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3 Status Quo of Methods for Evaluating Filtration Performance and Mud Cake Quality of Drilling Fluid
4 Progresses in Studying Drilling Fluid Nano Material Plugging Agents
5 Drilling Fluid Technology for “Three High” Wells in Qaidam Basin in Qinghai
6 Synthesis and Evaluation of A Primary Emulsifier for High Temperature Oil Base Drilling Fluid
7 A New Fracturing Fluid with Temperature Resistance of 230℃
8 Development of Extreme Pressure Anti-wear Lubricant MPA for Water Base Drilling Fluids
9 Plugging Micro-fractures to Prevent Gas-cut in Fractured Gas Reservoir Drilling
10 A Temperature Sensitive Expanding Microcapsule Anti-Gas-Channeling Cement Slurry
2 Study and Performance Evaluation of Ultra-High Temperature High Density Oil Based Drilling Fluids
3 Synthesis and Evaluation of A Primary Emulsifier for High Temperature Oil Base Drilling Fluid
4 Progresses in Studying Drilling Fluid Nano Material Plugging Agents
5 Hole Cleaning Technology for Horizontal and Deviated Drilling: Progress Made and Prospect
8 High Performance Water Base Drilling Fluid for Shale Gas Drilling
9 A New Fracturing Fluid with Temperature Resistance of 230℃
10 High Performance Water Base Drilling Fluid for Shale Gas Drilling
Good mechanical properties of a set cement are of significance to the sealing integrity of the cement sheath. In recent years, with unconventional oil and gas resources becoming the main contributor to the production of oil and gas, and with more gas storage facilities being developed and constructed, set cement in well cementing with better mechanical properties is required to satisfy the needs of sealing integrity in complex oil and gas wells. In this paper, the investigation and survey done on set cement mechanical property improvement both at home and abroad are described, the methods and materials, as well as the mechanisms for the methods and the materials to work in improving the mechanical properties of set cement are systematically elaborated, the way in which the ultra-high performance concreate improves the mechanical properties of the oil well cement is introduced with emphasis, and the newest progresses made in the study of nanofibers, nanotubes and whiskers are expounded. The information and the thoughts of this article will hopefully be helpful in future studying on the improvement the mechanical properties of oil well set cement.
In Tarim Basin, borehole wall instability has been an issue encountered in deep and ultra-deep well drilling in the Taipen block, the studies of which are insufficient and the understanding of the mechanisms of which is not clear. In laboratory studies, cores taken from the outcrop rocks of the Silurian, Ordovician and Cambrian strata buried at depths between 5,595 m and 10,900 m in the Taipen block were analyzed, and it was found that fractures with opening sizes between 300 nm and 800 nm are good passages for the invasion of a drilling fluid; borehole pressure is easy to transfer across these fractures and the collapse pressure of the formation is hence increased. The contact angles of water and oil on the surfaces of the mudstone are 5.8° and 5.3° respectively, the contact angles of water and oil on the surfaces of the limestone are 42.5° and 15.6°, respectively. The percent water adsorption and the percent oil adsorption of the mudstones are 2.74% and 3.63%, respectively, and those of the limestones are 1.42% and 2.14%, respectively. The percentages of the recovery of the Silurian system rocks, the Sangtamu mudstone and the Awatage argillaceous dolomite on hot rolling test are 86.3%, 92.9% and 98.2%, respectively, and those of the limestone and the dolomite are both basically 100%. Part of the formations, because of the hydration effect and dispersion in water, have the rock cohesion reduced. These are the main mechanisms that cause borehole wall instability. Based on the mechanisms of borehole wall instability understood, a water based drilling fluid was formulated with a high efficiency nanometer plugging agent, a salt-resistant polymer filter loss reducer and other additives for ultra-deep well drilling. The nanometer plugging agent and the filter loss reducer are all ultra-high temperature resistant. By enhancing the plugging capacity, reducing the filtration rate of the drilling fluid and minimizing the amount of the drilling fluid lost into the formations, the collapse pressures of the formations are reduced. By improving the inhibitive capacity of the drilling fluid, the hydration and dispersion of the formations are inhibited, and the cohesion of the rocks is increased. With these measures, the borehole wall instability issue encountered in drilling the deep complex formations in the Tarim Basin is successfully solved.
