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Articles in press have been peer-reviewed and accepted, which are not yet assigned to volumes /issues, but are citable by Digital Object Identifier (DOI).
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Research on Class Structural Environmentally Friendly Emulsifiers for Oil-based Drilling Fluids
CHENG Bingfang, WANG Chengjun, BU Fankang, BAO Linghan, WANG Chongchong, XIANG Peng
Abstract(72) HTML(94) PDF (3264KB)(3)
Abstract:
Using environmentally friendly ester derivatives such as epoxy fatty acid esters as raw materials, react with polyamines to form a main emulsifier with a Gemini surfactant structure. Then, using the main emulsifier as raw material, partially sulfonate it to form a multi class environmentally friendly emulsifier with a similar structure for oil-based drilling fluids. The molecular structure of the emulsifier was determined through infrared and mass spectrometry characterization, with a temperature resistance of up to 180℃, a demulsification voltage of over 900V, and an emulsification rate of over 90%. Capable of adapting to low oil-water ratio oil-based drilling fluid environments and drilling fluid systems formulated with different base oils. Adapt to drilling fluid systems with different densities. Has excellent biodegradability. A method for evaluating the microstructure of emulsion droplets was established to determine the stability of emulsion droplet formation, and it was determined that high emulsifier dosage can effectively improve the uniformity and high-temperature stability of oil in water emulsion droplets.
Flow Characteristics of Dual-Increasing Stimulation Slurry in Unconsolidated Silty Sandstone
LIU Xilong, SUN Qian, ZHANG Guobiao, LI Bing, ZHANG Kewei
Abstract(848) HTML(650) PDF (7827KB)(12)
Abstract:
The dual-increasing stimulation slurry is a novel stimulation fluid developed for weakly cemented reservoirs, such as submarine methane-hydrate-bearing silty sandstones. After injection into the formation, it consolidates to form porous-media slurry veins that enhance permeability. This study employed a slurry fracture flow visualization apparatus to investigate the flow characteristics of the slurry within muddy silty sediments. The experiments revealed the influence of geological parameters, slurry formulation, and operational parameters on slurry flow, fluid loss, and slurry-vein porosity. The results indicate that the slurry flows uniformly and exhibits a convex fracture flow profile, flowing to the end of main fracture and branch fracture, effectively filling fractures. Lower fluid loss increases the proportion of medium-to-large pores within the slurry veins. Adjusting the slurry formulation can reduce fluid loss in formations of varying permeability, whereas a high injection rate expands the fluid loss zone. The effective porosity ranges from 50% to 60% with a uniformly distributed pore space, forming a structure dominated by large pores (pore diameter > 50 nm) and densely distributed micro- to mesopores (pore diameter < 50 nm). This pore network can serve as high-conductivity channels for gas and water migration, while the dense distribution of small and medium pores is conducive to sand control.
A New High-temperature Tackifier for Solid-free Drilling Fluids
ZHOU Guowei, ZHANG Xin, YAN Weijun, HUA Guiyou, ZHUANG Zhenhua, QIU Zhengsong
Abstract(766) HTML(639) PDF (2972KB)(16)
Abstract:
The Ordovician buried-hill reservoir in Liaohe Oilfield exhibits a challenging high-temperature (200℃ at reservoir center) and low-pressure (pressure coefficient 1.01~1.06) environment characteristic of typical high-temperature, low-pressure oil/gas reservoirs. To achieve formation protection, a solids-free water based drilling fluid was prioritized, with tackifier selection being critical. Through molecular structure optimization, a novel high-temperature/salt-resistant tackifier was developed using four monomers: N-vinylpyrrolidone (NVP), 2-acrylamido-2-methylpropane sulfonic acid (AMPS), N'N-diethylacrylamide (DEAA), and 1-(3-sulfopropyl)-2-vinylpyridinium hydroxide inner salt. The synthesis employed N'N-methylene bisacrylamide as crosslinker with potassium persulfate and sodium bisulfite as redox initiators. FTIR and TGA analysis confirmed successful polymerization, demonstrating superior thermal stability with 296.66℃ initial decomposition temperature and only 45.96% mass loss during degradation phase, outperforming commercial HE300. The fluid achieved remarkable rheological performance with 722 consistency coefficient (K) at 0.5% concentration. Laboratory evaluations verified exceptional thermal stability up to 220℃ and saturated salt tolerance. Field applications demonstrated excellent viscosity-enhancing performance and robust durability of this novel tackifier, providing vital technical support for buried-hill reservoir development and high-temperature formation drilling operations.
