oil-based drilling fluid is the preferred drilling fluid system, but its preparation cost is high, and there are hidden safety risks. Therefore, the new progress of high-performance anti-collapse water-based drilling fluid at home and abroad is analyzed. It is difficult to prevent and control the well collapse. Once the well wall instability problem occurs, it will often bring huge economic losses to the enterprises, and the underground safety accidents will occur. In order to ensure the stability of the well wall and improve the downhole safety, the key treatment agent of water-based collapse drilling fluid is selected, the anti-collapse drilling fluid system is formulated, the evaluation method of drilling fluid prevention performance is established, and a set of water-based drilling fluid system suitable for easy to collapse strata in China is selected to ensure the downhole safety. The development trend of high performance anti-collapse water-based drilling fluid is expected to provide a reference for the research of high performance anti-collapse water-based drilling fluid system and key treatment agent.

Application of new tetra-cationic imidazolium ionic liquids for capture and conversion of CO_(2)to amphiphilic calcium carbonate nanoparticles as a green additive in water based drilling fluids

Conversion and capture of carbon pollutants based on carbon dioxide to valuable green oil-field chemicals are target all over the world for controlling the global warming.The present article used new room temperature amphiphilic imidazolium ionic liquids with superior surface activity in the aqueous solutions to convert carbon dioxide gas to superior amphiphilic calcium carbonate nanoparticles.In this respect,tetra-cationic ionic liquids 2-(4-dodecyldimethylamino)phenyl)-1,3-bis(3-dodecyldimethylammnonio)propyl)bromide-1-H-imidazol-3-ium acetate and 2-(4-hexyldimethylamino)phenyl)-1,3-bis(3-hexcyldimethylammnonio)propyl)bromide-1 H-imidazol-3-ium acetate were prepared.Their chemical structures,thermal as well as their carbon dioxide absorption/desorption characteristicswere evaluated.Theywere used as solvent and capping agent to synthesize calcium carbonate nanoparticles with controlled crystalline lattice,sizes,thermal properties and spherical surface morphologies.The prepared calcium carbonate nanoparticles were used as additives for the commercial water based drilling mud to improve their filter lose and rheology.The data confirm that the lower concentrations of 2-(4-dodecyldimethylamino)phenyl)-1,3-bis(3-dodecyldimethylammnonio)propyl)bromide-1-H-imidazol-3-ium acetate achieved lower seawater filter lose and improved viscosities.

环境友好型水基钻井液GREEN-DRILL的研制与应用

为了提高海上油气田钻井液的环保性能,在开发环保型高效封堵剂GS、水基润滑剂GL和水溶性抑制剂GG的基础上,研制出了环境友好型水基钻井液GREEN-DRILL。性能评价结果表明,水基钻井液GREENDRILL的基本性能稳定,抑制性能与聚合醇钻井液基本相当,其生物需氧量与化学耗氧量的比值为67.5%,对蒙古裸腹溞Ⅰ龄幼体72h半数致死浓度大于60 000mg/L,高于国家一级海域生物毒性容许值,符合国家一级海域排放标准。同时,在水中稀释后无油膜、无黑色漂浮物。渤海油田5井次的现场应用表明,水基钻井液GREENDRILL能解决渤海油田存在的渗漏和井漏问题,性能稳定,环保性能优良。

水基钻井液封堵理论和材料研究现状及发展趋势

地层孔隙、微裂缝、裂缝发育会导致井壁坍塌频发,严重阻碍了安全、高效地钻井。封堵理论的成熟性是研发高性能封堵剂的重要保证。通过封堵剂高效封堵孔隙、微裂缝及裂缝,是稳定井壁的关键。本文综述了不同封堵理论(刚性封堵理论、柔性封堵理论、成膜封堵理论)以及各类封堵材料(沥青类、聚合醇类、硅酸盐类、纳米材料类)研究现状,指出了现有封堵理论和封堵材料所存在的不足,总结了目前封堵理论及封堵材料研发面临的难点,并提出应通过数值模拟等方法深入研究储层孔喉尺寸分布规律以及储层形貌结构,且应试图从树枝状聚合物、刚性外壳与柔性内核复合材料、生物质基纳米材料改性沥青、纳米材料分散稳定性等方面开展研发高效封堵材料。

水基钻井液用多元协同纳米润滑剂的研究进展

纳米技术在钻井液中的应用是目前油田化学领域的研究热点之一,受到国内外钻井液行业的普遍关注。随着纳米粒子的研究越来越深入,国内外已开始将其用于钻井液润滑改性,其用量少、对环境潜在的负面影响小,开发与应用新型环保钻井液纳米润滑剂是当前的发展趋势。本文围绕钻井液用纳米润滑材料的研究进展进行了详细的综述,包含纳米材料抗磨减摩机理、纳米粒子种类及形态、纳米材料在钻井液中的润滑效果,指出了纳米润滑材料应用于钻井液存在的问题,重点探讨了纳米粒子表面修饰改性进展并对多元协同及多效发挥进行了展望。

