Lost circulation is a phenomenon in which a large amount of drilling fluid is lost into the formation during the drilling process, and the morphology and multi-scale characteristics of the formation fractures are essential factors affecting the degree of drilling fluid lost and the efficiency of fracture plugging. Most of the research on fracture plugging is aimed at single-width fractures, and the fracture morphology is usually simplified. In this paper, the 3D scanning, 3D reconstruction and 3D printing technologies were used to observe the plugging performance of lost circulation materials (LCMs) in complex fracture formations. The Joint Roughness Coefficient (JRC) and fractal dimension were calculated based on the fracture surface point cloud data obtained by 3D laser scanning technology, which can realize the quantitative characterization of fracture surface morphology characteristics. The fracture plugging evaluation method was established by combining 3D reconstruction and 3D printing technologies, which can simulate the actual fracture morphology characteristics and the coexistence conditions of various fracture widths. The multi-scale fracture simulation samples with various widths and actual morphology characteristics were prepared. Based on the prepared multi-scale fracture simulation samples, complex fracture plugging simulation experiments were carried out to clarify the plugging behavior of LCMs on multi-scale fractures. The experimental results show that the effective retention of LCMs and the high pressure-bearing capacity of the plugging zone are essential to successful plugging. The retention capacity of LCMs in fractures can be improved by appropriately reducing the particle size of rigid LCMs. On this basis, further compounding elastic particles and fiber materials insert improves the pressure-bearing capacity of the plugging zone.

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The irregularity and complexity of formation fracture morphology lead to great uncertainty in lost circulation control. At present, the fracture morphology is simplified to be smooth in the process of fracture plugging investigation, thus the influence of fracture surface morphology on the retention behavior and pressure bearing capacity of granular lost circulation materials (LCMs) remains unknown. To fill this gap, the reverse engineering technology was utilized for investigating the influence of fracture surface morphology on plugging performance. In this study, the three-dimensional (3D) reverse reconstruction and quantitative characterization of fracture surface were realized based on the 3D coordinates of real fracture surfaces, which were obtained through the 3D structured light scanning. A new parameter "particle size matching factor" was established to analysis the retention behavior of LCM particles. A new method for fracture plugging experiments was established based on 3D printing technology, which can obtain the structure of the sealing zone in fracture with real morphology. The results show that the irregularity of the real fracture surface leads to the local shrinkage of the flow channels, while provide support force to LCMs, which has an important influence on the plugging performance of LCMs. The larger the "particle size matching factor", the easier to form retention in fractures. With the increase of Joint Roughness Coefficient (JRC) and fractal dimension, the pressure bearing capacity of the sealing zone is significantly improved. The research results are helpful to more accurately realize the plugging mechanism of granular LCMs, which contributes to improve efficiency of lost circulation control.

An environmentally friendly clay stabilizer ZWS-2 was synthesized by the reaction of γ-（2,3-epoxypropoxy） propyltrimethoxysilane（KH560） with trimethylamine hydrochloride. The anti-swelling performance and washing resistance of clay stabilizer under different conditions were studied. It is found that the optimum synthesis conditions are as follows: the molar ratio of KH560 to trimethylamine hydrochloride is 1.1∶1, the reaction temperature is 70 ℃, and the reaction time is 6 h. The anti-swelling rate of ZWS-2 aqueous solution with mass fraction of 4% is 96.6% at 150 ℃ and 90.3% at 300 ℃. The optimal compounding scheme is 1.5% ZWS-2 + 4% KCl. After compounding with the main agent of slippery hydraulic fracturing fluid, the anti-swelling rate is 99.6% and the 1st washing resistance rate is 99.5%.