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DRILLING FLUID
Salt-Resistant Lubricant for Deep Water Drilling Fluids
LIU Xiaodong, MA Yongle, LIU Tao, ZHANG Yong, LI Qingyong, LUO Ningzi
2026, 43(1): 1-8.   doi: 10.12358/j.issn.1001-5620.2026.01.001
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Abstract:
In deepwater drilling, drilling fluids are affected by seawater, highly mineralized brine, and polyvalent metal ions. Conventional lubricants such as mineral oils, vegetable oils, and fatty acids often exhibit poor dispersion and incompatibility in high salinity environments,separating out as oily or cheese like pastes, which reduces or even eliminates the lubricating performance of the drilling fluid. Currently, there are limited efficient lubricants in China suitable for brine-based drilling fluids, making it difficult to meet the demands of deepwater operations.To address this issue, this study reviews and analyzes international research progress on high performance water-based drilling fluids and salt-resistant lubricants for deepwater drilling. Laboratory evaluations were conducted on six lubricants with different compositions. The results show that all of them suffer from poor compatibility and fail to meet the required lubrication coefficient standards in seawater-based fluids.Based on these findings, a high-efficiency lubricant suitable for brine drilling fluids was developed using long-chain modified fatty acid esters compounded with non-ionic surfactants. This lubricant demonstrates good compatibility with seawater and brine-based fluids, with no separation of oily or cheese-like substances. It can reduce the lubrication coefficient of seawater-based fluids prepared with inorganic and organic salts to below 0.10. After hot rolling at 185℃, no oily material separates on the surface of the slurry, and the lubricating performance remains stable. Additionally, the lubricant does not cause foaming, does not affect the rheological properties of the drilling fluid, is environmentally friendly, has low biotoxicity, and does not harm the marine environment.
Simulation Research on Friction Characteristics of Borehole Wall Fracture Surfaces and Structural Instability in Maokou Carbonate Formation in Southern Sichuan
MA Yong, RAN Hang, WANG Yangsong, YANG Huajian, XU Weining, HUANG Tao, YU Wenshuai
2026, 43(1): 9-17.   doi: 10.12358/j.issn.1001-5620.2026.01.002
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Abstract:
To reveal the mechanisms of borehole wall instability occurred in drilling the Maokou carbonate formation in southern Sichuan province, systematic testing and discrete element numerical simulation were conducted on the friction characteristics of the surfaces of the fractures in the formation. Field data analysis confirms that borehole wall instability mainly takes place in the broken rocks in the Maokou formation in which fractures are developed. When drilling into this formation, caving and sloughing of the formation rocks frequently take place and serious local wash-out leads to enlarged holes, posing a threat to safety of drilling operation. Experimental results show that in the limestones of the Maokou formation, the surfaces of the natural/artificial fractures have coefficients of friction (COFs) ranging in 0.691-0.743 and 0.501-0.588. After contacting with the drilling fluid, the mechanical strengths of the surfaces of the fractures are reduced and the surfaces are also lubricated by the fluid, the COFs of the surfaces of the fractures are reduced by 16.9%-31.8% in average. In high stress condition, the micro convex spots on the surfaces of the fractures become softened and damaged, the COFs of some filled fractures can be reduced to 0.2-0.3. Simulation using discrete element method of the borehole wall instability in the Maokou formation which contains complex structural faces shows that when the angle between the orientation of a fracture and the maximum horizontal principal stress is between 45° and 60°, the fracture around the wellbore is easiest to be activated; a decrease in the friction coefficient of the surfaces of the fracture significantly increases the risk of shear slip of the rocks, thereby inducing wellbore instability such as caving and sloughing of the borehole wall and hole enlargement. Based on the above understanding, for a carbonate rock formation with high matrix strength and plenty of natural fractures, it is necessary to accurately assess the friction strength of the natural fractures, and use anti-collapse drilling fluids with excellent plugging capacity to effectively plug the fractures, suppress their lubrication effects, and enhance the friction strength of the surfaces of the fractures, thereby ensuring borehole wall stability and drilling safety.
