Application of micro-foam drilling fluid technology in Haita area

In recent years, a new kind of drilling fluid system with unique structure micro-foam has been developed. Compared with other drilling fluid systems, it possesses many advantages. And it has been successfully applied in hundreds of wells to drill depleted reservoirs in the world wide. The geological structure is very complex in Haita area, it is difficult to achieve the requirement of increasing drilling rate by conventional drilling methods, even can’t make footage. The micro-foam drilling fluid can apply to Haita area, and solve the drilling problems commendably, which is comprehended by studying the structure and plugging, prevent caving, speed mechanism of the micro-foam drilling fluid. Field practice indicates that micro-foam drilling fluid technology can resolve the drilling problem effectively in Haita basin. It has the extremely vital significance to improve drilling speed, discover and protect reservoir stratum, decrease the risk of circulation loss and save the drilling cost.

Development and applications of solids-free oil-in-water drilling fluids

The increasing application of near balanced drilling technology to low-pressure and depleted fractured reservoirs requires the use of low-density drilling fluids to avoid formation damage. Solidsfree oil-in-water （O/W） emulsion drilling fluid is one type of low-density drilling fluid suitable for depleted fractured reservoirs. In this paper, the solids-free O/W drilling fluid was developed and has been successfully used in the Bozhong 28-1 oil and gas field, by which lost circulation, a severe problem occurred previously when drilling into fractured reservoir beds, was controlled, thereby minimizing formation damage. The O/W emulsion drilling fluid was prepared by adding 20% （by volume） No. 5 mineral oil （with high flash point, as dispersed phase） into seawater （as continuous phase）. Surfactant HTO-1 （as a primary emulsifier） and non-ionic surfactant HTO-2 （as a secondary emulsifier） were added into the drilling fluid system to stabilize the emulsion; and YJD polymer was also added to seawater to improve the viscosity of the continuous phase （seawater）. The drilling fluid was characterized by high flash point, good thermal stability and high stability to crude oil contamination.

Research progress and development of deep and ultra-deep drilling fluid technology

The research progress of deep and ultra-deep drilling fluid technology systematically reviewed,the key problems existing are analyzed,and the future development direction is proposed.In view of the high temperature,high pressure and high stress,fracture development,wellbore instability,drilling fluid lost circulation and other problems faced in the process of deep and ultra-deep complex oil and gas drilling,scholars have developed deep and ultra-deep high-temperature and high-salt resistant water-based drilling fluid technology,high-temperature resistant oil-based/synthetic drilling fluid technology,drilling fluid technology for reservoir protection and drilling fluid lost circulation control technology.However,there are still some key problems such as insufficient resistance to high temperature,high pressure and high stress,wellbore instability and serious lost circulation.Therefore,the development direction of deep and ultra-deep drilling fluid technology in the future is proposed:(1)The technology of high-temperature and high-salt resistant water-based drilling fluid should focus on improving high temperature stability,improving rheological properties,strengthening filtration control and improving compatibility with formation.(2)The technology of oil-based/synthetic drilling fluid resistant to high temperature should further study in the aspects of easily degradable environmental protection additives with low toxicity such as high temperature stabilizer,rheological regulator and related supporting technologies.(3)The drilling fluid technology for reservoir protection should be devoted to the development of new high-performance additives and materials,and further improve the real-time monitoring technology by introducing advanced sensor networks and artificial intelligence algorithms.(4)The lost circulation control of drilling fluid should pay more attention to the integration and application of intelligent technology,the research and application of high-performance plugging materials,the exploration of diversified plugging techniques and methods,and the improvement of environmental protection and production safety awareness.

深层超深层钻井液技术研究进展与展望

系统论述目前国内外深层超深层钻井液技术研究进展,分析存在的关键问题并提出未来发展方向。针对深层超深层复杂油气层钻井过程中面临的高温高压高应力、裂缝发育、井壁失稳、钻井液漏失等问题,国内外学者研发了深层超深层抗高温高盐水基钻井液技术、抗高温油基/合成基钻井液技术、储层保护钻井液技术以及钻井液防漏堵漏技术,但仍存在抗高温高压和高应力能力不足、井壁易失稳以及钻井液漏失严重等关键问题。由此提出未来深层超深层钻井液技术的发展方向:(1)抗高温高盐水基钻井液技术需致力于提升高温稳定性,改进流变性能,强化滤失量控制,提高与地层的相容性。(2)抗高温油基/合成基钻井液技术需在高温稳定剂、流型调节剂等低毒易降解的环保型添加剂和相关配套技术方面进一步攻关。(3)储层保护钻井液技术应致力于新型高性能添加剂和材料的研究,通过引入先进的传感器网络和人工智能算法,完善实时监测技术。(4)钻井液防漏堵漏技术应更加注重智能化技术的集成与应用、高性能堵漏材料的研发与应用、多元化堵漏技术与方法的探索以及环境保护与安全生产意识的提高。

