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DRILLING FLUID
Effect of Water on BaSO4 Particles/GTL Suspensions
ZHANG Xuemei, ZHANG Guilei, GUO Xiaoxuan, GENG Tie, LI Bin, FENG Zongtao, SUN Dejun
2022, 39(1): 1-7.   doi: 10.12358/j.issn.1001-5620.2022.01.001
Abstract(8) HTML(0) PDF (2626KB)(3)
Abstract:
The dispersion state of weight material has a great effect on the rheology of oil based drilling fluids. In laboratory experiment, the effects of water on the settling stability and the viscosity of the suspension were studied. The suspension used in the experiments was formulated with fatty alcohol polyoxyethylene ether carboxylic acid (C12E9Ac) as the dispersant, BaSO4 as the dispersed phase and a gas to liquids (GTL) as the dispersing medium. It was found through the experiments that with the increase in the water content in the suspension, the dominant forces between the dispersed particles can be turned from repulsive force to attractive force. When the water is added in a concentration that is less than 0.5%, the settling stability and viscosity of the suspension are almost not affected, and the re-dispersibility of the suspension is enhanced. When the water is added at a concentration between 0.5% and 2.5%, water will not only cause the particles in the suspension to aggregate, the “big particles” formed by the aggregation of the particles will connect with each other through water bridge to form a complex network structure. When the water is added at a concentration greater than 25%, part of the particles in the suspension is dispersed in the water phase, decreasing the network structures formed by the particles, and hence the viscosity of the suspension. Thus, adding some water into a suspension stabilized by the C12E9Ac will help improve the re-dispersibility of the sediments in the suspension without disturbing the dispersion stability and viscosity of the suspension. The conclusions drawn from these experiments have provided a research method for controlling the settling stability of the particles in an oil based drilling fluid.
Study on Rheological Modifier of High Temperature High Density Clay-free Oil-based Drilling Fluid
SHI He, SHI Haimin, NI Xiaoxiao, CHENG Rongchao, ZHANG Jiaqi, WANG Jianhua, YAN Lili
2022, 39(1): 8-14.   doi: 10.12358/j.issn.1001-5620.2022.01.002
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Abstract:
Aiming at the problem of insufficient settlement stability of oil-based drilling fluids in high temperature environments, a small molecule fatty acid amide type rheological modifier FAA which can be used in high temperature environment was synthesized by reacting dimer fatty acids and diethylene triamine at a molar ratio of 1∶2, with the structural characterization, mechanism analysis and performance evaluation were also carried out. The results of rheological experiments and microscopic observations show that the FAA effectively improves the structural strength of the oil-based drilling fluid system by bridging the emulsion droplets to form a gel-like network structure, thereby effectively improving its solid-phase suspension ability and settlement stability. The evaluation results in the diesel-based drilling fluid system show that the FAA can effectively improve the yield point, φ6/φ3 revolution reading and yield point/plastic viscosity ratio of the system, and can effectively improve the high-temperature sedimentation stability of the system, making it standing at 220℃ for 5 days with the sedimentation factor SF less than 0.52 and no obvious sedimentation phenomenon occures.
Mechanisms of Oleamide as Thinner in Oil Based Drilling Fluids
WANG Jing, ZHANG Shuncong, LI Changling, SHU Jia, ZHONG Dehua, LU Fuwei
2022, 39(1): 15-22.   doi: 10.12358/j.issn.1001-5620.2022.01.003
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Abstract:
In laboratory experiment, different types of clay were added to a base mud to investigate the effect of formation clays on the viscosity of the base mud, and an asphalt filter loss reducer was added to a base mud at different concentrations to investigate the effect of asphalt on the viscosity of the mud. After adding 5% organophilic clay and 15.5% asphalt filter loss reducer into the base mud, the plastic viscosity of the base mud was increased by 100%, and the yield point of the base mud was increased by at least 370%. An oleamide type thinner was then added into the base mud contaminated with organophilic clay at 1% and the viscosity of the base mud was reduced by 10%, and the yield point reduced by at least 80%. After adding 1% oleamide type thinner into the base mud treated with 15.5% asphalt, the yield point of the base mud was reduced by at least 73%. These experimental results indicate that oleamide is able to disassemble the network structure formed by the low quality solids in the mud. An oil based mud (density 2.25 g/cm3) sample was taken from a well and was treated with 1% oleamide thinner, the viscosity and yield point of the mud were reduced by 15% and at least 30%, respectively. The major role of the oleamide thinner in the oil based mud sample is to disassemble the network structure formed by the low quality solids in the mud, the mechanism of viscosity reducing is the same as that of the mud contaminated with excessive amount of organophilic clay and asphalt. Rheology test at high temperature high pressure conditions has shown that at 205 °C, oleamide can still reduce the viscosity of an old oil based mud by 4.76% and the yield point of the old oil based mud by 8.70%. The oleamide thinner disassembles the excessive network structure in the mud taken from the rig-site and effectively improves the rheology of the mud.