Experimental Study on Lost Circulation Control with Particle-Gel Composite Plugging on a Novel Dynamic Circulating Lost Circulation Device
HU Zhaowen, ZHANG Yiqun, LIU Yanjun, WANG Xinyu, YANG lili, LIU Ya
2026, 43(1): 18-27.   doi: 10.12358/j.issn.1001-5620.2026.01.003
Abstract(3) HTML(1) PDF (6664KB)(0)
Abstract:
Experimental devices currently in use for lost circulation control test have such shortages in simulating dynamic circulation and evaluating the performance of lost circulation slurries. To overcome these shortages, a multiparameter dynamic lost circulation control experimental device was developed which integrates heterogeneous tortuous fracture simulation, temperature-pressure coupling control and real-time monitor functions. This device consists of a temperature-pressure controlled reactor (0-150℃)/(0-25 MPa), a work fluid synthesis system, a circulation pump set and a data acquisition and control system. It can be used to reconstruct tortuous fractures with lengths of 50-60 cm, and simulate the alternate migration-plugging process of lost circulation materials under dynamic circulation conditions. Using prefabricated heterogeneous artificial cores and reticulate metal frameworks, experiments were conducted on controlling lost circulation in multiscale fractures and nested frameworks, and the synergistic mechanism of the particle-gel composite system was revealed. Experimental results show that the lost circulation control slurry formulated based on the D90 rule achieves a coordinated improvement of suspension stability and plugging capacity through the “coarse particle bridging-fine particle filling – gel gap plugging” process, with the pressure bearing capacity of the plugging layer being over 12 MPa. The curing of the preinjected gel can significantly shorten the circulation time: the time for plugging a single fracture is shortened to 4 min, a plugging efficiency of at least 45% higher than plugging with single-particle lost circulation slurries, and this time is further reduced to 2.7 min when metal frameworks are used. This study has verified the engineering applicability of time-sequential synergistic process of lost circulation control with composite slurries under dynamic circulation conditions, providing theoretical support for the prevention and control of lost circulation in fractured-vuggy formations.
The Influence of the Synergistic Effect between Thermo-Responsive Polymers and Bentonite on the Rheology of Water-Based Drilling Fluids
XIAO Sizhuo, SHI Yuzhao, SUN Yanyu, GONG Lu, XIE Binqiang
2026, 43(1): 28-34.   doi: 10.12358/j.issn.1001-5620.2026.01.004
Abstract(3) HTML(0) PDF (3066KB)(0)
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To address the challenge of drilling fluid rheology instability resulted from high-temperature degradation of conventional polymers, three polymers PAANVCL, PAADEAM and PAANIPAM, with different thermo-responsive groups, were synthesized via free-radical polymerization using thermo-responsive monomers, including N-vinyl caprolactam (NVCL), N,N-diethylacrylamide (DEAM) and N-isopropylacrylamide (NIPAM), and hydrophilic monomers, including acrylamide (AM) and sodium 2-acrylamido-2-methylpropylsulfonate (NaAMPS). The lower critical solution temperature (LCST) of the polymer solutions was determined by the turbidimetric method, the structural changes of the polymers before and after interaction with bentonite were characterized using Fourier transform infrared spectroscopy (FT-IR), and the interactions between the polymers with different thermo-responsive groups and bentonite were comparatively analyzed via X-ray diffraction (XRD), Zeta potential measurement and isothermal adsorption test. Additionally, the influence of thermo-responsive group types on the high-temperature rheology of the polymers in bentonite-based slurries was investigated. It was found that the LCST of the thermo-responsive polymer PAANVCL is as high as 85℃, and those of the polymers PAADEAM and PAANIPAM are 77℃ and 73℃, respectively. At room temperature and 90℃, PAANVCL exhibits the highest adsorption capacity on bentonite particles, followed by PAADEAM and PAANIPAM. After aging at 160℃ for 16 hours, the retention rate of the apparent viscosity (AV) of the PAANVCL-bentonite water-based drilling fluid is 81.13%, compared with 72.52% for the PAADEAM-bentonite drilling fluid and 69.44% for the PAANIPAM-bentonite drilling fluid. Furthermore, at temperatures between 100℃ and 160℃, the AV, plastic viscosity (PV) and yield point (YP) of the PAANVCL-bentonite drilling fluid fluctuate in ranges of less than 15%, demonstrating good high-temperature rheological stability. The types of the thermo-responsive groups exhibit significant impact on the interaction between polymers and bentonite; PAANVCL, a polymer with cyclic thermo-responsive groups, exhibits superior rheological stability in water-based drilling fluids.