深层煤层气防塌钻井液优化研究

辽河油田宜川-黄龙地区井壁失稳、阻卡等问题严重制约了开发进程。针对该地区深层煤层气A井井壁失稳问题,对煤岩矿物组成、微观结构进行了分析并揭示了井壁失稳机理。发现:钻井过程中滤液侵入,易发生水化膨胀和裂缝扩展等情况,导致井壁失稳。构建了适用于该地区的防塌钻井液体系,特征为强封堵、强抑制性,以及较好的流变性和耐高温性,且在现场应用中表现出良好的性能。为深层煤层气井的高效开发提供了有效的技术支持。

基于格子Boltzmann模型的裂缝性储层钻井液漏失数值模拟

针对裂缝性碳酸盐岩储层钻井过程中钻井液漏失问题,基于简化的基块-裂缝双重介质物理模型,建立了描述表征单元体(REV)尺度的基块-裂缝内钻井液漏失的格子Boltzmann数学模型,数值模拟分析了钻井液漏失过程基块-裂缝内渗流场分布,揭示了不同条件下基块-裂缝内钻井液漏失行为。模拟结果表明,裂缝性致密碳酸盐岩储层中的裂缝为主要漏失空间,基块的钻井液漏失量在低值范围内随基块孔隙度增加呈指数增加。裂缝宽度越大,平均流速越大,裂缝空间内速度分布越均匀,组合裂缝总宽度相等条件下,单条裂缝的钻井液漏失速率高于多条裂缝组合情形。研究通过格子Boltzmann方法表征钻井液漏失行为,表明该方法可较好地用于分析裂缝性介质中钻井液漏失行为和裂缝至基块的跨尺度滤失过程,研究成果可为裂缝性致密储层钻井液漏失防控及储层保护提供理论依据。

水基钻井液废弃固液处置及配套技术

为满足环保要求,长庆区域实行钻井废弃物“不落地”政策,但在施工中存在水基钻井液净化困难、岩屑废弃物含水率高且处理量大、固体废弃物无法重复使用、钻井施工占地面积大幅增加等技术难点,通过研制新型固控设备、“钻屑不落地”装置,优化钻井液循环净化工艺,研发阳离子型聚合物水基钻井液净化剂,优选废弃钻屑处理技术,形成了水基钻井液废弃固液处置及配套技术。该技术已在长庆钻井区域全面推广应用,岩屑减量29.82%,岩屑含水率≤35%,钻井废液循环利用率≥94%,钻井占地面积降低23.7%,现场应用效果显著。通过技术的集成及配套应用,大幅降低了钻井液废弃固液总量,实现绿色、安全、环保钻井,助力我国早日实现“碳达峰”和“碳中和”。

水基钻井液用耐高温凝胶堵漏剂的制备与评价

以丙烯酰胺、2-丙烯酰胺基-2-甲基丙磺酸和乙烯基吡咯烷酮为耐高温凝胶的单体,引发剂优选过硫酸钾和亚硫酸氢钠,交联剂优选N,N'-亚甲基双丙烯酰胺,合成方法选择水溶液聚合法,制备了一种水基钻井液用耐高温凝胶堵漏剂。采用红外光谱分析、核磁共振分析和热重分析对耐高温凝胶的分子结构和抗温能力进行了表征。采用高温高压失水仪和长裂缝堵漏评价实验装置对耐高温凝胶的渗透型漏失堵漏效果和裂缝型漏失堵漏效果进行了评价。当温度为150℃时,耐高温凝胶堵漏剂对渗透型漏失堵漏效果可达7 MPa,对2×1 mm裂缝的漏失堵漏效果可达1.88 MPa。

多工艺反循环钻井技术发展现状与展望

反循环钻井技术与正循环钻井技术相反,循环介质和地层岩屑从钻具水眼返出井口,其裸眼环空保持相对静止,此种钻井方式有利于实现超大尺寸井眼高效携砂、恶性井漏井段的防漏治漏以及敏感性储层的有效保护,同时也为水平井钻井过程中的窄钻井液密度窗口、井眼净化和水平段长度延伸等需求提供新的技术方案。文章通过梳理开展反循环钻井技术以来各家反循环钻井技术的研究进展与成果,总结了单壁钻杆反循环钻井技术、双壁钻杆反循环钻井技术、单壁钻杆+双壁钻杆反循环钻井技术、多通道钻具反循环钻井技术的工作原理及技术特色、适应的工作环境等,并在此基础上提出了反循环钻井技术在油气钻井领域的发展方向及建议。文章的研究成果可以为反循环研究工作提供信息,助力深井超深井超大尺寸井眼提速钻进、井漏等复杂井眼处理以及非常规油气资源安全效益开发提供技术支撑。