Effects of the Molecular Structure of Block Polymer Developed through RAFT Polymerization on Filtration Property of Drilling Fluids
YANG Lili, WANG Aijia, JIANG Guancheng, AO Tian, ZHAO Zhengguo, TANG Runping
2022, 39(1): 23-28.   doi: 10.12358/j.issn.1001-5620.2022.01.004
Abstract(0) HTML(0) PDF (2360KB)(0)
Abstract:
A series of isomeric zwitterionic filter loss reducers have been developed for investigating the effects of the molecular structure of polymers on their filtration control performance. These isomeric zwitterionic filter loss reducers were synthesized through reversible addition-fragmentation chain transfer polymerization (RAFT) with monomers such as AMPS (ionic monomer), 1-vinyl-3-ethylimidazollium bromide (VeiBr, as cationic monomer) and acrylamide (AM, as neutral monomer). By adjusting the sequence of adding different monomers, three copolymers, which are a random copolymer, a partial block polymer and a full block copolymer, respectively. These three copolymers have precise molecular structures, different bonding sequence (of atoms) and narrowly distributed and controllable molecular weights. Laboratory performance evaluation of these copolymers have shown that under the same test conditions, the random copolymer has the best filtration control performance, while the block copolymers can be used to make high YP/PV ratio flow pattern modifiers. By changing the concentration of the chain transfer agent, the molecular weight of the copolymers can be effectively adjusted, and this helps analyze the effects of copolymers with the same molecular structure and different molecular weights. It was found that the higher the molecular weight, the higher the viscosity and the better the filtration control performance of the copolymers. It is thus concluded that block polymers with random sequence structure are more suitable for filtration control in drilling fluids, and polymers with higher molecular weight will perform better in this aspect. This study has provided a theoretical base for developing high efficiency molecular structure oriented filter loss reducers.
Study on Mechanisms of Carbon Nanotube as a Nanosized Plugging Agent in Water Based Drilling Fluids
CHEN Lili, GUO Jianhua, XIE Gang
2022, 39(1): 29-35.   doi: 10.12358/j.issn.1001-5620.2022.01.005
Abstract(0) HTML(0) PDF (2384KB)(0)
Abstract:
Micron-scale plugging agents are unable to effectively plug the nanosized fractures. To overcome this problem, aminated multi-walled carbon nanotubes were selected as the nanosized plugging agent. The effects of the aminated multi-walled carbon nanotubes on the rheology of drilling fluids were studied using the micron-scale ultrafine CaCO3 as a comparison. The plugging mechanism of the aminated multi-walled carbon nanotubes was studied through filtration test on artificial mud cakes and osmosis experiment on artificial cores. The study results showed that the carbon nanotube has almost no effect on the rheological parameters of the drilling fluid, and addition of ultra-fine CaCO3 into the drilling fluid made its rheology deteriorated. Plugging of the artificial mud cakes with the aminated multi-walled carbon nanotube becomes improved with the increase in the amount of the nanotubes added. When the concentration of the aminated multi-walled carbon nanotube was 3%, 77.70% of the mud cakes can be plugged, while the addition of the same concentration of ultra-fine CaCO3 only plugged 45.28% of the artificial mud cakes. Experiment on artificial cores showed that at a concentration of 3% aminated multi-walled carbon nanotube, the core was plugged by 79.41%, while at a concentration of 3% ultra-fine CaCO3, the core was plugged only by 61.76%. These experimental results fully demonstrate that the nanosized plugging agents are much better than micron-scale plugging agents in terms of plugging; the calcium carbonate can only accumulate on the face of a fractured surface, while the aminated multi-walled carbon nanotube can penetrate into the nanosized fractures and form bridges therein. By tightly adsorbing on the surfaces inside the fractures with the amino groups, the aminated multi-walled carbon nanotube prevents the filtrate from going into the fractures.
Viscoelasticity of Polymers and Carrying Capacity of Drilling Fluids When Sidetracking through Surface Casing
FU Jianmin, ZHANG Peng, GUO Lei, PENG Sanbing
2022, 39(1): 36-40.   doi: 10.12358/j.issn.1001-5620.2022.01.006
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Abstract:
Through-casing sidetracking is one of the important technical methods for production and efficiency enhancement. When opening windows on the walls a several layers of casing strings, large quantities of iron fillings are produced, imposing a challenge to the hole cleaning capacity of the drilling fluid used. The iron fillings produced in the windowing operation have high density and are therefore settling fast in the drilling fluid. Meanwhile, the iron fillings have different shapes, when carried up the annular space they tend to intertwine with each other to form cage-shaped structures, further increasing the difficulty of borehole cleaning. Several polymer solutions, each with different concentrations of the same polymer, have been evaluated on a laboratory dynamic carrying efficiency tester for their ability to carry the iron fillings. Through these tests, the rheological property of the polymer solutions affecting the carrying of the iron fillings during window-opening operation was studied from the viscoelasticity aspect of these polymers.
