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A Cement Slurry for Large Temperature Difference in Wells of Ten Thousand Meter Depth
LIU Jingli, LIU Pingjiang, REN Qiang, LIU Yan, PENG Song, CAO Hongchang, ZHANG Wenyang, CHENG Xiaowei
 doi: 10.12358/j.issn.1001-5620.2023.06.012
Abstract(0) HTML(0) PDF (3397KB)(0)
In cementing operation in ultradeep wells with long cementing sections, there is a large difference between the temperature at the top of the cement slurry and that at the bottom of the cement slurry. The low temperature at the top of the cement slurry retards the development of the strength of the set cement. To solve this problem, an early strength additive named EDTA-LDH (EDTA intercalated hydrotalcite) was developed through water solution polymerization. A cement slurry for working at big temperature difference conditions was formulated with EDTA-LDH. Laboratory experimental results show that this early strength additive has retarding effect to some extent; at a concentration of 2.0% EDTA-LDH and 4.0% retarder, a cement slurry has thickening time of 509 min at 240 ℃. After aging at 60 ℃ for 1 d or at 30 ℃ for 6 d, the cement slurry has compressive strengths of both greater than 7 MPa, and experiences maximum temperature difference of 210 ℃. The use of EDTA-LDH is beneficial to the development of the strength of the cement slurry column in low temperature without affecting the adjustability of the thickening time of the cement slurry. This early strength additive can work normally at temperatures above 300 ℃, and is suitable for cementing wells with large temperature differences.
Effects of Thermal Physical Parameters on Circulation Temperature of Cement Slurries
ZHENG Rui, GUO Yuchao, ZHANG Chunhui, ZHANG Hua, WANG Guifu
 doi: 10.12358/j.issn.1001-5620.2023.06.013
Abstract(47) HTML(16) PDF (2806KB)(5)
In well cementing operation, to ensure that the cement slurry is safely pumped int the hole, the cement slurry shall have an appropriate thickening time. The circulating temperature of the cement slurry is one of the important factors affecting the thickening time of the cement slurry. The methods for calculating the circulating temperature of a cement slurry in the API Recommended Practice do not satisfy the need for calculating the circulating temperature in different areas and different borehole conditions. Thus, an unsteady state flow heat transfer model is established. By measuring the thermal physical parameters, the coefficients of heat conductivity and specific heat capacities of the drilling fluid, the casing strings, the rocks and the cement slurry are determined, and the temperature field of the cement slurry during injection and displacement is thus simulated. The simulation results show that increasing the coefficients of heat conductivity of the cement slurry and the spacer fluid reduces the circulating temperature of the cement slurry. Decreasing the coefficients of heat conductivity of the casing string and the rocks, the circulating temperature of the cement slurry changes in less than 1 ℃. Data acquired from the Zhejiang Oilfield and the Tarim Oilfield show that the difference between the measured well cementing temperatures and the simulated well cementing temperatures is less than 5 ℃, indicating that the simulated data is accurate and has good consistency with the measured data. Studies on the factors affecting the circulating temperatures of a cement slurry during injection and displacement in well cementing operations provide theoretical supports to the design of the properties of the cement slurry, thereby ensuring the efficient and safe well cementing operations.
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Study on Methods of Gas Hydrate Inhibition and Blockage Treatment Using Seawater Polymer Muds in Deepwater Well Drilling
WU Yanhui, DAI Rui, ZHANG Lei, ZHU Zhiqian, GAO Yu, LIU Kai, XU Peng, ZHANG Yu
2023, 40(4): 415-422.   doi: 10.12358/j.issn.1001-5620.2023.04.001
Abstract(175) HTML(49) PDF (2516KB)(78)
The methods of preventing and curing gas hydrate in deepwater drilling are too preservative. In the west of the South China Sea, the gas hydrate inhibitive drilling fluid HEM used in the deepwater drilling is quite expensive and the penetration rate is low. To reduce the mud cost and shorten the drilling time, several issues were studied, including the phase equilibrium curves of hydrate generation with different gas components, the regions for gas hydrate generation under different operating conditions, and the methods of dealing with borehole blockage by the gas hydrates. All these studies were conducted with the low cost polymer drilling fluids used in the deepwater drilling in the BD block in the Yinggehai basin (South China Sea). Potential regions for the generation of gas hydrates under different operating conditions were obtained. Based on these studies, poly (M-vinyl caprolactam) was selected as the kinetic gas hydrate inhibitor to inhibit the generation of gas hydrates glycol selected as the thermodynamic inhibitor to remove blockage in a wellbore by gas hydrates. Ten new kinetic inhibitors were designed in laboratory study, of which the DS-A3 inhibitor has good inhibitive capacity for gas hydrate generation. Laboratory study and field (block BD) application showed that: 1) in operating conditions such as normal drilling, circulation and well shut-in, no gas hydrate generation region exists, as such, there is no risks of wellbore blockage. 2) Considering the inhibitive effect and cost together, 0.8% poly (M-vinyl caprolactam) has the best inhibitive effect for gas hydrate generation, and 45% glycol has the best effect for removing blockage of a wellbore by gas hydrate. 3) When there are no complex downhole operating conditions, if the rig down time does not exceed 15 hours, polymer drilling fluids can be directly used in deepwater drilling. In this way the drilling fluid cost for a single well can be reduced by 50%-70%, a good economic benefit.