Research progress and prospect of plugging technologies for fractured formation with severe lost circulation

By reviewing the mechanisms of drilling fluid lost circulation and its control in fractured formations, the applicability and working mechanisms of different kinds of lost circulation materials in plugging fractured formations have been summarized. Meanwhile, based on the types of lost circulation materials, the advantages, disadvantages, and application effects of corresponding plugging technologies have been analyzed to sort out the key problems existing in the current lost circulation control technologies. On this basis, the development direction of plugging technology for severe loss have been pointed out. It is suggested that that the lost circulation control technology should combine different disciplines such as geology, engineering and materials to realize integration, intelligence and systematization in the future. Five research aspects should be focused on:(1) the study on mechanisms of drilling fluid lost circulation and its control to provide basis for scientific selection of lost circulation material formulas, control methods and processes;(2) the research and development of self-adaptive lost circulation materials to improve the matching relationship between lost control materials and fracture scales;(3) the research and development of lost circulation materials with strong retention and strong filling in three-dimensional fracture space, to enhance the retention and filling capacities of materials in fractures and improve the lost circulation control effect;(4) the research and development of lost circulation materials with high temperature tolerance, to ensure the long-term plugging effect of deep high-temperature formations;(5) the study on digital and intelligent lost circulation control technology, to promote the development of lost circulation control technology to digital and intelligent direction.

Lost circulation material for abnormally high temperature and pressure fractured-vuggy carbonate reservoirs in Tazhong block, Tarim Basin, NW China

To effectively solve the problem of lost circulation and well kick frequently occurring during the drilling of abnormally high temperature and pressure fractured-vuggy reservoirs in the Tazhong block, a rigid particle material, GZD, with high temperature tolerance, high rigidity(> 8 MPa) and low abrasiveness has been selected based on geological characteristics of the theft zones in the reservoirs. Through static pressure sealing experiments, its dosage when used alone and when used in combination with lignin fiber, elastic material SQD-98 and calcium carbonate were optimized, and the formula of a new type(SXM-I) of compound lost circulation material with high temperature tolerance and high strength was formed. Its performance was evaluated by compatibility test, static sealing experiment and sand bed plugging experiment. The test results show that it has good compatibility with drilling fluid used commonly and is able to plug fractures and vugs, the sealed fractures are able to withstand the static pressure of more than 9 MPa and the cumulative leakage is 13.4 mL. The mud filtrate invasion depth is only 2.5 cm in 30 min when the sand bed is made of particles with sizes between 10 mesh and 20 mesh. Overall, with good sealing property and high temperature and high pressure tolerance, the lost circulation material provides strong technical support for the safety drilling in the block.

自修复凝胶堵漏技术研究

智能凝胶能够对外界环境作出响应,进行不同状态的转换,提高封堵效果,是一种新型的堵漏材料。为遏制井漏并防止复漏,通过自由基聚合方法制备了一种基于阳离子-π、静电力、氢键的自修复水凝胶用于地层堵漏。实验结果表明,该水凝胶在恶劣环境中的自修复效率达70%,具有较强的盐适应性和耐高温性;能有效封堵180 D砂盘孔隙,封堵率接近90%,对其他固结砂盘(渗透率2 D、5 D、20 D)和未固结砂床(20~40目、40~60目、60~80目)也表现出良好的堵漏能力。相比于常规材料,该水凝胶可通过降低作业压差实现自修复,达到高效封堵;可通过二次降低封堵层渗透率有效提高封堵层的致密性,提高了水凝胶的高温稳定性,高温老化后依然具备良好的封堵能力。水凝胶颗粒在盐水中分散良好,热滚后保持稳定的流变学性能,有利于钻井液循环。研究结果表明,自愈材料作为堵漏材料在石油钻井工业中具有应用潜力。

