A novel responsive stabilizing Janus nanosilica as a nanoplugging agent in water-based drilling fluids for exploiting hostile shale environments

Thermo-responsive nanocomposites have recently emerged as potential nanoplugging agents for shale stabilization in high-temperature water-based drilling fluids(WBDFs). However, their inhibitory properties have not been very effective in high-temperature drilling operations. Thermo-responsive Janus nanocomposites are expected to strongly interact with clay particles from the inward hemisphere of nanomaterials, which drive the establishment of a tighter hydrophobic membrane over the shale surface at the outward hemisphere under geothermal conditions for shale stabilization. This work combines the synergistic benefits of thermo-responsive and zwitterionic nanomaterials to synchronously enhance the chemical inhibitions and plugging performances in shale under harsh conditions. A novel thermoresponsive Janus nanosilica(TRJS) exhibiting zwitterionic character was synthesized, characterized,and assessed as shale stabilizer for WBDFs at high temperatures. Compared to pristine nanosilica(Si NP)and symmetrical thermo-responsive nanosilica(TRS), TRJS exhibited anti-polyelectrolyte behaviour, in which electrolyte ions screened the electrostatic attraction between the charged particles, potentially stabilizing nanomaterial in hostile shaly environments(i.e., up to saturated brine or API brine). Macroscopically, TRJS exhibited higher chemical inhibition than Si NP and TRS in brine, prompting a better capability to control pressure penetration. TRJS adsorbed onto the clay surface via chemisorption and hydrogen bonding, and the interactions became substantial in brine, according to the results of electrophoretic mobility, surface wettability, and X-ray diffraction. Thus, contributing to the firm trapping of TRJS into the nanopore structure of the shale, triggering the formation of a tight hydrophobic membrane over the shale surface from the outward hemisphere. The addition of TRJS into WBDF had no deleterious effect on fluid properties after hot-treatment at 190℃, implying that TRJS could find potential use as a shale stabilizer in WBDFs in hostile environments.

Thermo-sensitive polymer nanospheres as a smart plugging agent for shale gas drilling operations

Emulsifier-free poly（methyl methacrylate-styrene） [P（MMA-St）] nanospheres with an average particle size of 100 nm were synthesized in an isopropyl alcoholwater medium by a solvothermal method. Then, through radical graft copolymerization of thermo-sensitive mono- mer N-isopropylacrylamide （NIPAm） and hydrophilic monomer acrylic acid （AA） onto the surface of P（MMA- St） nanospheres at 80 ℃, a series of thermo-sensitive polymer nanospheres, named SD-SEAL with different lower critical solution temperatures （LCST）, were prepared by adjusting the mole ratio of NIPAm to AA. The products were characterized by Fourier transform infrared spectroscopy, transmission electron microscopy, thermogravimetric analysis, particle size distribution, and specific surface area analysis. The temperature-sensitive behavior was studied by light transmittance tests, while the sealing performance was investigated by pressure transmission tests with Lungmachi Formation shales. The experimental results showed that the synthesized nanoparticles are sensitive to temperature and had apparent LCST values which increased with an increase in hydrophilic monomer AA. When the temperature was higher than its LCST value, SD- SEAL played a dual role of physical plugging and chemical inhibition, slowed down pressure transmission, and reduced shale permeability remarkably. The plugged layer of shale was changed to being hydrophobic, which greatly improved the shale stability

Numerical simulation on the multiple planar fracture propagation with perforation plugging in horizontal wells

Intra-stage multi-cluster temporary plugging and diverting fracturing(ITPF)is one of the fastest-growing techniques to obtain uniform reservoir stimulation in shale gas reservoirs.However,propagation geometries of multiple fractures during ITPF are not clear due that the existing numerical models cannot capture the effects of perforation plugging.In this paper,a new three-dimensional FEM based on CZM was developed to investigate multiple planar fracture propagation considering perforation plugging during ITPF.Meanwhile,the fluid pipe element and its subroutine were first developed to realize the flux partitioning before or after perforation plugging.The results showed that the perforation plugging changed the original distribution of the number of perforations in each fracture,thus changing the flux partitioning after perforation plugging,which could eliminate the effect of stress interference between multiple fractures and promote a uniform fluid distribution.The standard deviation of fluid distribution in the perforation plugging case was only 8.48%of that in the non-diversion case.Furthermore,critical plugging parameters have been investigated quantitatively.Specifically,injecting more diverters will create a higher fluid pressure rise in the wellbore,which will increase the risk of wellbore integrity.Comprehensively considering pressure rise and fluid distribution,the number of diverters should be 50%of the total number of perforations(N_(pt)),whose standard deviation of fluid distribution of multiple fractures was lower than those in the cases of injecting 10%N_(pt),30%N_(pt)and 70%N_(pt).The diverters should be injected at an appropriate timing,i.e.40%or 50%of the total fracturing time(tft),whose standard deviation of the fluid distribution was only about 20%of standard deviations in the cases of injecting at20%tftor 70%tft.A single injection with all diverters can maintain high bottom-hole pressure for a longer period and promote a more uniform fluid distribution.The standard deviation of the fluid distribution in the case of a single injection was 43.62%-55.41%of the other cases with multiple injection times.This study provides a meaningful perspective and some optimal plugging parameters on the field design during IPTF.