Research on Preparation Technology of Temperature-Controlled Expansion Plugging Agent Based on Shape Memory Polymer
WANG Baotian, YANG Qianyun, YANG Hua
2022, 39(1): 41-45.   doi: 10.12358/j.issn.1001-5620.2022.01.007
Abstract(0) HTML(0) PDF (2121KB)(0)
Abstract:
A kind of temperature-controlled expansion plugging agent based on temperature-triggered shape-memory material is prepared to achieve expansion bridging in fractured stratum after the temperature reaches the excitation temperature point. This paper discusses the preparation technology of the temperature-controlled expansion plugging agent. Firstly, an oligomer resin monomer and different high-temperature cross-linking agents are mixed to reaction by a catalyst under different heating temperature and time, then the mixture will be solidified through crosslinking. Secondly the reaction product after taking off the mold is pressed in the specific temperature in order to reserve deformation memory function. Finally the new polymer is crushed and granulated into various particle sizes according to demand at room temperature. The new plugging agent prepared has adjustable glass transition temperature, adjustable particle size, large compressive strength, large expansion at high temperature and high pressure, and the particle size growth rate of D90 after aging at 150 ℃ and 20 MPa is 44.71% ~ 54.17%. It can adapt to crack size to bridging, moreover, block leaking channels deformed by squeezing to improve the retention capacity and pressure endurance capacity of the plugging fluid.
Study and Application of a High Efficiency Liquid Pipe Freeing Agent in Pakistan
LI Wei, JI Yongzhong, YANG Gang, LI Ling, CHEN Wenbo
2022, 39(1): 46-52.   doi: 10.12358/j.issn.1001-5620.2022.01.008
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Abstract:
Black Magic is a widely used pipe freeing agent in Pakistan. Problems existed with the use of this pipe freeing agent include long time of preparation, weighting agents in the pipe freeing slurry which are easy to settle, poor compatibility of the Black Magic with drilling fluids used and low success rate of pipe freeing operations. A new high efficiency pipe freeing agent, ZL SPOT, was selected to solve these problems based on three evaluation parameters, say, degree of mud cakes broken down by the pipe freeing agent, time spent penetrating the mud cakes and extreme pressure friction coefficient. By studying the effects of oil/water ratio, pipe freeing agent and viscosifier on the break-down and penetration of the mud cakes, a weighted pipe freeing slurry was formulated with 0# diesel oil, ZL SPOT, water and organophilic clay. Laboratory experimental results showed that for unweighted pipe freeing slurry, at a concentration of the pipe freeing agent between 1% and 2.5%, the extreme pressure friction coefficient was 0.069, time for 100 mL pipe freeing slurry to penetrate the mud cakes was only 15 min, and after soaking in the pipe freeing slurry, mud cakes were obviously developed with fracture network on the surfaces, indicating the ZL SPOT is superior to the dry pipe freeing agent Black Magic. For weighted pipe freeing slurry, addition of solids into the slurry greatly affects the efficiency of freeing a stuck pipe. However, when the concentration of the ZL SPOT was increased to 8%, the mud cakes were developed with fracture network after being soaked in the pipe freeing slurry. When stood still for 16 h at 120 ℃, the pipe freeing slurry with its density between 1.32 g/cm3 and 1.80 g/cm3 showed no signs of barite settling. When mixed with water based drilling fluid at a ratio of 1∶1, the pipe freeing slurry basically did not affect the rheology and filtration rate of the drilling fluid. This liquid pipe freeing agent has been successfully used on two wells drilled in Pakistan, proving its pipe freeing ability. Field operation with this pipe freeing agent is easy, and the application of this pipe freeing agent will popularize in the future.
