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.

A Gel-Based Solidification Technology for Large Fracture Plugging

Fault fractures usually have large openings and considerable extension. Accordingly, cross-linked gel materials aregenerally considered more suitable plugging agents than water-based gels because the latter often undergo contaminationvia formation water, which prevents them from being effective over long times. Hence, in this study, aset of oil-based composite gels based on waste grease and epoxy resin has been developed. These materials havebeen observed to possess high compressive strength and resistance to the aforementioned contamination, therebyleading to notable increase in plugging success rate. The compressive strength, thickening time, and resistance toformation water pollution of these gels have been evaluated indoors. The results show that the compressivestrength of the gel can reach 11 MPa;additionally, the related gelation time can be controlled to be more than3 h, thereby providing a safe construction time;Invasion of formation water has a small effect on the gel strengthand does not shorten the thickening time. All considered performance indicators of the oil-based gel confirm itssuitability as a plugging agent for fault fractures.

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

Development of degradable pre-formed particle gel(DPPG)as temporary plugging agent for petroleum drilling and production

Temporary plugging agent(TPA)is widely used in many fields of petroleum reservoir drilling and production,such as temporary plugging while drilling and petroleum well stimulation by diverting in acidizing or fracturing operations.The commonly used TPA mainly includes hard particles,fibers,gels,and composite systems.However,current particles have many limitations in applications,such as insufficient plugging strength and slow degradation rate.In this paper,a degradable pre-formed particle gel(DPPG)was developed.Experimental results show that the DPPG has an excellent static swelling effect and self-degradation performance.With a decrease in the concentration of total monomers or cross-linker,the swelling volume of the synthesized DPPG gradually increases.However,the entire self-degradation time gradually decreases.The increase in 2-acrylamide-2-methylpropanesulfonic acid(AMPS)in the DPPG composition can significantly increase its swelling ratio and shorten the self-degradation time.Moreover,DPPG has excellent high-temperature resistance(150°C)and high-salinity resistance(200,000 mg/L NaCl).Core displacement results show that the DPPG has a perfect plugging effect in the porous media(the plugging pressure gradient was as high as 21.12 MPa),and the damage to the formation after degradation is incredibly minor.Therefore,the DPPG can be used as an up-and-coming TPA in oil fields.

LEAKAGE-PLUGGING WHILE DRILLING AND PLUGGING AGENTS

This paper describes a series of plugging agents which have been developed these years by the authors. The features of these agents can bestated as: (1) Stopping losses without stopping drilling; (2) High ratio of success; (3) Improving fluids properties; (4) Suiting to many types of losses, even large cracks and caves; (5) Perfect efficiency in different conditions of pollution such as calcium, salt pollution and high temperature; (6) Sufficient resources of raw materials, nopoison, noharm, no pollution to the environment; (7) Convenience in use; (8) Lower cost. The properties, mechanisms and applications of these agents are also described in this paper.

Experimental Study of Engineered Cement Plug to Effectively Cure Losses While Drilling in Iranian Oil/Gas Well

Mud losses are one of the most severe problems encountered in drilling. This is commonly known as lost circulation. It can occur in naturally fractured formations and also can be induced in formations through drilling. Mud losses while drilling leading to cost overruns and HSE concerns, primary cement job failure due to not getting the cement up to the desired height resulting in subsequent sustained casing pressure and corrosion, not able to perform work over activity on certain wells due to losses. The objective of this paper is to explain extreme lost circulation problem and introduce cement plug formulation to cure or mitigate this problem. In addition, the cement plug has certain compressive strength that this is proper for use to control lost circulation in field. And finally, the application of a cement plug is described in one well of the Gas Field (National Iranian Oil Company).

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.

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。

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。

厚煤层沿空留巷变形漏风机制及多元协同防治技术

为解决厚煤层沿空留巷墙体变形机理及采空区漏风流场不清、瓦斯防治效果不佳的问题,以山西沁城煤矿20107工作面为工程背景,采用力学建模、理论分析研究了沿空留巷顶板断裂位置对应力集中及传播路径的控制作用,并指出断裂线位于留巷外侧时,可有效转移支撑应力并卸压,并提出了分段压裂切顶关键位置的计算方法。采用单元法实测,从采空区漏风量分布及留巷漏风通道两方面,揭示了沿空留巷采空区漏风流场及瓦斯浓度分布规律,进而提出了沿空留巷采空区瓦斯多元防治技术,即采用定向钻孔分段压裂切顶卸压-强化瓦斯抽采超前协同共治为主,弱化转移顶板来压避免墙体变形产生裂隙漏风的同时提高采空区瓦斯抽采效率;采用硅酸盐复合材料对已有墙体裂隙发育区(顶板交界处、插管外壁周围)进行喷涂堵漏,封堵留巷漏风通道;辅以留巷插管参数优化及控风降压,进一步减小采空区漏风及瓦斯涌出,并通过现场考察验证。研究结果表明:①20107采空区漏风以运输巷进风流正压漏入为主、回风侧以高浓瓦斯漏入沿空留巷为主,工作面倾向0~36 m区段正压漏风量332.84 m^(3)/min,占工作面总体漏入采空区风量(572.15 m^(3)/min)58.17%;留巷走向54~108 m区段留巷漏入风量408.45 m^(3)/min,占采空区总体漏入沿空留巷风量(469.01 m^(3)/min)87.09%;②优化后,裂隙带定向钻孔(压裂孔+抽采孔)平均瓦斯抽采纯量为7.46 m^(3)/min,压裂切顶后留巷墙体变形、裂隙控制大幅改善,沿空留巷平均瓦斯体积分数由原0.59%逐渐降至0.34%,实现工作面高效达产。