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.

Formation mechanisms of fracture plugging zone and optimization of plugging particles

As formation mechanisms of plugging zone and criteria for fracture plugging remain unclear,plugging experiments and methods testing granular material mechanical properties are used to study the formation process of the plugging zone in fractured formations,analyze composition and ratios of different sizes of particles in the plugging zone,and reveal the essence and driving energy of the formation and damage of the plugging zone.New criteria for selecting lost circulation materials are proposed.The research results show that the formation of the plugging zone has undergone a process from inertial flow,elastic flow,to quasi-static flow.The plugging zone is composed of fracture mouth plugging particles,bridging particles and filling particles,and the proportion of the three types of particles is an important basis for designing drilling fluid loss control formula.The essence of the construction of the plugging zone is non-equilibrium Jamming phase transition.The response of the plugging zone particle system to pressure is driven by entropy force;the greater the entropy,the more stable the plugging zone.Lost circulation control formula optimized according to the new criteria has better plugging effect than the formula made according to conventional plugging rules and effectively improves the pressure-bearing capacity of the plugging zone.The research results provide a theoretical and technical basis for the lost circulation control of fractured formations.

A high-temperature resistant and high-density polymeric saturated brine-based drilling fluid

Three high-temperature resistant polymeric additives for water-based drilling fluids are designed and developed:weakly cross-linked zwitterionic polymer fluid loss reducer(WCZ),flexible polymer microsphere nano-plugging agent(FPM)and comb-structure polymeric lubricant(CSP).A high-temperature resistant and high-density polymeric saturated brine-based drilling fluid was developed for deep drilling.The WCZ has a good anti-polyelectrolyte effect and exhibits the API fluid loss less than 8 mL after aging in saturated salt environment at 200°C.The FPM can reduce the fluid loss by improving the quality of the mud cake and has a good plugging effect on nano-scale pores/fractures.The CSP,with a weight average molecular weight of 4804,has multiple polar adsorption sites and exhibits excellent lubricating performance under high temperature and high salt conditions.The developed drilling fluid system with a density of 2.0 g/cm^(3)has good rheological properties.It shows a fluid loss less than 15 mL at 200°C and high pressure,a sedimentation factor(SF)smaller than 0.52 after standing at high temperature for 5 d,and a rolling recovery of hydratable drill cuttings similar to oil-based drilling fluid.Besides,it has good plugging and lubricating performance.

天然气井井筒解堵工作液的研究进展

通过文献调研,分析了各种井筒解堵工作液的解堵机理,综述了各类型常用井筒解堵工作液的应用进展及优缺点;介绍了有机解堵工作液、有机缓释微乳酸解堵工作液、复合型解堵工作液等新型解堵工作液的研究进展;分析了解堵工作液在制备与实际应用过程中存在的问题,并提出了未来解堵工作液的发展趋势。

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。

复杂泥页岩地层井壁稳定钻井液材料研究现状

针对复杂泥页岩地层钻井过程中频繁出现的井壁失稳问题,目前国内外已形成了用于稳定井壁的钻井液技术,包括泥页岩水化抑制技术、地层孔隙封堵技术和化学固壁技术。但以上多种技术均无法抑制泥页岩的表面水化作用,高温条件下快速封堵和化学固壁剂的效果也相当有限,因此井壁失稳问题仍难以解决。系统总结了复杂泥页岩地层井壁稳定钻井液材料的研究工作,通过对井壁稳定钻井液材料研究现状进行分析,阐述了不同钻井液材料包括泥页岩水化抑制剂、封堵剂、化学固壁剂的作用机理,探讨了不同种类井壁稳定材料的优势和缺陷。据此指出开展泥页岩水化基础理论研究、开发高温高盐条件下稳定有效的新型纳米材料、建立能够模拟井下条件的化学固壁剂的评价方法将成为未来复杂泥页岩地层井壁稳定钻井液材料和技术研究的热点和难点。最后对复杂泥页岩地层井壁稳定钻井液技术和材料的发展方向进行了展望。

单裂隙内浆液基本流动规律的理论、试验、模拟对比分析

工程中广泛使用的水泥浆液是一种非牛顿流体,在裂隙内扩散时表现出复杂的宏观非线性渗流特征,在细观流场上也因屈服应力的作用呈现出柱塞流等特殊流动现象。配制符合Herschel-Bulkley(H-B)模型的模拟浆液,利用粒子图像测速(particle image velocity,PIV)技术开展平直裂隙内的可视化渗流试验,同时求解H-B-P(H-B-Papanastasiou)方程开展浆液渗流有限元数值模拟。基于平直裂隙中单相屈服幂律流体渗流解析解,从理论、试验、模拟相结合的角度分析了平直裂隙内注浆压力与流速的非线性关系;通过对流速剖面图的对比,分析了H-B流体的柱塞流特征;通过与Bingham模型的对比证明了H-B流体更符合实际浆液流动规律。通过原创的可视化测试手段验证了理论和数值模型,提出了参数取值依据,对提升复杂工程岩体中的注浆工艺具有参考价值。