Study and Treatment on Carbonate/Bicarbonate Pollution in Shale Gas Wells in Sichuan
LI Wentao
2022, 39(1): 53-58.   doi: 10.12358/j.issn.1001-5620.2022.01.009
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Abstract:
Shale gas drilling in Sichuan basin is moving from the block Wei-202 to block Wei-204, where the water based drilling fluids used in the second interval were generally contaminated with CO32- and HCO3-. The source of the contamination is the Changxing, Longtan and Maokou formations. Contamination of the drilling fluids resulted in fast increase in viscosity and gel strengths, and it was difficult to bring under control the increase in viscosity and gel strengths. To deal with this problem, the source of CO32- and HCO3- was first analyzed. It was believed that CO2 invasion took place in drilling the Changxing and Longtan formations, and some mud materials contain high concentration of HCO3- (>10,000 mg/L). Measures have been taken to prevent the contamination from mud materials. Using pH meter, the concentrations of CO32- and HCO3- can be accurately measured. Preventing measures and two treatment methods (CaO and CaCl2) were discussed, and it was concluded that CaCl2 is the best additive to deal with the contamination. Previously CaO had been used to treat out the CO2 contamination on well Wei-204H23-5 and well Huang-206, but the results were not satisfactory. After using CaCl2 to treat out the CO2 contamination, the concentration of HCO3- was reduced from 15,420 mg/L to 1120 mg/L, and the viscosity of the mud was reduced from above 300 sec to 54 sec, which was the viscosity of the mud before HCO3- contamination. The viscosity of the mud in well Huang-206 was 180 sec after HCO3- contamination, and was reduced to 57 sec, as that before the contamination. This method of eliminating CO2 contamination has the advantages of is high efficiency, cost-effective and strong pertinence. Keep in mind that the technical measures should be well prepared to avoid contamination of the mud by both Ca2+ and HCO3-.n recent years, with the transfer of the construction block from Wei202 to Wei204, the pollution problem of carbonate/bicarbonate in the water base drilling fluid was widely encountered. The pollution occurred mainly in Changxing, Longtan and Maokou, and the viscosity/shear increased rapidly and was difficult to control. In view of this problem, the sources of pollution were firstly discussed, and the analysis showed that CO2 intrusion and coal interlayer in Changxing and Longtan were important pollution sources of carbonate/bicarbonate. Some materials contained a large amount of bicarbonate (>10 000 mg/L), and measures had been taken at present. The accurate test of carbonate/bicarbonate can be achieved by using a pH meter. Secondly, preventive measures and two treatment schemes are discussed, and it is suggested that CaCl2 treatment is more suitable for this block.Finally, the CO2 pollution treatment technology of Wei 204H23-5 and Huang 206 was explored. Two wells were treated with the CaCl2 solution when the CaO treatment was not ideal. HCO3 in Wei 204H23-5 decreased from 15,420 mg/L to 1120 mg/L, FV >300 s decreased to 54 s as pre-pollution state. After the pollution, the FV of Huang 206 well was up to 180 s, and after the treatment, the FV was reduced to 57 s as pre-pollution state. This method has the advantages of high efficiency, economy and strong pertinence, but technical measures should be implemented to avoid the double contamination of drilling fluid by Ca2+ and HCO3.
CEMENTING FLUID
Development of Strength of Set Aluminate Cement in Liquid and Gaseous CO2 Environment
FAN Baitao, WU Zhiqiang, ZHANG Dangsheng
2022, 39(1): 59-64.   doi: 10.12358/j.issn.1001-5620.2022.01.010
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Abstract:
In in-situ combustion operation, the set cement has to experience temperatures up to 500 ℃, under which the silicate cement is unable to retain its stability, and large amount of corrosive gas will be produced in the wellbore. To deal with these problems, the calcium aluminate cement (CAC) modified with slag was chosen to study its mechanical feasibility in cementing high temperature wells. The strength development pattern of the slag CAC was studied in a simulated real in-situ combustion work condition. The material composition and micromorphology of the slag CAC before and after corrosion were tested using X-ray and SEM, and the strength development of the slag CAC under simulated in-situ combustion work condition was investigated. It was found that with the increase in the amount of slag in the CAC, the compressive strength of the set cement first increased and then decreased, a top value was obtained at slag concentration of 30% in the cement. At elevated temperatures, the slag CAC can still retain higher compressive strength, and after secondary curing at high temperature, the strength of the set slag CAC was further developing, indicating that the slag cement has good high temperature resistance. In 50 ℃ liquid environment, corrosion of the set cement produced calcium carbonate and in the set cement there were pores and micro fractures because of the corrosion, all these damaged the integrity of the set cement and caused the strength of the set cement to reduce. In high temperature gaseous environment, CO2 did not cause corrosion damage to the set cement. This study has provided a theoretical base for optimizing the mechanical performance and improving the CO2 corrosion resistance of the set CAC under in-situ combustion work condition.