Prediction of Four Kinds of Sensibility Damages to Hydrocarbon Reservoirs Based on Random Forest Algorithm
SHENG Keming, JIANG Guancheng
2023, 40(4): 423-430.   doi: 10.12358/j.issn.1001-5620.2023.04.002
Abstract(151) HTML(55) PDF (3412KB)(56)
Many kinds of hydrocarbon reservoir damages with complex mechanisms have been encountered in every phase of oil and gas field exploration and development. Conventional core flow test used in evaluating the sensibility damage of a reservoir can give reliable test results, however, this test is both expensive (coring, for instance) and time consuming. Researches have shown that a model established with neural network and random forest algorithm on small-scale samples can be used to save time and money in predicting the properties of samples. In this study, the data of a set of small-scale samples tested in laboratory is obtained from the block X. The training-sets and testing-sets are then selected on the samples. By extensively comparing the results of three algorithms, which are the BP neural network algorithm, the radial basis function neural network algorithm and the random forest algorithm, the random forest algorithm is finally selected as the main method of quantitatively diagnosing the sensitivity damage of hydrocarbon reservoirs. To improve the prediction accuracy, algorithms such as grid search are used in hyperparameter optimization, and data dimensionality reduction is performed based on factor weight. A complete model is finally established based on the studies conducted. The average R2 value of the four kinds of reservoir damage model is 0.852, with a prediction accuracy between 90.00% and 95.68%.
Research and Application of Dual-protective Oilfield Water Drilling Fluids System Without Solid
LI Sheng
2023, 40(4): 431-437.   doi: 10.12358/j.issn.1001-5620.2023.04.003
Abstract(148) HTML(44) PDF (2015KB)(58)
During the development of the carbonate reservoir of the Tahe oilfield, the conventional polysulfonate drilling fluid damages reservoir duo to non-acid-soluble solid phase after loss, and sulfonalized agent does not conform to the concept of green development. The oilfield water is introduced to formulate a solid free drilling fluid to avoid damage reservoir from solid, and the key treatment agents such as anti-high temperature anti-calcium viscosifier, flow pattern modifiers, high-temperature anti-calcium polymer filtrate reducer. The dual-protective oilfield water drilling fluids system without solid was developed. Indoor evaluation datas show that the drilling fluid was heat resistant to 150 ℃, the ratio between yield point and plastic viscosity is as high as 0.68~0.76 Pa/mPa·s, the EC50 value of biological toxicity indicators is as high as 28,600 mg/L, and the bio-degradation index BOD5/CODCr is as high as 21.35%. The dynamic permeability recovery value is as high as 91.8%, which has good formation damage control performance. The developed dual-protective oilfield water drilling fluids without solid were successfully used in more than ten sidetrack wells,and the application effect was significant.