抗180℃水基钻井液随钻堵漏剂的研制及性能评价

钻井液漏失严重增加了钻井作业风险,有效封堵漏层是钻井提速的重要保障之一。针对水基钻井液随钻堵漏剂封堵范围窄、抗温性不足等问题,优选出高分子刚性颗粒、改性聚酯橡胶、改性植物纤维复配玻璃纤维分别作为架桥颗粒、填充材料、纤维“拉筋”材料。根据颗粒级配原则,优选出随钻堵漏剂最佳配方:15%刚性树脂(40~80目)+15%刚性树脂(100~200目)+35%刚性树脂(1 000~3 000目)+5%改性植物纤维(0.1 mm)+10%玻璃纤维(150目)+20%改性聚酯橡胶(800目)。该随钻堵漏剂配方砂床承压能力达5 MPa,漏失量为0 mL。抗高温随钻堵漏剂粒径级配合理,封堵覆盖裂缝孔隙范围广,丰富了水基钻井液随钻堵漏剂配方。

安全环保的新型水基钻井液ULTRADRILL

针对渤海地区钻进过程中遇阻遇卡 ,起下钻困难 ,密度难以控制 ,机械钻速低等问题 ,采用了安全环保的新型水基钻井液ULTRADRILL ,ULTRADRILL新型钻井液的合成聚合物不含铬及其它对环境有害的物质。该钻井液主要由两种基本的页岩抑制剂和钻速增效剂组成。该钻井液能提供优异的页岩抑制性、润滑性和井眼稳定性 ;滤失量小、滤饼薄 ,可防止钻头泥包 ;携砂能力强 ,流变性易于控制 ;具有较广的密度和盐的选择性。现场应用表明 ,ULTRADRILL钻井液性能稳定 ,具有独特的流变性能 ,滤失量小、泥饼坚韧、致密而光滑 ;钻井过程中悬浮携砂能力强 ,钻速快 ,井壁稳定。该钻井液容易降解 ,且无生物毒性 ,满足了海洋环保的要求。

增效型无土相仿生油基钻井液技术的研究与应用

针对深井超深井钻井过程中钻遇高温高压、井壁失稳及井下复杂情况的难题,基于仿生学、超分子化学以及岩石表面润湿性理论,通过优选仿生增效剂、仿生提切剂及仿生降滤失剂,配套相关处理剂,最终形成了一套适用于深井、超深井地层钻探的增效型无土相仿生油基钻井液体系。研究发现,建立的增效型无土相仿生油基钻井液体系可抗220℃高温,配制密度为2.4 g/cm^(3),破乳电压大于400 V,高温高压滤失量为3.2 mL,人造岩心在该体系中220℃下老化后的抗压强度达到7.1 MPa,平均渗透率恢复值为93.9%。现场应用情况表明,体系流变性能稳定,平均机械钻速比邻井提高16%,平均井径扩大率仅为1.25%,可有效解决深井超深井钻井过程中出现的井壁失稳难题,为我国深井超深井的钻探提供了技术保障。

钻井利器的故事之“护壁堵漏材料”

近年来,作为入地最为关键手段的钻探所面临的地层越来越复杂,钻孔垮塌、掉块、缩径和超径等事故发生概率增加,严重制约了钻探工程质量与效率的提升。护壁堵漏材料是钻探工程不可或缺的关键性工程材料,护壁堵漏技术则是保证钻进工作安全、快速以及持续进行的重要技术环节,是复杂地层钻孔处理的主要内容。本文从科普的角度介绍了护壁堵漏材料的基本概念与组成、冲洗液护壁堵漏作用、水泥基材料护壁堵漏作用、护壁堵漏材料的进一步发展空间等,以期加深对护壁堵漏材料的认识,促进新型护壁堵漏材料的研发和应用。

海上某盆地胶结型防漏堵漏钻井液技术

分析了我国海上某盆地地质特征和历史井漏情况,明确了该盆地钻井防漏堵漏难点:地层裂缝发育且存在微米级至毫米级的多尺度裂缝,甚至裂缝和孔、洞并存,导致堵漏材料选配难、一次堵漏成功率低;地层发育大段风化壳、部分地层破碎严重、钻井中裂缝极易二次发育等,导致恶性漏失甚至失返性漏失等复杂情况。针对上述难点,以聚乙烯醇、聚丙烯酸以及含邻苯二酚结构的有机物为原料,合成了一种胶结型堵漏剂BFD-1。实验结果表明,人造疏松岩心在加有4%BFD-1的水溶液中浸泡后,岩心抗压强度提高率达19.34%。以BFD-1为核心,复配现场常用堵漏材料,构建了适用于不同尺寸范围漏失通道的防漏堵漏钻井液体系,具良好的防漏堵漏性、胶结性,并可有效阻止压力传递。研究成果可为该地区钻井井漏防治提供有力技术支撑。