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Status Quo of Water Base Drilling Fluid Technology for Shale Gas Drilling in China and Abroad and Its Developing Trend in China
SUN Jinsheng, LIU Jingping, YAN Lili
2016, 33(5): 1-8.   doi: 10.3969/j.issn.1001-5620.2016.05.001
[Abstract](601) [PDF 1051KB](912)
摘要:
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。
High Performance Water Base Drilling Fluid for Shale Gas Drilling
LONG Daqing, FAN Xiangsheng, WANG Kun, FAN Jianguo, LUO Renwen
2016, 33(1): 17-21.   doi: 10.3969/j.issn.1001-5620.2016.01.004
[Abstract](635) [PDF 540KB](271)
摘要:
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。
Preparation and Characteristics of Nano Polymer Microspheres Used as Plugging Agent in Drilling Fluid
WANG Weiji, QIU Zhengsong, HUANG Wei'an, ZHONG Hanyi, BAO Dan
2016, 33(1): 33-36.   doi: 10.3969/j.issn.1001-5620.2016.01.007
[Abstract](448) [PDF 2843KB](220)
摘要:
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%。
Synthesis and Evaluation of A Primary Emulsifier for High Temperature Oil Base Drilling Fluid
QIN Yong, JIANG Guancheng, DENG Zhengqiang, GE Lian
2016, 33(1): 6-10.   doi: 10.3969/j.issn.1001-5620.2016.01.002
[Abstract](974) [PDF 4926KB](473)
摘要:
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。
Progress Made and Trend of Development in Studying on Temporarily Type Plugging Reservoir Protection Drilling Fluids
JIANG Guancheng, MAO Yuncai, ZHOU Baoyi, SONG Ranran
2018, 35(2): 1-16.   doi: 10.3969/j.issn.1001-5620.2018.02.001
[Abstract](307) [PDF 4562KB](378)
摘要:
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。
Progresses in Studying Drilling Fluid Nano Material Plugging Agents
MA Chengyun, SONG Bitao, XU Tongtai, PENG Fangfang, SONG Taotao, LIU Zuoming
2017, 34(1): 1-8.   doi: 10.3969/j.issn.1001-5620.2017.01.001
[Abstract](628) [PDF 2528KB](574)
摘要:
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。
Experimental Study on Airtightness of Cement Sheath Under Alternating Stress
LIU Rengguang, ZHANG Linhai, TAO Qian, ZHOU Shiming, DING Shidong
2016, 33(4): 74-78.   doi: 10.3969/j.issn.1001-5620.2016.04.015
[Abstract](249) [PDF 2049KB](153)
摘要:
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。
Effect of Retained Fracturing Fluid on the Imbibition Oil Displacement Effciency of Tight Oil Reservoir
GUO Gang, XUE Xiaojia, LI Kai, FAN Huabo, LIU Jin, WU Jiang
2016, 33(6): 121-126.   doi: 10.3969/j.issn.1001-5620.2016.06.022
[Abstract](303) [PDF 11047KB](192)
摘要:
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。
Cement Slurry Treated with Latex Nano Liquid Silica Anti-gas-migration Agent
GAO Yuan, SANG Laiyu, YANG Guangguo, CHANG Lianyu, WEI Haoguang
2016, 33(3): 67-72.   doi: 10.3969/j.issn.1001-5620.2016.03.014
[Abstract](471) [PDF 6834KB](234)
摘要:
针对顺南区块超深高温高压气井固井面临井底温度高、气层活跃难压稳的问题,研究了胶乳纳米液硅高温防气窜水泥体系。通过将纳米液硅防气窜剂与胶乳防气窜剂复配使用,协同增强水泥浆防气窜性能;不同粒径硅粉复配与加量优化,增强水泥石高温稳定性;无机纤维桥联阻裂堵漏,抑制裂缝延展,提高水泥浆防漏性能和水泥石抗冲击性能。该水泥浆体系具有流动性好、API失水量小于50 mL、直角稠化、SPN值小于1,水泥石具有高温强度稳定性好、胶结强度高、抗冲击能力强的特点。密度为1.92 g/cm3的水泥浆体系在190℃、21 MPa养护30 h后超声波强度逐渐平稳,一界面胶结强度达12.6 MPa;水泥石弹性模量较常规低失水水泥石降低52%,抗冲击强度增加了188%,且受霍普金森杆冲击后仅纵向出现几条未贯穿的裂纹。该高温防气窜水泥浆体系在顺南5-2井和顺南6井成功应用,较好地解决了顺南区块超深气井固井难题。
Temporary Plugging Diverting Test with Fuzzy Ball Fluids in Non-Water Producing Coal Beds in Re-fracturing Well Zheng-X
ZHENG Lihui, CUI Jinbang, NIE Shuaishuai, LIU Bin, FU Yuwei, LI Zongyuan
2016, 33(5): 103-108.   doi: 10.3969/j.issn.1001-5620.2016.05.022
[Abstract](488) [PDF 1759KB](486)
摘要:

郑庄煤层气田郑X井欲实施绒囊暂堵流体重复压裂转向,既形成新裂缝又不影响原缝生产,增加供气体积以达到满意产量。室内先用绒囊流体暂堵直径38 mm煤岩柱塞的中间人工剖缝,后用活性水测试绒囊流体暂堵剖缝承压能力达20 MPa,超过地层18 MPa的破裂压力,满足转向要求;绒囊暂堵流体伤害郑庄煤岩柱塞渗透率恢复值85%,满足原缝继续生产要求;现场利用混砂车和水罐建立循环,通过剪切漏斗配制密度为0.94~0.98 g/cm3、表观黏度为30~34 mPa·s的绒囊暂堵流体。先用活性水顶替检测原缝是否存在后,用排量为3.0~3.5 m3/h注入绒囊暂堵流体60 m3,停泵30 min油压稳定在12 MPa,表明绒囊封堵原缝成功。用活性水压裂液压裂,油管压力上升至18 MPa时出现破裂。微地震监测新缝方位为N13°W,相对于原缝N42°E转向55°。压后间抽2 h产气200 m3,是压裂前产量的2倍以上。采用微地震监测和对比压裂前后产量证明,绒囊可迫使压裂液转向压开新缝,且不伤害原裂缝,适用于煤层气老井重复压裂恢复生产。

Status Quo of Water Base Drilling Fluid Technology for Shale Gas Drilling in China and Abroad and Its Developing Trend in China
SUN Jinsheng, LIU Jingping, YAN Lili
2016, 33(5): 1-8.   doi: 10.3969/j.issn.1001-5620.2016.05.001
[Abstract](601) [PDF 1051KB](28)
Abstract:
This paper summarizes the studies and applications of the mechanism of borehole collapse, the main methods used for stabilizing instable borehol, and the status quo of water base drilling fluid technology, discusses the major difficulties presently faced in shale gas drilling in China, analyzes the differences between the mechanisms of borehole collapse both in China and in the America, illustrates the misconceptions and deficiencies existed in the studies on water base drilling fluids for shale gas drilling in China, and points out the technical direction for the development of water base drilling fluids for shale gas drilling in China.