When drilling into a naturally fractured tight reservoir, mud losses into the fractures can easily induce reservoir damage, block the pore throats and fractures in the reservoir formation, thereby reducing the permeability of the reservoir and hindering the stable production of oil and gas. In this study, the buried hill fractured tight metamorphic rock reservoir in a block in the Bohai Bay Basin was taken as the object of study, experiments such as fluid sensitivity, dynamic damage by drilling fluid and pressure bearing capacity of mud cakes were conducted. With these experiments, the degree of drilling fluid dynamic damage to the reservoir and the pressure bearing capacity of mud cakes were understood and the mechanisms of reservoir damage by fluid sensitivity were analyzed. The study results show that the matrices of the reservoir rocks have strong salt sensitivity, moderate to weak alkali sensitivity and weak water sensitivity. The incompatibility between the drilled solids particle sizes and the opening widths of the fractures in the reservoir causes the solids particles to invade into the deep fractures, plugging them and damaging the permeability of reservoir rocks. The drilling fluid used has good ability to plug fractures with opening widths ≤ 150 μm, but is unable to effectively plug fractures with opening widths ≥ 300 μm. The fractured tight metamorphic rock reservoir contains plenty of clay minerals and heavy minerals, mud losses cause the clay minerals to become hydrated and swollen, and migration of particles takes place, reacting with the heavy minerals to produce iron hydroxide precipitates which in turn exacerbate reservoir damage. When drilling metamorphic rock reservoirs, the protection of fractures with opening widths greater than 300 μm should be strengthened, and special attention paid to the reservoir damage induced by the interaction between the metamorphic rocks and the work fluids. Also presented in this paper are the measures to be taken in protecting reservoirs from being damaged.
To address the challenge of inadequate structural strength in the spatial framework of oil-based drilling and completion fluids under ultra-high temperatures and extended durations, which leads to poor solid phase carrying and suspension capabilities, two key materials were developed: an amphiphilic multiblock polymer viscosifier (HT-TQ) and an oil-soluble small molecule gelling agent (HT-CB). HT-TQ effectively enhances the yield point and low shear rate viscosity of the base emulsion, while HT-CB significantly improves the static yield point. Sepiolite fibers were selected as suspension enhancers, which, in synergy with HT-TQ and HT-CB, further improve the rheological properties of the emulsion after ultra-high temperature rolling and strengthen the spatial framework structure. Using these three suspension stabilizing materials as the core, optimal additives were selected to construct a highly stable oil-based drilling fluid system suitable for ultra-high temperatures. This system withstands temperatures up to 240 ℃, maintains a viscosity retention rate greater than 78% after five days of continuous ultra-high temperature rolling, with a yield point greater than 5 Pa and LSYP greater than 3 Pa, and exhibits excellent rheological properties under high temperature and high pressure. Additionally, by using compounded barite as a weighting material, a stable oil-based completion fluid system was developed, which withstands temperatures up to 240 ℃ and remains homogeneous without hard settling after ten days of static exposure to ultra-high temperatures, with a settlement degree less than 1.2 N. These research findings provide technical support for efficient drilling and completion fluids in deep and ultra-deep oil and gas reservoirs.
In response to conventional viscosifiers exhibiting poor performance under high temperature and high salt conditions rendering them ineffective for high-temperature deep reservoirs, this study prepared a novel nanocomposite (E-APNC) via in situ polymerization using 2-acrylamido-2-methylpropanesulfonic acid, N, N diethylacrylamide, N, N methylenebisacrylamide and nano-SiO2 particles (E-np) as raw materials. E-APNC synthetic condition was optimized by orthogonal experimentation, and the molecular structure of E-APNC was evidenced by FT-IR, E-APNC polymer fluid displayed good thickening performance at high temperatures with excellent rheological parameter such as viscosity increase, shear resistance, thermal stability, and salt tolerance. Through the 24 h static experiment, E-np has better dispersibility compared with nps and N-np. At 1%E-APNC, the apparent viscosity at room temperature reached 66 mPa·s, whereas the viscosity shear rate reached 60 mPa·s at high shear rate of 1021 s−1, showcasing the excellent viscosity increasing ability and good anti-shear performance of E-APNC. The apparent viscosity retention rate of the drilling fluid was 65% after aging at 200 ℃ for 16 h under 20% NaCl concentration probing its good temperature and salt resistance performance. Compared with polymer APNC and N-APNC, E-APNC showed strong shear resistance and good temperature resistance, salt resistance.