An Environmentally-Friendly Drilling Fluid for Stabilizing Shaximiao Formation in Block Zhongjiang
SHAN Haixia, ZHANG Yi, ZHANG Han, ZHAO Tiantian
2026, 43(1): 35-40.   doi: 10.12358/j.issn.1001-5620.2026.01.005
Abstract(2) HTML(1) PDF (3467KB)(0)
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The Shaximiao formation during drilling has found serious borehole wall collapse and the fallen debris were difficult to be brought out of the hole. To deal with this problem, an environmentally friendly drilling fluid suitable for drilling the Shaximiao formation in block Zhongjiang was selected and optimized for hole stabilization. The Shaximiao formation is developed with stack-structured fractures, and the bonding strengths between the clay minerals and the other minerals are low, thus, in the long-term exposure of the borehole walls into a water-based drilling fluid, it is easy to induce the propagation of the fractures in the formation to produce spalling and fallen debris, causing the borehole wall to collapse. The drilling fluid selected is an environmentally friendly biomass synthetic-based drilling fluid having good compatibility with the formation. Laboratory evaluation results showed that this drilling fluid has good inhibitive capacity, the 16 h linear expansion rate of rock cores tested with this drilling fluid is 0.62%, the permeability of the drilling fluid is low, and the wetting angle is 28.9°. This drilling fluid has the property of low viscosity and high gel strength, at 80℃-100℃ and 40 MPa, the YP/PV ratio is higher than 0.3 Pa/(mPa·s). The drilling fluid has stable properties at low temperature and high density. The PPA filtration rate of the drilling fluid tested on sand disks of different pore sizes is zero, and the penetration depths of the mud filtrates into visual sand-beds of different meshes are between 7 mm and 20 mm, indicating that the drilling fluid performs very well in plugging micropores and microfractures. Using this drilling fluid, borehole wall instability problem was solved, and all wells were successfully drilled to the designed depths with no downhole problems. The use of this drilling fluid provides an environmentally friendly technical guarantee for efficiently drilling the Shaximiao formation in the block Zhongjiang.