Status Quo of Methods for Evaluating Filtration Performance and Mud Cake Quality of Drilling Fluid
YAO Rugang, ZHANG Zhenhua, PENG Chunyao, FENG Yanyun, DING Guangbo
2016, 33(6): 1-9.   doi: 10.3969/j.issn.1001-5620.2016.06.001
[Abstract](386) [PDF 2116KB](14)
Abstract:
This paper discusses the instruments and procedures available presently for evaluating fltration property, sizes of pore throats, thickness and compressibility of mud cake. Analyzed in this paper are the status quo of using SEM and energy spectrum in studying the microstructure of mud cake and the distribution of mud cake constituents. Studies presently conducted were focused on the observation of surface topography, while knowledge about the interior microstructure of mud cake is still in demand when optimizing the quality of mud cake. The spatial distribution of the microstructure of mud cake needs to be extensively studied in the future to further understand the mechanism of fltration control and the way of reducing fltration rate. These studies are of help to the development and perfection of the basic theory of controlling drilling fluid fltration and ability of building mud cake, and will provide guide and technical support to the development of new high performancemud additives and to the improvement of drilling fluid technology.
Drilling Fluid Technology for “Three High” Wells in Qaidam Basin in Qinghai
WANG Xin, ZHANG Minli, WANG Qiang, ZHUANG Wei, ZHANG Weijun, WANG Zhibin, LI Yifeng
2016, 33(6): 45-50.   doi: 10.3969/j.issn.1001-5620.2016.06.008
[Abstract](292) [PDF 729KB](11)
Abstract:
Four blocks in the Qaidam Basin, Niudong, Lenghu, Zahaquan and Yingxi, have formation rocks with complex lithology, such as salt, gypsum, mirabilite, and hard and brittle shales etc. Downhole troubles have been frequently encountered in previous drilling operations. The Niudong nasal structure in the piedmont of the Altun Mountain in the basin, affected by the orogenesis, has overall formation dipping angles between 60° and 70°. High formation stress, high pressure saltwater and varied coeffcients of pressure have resulted in frequent borehole wall instability in open hole section. A BH-WEI drilling fluid for the so-called "three high" (high pressure, high sulfde, and high risk area) wells, has been used in drilling 20 wells since 2013. To perform well in drilling fluid technical service, relevant data were investigated prior to drilling. Based on laboratory experiment and feld practice, it was concluded that drilling fluid with low activity, strong plugging and inhibitive capacity was benefcial to borehole wall stability. Four key exploratory wells, the frst multi-lateral horizontal well and the frst horizontal well in Zahaquan have been completed, the maximum mud density used was 2.35 g/cm3, the average percentage of hole enlargement was 4.67%, and the ratio of successful wireline logging was 100%. The well Zaping-1 is the frst horizontal well targeted with tight oil reservoir in Zahaquan. In the block Dongping, a four-interval horizontal well was drilled in 2013 with Weatherford's MEG drilling fluid. This well was not be able to drill to the designed depth because of severe mud losses and other downhole troubles. Using the BH-WEI drilling fluid, six horizontal wells were completed successfully in 2013-2014 in the same block, and no downhole trouble has been encountered throughout the drilling operations. Two horizontal wells, Ping-1H-2-1 and Ping-1H-2-2, put into production in 2014, were both high production rate wells in the same block; the average daily gas production rate was 50×104 m3/d. Field application has shown that the BH-WEI drilling fluid had simple formulation, and the mud properties were thus easy to maintain. The BH-WEI drilling fluid had good shear thinning property, high YP/PV ratio, low plastic viscosity, low pressure loss in annular space, good hole cleaning performance and good lubricity and inhibitive capacity. Using this drilling fluid, borehole collapse in drilling the dark gray Jurassic mudstone, inability to exert WOB in horizontal drilling and differential pipe sticking were avoided. To concluded, the BH-WEI drilling fluid is a unique drilling fluid suitable for use in drilling exploratory well and horizontal well in the troublesome drilling areas in Qinghai oilfeld.