Mechanisms of Borehole Instability of the Shaximiao Formation in Block Zhongjiang and the Anti-collapse Alkyl Glycoside Drilling Fluid
CHEN Wenke, ZHENG He, GONG Houping, XU Chuntian, CAI Wei, SHI Shuijian, ZHOU Chengyu, BAO Dan
2023, 40(4): 438-445.   doi: 10.12358/j.issn.1001-5620.2023.04.004
Abstract(150) HTML(42) PDF (3949KB)(56)
Borehole wall instability has long been a problem encountered in drilling the Shaximiao formation in the block Zhongjiang, western Sichuan. To solve this problem, the claystones from the Shaximiao formation was studied for their mineral composition, microstructure and physical-chemical properties. The study results have revealed the mechanisms of borehole wall instability of the Shaximiao formation. The Shaximiao formation is a typical hard and brittle rock with high content of clay minerals (mostly illite) which are strongly hydratable. The formation is developed with plenty of micrometer- and nanometer-sized fractures, which will expand continually when mud filtrate invasion take place and finally, collapse. The inhomogeneous distribution of illite and illite/montmorillonite mixed layer in the rocks, high specific water absorptivity and high repulsive force of the hydration films have made the expansion of the microfractures even worse. An alkyl glycoside inhibitive agent and a nanometer plugging agent were selected to formulate a high-performance anti-collapse drilling fluid based on the “Multivariate collaboration” borehole stabilization theory. Laboratory experiment on the performance of this drilling fluid has shown that this drilling fluid has good rheology, API filter loss of less than 3 mL, HTHP filter loss of 8 mL or less, percent cuttings recovery of 98.87%, swelling rate of less than 3%. These data indicate that the drilling fluid has good inhibitive capacity and good capacity of plugging the microfractures and micropores. Field application has shown that the alkyl glycoside drilling fluid can effectively inhibit the collapse of the Shaximiao formation. High ROP was obtained with this drilling fluid, and no downhole troubles have been encountered. The use of the alkyl glycoside drilling fluid has provided a technical support to safely, efficiently and economically drill the Shaximiao formation.
Study and Application of an Oil-based Gel Fluid for Sealing Induced Micro-fractures
LI Wenzhe, FU Zhi, ZHANG Zhen, LIU Yingmin, WU Shuang
2023, 40(4): 446-452, 461.   doi: 10.12358/j.issn.1001-5620.2023.04.005
Abstract(132) HTML(47) PDF (3211KB)(49)
The Longmaxi formation in the Changning block (Sichuan Oilfield) is drilled with oil-based drilling fluids. This formation is developed with microfractures and hence mud losses have frequently happened in the past. Mud losses have been controlled with bridging particles formulated in oil-based slurries, which has been proved unsuccessful and time consuming. To deal with this problem, a compound oil-based gel has been developed with animal fats, vegetable oils and epoxy resin. This oil-based gel can invade into the fractures in the formation rocks to seal them off, thereby increasing the success rate of mud loss control. Considering the practicability of field application, the compressive strength, thickening time and performance against contamination from oil-based muds of this gel were evaluated in laboratory test, and its ability to combat mud losses was also evaluated. The laboratory test results have shown that the gel has compressive strength of 5.1 MPa, and the gelling time can be controlled at more than 3 hours, which is enough to perform field operation safely. Oil-based drilling fluids have only a very slight effect on the gel strength of the gel and do not cause the thickening time of the gel to shorten. All properties of the oil-based gel indicate that it is suitable for use in controlling mud losses through microfractures in hole sections drilled with oil-based drilling fluids.
Development of Ultra-high Temperature Polymer Brush Lubricant for Water Based Drilling Fluids
GAO Chongyang, HUANG Xianbin, BAI Yingrui, SUN Jinsheng, LYU Kaihe, ZHANG Yu, ZONG Jiajiang, LIU Fengbao
2023, 40(4): 453-461.   doi: 10.12358/j.issn.1001-5620.2023.04.006
Abstract(186) HTML(59) PDF (2624KB)(58)
During oil and gas drilling in deep complex formations, the technical requirements of high temperature and salt-resistance of drilling fluid should be met. In this paper, a polymer brush lubricant (HLM) for water-based drilling fluids was prepared using methyl methacrylate, lauryl acrylate and 2-hydroxyethyl acrylate as the main raw materials and 2-methylpropionitrile as the initiator. The HLM was characterized by means of Fourier infrared spectroscopy, nuclear magnetic resonance spectroscopy, thermogravimetric analysis and gel chromatography. The compatibility of HLM with drilling fluids and the lubricity performance of HLM under high temperature, high salt and high density conditions were evaluated. The lubricity was further analyzed using a multifunctional material surface performance tester and a four-ball friction tester. The experimental results showed that HLM had a good thermal stability with a weight average molecular mass of 3494. HLM had good compatibility with the bentonite-based mud at room temperature and had essentially no effect on rheology. The temperature resistance can reach 260 ℃.When concentration of HLM was 2%, the lubrication coefficient reduction rates were 91.16% under room temperature, 88.24% after ageing at 260 ℃, 75.69% for the saturated salt-based mud, and larger than 40% in the high-density drilling mud. The multifunctional material surface performance experiment further demonstrated that HLM could substantially reduce metal-to-metal friction. The four-ball friction experiment demonstrated that HLM could form a stable lubricating film on metal surfaces. Since HLM had multiple adsorption sites and strong adsorption capacity, the adsorption film still had high strength under high temperature and high salt conditions, giving HLM good lubricating properties. This paper can provide technical reference for the construction of drilling fluids for deep/ultra-deep formations.