针对川西低渗气藏水平井开发过程中存在的井壁失稳与定向段托压难题,采用水分散聚合方法设计合成了一种能够在温度激发下吸水膨胀的井壁修补强化剂(SM-SCH),形成了可对不同尺寸微裂隙实施准确匹配与有效封堵的材料配方.在此基础上,优选了聚胺抑制剂、环保高性能润滑剂等核心处理剂,研制了适用于川西低渗气藏的井壁修补强化钻井液.室内评价表明:SM-SCH初始粒径在0.5～7.0 μm,主要粒径范围集中在2.5 μm左右,能够在温度超过75℃时被激发产生吸水膨胀,膨胀倍率达15倍以上,可以有效提高钻井液体系的封堵范围,实现对不同尺寸微裂隙的准确匹配与有效封堵;由此研制的井壁修补强化钻井液在120℃下热滚老化16 h后,沙溪庙组岩心的线性膨胀率为3.31％,岩屑滚动回收率为96.33％,极压润滑系数为0.061,泥饼黏附系数为0.038,表现出优异的封堵防塌和润滑减阻性能.现场试验结果表明,井壁修补强化钻井液体系能够有效解决川西低渗气藏水平井施工过程中存在的井壁失稳和定向段托压难题.

针对页岩水平井钻井过程中使用水基钻井液时面临的井壁易失稳、钻具摩阻扭矩大,井眼清洁困难等技术难题,通过引入硅酸钾钠、有机硅改性腐植酸钾盐、聚倍半硅氧烷等硅基处理剂,构建了环保型多硅基水基钻井液体系.该体系所用处理剂EC50>3×104 mg/L,为无毒级别,抗温180℃,流变性能稳定,具有良好的抑制性、封堵性和润滑性,页岩滚动回收率98.53％,页岩线性膨胀率0.26％,HTHP失水量≤2.8 mL,极压润滑系数0.081,泥饼黏滞系数0.042,重金属含量满足二级排放标准,BOD值/COD值高达31.7％,易生物降解,表现出优异的环境友好性.环保型多硅基水基钻井液在东平1井页岩水平段进行了成功应用,钻进期间未发生任何井下复杂情况,动塑比保持在0.41～0.48,钻具摩阻6～8 t,平均井径扩大率仅为3.85％,平均机械钻速达10.28 m/h,在国内首次实现了水基钻井液在页岩水平段中的应用.

针对川西低渗气藏储层特性及损害机理,在重质碳酸钙类刚性颗粒表面接枝部分交联的聚合物制得储层保护剂SMRP-1,将其与井壁修补强化剂等复配制得低损害钻井液.室内评价了SMRP-1的阻渗性、酸溶性、与常见水基钻井液体系的配伍性,考察了低损害钻井液的各项性能,并在川西陆相低渗气藏储层江沙209HF井进行了现场应用.结果表明,SMRP-1的阻渗性能和酸溶性良好.SMRP-1对水基钻井液流变性的影响小,配伍性良好.低损害钻井液具有较好的阻渗、抗钙离子污染性能.含3％SMRP-1的钻井液形成的泥饼在15％盐酸中浸泡4 h的泥饼酸溶率为27％,酸溶性较好.低损害钻井液的储层保护效果较好,解堵作业后岩心的平均渗透率恢复值为89.59％.在现场应用中,低损害钻井液性能稳定,对储层的保护效果较好.低损害钻井液体系具有较强的井壁稳定和储层保护能力,对钻井液液相的渗透效应也具有良好的降低作用.图6表4参13

碳酸盐岩储藏资源潜力巨大,是当前研究的热点和难点领域.为了准确评价缝洞型油藏产能特征,以三重介质流体渗流方程为基础,考虑应力敏感对储层渗透率的伤害,建立基质-孔隙-裂缝的三重介质试井分析模型.研究结果表明:无量纲压力及压力导数曲线随应力敏感性增强而整体向上抬升,随着时间的增加,上升幅度逐渐增大;将无量纲压力导数曲线的水平段取值作为特征值,当其值大于0.5时应考虑应力敏感的影响,反之亦反;"双下凹"形态可作为判断三重介质缝洞型油藏的曲线特征.对于强应力敏感性储层,应力敏感的影响不可忽视,渗透率应力敏感的准确表征有利于提高产能预测精度.