Plugging Micro-fractures to Prevent Gas-cut in Fractured Gas Reservoir Drilling
HAN Zixuan, LIN Yongxue, CHAI Long, LI Daqi
2017, 34(1): 16-22.   doi: 10.3969/j.issn.1001-5620.2017.01.003
[Abstract](478) [PDF 2831KB](26)
Abstract:
The Ordovician carbonate rock reservoirs drilled in Tazhong area (Tarim Basin) have complex geology and developed fractures, 50% of which with widths between 20 μm and 400 μm. These fractures have led to frequent lost circulation, well kick and severe gas cut, which in turn resulted in well control risks. Complex distribution of fractures and high formation temperatures (180℃) make bridging with sized particles less effective in controlling mud losses. In laboratory experiment, commonly used testing methods for evaluating the performance of plugging drilling fluids are unable to effectively simulate the real fractures, and hence there is a big discrepancy between the laboratory evaluation and practical performanceof the plugging agents. To solve this problem, a new method has been presented based on the idea of plugging micro-fractures to prevent gas-cut. In this method, natural/artificial cores are used to make test cores with fractures of 20 μm-400 μm in width and roughness that is closely simulating the fractures encountered in the reservoirs drilled. Included in the new method are a device used to evaluate the performance of a drilling fluid in plugging micron fractures, and an evaluation procedure. With this method, particle, fiber and deformable LCMs sized in microns and nanometers were selected and an LCM formulation compatible with polymer sulfonate drilling fluid and ENVIROTHERM NT drilling fluid developed. This plugging PCM formulation, having acid solubility of greater than 70%,does not render contamination to reservoir.
Progresses in Studying Drilling Fluid Nano Material Plugging Agents
MA Chengyun, SONG Bitao, XU Tongtai, PENG Fangfang, SONG Taotao, LIU Zuoming
2017, 34(1): 1-8.   doi: 10.3969/j.issn.1001-5620.2017.01.001
[Abstract](628) [PDF 2528KB](30)
Abstract:
This paper analyzes the mechanisms under which the hard and brittle shale formations destabilize, introduces the characteristics and application of nano materials, and summarizes the progresses made in the studies of drilling fluid nano material plugging agents, including organic and inorganic nano plugging agents. Also discussed in this paper are several case histories of the application of nano plugging agents. The authors believe that plugging agents having core-shell structures, which take advantage of the rigidity of inorganic nano materials and the deformability and filming ability of organic polymers, do not heavily affect the viscosity and gel strength of the drilling fluids in which the plugging agents can well dispersed. This kind of nano plugging agents can plug the pore throats of shales at low concentrations, thereby produce a pseudo hydrophobic "borehole wall" with some strength. This pseudo "borehole wall" not only hinders the invasion of drilling fluids, it also increases the pressure bearing of formation. The authors thus believe that the combination of inorganic nano materials and organic polymers indicates the direction for the development of anti-collapse additives in the future.
Progress in Studying Cement Sheath Failure in Perforated Wells
LI Jin, GONG Ning, LI Zaoyuan, HAN Yaotu, YUAN Weiwei
2016, 33(6): 10-16.   doi: 10.3969/j.issn.1001-5620.2016.06.002
[Abstract](388) [PDF 2703KB](15)
Abstract:
Perforation well completion is a widely used completion method, and is of great importance to oil and gas well stimulation. With more and more wells completed with perforation, more attentions have been paid to the sealing integrity of cement sheaths after perforation, especially the perforation of wells with thin pay zones. Research work presently done has been focused on the effects of perforation on casing strings, while little attention has been paid to the damage of cement sheath. Oil and gas well perforation has characteristics such as being powerful, short time, high temperature, and being highly destructive. It is pointed out in this paper, based on analysis, that the diffculties in studying the failure of cement sheath mainly lie in laboratory simulation, determination of the degree of damage to the cement sheath, determination of the cement sheath's resistance to impact under practical conditions, and ascertaining the effects of perforation parameters on the integrity of cement sheath, etc. Researches presently done on the topics such as perforation simulation methods used both in China and abroad, integrity of cement sheath after perforation, shock or impact resistance of cement sheath, and the effects of perforation parameters, are summarized in this paper. Defciencies of the researches are also discussed herein. Also included in this paper are technical measures concerning self-healing cement, cement slurry and set cement performance designs, optimization of perforation parameters, and prediction of dynamic damage to downhole cement sheath etc.