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。

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。

烟草中甲霜灵的手性分离方法差异研究

对比反相液相色谱-串联质谱(RPLC-MS/MS)和超临界流体色谱-串联质谱(SFC-MS/MS)手性分离烟草中甲霜灵的差异。烟草样品经乙腈提取、盐析分层、快速滤过型净化(multi-Plug Filtration Cleanup,m-PFC)柱净化后,分别采用RPLC-MS/MS和SFC-MS/MS进行手性分离。从多个性能参数(分离效率、线性、选择性、回收率、重复性、灵敏度、基质效应等)对两种方法进行了全面比较。采用不同的分离方法,在10~500 ng/mL范围内,甲霜灵的不同异构体均可呈现良好的线性关系(R^(2)≥0.9993)。在各异构体加标浓度为0.1、0.5、2.0 mg/kg水平下,采用不同的分离方法均可获得满意的回收率(88.7%~96.2%)和良好的重复性(RSD<7.0%)。结果表明:RPLC-MS/MS和SFC-MS/MS具有互补性,均适用于手性分离和测定烟草基质中的甲霜灵。

碳酸盐岩储层高酸溶多级架桥暂堵型钻井完井液体系

以顺北二区碳酸盐岩储层为研究对象,通过岩心裂缝稳定性校正评价了储层敏感性,开展了现用钻井液伤害评价,明确了储层损害主控因素为应力敏感伤害和固相伤害,2种伤害因素累计占比达78.07%。采取“钻井可暂堵、完井可解堵”理念和保护微裂缝为主的储层保护思路,根据裂缝架桥封堵理论,研选了高酸溶固相封堵材料耦合可降解纤维关键材料。通过抗温、抗盐抗钙、沉降稳定性、配伍性及储层保护性能评价,形成了耐高温180℃多级架桥储层保护钻井完井液体系,其承压超过10 MPa,酸化后渗透率恢复率均值可达96.86%,相对常规不含酸溶暂堵材料体系提高了16.23%,具有强封堵、高返排的特点,有望减轻顺北二区碳酸盐岩储层的损害。

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。

绒囊暂堵液堵漏机理研究

绒囊流体因其具有较好堵漏性能,广泛应用于钻完井、修井等石油工程勘探开发各个阶段。明确绒囊流体堵漏的微观机理可以更好的指导现场堵漏。室内测定了绒囊内绒囊的粒径分布、封堵岩心的孔喉分布及封堵压力,利用微观实验装置观测其基质孔隙内的充填暂堵过程,最后结合理论分析明确绒囊流体微观堵漏机理。结果表明,体系内绒囊的粒径分布0~350 μm,岩心孔喉的粒径分布0.7~15 μm,同一绒囊流体封堵4种岩心封堵压5.42~17.65 MPa且随着渗透率的减小而增大,绒囊通过聚集、变形可对基质孔喉、微裂缝进行全面封堵。根据拉普拉斯定理结合室内实验结果可知,绒囊流体堵漏的微观机理为:岩心内的绒囊流体在流动过程中压缩变形产生了附加阻力,大量的附加阻力相互叠加产生了封堵压力,阻止了井漏的发生。

浅谈金坛储气库钻井提速提质技术

金坛储气库已经钻井近20年,在钻进中存在漏失、盐层段井径扩大率高、砂砾石钻头磨损大等施工问题,导致钻井周期长、钻进时效低。针对金坛盐矿钻进中出现玄武岩漏失、阜宁组盐层易溶解、砂砾岩发育、直井轨迹控难、固井质量要求高等问题,总结现有已钻井施工的问题,形成了防斜打直钻井技术、新型饱和盐水钻井液技术、防漏堵漏技术、防气窜固井技术等金坛矿区盐井钻井关键技术,为后续钻井的设计和施工提供新的思路。

基于OpenFOAM的旋塞阀流场分析及结构参数的影响

为了探究锥形旋塞阀内部流体动态特性,需对旋塞阀结构进行优化设计。本文基于k-ε湍流模型,使用开源软件OpenFOAM、应用PIMPLE算法、以锥形旋塞阀为研究对象,模拟研究了不同开度、不同阀芯圆角时旋塞阀的流动性能;研究了阀芯关闭过程中随着旋转角度的增加,流体流速、压差、流线、流量系数以及阻力系数等参数的变化规律,并绘制了相关曲线;对比分析了不同圆角半径下流体介质的速度、流量系数曲线等参数的变化。结果表明:旋塞阀旋转角度越大,阀门前后压差越大,流量损失也就越大;流量系数随着旋塞阀开度的增加而减小,且在相同开度下随着阀芯圆角半径的增加而增大。

铝土岩水平井快封堵防塌钻井液技术

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