Synthesis and Performance Evaluation of Multifunctional Drilling Fluid Additive MPA-1
LI Xiong
2026, 43(1): 41-50.   doi: 10.12358/j.issn.1001-5620.2026.01.006
Abstract(1) HTML(0) PDF (2935KB)(0)
Abstract:
This study presents an idea of developing multifunctional drilling fluid additives to deal with the problems encountered in field drilling fluid engineering, such as too many kinds of drilling fluid additives, drilling fluid additives with their main function being prominent and secondary functions being unsatisfactory, as well as many drilling fluids with complex compositions, difficulties in property maintenance and poor compatibility among the additives. A multifunctional drilling fluid additive MPA-1 with three functions, which are filtration reduction, shale inhibition and lubricity improvement, was developed through L9(34) orthogonal experiment with which the monomers and their optimal concentrations, and the optimal reaction conditions were determined. The number average molecular weight and the weight average molecular weight of MPA-1 are 15.6×104 and 28.2×104, respectively. TGA results show that the initial decomposition temperature of the MPA-1 molecules is about 255℃. Compared with many other commonly used single-function additives, 1%MPA-1 in a 5% sodium bentonite slurry exhibits better performance in filtration control, lubrication and shale inhibition after the slurry is aged at 120℃ for 16 h. In 5% sodium bentonite slurry containing 5%-10%KCl, MPA-1 exhibits good salt resistance. When three samples of a potassium amine/potassium polymer sulfonate drilling fluid, which was used to drill 3 wells, were treated with 0.3%-0.5%MPA-1 and then allowed to age at 120℃ for 16 h, the viscosity of the samples increased moderately, the API filtration rate decreased significantly, and the lubricity of the mud cakes was improved. Replacing the 1%KPAM+1%Lube-3+1%SMJA-1 in the field potassium amine drilling fluid with 1.5%MPA-1, the composition of the drilling fluid was simplified, and the filtration rate, viscosity, viscosity coefficient of the drilling fluid, as well as the relative rate of expansion of bentonite pallets were wholly reduced. Mechanism analysis shows that the cationic groups in MPA-1 molecules moderately improve the hydrophobicity of clay particles by adsorbing on their surfaces, thereby inhibiting the clay particles and improving the lubricity of the drilling fluid at the same time. The anionic groups in the MPA-1 molecules, on the other hand, enter the hydration layer of clay particles, thereby enhancing the electronegativity of the clay particle surfaces, and increasing the thickness of the hydration films. These effects, together with the encapsulating effect of the main chains of the MPA-1 molecules, enlarge the range of the particle size distribution of the clay particles, which in turn helps produce thinner and denser mud cakes, reducing the filtration rate of the drilling fluid. The results of the research indicate that the multifunctional drilling fluid additive MPA-1 has the ability to reduce filtration rate, enhance lubricity and improve shale inhibition which satisfy the requirements of drilling a well with bottomhole temperatures less than 150℃, and this is beneficial to simplifying mud composition and reducing the difficulties in the maintenance and treatment of a drilling fluid in field operation.
Development and Application of a High Temperature High Filtration Rate Acid Soluble Lost Circulation Agent for Oil Based Drilling Fluids
LIU Yutong, FAN Pengfei, JIANG Xueqing, HU Xiaoyan
2026, 43(1): 51-56.   doi: 10.12358/j.issn.1001-5620.2026.01.007
Abstract(2) HTML(0) PDF (2530KB)(0)
Abstract:
High filtration rate lost circulation materials have several shortcomings such as inability to use at elevated temperatures, inability to mix with oil-based drilling fluids and low acid solubility etc. A high filtration rate lost circulation agent for use in oil-based drilling fluids have been developed to deal with these problems. This new lost circulation agent can be used at 150℃-190℃, and has acid solubility of 75.7%. It is composed mainly of a high softening point epoxy resin, a latent curing agent, and a highly acid soluble fiber, which has certain strength after filtering and piling. Laboratory evaluation experiment shows that this lost circulation agent can effectively consolidate after filtering, the plugging layer formed by the lost circulation agent after filtering has compressive strength that is greater than 4 MPa. The plugging layers formed in 1-5 mm fractures have compressive strengths that are greater than 11.5 MPa. The plugging layers do not cure at low temperatures and the curing time at elevated temperatures is 3.3-6.5 h, meaning that the use of this lost circulation agent is safe. A technology of using this lost circulation agent to formulate a high temperature high filtration rate acid soluble lost circulation slurry for use with oil-based drilling fluids has been used to control the loss of oil-based drilling fluid occurred on the well Yong-X. The operation temperature was 151℃, and the severe mud losses into the pay zones were successfully brought under control.