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。

顺北油气田二叠系火成岩钻井技术研究与应用

塔里木盆地顺北区块二叠系火成岩地层厚度大、硬度高、裂缝发育、非均质性强,导致机械钻速低与堵漏耗时长,相比邻区平均钻井周期增加达1.5倍。近几年,通过持续强化钻井液堵漏技术与优选高效钻井工艺,漏失量与堵漏时间逐步缩短,钻井指标逐年提高。本文分析了影响堵漏时间长与机械钻速低的主控因素,提出堵漏浆中加入竹纤维、变形颗粒以改善堵漏工艺技术,明确了冲击工具的适用条件,优选攻击性与抗冲击性的PDC钻头,改进混合钻头结构以及配套大扭矩、长寿命螺杆等技术对策,提速降本成效显著,为加快顺北油气田的高效勘探开发提供了指导。

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。

铝土岩水平井快封堵防塌钻井液技术

陇东铝土岩属于长庆油田重要的资源接替储层,近期完试的陇**井、宁**井在太原组铝土岩勘探获得重大突破。针对该类储层溶孔和裂缝发育,井壁垮塌、漏失风险高及井眼清洁能力差的技术难题,通过铝土岩物性参数、理化性能、力学性能和敏感性测试分析等,明确了陇东铝土岩主要坍塌因素,研发出适用于铝土岩安全钻进的快封堵防塌钻井液技术。该体系在170℃高温高压滤失量小于10 mL,钻井液二次回收率大于91%,铝土岩样品在钻井液体系中浸泡15 d后和清水浸泡15 d后的抗压强度相比提升81.8%。快封堵防塌钻井液技术在长庆首口铝土岩水平井陇4**井进行了试验应用,助力该井700 m水平段的安全钻进,该井投产获日产无阻流量3.53×10^(6)m^(3)高产气流,创鄂尔多斯盆地上古生届勘探开发50多年新纪录,为该类储层的勘探开发提供了技术支撑。

钻井液微纳米封堵性能评价方法研究进展

综述了国内外钻井液微纳米封堵性能的评价方法及发展动态,阐述了各评价方法的特点。并且对微纳米封堵评价方法的智能化、精确化发展进行了展望。为开发高效、智能、落地性强的微纳米封堵评价方法提供了新思路。

LCST型温度敏感聚合物的研究及其在钻井液领域的应用进展

低临界溶解温度(LCST)型温度敏感聚合物是指聚合物链在相转变温度前呈伸展溶解态、相转变温度后为收缩聚集态的温度敏感型聚合物,其在环境温度变化刺激下能智能且可逆响应,已在有机化工、材料科学、生物医学和石油天然气工业等领域得到了广泛研究。该文对不同空间构象的LCST型温度敏感聚合物进行了分类,重点介绍了线形结构、温敏水凝胶、嵌段结构、接枝复合结构和特殊结构的LCST型温度敏感聚合物的研究进展;总结了不同空间构象的LCST型温度敏感聚合物在低温流变调控、温敏智能封堵、增黏提切和防漏堵漏钻井液领域的应用现状,提出了LCST型温度敏感聚合物存在的关键问题及其在钻井液领域的应用前景。

微米刚性氧化石墨烯颗粒的制备及协同堵漏性能评价

泸州区块深层页岩气地层微米级裂缝发育,且偶有天然裂缝存在,结构面节理特征弱,钻井过程中,容易造成滤液侵入地层,引起井壁坍塌,亟待研制一款能抗压抗高温的微米尺度刚性封堵剂,既能应对微米裂缝带来的威胁,又可以与大片径堵漏剂有很好的协同堵漏作用。采用改进Hummers法制备氧化石墨烯(GO)水凝胶,经超长时间高温真空干燥之后,将其粉碎,获得了一种刚性氧化石墨烯颗粒(GO-RP)。这种颗粒属于氧化石墨烯纳米片的多重叠加,用超声波无法使之分散,单体能够承受215℃以下的温度。采用可驱替式堵漏仪评价这种颗粒的协同堵漏性能,实验结果表明,GO-RP可在压力作用下不断地冲进裂缝孔隙进行填充,搭配混合堵漏剂,尤其是带有柔性纤维的材料,能够形成更致密的承压封堵层,承压能力高达9 MPa,降漏失率提升了约70百分点。将封堵剂GO-RP加入水基钻井液中,可使钻井液漏失量显著降低,同时,在高温下仍能保持较好的摩擦性能和抗压能力。这种刚性氧化石墨烯颗粒封堵剂在钻井堵漏领域有良好的应用前景。