In view of the fact that the characteristics of the easy-to-leak formation are not accurately grasped during the plugging process, the self-adaptive ability of the field plugging material is poor, and it is easy to cause the bad plugging effect and the repeated leakage after plugging. Through the optimization of the deformable material and the use of the characteristics of the rigid plugging material, a screw extruder is used to coat the deformable material on the surface of the rigid plugging material to achieve the effective combination of the two, an adaptive plugging material with good compression resistance and elasticity has been developed. The temperature resistance reaches 170 ℃, it can deform without breaking under 69 MPa pressure and the springback rate reaches 80% after the pressure is removed. The self-adaptive plugging formula can effectively plug the changing seam width of 1mm-6mm with less leakage and pressure bearing capacity of 6 MPa.
Measurement of mud gains in mud pits is a conventional method of detecting downhole gas kick and is still in use in present. Using this method, the detection of a gas kick sometimes remarkably lags the occurrence of the gas kick. Another gas kick detecting method is the monitoring-while-drilling method with which gas kick can be timely detected, but the functions of this method are very limited. In this study a new method with which a gas kick can be qualitatively detected in an early time and quantitatively explained is presented, the changes of the flowrates of the fluids in the annular space while a gas kick is encountered are analyzed, a gas kick risk index (KRI) is designed, and the mapping relationship between the KRI and the volume fraction of the kicked gas is derived. Based on the difference between downhole dual measurement points pressure (DDMP), using the grey wolf optimization (GWO) algorithm, a real-time method for calculating the flow velocities of the fluids in the annular space is constructed. Using a simulated gas kick scenario, the stability and effectiveness of the method for early detection of gas kick are analyzed. The study shows that when a gas kick occurs, the flowrates of the fluids in the annular space are increasing, and this can be used as a key characteristic parameter for gas kick detection. The volume fraction of the gas in the annular space has a linear relationship with KRI. Errors made in calculating the flowrate of the fluids in the annular space first decrease and then increase as the distance between the two measurement points increases, and are less affected by the errors made in pressure and temperature measurement. Using this new method, the lag time for detecting a gas kick is 13.8 min, and the inversion error of the gas volume fraction in the annular space is less than 10%. This method is not only able to detect gas kick earlier, it also provides key parameters for well control design such as the gas fraction of the fluids in the annular space at a mud gain in the mud pits of only 0.017 m3, a volume that does not cause the fluid levels in the mud pits to change significantly.
Using micro-CT scanning technology, the characterization and evolution of the fractures in the Fuxing continental shales before and after high-temperature soaking are quantitatively analyzed. The continental shales are soaked in bentonite slurry, Nanodrill water based drilling fluid and white oil based drilling fluid, and are scanned with micro-CT at different soaking times. The effects of the different drilling fluids on the evolution of the fractures are analyzed. The study results show that the rock samples taken from the Liangshan Formation have more fractures than other rock samples, and different drilling fluids have different inhibitive capacities for the extension of the fractures. After soaking for 10 d in bentonite slurry, the percent layered fractures with the maximum width found in the rock samples is 12%, significantly higher than that of the rock samples in the white oil based drilling fluid, which is 6.13%, and the percent layered fractures with the maximum width of the rock samples in the water based drilling fluid lies in between the two. Using microscope, the distribution of the fracture widths of the rock samples before soaking is studied, and the percent increase of the fracture widths of the rock samples after soaking for 10 d is analyzed; the rock samples in the bentonite slurry have the highest percent increase in fracture width, which is 61.6%, the rock samples in the Nanodrill water based drilling fluid have the intermediate percent increase in fracture width, which is 52.1%, and the rock samples in the white oil based drilling fluid have the lowest percent increase in fracture width, which is 39.8%. Quantitative study on the distribution of the lengths of the fractures shows that the rock samples soaked in the bentonite slurry have the most fractures with lengths between 50 μm and 100 μm, and the numbers of the fractures with the same length distribution in the rock samples soaked in the Nanodrill water based drilling fluid and in the white oil based drilling fluid are basically remained unchanged. These data indicate that the white oil based drilling fluid has the best inhibitive capacity in inhibiting fracture extension in shales, with the Nanodrill water based drilling fluid inferior in inhibiting fracture extension to the oil based drilling fluid, and the bentonite slurry performs the poorest in this aspect. The results of this study can be used as a technical reference for efficient and safe drilling of the continental shale formations in the Fuxing area.