针对顺北5-7井奥陶系地层采用水基钻井液钻进时坍塌掉块严重且井下复杂情况频发的问题,开展了油基钻井液在超深层奥陶系地层的探索性应用研究.分析了奥陶系地层井壁失稳的原因,对比评价了不同配比的主乳化剂、辅乳化剂、润湿剂等自主产品以及柴油对钻井液乳化稳定性能的影响,形成了油基钻井液性能现场调控方法;采用"密度控制"与"段塞堵漏+随钻堵漏"相结合的堵漏工艺,在小井眼储层段堵漏材料类型与粒径选择受限的情况下,有效降低了油基钻井液损耗.该井油基钻井液施工井段扭矩平稳,无掉块,平均井径扩大率仅为12.22％;裂缝性储层段钻进过程中油基钻井液漏失量控制在0.44m3/h以下;酸压后自喷求产小时产油19.8m3,折合日产气136535m3,表现出良好的井筒强化效果和储层保护效果,为探索油基钻井液在超深层奥陶系地层的应用提供了有益参考.

高温高压油基钻井液乳化稳定性评价仪主要由高温高压不锈钢腔体、测试电极、温度控制系统、压力控制系统以及测试系统组成,高温电极选用PEEK材料,测试的电极距离设计为1.5 mm,电极的放电电压最高设计为2000 V,温度控制系统以T89C51单片机为核心,采用铸铝电加热器包裹在高温高压不锈钢腔体外部进行加热,压力控制系统采用液压方式加压.对仪器的稳定性进行了测试并与常温常压下电稳定性测试仪进行了对比,结果表明,该仪器可以实现高温高压油基钻井液乳化稳定性评价,并且测试数据稳定、可靠,测量误差不大于5％.研究了油基钻井液在高温高压下乳化稳定性的规律,当维持压力不变时,随着温度的升高,破乳电压值呈下降趋势;当温度低于120℃时,随着压力的升高,破乳电压值有所减小,当温度达到120℃以上时,破乳电压值基本不随压力的变化而发生改变.

针对现有钻井液润滑剂耐温与环保性能难以兼顾的不足,以天然脂肪酸、有机多元醇等为原料,合成了钻井液环保润滑剂SMLUB-E.室内试验发现:膨润土浆中加入1.0％ SMLUB-E时,摩阻系数可降至0.05,且形成的润滑膜强度高;聚磺钻井液中加入2.0％ SMLUB-E,可使摩阻系数从0.31降至0.08,其润滑性能优于加入8.0％原油;SMLUB-E耐温160℃,对钻井液的流变性、滤失量无不利影响,无毒,环保性能好.SMLUB-E在塔河油田TP238CH井等深井进行了现场应用,加入SMLUB-E的钻井液中表现出良好的润滑降摩性能,大幅降低了井下摩阻,避免了托压、卡钻等复杂情况发生.研究结果表明,SMLUB-E具有良好的耐温性与环保性,能有效解决深井超深井钻井井下摩阻大的技术难题.

介绍了国内水基钻井液用降黏剂的评价标准,分析了国家、行业、企业、供应商以及API相关降黏剂标准,指出降黏能力评价参数、评价过程中基浆配制等方面存在的问题.针对石油天然气行业标准SY/T 5243-1991《水基钻井液用降黏剂评价程序》进行了评价方法实验研究,通过对现行配浆用土配制基浆过程的实验研究,初步给出了评价降黏剂用基浆的配制方法.

针对裂缝与溶洞恶性漏失堵漏成功率低、时间长、风险高的难题,构建了钻井液漏失预测-诊断-控制系统方法,揭示了缝洞地层钻井液漏失动力学机制,创造性形成了漏失预测、诊断新方法;开发了多点压力测试堵漏装置,并建立了评价新方法;研发出3类12种关键助剂,开发了适用于压力敏感裂缝、破碎性漏失层和溶洞漏失层的交联成膜、化学固结和化学触变3套堵漏技术;研发了间歇式蹩压工艺、双液触变堵漏工艺和延迟触变堵漏工艺.形成了从漏失诊断、配方制定到现场施工的一整套缝洞恶性漏失综合堵漏技术,在中石化西北、西南、东北、鄂尔多斯及缅甸、伊朗等地区推广应用1,500余口井,堵漏周期缩短65％以上,经济、社会效益巨大.