A Temperature Sensitive Expanding Microcapsule Anti-Gas-Channeling Cement Slurry
ZHANG Xingguo, YU Xuewei, GUO Xiaoyang, YANG Jixiang, YAN Rui, LI Zaoyuan
2018, 35(1): 71-76.   doi: 10.3969/j.issn.1001-5620.2018.01.014
[Abstract](212) [PDF 4092KB](9)
Abstract:
A temperature sensitive expanding microcapsule anti-gas-channeling agent has been synthesized with acrylonitrile (AN), methylmethacrylate (MMA) and methyl acrylate (MA) as the wall material, and iso-butane as the core material. The effects of the amount of iso-butane used in the synthesis on the performance of the anti-gas-channeling were studied, and the performance of the temperature sensitive expanding microcapsule anti-gas-channeling cement slurry in controlling gas channeling was evaluated. The studies and the evaluation results showed that the temperature sensitive expanding microcapsule anti-gas-channeling agent can be obtained under the following conditions:in 100 g of deionized water add AN, MMA and MA in a ratio of 3:0.4:2, 30% iso-butane, 1% lauroyl peroxide (LPO, as initiator), 0.1% 1, 4-butanediol dimethacrylate (BDDMA, as crosslinking agent), 20% nano silicon dioxide (as dispersant), and react these substances at 65℃ with the protection of nitrogen. The anti-gas-channeling agent has initial expansion temperature of 65℃, optimal expansion temperature of 83℃, and is resistant to temperature as high as 120℃. Rate of expansion of the anti-gas-channeling agent is 50. Stimulation of water-channeling/gas-channeling in oil well cement and test of cement slurry condensation and contraction indicated that volumetric contraction of cement slurry can be made up for with less than 2% of the synthesized anti-gas-channeling agent, meaning that this anti-gas-channeling agent has good gas-channeling prevention ability.
Development of Extreme Pressure Anti-wear Lubricant MPA for Water Base Drilling Fluids
QU Yuanzhi, HUANG Hongjun, WANG Bo, FENG Xiaohua, SUN Siwei
2018, 35(1): 34-37.   doi: 10.3969/j.issn.1001-5620.2018.01.006
[Abstract](288) [PDF 963KB](21)
Abstract:
An extreme pressure organic sulfur anti-wear additive has been developed for use in water base drilling fluids. Structural characteristics and extreme pressure anti-wear performance evaluation showed that the organic sulfur compound is a saturated alkane, with sulfur content as high as 35.49%, and has good extreme pressure anti-wear property. An extreme pressure anti-wear additive, MPA, was developed with a modified vegetable oil as the base oil, the extreme pressure organic sulfur anti-wear additive and surfactants. The components of MPA are all environmentally friendly. Performance evaluation showed that MPA has good compatibility with other additives, and is completely dispersible in fresh water or drilling fluids. It helps optimize the properties of drilling fluids and has excellent lubricity.
A New Fracturing Fluid with Temperature Resistance of 230℃
YANG Zhenzhou, LIU Fuchen, SONG Lulu, LIN Lijun
2018, 35(1): 101-104.   doi: 10.3969/j.issn.1001-5620.2018.01.019
[Abstract](356) [PDF 604KB](57)
Abstract:
The natural vegetable gum fracturing fluid presently in use works effectively at temperatures up to 177℃. To fracture formations with higher temperatures, a fracturing fluid with temperature resistance of 200-230℃ has been developed with ultrahigh temperature thickening agent, high temperature resistant zirconium crosslinking agent, high temperature stabilizer and efficient gel breaker through large quantity of laboratory experiments. The experimental results showed that, under the synergetic effect of these additives, the fracturing fluid is suitable for use in fracturing formations whose temperatures are higher than the temperature limit of conventional gels. The fracturing fluid has good shear-resistance property at high temperatures up to 230℃, and the polymer consumption for formulating the fracturing fluid is obviously reduced. Complete gel breaking can be realized with the fracturing fluid, and damage to the fluid conducting formations with proppants is low.
Progress on Drilling Fluid Technology for Hot Dry Rock Drilling
LIANG Wenli
2018, 35(4): 7-13.   doi: 10.3969/j.issn.1001-5620.2018.04.002
[Abstract](258) [PDF 535KB](20)
Abstract:
Two key issues encountered in hot dry rock drilling are high temperature and lost circulation. This paper introduces the analyses made on the geological characteristics of hot dry rock and the drilling fluid technology required for drilling the hot dry rock, and surveying performed on drilling fluid system for hot dry rock drilling and the field applications of the drilling fluids. New technologies for hot dry rock drilling found both in China and abroad suitable for different formation conditions are summarized. Problems found of the hot dry rock drilling fluid are also presented with the prospecting for the development of the technology. Presently, polymer sulfonate water base drilling fluid is mainly used for hot dry rock drilling, however, some other drilling fluids, such as high temperature foam mud, aerated drilling fluid, liquefied nitrogen fluid etc. are also prospective fluids for hot dry rock drilling. These new hot dry rock drilling fluids have been successfully applied in field operation with good results; they impose low formation damage, and are high temperature and salt resistant. Other advantages include good adaptability to different formation conditions and performance in environment protection, all of which represent the future of the development of the hot dry drilling fluid technology.
Competent Authorities:China National Petroleum Corporation Ltd
Sponsored by:CNPC Bohai Drilling Engineering Co. LtdPetroChina Huabei Oilfield Company
Editor-in-Chief:Shi-chun Chen
Address: Editorial Department of Drilling Fluid and Completion Fluid, Bohai Drilling Engineering Institute, Yanshan South Road, Renqiu City, Hebei Province
Postcode: 062552
Tel:(0317)2725487 2722354
E-mail: zjyywjy@126.com
   CN13-1118/TE
ISSN1001-5620