The formations in the Bayan block are complex in nature, mud losses, borehole wall collapse and pipe sticking etc. have long been problems hindering the drilling efficiency. Using laboratory methods such as X-Ray, electron microscopy and particle size analysis etc., the lithology, micromorphology and particle size distribution of the rock samples taken from the unstable section of the formations were studied. The primary cause of wellbore instability is identified as the inadequate sealing capability of the drilling fluid concerning the micro-nano fractures within the formation, which leads to fluid invasion and results in the dissolution and detachment of salt and gypsum from the Linhe Formation. To deal with these problems, a powdered rigid micrometer and nanometer resin plugging agent XNZD and a flexible high molecular weight modified paraffin XNEP were introduced into the drilling fluid to improve its plugging capacity. The self-developed XNZD plugging agent has a particle size distribution that is compatible with the fractures’ sizes of the unstable formations encountered in the Bayan block. Also introduced into the drilling fluid was a self-developed amine-based compound shale inhibitor XNYZ which was used in combination with potassium formate or other organic salts to improve the inhibitive capacity of the drilling fluid. In laboratory experiment with the optimized drilling fluid on a mud loss tester with fracture size of 0.03 mm, the amount of the drilling fluid lost was reduced by 98% because of the good plugging capacity of the drilling fluid. In core expansion test, the percent linear expansion of shale cores tested with the drilling fluid was reduced by 89.2%. These experimental results indicate that the drilling fluid has good plugging capacity and inhibitive capacity, and has provided an important technical support for the high efficiency drilling in the complex formations in the Bayan Hetao block.
The flushing efficiency of a cementing ahead fluid is one of the key factors affecting the job quality of well cementing. A reasonable method for evaluating the flushing efficiency of an ahead fluid and a reasonable experimental object are key factors for selecting ahead fluid formulation and volume. The evaluation results obtained with the methods presently in use for evaluating the flushing efficiency of ahead fluids cannot objectively and truthfully reflect the flushing effect of an ahead fluid. To solve this problem, cores made with pores of different depths are used as the experimental object to simulate the actual rough borehole walls, and a magnetic agitator is used to simulate the whole process of flushing action of the ahead fluid on the borehole wall. The cores with pores and the magnetic agitator composed of the new evaluation method and the feasibility of this method is verified. The experimental results obtained show that this new method can simulate the real situation of the uneven borehole walls and takes into account the effects of several factors, such as the detention and adsorption of the barite particles in the drilling fluid and the spacers in the pores and on the surface of the borehole walls. The evaluation results are regarded as being more objective and are able to truthfully reflect the flushing effect of an ahead fluid, and they can be used as the technical reference and the bases for optimization of ahead fluid formulation and for volume design of an ahead fluid. Using this method, the flushing efficiencies of several ahead fluids of different densities and contact time lengths are evaluated. The evaluation test gives results that are repeatable, and objectively and truthfully reflect the performance of the flushing additives. With this method, the composition and volume of an ahead fluid for cementing a well drilled in a gas field in East China Sea is optimized and modified. The flushing efficiency of the ahead fluid after optimization is 97%, and the job quality of the well cementing operation is improved by 10.3%.