页岩油储层环保型高性能水基钻井液体系研究及应用

为了满足页岩油储层钻井对钻井液环保性能的要求,以环保型页岩抑制剂HBY-S和环保型复合润滑剂HBR-L为主要处理剂,并结合其他环保型处理剂,研制出了一种适合页岩油储层钻井的环保型高性能水基钻井液体系。室内对钻井液体系的耐温性能、抗污染性能和环保性能进行了评价,结果表明:体系具有良好的耐温性能,经过160℃老化后钻井液体系的高温高压滤失量为9.6mL,岩屑滚动回收率可以达到90.6%,润滑系数为0.089;体系具有较强的抗污染能力,钻井液中加入10%NaCl、1.0%CaCl_(2)或者15%岩屑粉时流变性能和滤失性能均比较稳定;体系的环保性能优良,钻井液的EC_(50)值为85000(无毒),BOD_(5)/COD值为26.5%(易降解),重金属含量均低于行业标准值。环保型高性能水基钻井液在某页岩油区块水平井钻井过程中进行了成功应用,其中DG-1井钻井期间未出现井下复杂事故,现场钻井液性能稳定,环保性能达标,实现了安全高效钻井的目标,在页岩油水平井钻井中具有良好的推广应用前景。

纳米流体和两性表面活性剂改善钻井液性能实验研究

本文研究了碳化硅纳米流体和表面活性剂对水基钻井液物理和化学性质(热稳定性、黏度、表面张力和滤失特性)的影响。将碳化硅纳米流体、表面活性剂溶液和水基钻井液混合形成表面活性剂——碳化硅(Si C)钻井液,分别用流变仪、张力仪和压滤机对混合钻井液的黏度、表面张力和滤失性等性质进行了研究。实验结果表明,与常规表面活性剂相比,两性表面活性剂对钻井液黏度的增量最大,此外,混合钻井液具有更好的热稳定性,随着温度的升高,黏度平均变化率为9%,表面张力和滤失性分别下降了31.0%和22.2%。

改性二氧化硅封堵剂的制备及性能评价

为了降低水基钻井液滤液对储层的扰动,以丙烯酰胺、苯乙烯、乙烯基三甲氧基硅烷对纳米SiO_(2)进行表面改性,将柔性链聚合物接枝在纳米刚性SiO_(2)粒子表面,形成一种新型的有机-无机复合封堵剂。实验结果发现:该封堵剂提高了泥饼的致密性和封堵性能,并对岩心孔隙进行了有效封堵,有效抑制岩屑水化现象,为水基钻井液在低渗-致密储层开发过程中的应用提供技术支持。

超深缝洞型碳酸盐岩储层超低密度钻井液技术

塔里木油田压力系数低于1.0的超深井碳酸盐岩低压储层常发生钻井液失返性井漏,其平均井深超过6000 m,井控风险极大,除了强钻再无更好手段,往往只能提前完井。为提升超深井水平段延伸能力,研究人员研发了高强度空心玻璃微珠,可配制密度为0.93~1.07 g/cm^(3)的超低密度水基钻井液。详述了中古262-H4C井井漏失返后利用低密度水基钻井液重建井筒循环、恢复常规定向钻进的施工过程。现场钻井液密度最低降至0.98 g/cm^(3),井漏失返后多钻373 m,实现了一井钻穿两个缝洞体的地质目的,保障了该井井漏失返后钻至设计井深,开创了空心玻璃微珠超低密度钻井液在国内垂深超6000 m的超深井应用先例,为我国类似老区低压地层应用提供了技术参考。

高分子纳米复合材料在水基钻井液中的研究进展

传统高分子聚合物材料难以满足日益复杂的井下环境要求,而无机纳米材料又存在分散性不足的缺陷,将纳米材料接枝到聚合物链上或将聚合物嵌入纳米材料中形成高分子纳米复合材料,可发挥两种材料的协同增效作用,进而提升水基钻井液的综合性能。文章介绍了高分子纳米复合材料在改善水基钻井液流变性、优化封堵降滤失性、增强封堵防塌性方面的应用,总结了其作用效果及作用机理。高分子纳米复合材料改善钻井液流变性的机理包括聚合物增强固体纳米颗粒在钻井液中的分散性、增加流体层间内摩擦力、通过聚合物与黏土颗粒之间的氢键和静电相互作用形成空间网络结构等。优化钻井液封堵降滤失性的机理包括利用无机纳米材料对微孔进行封堵,形成致密的泥饼,利用聚合物的强吸附性和两亲性,在泥饼表面形成疏水膜等。增强钻井液封堵防塌作用的机理包括纳米颗粒桥接和堵塞页岩纳米孔隙,形成致密屏障,阻止水分子侵入页岩;聚合物链上的多功能基团在黏土表面形成竞争吸附,降低黏土对水分子的吸附;成熟聚胺类聚合物的氨基嵌入和阳离子压缩双电层的综合作用,强化页岩水化抑制性能。提出了高分子纳米复合材料面临的挑战,如大规模生产过程中无机纳米颗粒在聚合物基质中可能出现的分散不均匀问题。最后,从降磨减阻、储层保护和可持续性3个方面对高分子纳米复合材料的研究方向进行了展望。