井漏地层钻井液堵漏材料研究现状与展望

井漏是制约油气钻井工程质量和效率提高的主要技术问题。提高一次性堵漏成功率是保障全球油田“安全、高效、经济”钻井的迫切需求。总结了钻井液漏失机理,介绍了架桥、高失水、固化、聚合物凝胶类、智能材料等各类堵漏材料的性质和相互作用机理,明确了各堵漏材料存在的问题。桥接堵漏材料价格低廉、操作简单、来源广泛、对钻井液流变性的影响小,但其粒径与地层漏失通道匹配性差,配方复杂。高失水类堵漏材料使用简单、见效快、封堵成功率高,但其组成复杂、失水速率难控制、不易解堵。可固化类堵漏材料拥有高的承压封堵能力,价格便宜,配制和操作工艺简单,但施工安全风险高。聚合物凝胶类堵漏材料对漏失通道的自适应性强、有良好的黏滞阻力和抗剪切稀释能力。然而,其抗高温能力较低、长期封堵性较差、与钻井液配伍性差、成胶时间不易控制。智能类堵漏材料可智能适应各种复杂地层、针对性强、对地层伤害性小,但其堵漏机理需进一步完善,材料的适应性需进一步提高。提出了堵漏材料未来发展的方向,如研发智能型堵漏材料和深井与超深井高温井钻井液堵漏材料。

常用钻井堵漏材料力学特征参数研究

井漏是指钻井液大量漏入地层的现象,是油气资源勘探和开发过:程的主要挑战之一。井漏事故的发生不仅会消耗大量钻井液,同时会引发井塌、卡钻等工程事故,严重拖慢钻井进度。目前,最广泛的解决方案是使用物理堵漏材料在裂缝中形成高强度封堵带,而堵漏效果与堵漏材料特征参数密切相关。本文对堵漏材料的摩擦系数、破碎率以及抗压强度进行了测量评价,得出以下结论:1)堵漏材料的颗粒粒径越小、强度越低,摩擦系数越大;2)随着堵漏材料目数、加载压力的增加,破碎率越低;3)随着刚性堵漏颗粒粒径的增加,堵漏颗粒的强度降低。进一步分析发现,当果壳和云母的颗粒粒径增大约53%时,堵漏材料强度降低15%。测试结果为堵漏材料设计以及堵漏模拟实验提供了必要参数和参考依据。

长庆油田米绥新区易漏地层漏失机理

米绥新区天然气资源丰富,是长庆油田快速上产的重要战略接替区,但近几年井漏问题的频繁出现已经严重制约效益开发的进程。为了遏制井漏的发生,通过多尺度定量岩石物性实验、微电极成像测井观测和单井四压力剖面分析对该区域的漏失机理展开了研究。结果发现米绥新区的漏层主要在刘家沟组和石千峰组,漏层存在大量微纳米级裂缝,岩心平均动态杨氏模量分别为17.94 GPa、8.47 GPa,平均动态泊松比分别为0.394、0.064;刘家沟组地层的黏土矿物含量超过一半,石千峰组的脆性矿物含量高达72%,成像测井图显示该区域含有张性缝;单井四压力剖面揭示漏层存在低压区,而钻井液密度为1.18g/cm^(3)。最终分析得出高含量的黏土矿物与脆性矿物造成地层内部容易形成水化裂缝和构造裂缝,同时地层压力较低,导致钻井液流向地层中的天然裂缝,最终发生漏失。研究成果不仅揭示了米绥新区的漏失机理,也为后续选择堵漏方法及减少米绥新区井漏事故提供技术指导。

一种新型亲油纤维堵漏剂的研发

油基钻井液堵漏大多采用水基堵漏材料,亲水性堵漏材料在油基钻井液中不容易分散、易团聚,导致堵漏难度大,钻井液漏失后堵漏时效长,严重制约了钻井提速提效,并会造成相当大的经济损失。为此,针对油基钻井液堵漏剂封堵承压能力不足的问题,对天然植物纤维进行了表面亲油改性,并通过氢氧化钠对非纤维素成分的碱化和硅烷偶联剂与纤维素的羟基反应改性制得亲油植物纤维,使植物纤维具有亲油分散性能,进而研发得到了一种新型亲油纤维堵漏剂。研究结果表明:①为增强多尺度裂缝封堵效果,优选亲油聚氨酯海绵、微米刚性颗粒和亲油胶体颗粒进行复配得到亲油纤维堵漏剂,室内评价了其对0.2 mm、0.5 mm、0.8 mm和1.0 mm微裂缝的封堵性能,并测试了亲油纤维堵漏剂与其他堵漏材料对2~5 mm裂缝的协同封堵性能;②亲油纤维堵漏剂对0.2 mm和0.5 mm裂缝封堵承压强度达到8 MPa以上,0.8 mm裂缝封堵承压强度达到3 MPa,1.0 mm裂缝封堵承压强度达到2.5 MPa;③对于2 mm、3 mm和5 mm等不同宽度裂缝,亲油纤维堵漏剂的加入可显著降低漏失量。结论认为:①亲油纤维堵漏剂在页岩油气井进行了14井次现场堵漏试验,一次堵漏成功率85.7%,展示了良好的应用前景;②亲油纤维堵漏剂更适合油基钻井液的堵漏,该新型堵漏剂为页岩油气的高效开发提供了技术保障。