以妥尔油脂肪酸和马来酸酐为主要原料合成了一种油基钻井液抗高温主乳化剂HT-MUL,并确定了妥尔油脂肪酸单体的最佳酸值及马来酸酐单体的最优加量。对HT-MUL进行了单剂评价,结果表明HT-MUL的乳化能力良好,配制的油水比为60:40的油包水乳液的破乳电压最高可达490 V,90:10的乳液破乳电压最高可达1000 V。从抗温性、滤失性、乳化率方面对HT-MUL和国内外同类产品进行了对比,结果表明HT-MUL配制的乳液破乳电压更大、滤失量更小、乳化率更高,整体性能优于国内外同类产品。应用主乳化剂HT-MUL配制了高密度的油基钻井液,其性能评价表明体系的基本性能良好,在220℃高温热滚后、破乳电压高达800 V,滤失量低于5 mL。HT-MUL配制的油基钻井液具有良好的抗高温性和乳化稳定性。
综述了国内外页岩气井井壁失稳机理、稳定井壁主要方法及水基钻井液技术研究与应用现状,讨论了当前中国页岩气井钻井液技术面临的主要技术难题,分析了美国页岩气井与中国主要页岩气产区井壁失稳机理的差异,指出了中国页岩气井水基钻井液技术研究存在的误区与不足,提出了中国页岩气井水基钻井液技术发展方向。
通常在勘探开发油气过程中会发生不同程度的油气层损害,导致产量下降、甚至"枪毙"油气层等,钻井液是第一个与油气层相接触的外来流体,引起的油气层损害程度往往较大。为减轻或避免钻井液导致的油气层损害、提高单井产量,国内外学者们进行了长达半个世纪以上的研究工作,先后建立了"屏蔽暂堵、精细暂堵、物理化学膜暂堵"三代暂堵型保护油气层钻井液技术,使保护油气层效果逐步提高,经济效益明显。但是,与石油工程师们追求的"超低"损害目标仍存在一定差距,特别是随着非常规、复杂、超深层、超深水等类型油气层勘探开发力度的加大,以前的保护技术难以满足要求。为此,将仿生学引入保护油气层钻井液理论中,发展了适合不同油气层渗透率大小的"超双疏、生物膜、协同增效"仿生技术,并在各大油田得到推广应用,达到了"超低"损害目标,标志着第四代暂堵型保护油气层钻井液技术的建立。对上述4代暂堵型保护油气层技术的理论基础、实施方案、室内评价、现场应用效果与优缺点等进行了论述,并通过梳理阐明了将来的研究方向与发展趋势,对现场技术人员和科技工作者具有较大指导意义。
页岩具有极低的渗透率和极小的孔喉尺寸,传统封堵剂难以在页岩表面形成有效的泥饼,只有纳米级颗粒才能封堵页岩的孔喉,阻止液相侵入地层,维持井壁稳定,保护储层。以苯乙烯(St)、甲基丙烯酸甲酯(MMA)为单体,过硫酸钾(KPS)为引发剂,采用乳液聚合法制备了纳米聚合物微球封堵剂SD-seal。通过红外光谱、透射电镜、热重分析和激光粒度分析对产物进行了表征,通过龙马溪组岩样的压力传递实验研究了其封堵性能。结果表明,SD-seal纳米粒子分散性好,形状规则(基本为球形),粒度较均匀(20 nm左右),分解温度高达402.5℃,热稳定性好,阻缓压力传递效果显著,使龙马溪组页岩岩心渗透率降低95%。
利用自主研发的水泥环密封性实验装置研究了套管内加卸压循环作用下水泥环的密封性,根据实验结果得出了循环应力作用下水泥环密封性失效的机理。实验结果显示,在较低套管内压循环作用下,水泥环保持密封性所能承受的应力循环次数较多;在较高循环应力作用下,水泥环密封性失效时循环次数较少。表明在套管内较低压力作用下,水泥环所受的应力较低,应力水平处于弹性状态,在加卸载的循环作用下,水泥环可随之弹性变形和弹性恢复;在较高应力作用下,水泥环内部固有的微裂纹和缺陷逐渐扩展和连通,除了发生弹性变形还产生了塑性变形;随着应力循环次数的增加,塑性变形也不断地累积。循环压力卸载时,套管弹性回缩而水泥环塑性变形不可完全恢复,2者在界面处的变形不协调而引起拉应力。当拉应力超过界面处的胶结强度时出现微环隙,导致水泥环密封性失效,水泥环发生循环应力作用的低周期密封性疲劳破坏。套管内压力越大,水泥环中产生的应力水平越高,产生的塑性变形越大,每次卸载时产生的残余应变和界面处拉应力也越大,因此引起密封性失效的应力循环次数越少。
分析了硬脆性泥页岩井壁失稳的原因,介绍了纳米材料特点及其应用,并概述了国内外钻井液用纳米封堵剂的研究进展,包括有机纳米封堵剂、无机纳米封堵剂、有机/无机纳米封堵剂,以及纳米封堵剂现场应用案例。笔者认为:利用无机纳米材料刚性特征以及有机聚合物可任意变形、支化成膜等特性,形成的一种核壳结构的无机/聚合物类纳米封堵剂,能够很好地分散到钻井液中,且对钻井液黏度和切力影响较小,这种类型的纳米封堵剂能够在低浓度下封堵泥页岩孔喉,建立一种疏水型且具有一定强度的泥页岩人工井壁,这不仅能够阻止钻井液侵入,而且还能提高地层承压能力,无机纳米材料与有机聚合物的结合是未来钻井液防塌剂的发展方向。