CEMENTING FLUID
Early Hydration Process of Well Cement Slurries for Cementing CO2-Contained Gas Reservoirs and Factors Affecting the Performance of the Cement Slurries
DENG Zhuoran, LIU Wenchao, BI Yi, LUO Yangli, CHENG Xiaowei, MEI Kaiyuan
2026, 43(1): 57-64.   doi: 10.12358/j.issn.1001-5620.2026.01.008
Abstract(465) HTML(408) PDF (3741KB)(8)
Abstract:
In cementing a gas well with CO2 contained in the reservoir, it is inevitable for the cement slurries to contact with the CO2. The length of the contact time will possibly affect the early hydration characteristics and the development of the microstructure of the cement slurries, and worse still is the negative effects of this contact on the quality of well cementing. In this study, the change patterns of the early hydration characteristics, the mechanical properties and the permeability of a cement slurry were systematically investigated by controlling the ventilation time of CO2. Using XRD, TG and SEM etc., the early phase composition and the evolution pattern of the cement slurry were analyzed. The study showed that the fluidity of the cement slurry was improved in the early stage and was then deteriorating with the time of CO2 ventilation. The setting time of the slurry, on the other hand, was shortened continuously. The hydration heat release curve showed that CO2 treatment significantly accelerated the cement hydration process, and increased the early cumulative released heat. However, as the time of CO2 ventilation increased, these effects became weakening. Compressive strength and permeability test results showed that CO2 treatment significantly enhanced the early strength of the cement slurry, and the best result can be obtained at ventilation time of less than 3 minutes. However, as the ventilation time of CO2 increased, the strength and permeability of the set cement both gradually decreased. XRD, TG and SEM analyses showed that CO2 treatment increased the formation of CaCO3, disrupted the coating structures formed by Ca(OH)2 and the C—S—H gel, and hence accelerated the hydration process of the cement particles.
Carbonation-Induced Corrosion Resistance and Mechanism of Ultrafine Slag Contained Oil Well Cement
DUAN Zhiwei, FU Junfang, HUANG Wei, FENG Keman
2026, 43(1): 65-72, 79.   doi: 10.12358/j.issn.1001-5620.2026.01.009
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To improve the ability of set cement to resist carbonation-induced corrosion, the mobility, the strength of set cement and the depth of carbonation-induced corrosion in supercritical CO2 environment were measured of a cement slurry in which ultrafine slag was substituted for oil-well cement. This measurement was aimed to determine the appropriate amount of the slag to substitute cement. Using low-field NMR, XRD and SEM with energy dispersive spectroscopy, the mechanisms with which the substituting ultrafine slag affects the ability of the set cement to resist carbonation-induced corrosion was studied. It was concluded that when the substituting amount of the ultrafine slag is less than 40%, it helps improve the mobility of the cement slurry; when increasing the substituting amount of the ultrafine slag, the strength of the set cement first increases and then decreases, and the depths of the carbonation-induced corrosion first decrease and then increase. Compared with the reference sample, the cement slurry sample with substituting amount of 10% ultrafine slag has more gel pore developed while the number of capillary pores decreases. The cement slurry sample with substituting amount of more than 50% ultrafine slag has less gel pores and more capillary pores. The cement slurry sample with substituting amount of 30%-50% ultrafine slag has basically gel pores and no evident capillary pores. By associating the pore structure of the sample with the depth of the carbonation-induced corrosion, it was found that the sample containing substituting amount of 30%-50% ultrafine slag showed no significant corrosion, and this is relevant to the fact that it has no evident capillary pores. The sample containing substituting amount of 40% ultrafine slag has compact structure and no evident pores in the micromorphology. The hydration product of this sample is mainly fine fluffy-shaped CSH gel with low Ca/Si ratio, and contains less Ca(OH)2 mineral phase which is easily being corroded. Therefore, it is recommended that the appropriate substituting amount of ultrafine slag be around 40%.