循环推送下套管系统的研制

如何将套管安全下到预定位置是大位移井、分支井以及丛式井等复杂结构井完井面临的技术难题之一,为此,研制了循环推送下套管系统。该系统能够自动连接套管、建立钻井液循环、旋转套管柱以及在套管柱末端产生轴向振荡力,减小套管下入摩阻,同时可通过切削井壁清除砂桥、台阶等。介绍了该系统套管循环旋转装置和套管推送下入装置的结构和工作原理,采用数值模拟方法分析了套管循环旋转装置的卡瓦承载能力。室内试验表明,套管循环旋转装置工作可靠,可承受轴向载荷2400 kN、扭矩30 kN·m,密封承压35 MPa,设计排量条件下,套管推送下入装置压降2.7 MPa、振荡力41 kN。现场试验表明,该循环推送下套管系统能够有效提高套管下入的安全性,可进一步推广应用。

泸州区块深层页岩气水平井优快钻井技术

泸州区块深层页岩气储层龙马溪组页岩埋藏深、温度高,钻井过程中面临井漏频发、难钻地层机械钻速低、旋转导向仪器高温下的故障率高和钻井周期长等技术难点。为此,在分析钻遇地层特征和钻井技术难点的基础上,进行了井身结构和井眼轨道优化、高效钻头优选、堵漏技术措施优化、油基钻井液地面降温技术和欠平衡钻井技术研究,形成了泸州区块深层页岩气水平井优快钻井技术。该技术在泸州区块34口页岩气水平井进行了应用,应用井平均完钻井深5760 m,平均水平段长1890 m,平均机械钻速由5.61 m/h提高至7.03 m/h,创造了造斜段+水平段一趟钻完钻、单趟钻进尺2330 m等纪录。泸州区块深层页岩气水平井优快钻井技术支撑了该区块深层页岩气安全钻井和钻井提速提效,对其他地区深层页岩气水平井钻井提速具有一定的借鉴价值。

基于ABAQUS的温度对钻井液漏失影响规律

深层油气储层高温、高压、高应力特点给钻井工程带来极大挑战,其中钻井液漏失是常见的钻井复杂工况之一,严重制约其勘探开发进度。为研究在深层钻井过程中温度对钻井液漏失的影响规律,以ABAQUS软件平台为基础,建立了考虑钻井液动态循环的热-流-固全耦合漏失有限元模型,分析了不同钻井液温度条件下的井周应力分布、地层温度场变化、漏失裂缝延伸规律和钻井液漏失规律。研究结果表明:当钻井液温度低于地层温度时,会产生“冷却”效应,导致地层遇冷收缩,井周应力降低;低温循环会降低漏失排量阈值,且相同排量下,低温循环漏失发生得更早。然而,低温钻井液对于地层温度场的影响仅存在于近井区域。短期内,诱导裂缝宽度和长度依然由钻井液排量主导,仅在近井区域的裂缝宽度上表现出了“冷却”效应的影响。建立的热-流-固全耦合模型可以描述动态钻井过程中温度对钻井液漏失规律的影响,可为高温地层钻井设计和现场施工提供研究方法和参考数据。

OBM-1油基钻井液用聚合物微球

目前的堵漏材料大多针对水基钻井液来研发,对油基钻井液的适用性不强。采用反相乳液聚合方法,通过引入亲油组分,合成了一种油基钻井液用聚合物微球OBM-1。OBM-1基本呈球形,粒径分布处于1~100μm之间,在油基钻井液中具有良好的分散能力。加入3%OBM-1后,能够保持油基钻井液流变性能稳定,有效降低高温高压滤失量和封闭滤失量。高温高压滤失实验表明,OBM-1可使120℃的高温高压滤失量降低50%,其抗温可达150℃;封堵承压实验表明,OBM-1能够封堵5~40μm砂盘,承压达15 MPa;封闭漏失实验表明,OBM-1能够有效封堵20~40目石英砂制备的砂床。现场应用结果表明,OBM-1可有效降低漏失量,试验井段每米油基钻井液消耗量同比下降30.3%,很大程度节约了钻井成本。该研究为使用油基钻井液进行安全高效钻进提供了有力的技术支持。