Study and Application of a Graphene Lugging Agent for Water Based Drilling Fluids
ZHANG Hongwei, HUANG Guoqiang, WU Hongling, YANG Yin, LU Changbo, CHENG Zhi
2023, 40(4): 462-466.   doi: 10.12358/j.issn.1001-5620.2023.04.007
Abstract(156) HTML(47) PDF (3203KB)(60)
Fast plugging of microfractures and micropores in the hard brittle shales and deep buried sandstone/mudstone interbeds is one of the challenges that needs to be dealt with in solving borehole wall collapse in drilling the shale formation and reservoir damage. Graphene materials, because of their excellent properties such as nanometer sizes and layered membrane structures, can be used to solve these downhole problems at low concentrations and with high efficiency. A graphene slurry with good stability is prepared in laboratory with graphite using rolling lift-off technique. Evaluation of the performance of the graphene slurry shows that the D50 of the graphene particles is ±5 μm. The graphene slurry has good filtration control property and shale swelling inhibitive capacity. PPA test results show that the graphene slurry is able to effectively seal off the micropores on the sand plate. The application of the graphene slurry on two wells shows that it has good compatibility with the water based drilling fluids used and improves the plugging efficiency of the drilling fluids. Using this graphene slurry, the borehole wall collapse problem previously encountered is successfully solved.
Reservoir Friendly Ultra-fine Manganese Tetroxide for Drilling Fluids
WANG Long, FANG Jing, DONG Xiumin, WANG Jinshu, FANG Junwei, GENG Yunpeng, ZHANG Jianjun, XU Tongtai
2023, 40(4): 467-474.   doi: 10.12358/j.issn.1001-5620.2023.04.008
Abstract(190) HTML(59) PDF (3514KB)(47)
High density drilling fluids weighted with barite were used in deep well and ultra-deep well drilling in the Shunbei block. Several problems were found with these drilling fluids during drilling, such as difficulties in maintaining mud rheology, poor settling stability as well as reservoir damage by the solid particles from the drilling fluids etc. Micromax as a weight material has been reported in dealing with these problems, but the use of Micromax in China has been limited because of technical monopolization and high cost. A new drilling fluid micro-manganese weighting additive DFMT01 was developed using the “manganese ore method”. As a cost-effective domestic micro-manganese product, DFMT01 was used to formulate reservoir protective drilling fluids. The molecular structure of DFMT01 was characterized, and the performance of DFMT01 was evaluated in the high density sulfonated drilling fluids used in the Shunbei block. The results of field application of DFMT01 show that it has good physical and chemical properties. DFMT01 has a density of 4.7 g/cm3, an acid solubility of at least 99%, a D50 of 1.17 μm and particle sphericity of 0.967, all these properties are comparable to the equivalent products from abroad. Drilling fluids weighted with DFMT01 have rheology, filtration property, erosion property and reservoir protective capacity equal to or better than those of the drilling fluids weighted with Micromax. A “neutralize to precipitate calcium carbonate – recover manganese ions with sulfuric acid – coagulate to treat the waste water” method was used in the treatment of high concentration acidic waste liquids containing manganese. Using this method, waste waters after treatment has mass concentration of manganese of 0.45 mg/L and SS of 10 mg/L, reaching the requirement of the first-level standard. The waste water treatment method can be used in the manufacturing, using and treatment of DFMT01 as a closed loop. DFMT01 is a weighting material having excellent property, low cost and very broad promotion and application prospects.