为解决顺北油气田超深水平井高摩阻难题,缓解环保压力,根据润滑机理,研制了抗高温环保润滑剂(SMLUB-ET),并以SMLUB-ET为核心,形成了适用于顺北油气田超深水平井的环保耐温低摩阻钻井液体系.研究表明:SMLUB-ET抗温达180℃,极压润滑系数降低率为92.8％,生物毒性、生物降解性、重金属含量等指标均满足环保要求;该环保耐温低摩阻钻井液体系抗温达180℃,高温流变性稳定,极压润滑系数为0.12.现场试验显示,顺北1-16H井钻进过程中未出现黏卡、托压问题,且摩阻低,机械钻速快,表明该环保低摩阻钻井液体系具有优异的抗温稳定和润滑降摩性能.该项研究为实现顺北深层油气钻井安全、快速、环保开发提供了技术保障.

针对顺北多口超深井采用水基钻井液钻遇奥陶系地层时井壁失稳和井漏并存的技术难题,通过井壁失稳机理分析,设计合成了具有三头双尾结构的Gemini型高温乳化稳定剂和支化型流型调节剂,采用微胶囊化处理方法研制了一种可在156℃以上的温度下激发后膨胀5.37倍以上的温度敏感型膨胀性堵漏材料,开发了一种抗高温强封堵低黏高切油基钻井液体系.室内评价结果表明,该体系抗温不小于180℃,所形成的油包水乳化液滴尺寸为1.2～26.9μm,具有较宽的粒径分布,高温高压滤失量为2.4 mL;塑性黏度不大于40 mPa·s,动塑比为0.31～0.40 Pa/mPa·s,与传统油基钻井液相比,塑性黏度降低10％～15％,动切力提高15％～25％,表现出优异的低黏高切特性和微裂缝的匹配性封堵能力.该体系在顺北Y井进行了现场应用,破碎性地层平均井径扩大率仅为7.77％,钻井过程中除出现一次短暂的放空性漏失外,未见其他明显漏失,避免了奥陶系破碎性地层井壁失稳,减少了裂缝性储层段油基钻井液损耗,助力了亚洲陆上最深定向井纪录的创造和顺北油气资源的提速、提效开发.

油气勘探开发不断向深部复杂地层深入,钻遇的高温、高压及高盐地层环境导致钻井液起泡严重且消泡困难,已成为影响钻井安全的重要因素之一.钻井液中具有表面活性的处理剂在搅动、气侵等情况下易产生气泡,由于钻井液的高黏切、高温下体系中处理剂的化学反应、高pH值等都影响钻井液消泡的效果,造成消泡困难.聚合物钻井液的推广曾削弱了消泡剂的使用,但目前复杂的地层环境和聚磺钻井液的广泛应用迫切需要高效的消泡剂.近年来应用于钻井液的消泡剂主要有有机硅型、非硅型和复配型,聚醚改性有机硅型消泡剂抗温、消泡抑泡效果好,在高温钻井液中有应用前景.消泡效果评价主要是采用高速分散法评价在起泡钻井液中加入消泡剂后泡沫体积的变化.今后钻井液消泡剂研究工作方向主要是,开发新型抗高温消泡剂以进一步提升高温下的抑泡能力,充分利用消泡活性组分之间的协同作用提高性价比,进一步加强其作用机理研究以提高钻井液消泡技术的整体水平.