统计长庆油田罗*区块2015年存地液量与油井一年累积产量的关系发现,存地液量越大,一年累积产量越高,与常规的返排率越高产量越高概念恰恰相反,可能与存地液的自发渗吸替油有关。核磁实验结果表明,渗吸替油不同于驱替作用,渗吸过程中小孔隙对采出程度贡献大,而驱替过程中大孔隙对采出程度贡献大,但从现场致密储层岩心孔隙度来看,储层驱替效果明显弱于渗吸效果。通过实验研究了影响自发渗吸效率因素,探索影响压裂液油水置换的关键影响因素,得出了最佳渗吸采出率及最大渗吸速度现场参数。结果表明,各参数对渗吸速度的影响顺序为:界面张力 > 渗透率 > 原油黏度 > 矿化度,岩心渗透率越大,渗吸采收率越大,但是增幅逐渐减小;原油黏度越小,渗吸采收率越大;渗吸液矿化度越大,渗吸采收率越大;当渗吸液中助排剂浓度在0.005%~5%,即界面张力在0.316~10.815 mN/m范围内时,浓度为0.5%(界面张力为0.869 mN/m)的渗吸液可以使渗吸采收率达到最大。静态渗吸结果表明:并不是界面张力越低,采收率越高,而是存在某一最佳界面张力,使地层中被绕流油的数量减少,渗吸采收率达到最高,为油田提高致密储层采收率提供实验指导。
目前中国页岩气水平井定向段及水平段钻井均使用油基钻井液,但油基岩屑处理费用昂贵,急需开发和应用一种具有环境保护特性的高性能水基钻井液体系。介绍了2种高性能水基钻井液体系的室内实验和现场试验效果。在长宁H9-4井水平段、长宁H9-3和长宁H9-5井定向至完井段试验了GOF高性能水基钻井液体系,该体系采用的是聚合物封堵抑制方案,完全采用水基润滑方式;在昭通区块YS108H4-2井水平段试验了高润强抑制性水基钻井液体系,该体系采用的是有机、无机盐复合防膨方案以及润滑剂与柴油复合润滑方式。现场应用表明,定向段机械钻速提高50%~75%,水平段机械钻速提高75%~100%。通过实验数据及现场使用情况,对比分析了2种体系的优劣,找出了他们各自存在的问题,并提出了改进的思路,为高性能水基钻井液的进一步完善提供一些经验。
解决环境污染问题是改善钻井液的关键,开发环保型抗高温降滤失剂是当前研究的重要领域之一。概述了国内外环保型降滤失剂的研究进展,对国内外在环保型降滤失剂研制中所使用的原材料及产品性能,以及中国抗温改性天然高分子降滤失剂的发展近况进行了介绍。天然高分子降滤失剂是通过对淀粉、纤维素及木质素等天然高分子材料进行改性以提高其抗温、抗盐能力,使其可以应用于井温更高的深井钻探中。目前,中国环保型降滤失剂普遍可以应用到150℃的高温中,部分抗温能力可达到180℃却未能推广使用。通过对现有降滤失剂的研究,分析其抗高温的作用机理,探寻能有效提高抗温能力的单体分子结构及发挥作用的功能基团,例如磺酸基团、内酰胺基团等,以期对环保型抗高温降滤失剂的研制起到一定的指导和参考作用,加快环保型抗高温降滤失剂的发展。
页岩气井水平井段井壁失稳是目前中国页岩气资源勘探开发的关键技术难题。通过云南昭通108区块龙马溪组页岩的X-射线衍射分析、扫描电镜(SEM)观察、力学特性分析、润湿性、膨胀率及回收率等实验,研究了其矿物组成、微观组构特征、表面性能、膨胀和分散特性,揭示了云南昭通108区块龙马溪组页岩地层井壁水化失稳机理。该地层黏土矿物以伊利石为主要组分,不含蒙脱石及伊蒙混层,表面水化是引起页岩地层井壁失稳的主要原因。基于热力学第二定律,利用降低页岩表面自由能以抑制页岩表面水化的原理,建立了通过多碳醇吸附作用改变页岩润湿性,有效降低其表面自由能、抑制表面水化,进而显著抑制页岩水化膨胀和分散的稳定井壁方法。
China National Petroleum Corporation Ltd
CNPC Bohai Drilling Engineering Co. LtdPetroChina Huabei Oilfield Company
Editorial Office of Drilling Fluid and Completion Fluid, Bohai Drilling Engineering Institute, Yanshan South Road, Renqiu City, Hebei Province