Research on the Thermal Conductivity of Ultrafine Graphite and Carbon Fiber Reinforced Cement for Well Cementing
DANG Donghong, HUANG Zhongwei, QI Pengfei, WANG Hongke, REN Qiang, PENG Song, CHENG Xiaowei
2026, 43(1): 73-79.   doi: 10.12358/j.issn.1001-5620.2026.01.010
Abstract(286) HTML(272) PDF (2957KB)(2)
Abstract:
To reduce the thermal resistance between the wellbore of a geothermal well and the rock formation and enhance the heat extraction capacity of the geothermal well, this paper selects graphite (SG) with excellent thermal conductivity as the heat-conducting material, and uses a surfactant to prepare a graphite dispersion. High aspect ratio carbon fibers (CF) are introduced to construct a heat-conducting network, which cooperatively improves the thermal conductivity of the cement paste. The performance of the graphite dispersion-cement slurry, as well as the mechanical and thermal conductivity properties of the cement paste, were evaluated. The phase composition, pore structure and microstructure of the cement paste were characterized by X-ray diffraction (XRD), thermogravimetric analysis (TG/DTG), mercury intrusion porosimetry (MIP) and scanning electron microscopy (SEM), and the thermal conduction mechanism was explored. The results show that when the W/S ratio is 0.51, the performance of the cement paste prepared by adding SG and CF meets the engineering requirements. The 24-hour compressive strength of the cement paste is not less than 17.0 MPa, the 7-day compressive strength is higher than 25.0 MPa, and its thermal conductivity can reach 2.86 W/(m·K). Under the combined effect of SG promoting hydration and CF inhibiting hydration, the weight loss of C—S—H and CH in the high-conductivity cement Ppaste was 10.91%, which was slightly lower than 11.04% of the pure cement paste. Appropriate SG can refine the pore size of the cement paste and reduce the porosity of the cement paste, while CF will significantly increase the porosity of the cement paste and increase the number of large pores. When the two are mixed, the porosity of the cement paste is 36.95%, which is higher than that of the pure cement paste. However, the number of pores larger than 70 nm in the high-conductivity cement paste is not much different from that of the pure cement paste. Adding SG and CF to the cement slurry can form a thermal conductivity network.
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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](3963) [PDF 4926KB](711)
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。
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](3469) [PDF 1051KB](1202)
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。
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](2187) [PDF 2843KB](275)
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%。
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](2580) [PDF 4562KB](470)
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。
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](1835) [PDF 2049KB](201)
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。
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](3639) [PDF 2528KB](805)
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。
Progress in Study and Application of Waste Mud Disposal Technologies
CHEN Gang, WANG Peng, ZHAO Yi, TONG Kun, ZHANG Jie, SUN Peizhe
2020, 37(1): 1-8.   doi: 10.3969/j.issn.1001-5620.2020.01.001
[Abstract](2086) [PDF 814KB](338)
摘要:
废弃钻井液污染大、种类多、处理难,给水质和土壤环境带来巨大的负面影响,随着近些年环保法规的日益完善,对废弃钻井液的处理技术也提出了新要求。概述了9种不同处理方法及其发展现状,重点分析了固化法、热解吸法、化学强化固液分离法、不落地技术和多种技术联用等处理技术,并对几种现行的主流处理技术进行了对比,指出了各类方法的发展前景,得出多种技术联用具有较好的发展潜力。分析认为今后的研究方向与热点在于如何低能耗、高效率地实现对废弃钻井液的资源化处理,具体工作既要包含污染物的源头、过程和结果控制,也要加强管理和相关制度的建立,综合开发新技术。
Borehole Wall Collapse and Control in Shale Gas Well Drilling
LIU Jingping, SUN Jinsheng
2016, 33(3): 25-29.   doi: 10.3969/j.issn.1001-5620.2016.03.005
[Abstract](1787) [PDF 7874KB](252)
摘要:
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。
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](1944) [PDF 11047KB](227)
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。
Progress in the Study of Environmentally Friendly Drilling Fluid Filtration Reducer
WU Xinlei, YAN Lili, WANG Lihui, WANG Fayun
2018, 35(3): 8-16.   doi: 10.3969/j.issn.1001-5620.2018.03.002
[Abstract](1865) [PDF 851KB](278)
摘要:
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。
Dissolution of Barite Filter Cake Using Chelating Agents: A review of Mechanisms, Diagnosis and Removal Strategies
WEI Zhongjin, ZHOU Fengshan, XU Tongtai
2020, 37(6): 685-693.   doi: 10.3969/j.issn.1001-5620.2020.06.002
[Abstract](7874) [PDF 5710KB](728)
Abstract:
As a weighting agent of drilling fluid, barite is easy to migrate, transform and precipitate in the reservoir to form acid insoluble barite mud cake, which causes serious damage to oil and gas reservoir. Therefore, it is necessary to remove the blockage of barite safely and reliably. However, many reasons, such as put too little emphasis on barite blocking, unclear mechanism of barite blocking and removal, improper design of removal methods, large investment but poor output, confidentiality of business, et al, have restricted the progress of remove barite blockage technology in China. The chelating agent with amino polycarboxylate as the main component is the most promising process choice for removing the barite blockage, while the chelating agent structure (amino group type, carboxyl number, ring chain size, chemical stability, et al), the properties of metal ions (charge, ion radius, ionization potential or alkalinity, co-associated metal ions, et al), medium environment (pH, temperature, pressure, et al) and so on, have a profound influence on the dissolution of barite. The economic and efficient design of chelating barite blocking remover and its removal process must take removal characteristics of different chelators, concentration, catalyst, converting agent, polymer breaker, bottom temperature, environment friendly, corrosiveness, formation rock matrix, secondary reservoir damage caused by removal process and other factors into account. With the help of modern experimental technique evaluation, such as filtrate cake dissolution, dissolution product composition and morphology, core flow, et al., and carefully design the details of chelating removal process, such as injection volume, injection pressure, soaking time, flow-back fluid treatment, et al, so as to fully understand the mechanism of barite blocking, the design of chelating removal agent and its application in oil and gas fields. In this paper, the systematic work of removing the blockage of barite filter cake is reviewed, which done by the previous researchers in recent years. Hoping to provide a new perspective for the readers, so as to improve the technical innovation level of drilling fluid and completion fluid in China.
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](3469) [PDF 1051KB](691)
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](2527) [PDF 2116KB](563)
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.
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](3639) [PDF 2528KB](671)
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.
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](2432) [PDF 729KB](587)
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.
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](3963) [PDF 4926KB](1014)
Abstract:
A primary emulsifier, HT-MUL, for high temperature oil base drilling fluid was developed using tall oil fatty acids and maleic anhydride, and the optimum acid value of tall oil fatty acids and optimum concentration of maleic anhydride for the reaction were determined. Evaluation of HT-MUL shows that HT-MUL performs very well as an emulsifier. Using HT-MUL, a water-in-oil emulsion (O/W ratio=60:40) was formulated, having electrical stability of 490 V, and another water-in-oil emulsion (O/W ratio=90:10), having electrical stability of 1,000 V. Comparison of HT-MUL with other primary emulsifiers demonstrates that emulsions formulated with HT-MUL have higher electrical stability voltage, lower filter loss and higher rate of emulsion, proving that HT-MUL has better general performance than other emulsifiers. A high performance high density oil base drilling fluid was formulated using HT-MUL, retaining electrical stability of 800 V and filter loss less than 5 mL after hot rolling at 220℃. Oil base drilling fluids formulated with HT-MUL have good high temperature performance and emulsion stability.
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](2768) [PDF 604KB](630)
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.
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](2456) [PDF 2831KB](560)
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.
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](2480) [PDF 963KB](607)
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.
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](2415) [PDF 2703KB](551)
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.
Governed by:
China National Petroleum Corporation Ltd
Sponsored by:
CNPC Bohai Drilling Engineering Co. Ltd
Editor-in-Chief:Shi-chun Chen(Engineer Technology Research Institute,BHDC)
Deputy Editor-in-chief:
Gui-juan Wang(Engineer Technology Research Institute,BHDC)Qiang Ren(Engineer Technology Research Institute,BHDC)
Address:
Room A517, China Petroleum Tianjin Building, No. 83, Second Avenue, Tianjin Economic and Technological Development Zone
Postcode: 300457
Tel:022-65278734
022-25275527
E-mail: zjyywjy@126.com
   CN   12-1486/TE
ISSN   1001-5620