Well Ying-1 is an ultra-deep key investigative risk management pre-exploration well deployed by Sinopec in the Shunbei Oil and Gas Field with designed well depth of 9 016.85 m (TVD 8 603.00 m). Drilling the welln encountered downhole problems including wellbore instability, well leakage and borehole wall sloughing. They also easily occur in drilling hard brittle mudstone formations, such as the Silurian Kepingtage Formation and the Ordovician Sangtamu Formation. For this reason, laboratory studies have been carried out to analyze mechanisms contributing to the instability of large section of hard brittle mudstone shale. As such, the reasons for leakage in the Silurian high pressure sensitive fissured formation, and the reasons for instability in Ordovician fractured formations. Based on the basic theory of multivariate synergistic” wellbore stability, the drilling fluid system SMHP-1 with strong inhibition and sealing capacity was constructed, and the technical measures of mud loss and borehole wall collapse prevention were worked out. The well successfully drilled through a large section of hard brittle mudstone and broken formation to a total depth of 8 588 m without borehole wall instability and drilling fluid loss, setting a record of the deepest onshore well depth in Asia. The field application showed that the drilling fluid system SMHP-1 could effectively solve the problems of wellbore stability and leakage in deep mudstone and broken formations by strong inhibition and sealing capacity, and provide best practices for safe drilling of deep or ultra-deep wells at home and abroad.

Filtration control of drilling fluid plays an important role in the process of well-bore construction and ensures the success of drilling operation. A swellable polymer microsphere (SPM) of methylmethacrylate (MMA), butyl acrylate (BA), and lauryl methacrylate (LMA) was synthesized with suspension polymerization. Its swelling property was characterized by oil adsorption capacity measurement. First, the effect of SPM on the filtration and rheological properties of virgin organic clay dispersion was investigated. Then the filtration and rheological properties of mineral oil-based drilling fluid in the presence of SPM were elucidated under the respective conditions of hot aging temperature, oil to water ratio and density. Furthermore, the filtration control properties between SPM and two traditional filtration loss additives including modified lignite and asphaltic additive was compared. Addition of SPM exhibited obvious influence on the viscosity of oil-based drilling fluid especially at high concentration of 3 w/v%, therefore, a concentration of lower than 1.5 w/v% was recommended. After hot aging at 200 degrees C, the oil-based drilling fluid containing 1 w/v% SPM exhibited an API filtration loss decrease of 85%, and HTHP filtration loss decrease of 79% in comparison with the base fluid. After hot rolling at 180 degrees C, the API filtration loss decreased by 2%, 24% and 53%, and the HTHP filtration loss decreased by 42%, 54% and 65% respectively when 1 w/v% asphaltic additive, modified lignite and SPM are in the presence of the base fluid. Besides decreasing the filtration loss volume under high temperatures, incorporation of SPM also improves the filter cake quality of oil-based drilling fluid. SPM is capable of adsorbing considerable base oil and become swellable. The swellable polymer microspheres with favorably deformable and compressible properties can effectively fill the voids of filter cake and reduce the permeability, which leads to low filtration loss and minimization of solids invasion.

从天然无机聚合物材料和合成无机聚合物材料两方面介绍了不同产品的性能及主要用途,着重介绍了合成无机聚合物材料的制备及在不同领域的应用,并指出无机聚合物材料因其丰富的来源、卓越的环保性能、良好的抗温性能和化学稳定性将会在高温钻井液、地热钻探钻井液、酸化压裂、固井、堵水调剖、驱油等油田化学领域具有良好的发展空间.

为解决威远区块深层页岩气水平井长水平段井眼失稳的问题,研制了具有强抑制性、强封堵能力的水基钻井液.分析了威远区块页岩储层矿物组分、储层物性和页岩地层井眼失稳机理,认为在该地层钻进水平段时,所用钻井液应具有较强的抑制性、封堵能力和一定的润滑性.在优选抑制剂、封堵剂和润滑剂的基础上,配制了深层页岩气水平井水基钻井液SM-ShaleMud,并对其性能进行了室内评价.室内试验结果表明:该钻井液流变性能好,高温高压滤失量低,润滑系数小;可抗温140℃,能有效抑制黏土水化和裂缝的产生、扩展;封堵能力和抗污染能力强.SM-ShaleMud水基钻井液在威远区块威页23平台3口井进行了应用,结果表明具有良好的综合性能,特别是井眼浸泡67 d后仍保持稳定,说明其具有强抑制性和强封堵能力.研究表明,SM-ShaleMud水基钻井液能够解决威远区块深层页岩气水平井长水平段井眼失稳问题,现场应用效果显著.