An Environmentally Friendly Non-foaming Anti-water Blocking Agent
2023, 40(4): 475-480.   doi: 10.12358/j.issn.1001-5620.2023.04.009
Abstract(128) HTML(46) PDF (2491KB)(46)
In order to improve the bubble inhibition and environmental protection performance of the waterproof locking agent for drilling fluid, a natural modified product SMFS-1 was synthesized from alginic acid, 2-(2-aminoethylamino)ethanol (AEEA), epichlorohydrin (ECH) and pentaerythritol (PETP) as raw materials. The molecular structure was characterized by Fourier infrared spectrometer (FT-IR). The test results of waterproof lock performance show that the surface tension of aqueous solution can be reduced to less than 25 mN/m after the addition of SMFS-1, which can reduce the volume of core self-absorption, promote the change of rock surface from hydrophilic to neutral, and increase the recovery value of core permeability to more than 80%. SMFS-1 is resistant to temperature up to 120 ℃, has excellent adsorption performance, no bubbling effect, and has little impact on rheological properties and filtration properties of drilling fluid. The environmental performance test results showed that the semi-lethal concentration (EC50) of SMFS-1 was 32,250 mg/L, and the biodegradability evaluation index (Y) was 17.36, which met the emission standard and was easy to biodegrade.
Improving the Performance of Filter Loss Reducer Lignite Resin with Ultrasonic Induction
PENG Bo, GUO Wenyu, MU Weirong, LI Yufeng
2023, 40(4): 481-486.   doi: 10.12358/j.issn.1001-5620.2023.04.010
Abstract(111) HTML(38) PDF (3255KB)(44)
A water based mud was formulated with lignite resin and bentonite in laboratory in accordance with the standard SY/T 5679—2017. After agitating the mud with high-speed mixer, the mud was treated with ultrasonic wave to investigate the effects of ultrasonic vibration on the colloidal properties of the mud. The purpose of this test is to find a new way of preparing mud with which the performance of the existing mud additives can be improved. The test results show that ultrasonic vibration can remarkably reduce the filtration rate of the water based mud formulated. In the test the filtration rate of the mud is continuously reduced at increased power of the ultrasonic wave and in the length of time the ultrasonic wave is working. Furthermore, the apparent viscosity of the mud is slightly reduced by the action of the ultrasonic wave. With an ultrasonic wave of 20 kHz/850 W acting on the mud for 14 min, the API and HTHP filtration rates of the water based mud are reduced by 26.7% and 27.6% (both maximum reductions) respectively. The thickness of the mud cakes is also reduced by 30%-35% after the action of the ultrasonic wave on the mud. Filtration test on a brine mud shows that the API and HTHP filtration rates are reduced by 29.5% and 32.7% (both maximum reductions) respectively after the action of the ultrasonic wave. Particle size distribution analysis, adsorption experiment and SEM observation show that ultrasonic wave is able to reduce the average size of the bentonite particles and increase the adsorptive capacity of the lignite resin on the particles of bentonite, thereby helping form a denser thin mud cake under the action of pressure differential of the mud. Laboratory studies show that mixing new mud with ultrasonic wave is beneficial to improving the filtration property of lignite resin water based drilling fluids. This performance of ultrasonic wave is the so-called “acoustic cavitation mechanisms”.
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](1355) [PDF 1051KB](1037)
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](1699) [PDF 4926KB](557)
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。
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](845) [PDF 2843KB](241)
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%。
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](1082) [PDF 540KB](290)
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](515) [PDF 2049KB](161)
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](1433) [PDF 2528KB](652)
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](656) [PDF 11047KB](200)
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 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](805) [PDF 4562KB](413)
Research on Mechanisms of Wellbore Instability of Longmaxi Shale Formation and High Performance Water Base Drilling Fluid Technology
TANG Wenquan, GAO Shuyang, WANG Chengbiao, ZHEN Jianwu, CHEN Xiaofei, CHAI Long
2017, 34(3): 21-26.   doi: 10.3969/j.issn.1001-5620.2017.03.004
[Abstract](744) [PDF 7199KB](177)
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](775) [PDF 6834KB](249)
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。
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](5211) [PDF 5710KB](197)
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](1355) [PDF 1051KB](195)
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](905) [PDF 2116KB](150)
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](1433) [PDF 2528KB](230)
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](737) [PDF 729KB](159)
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.
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](978) [PDF 604KB](214)
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](916) [PDF 2831KB](148)
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.
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](860) [PDF 2703KB](149)
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.
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](841) [PDF 963KB](157)
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 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](820) [PDF 4092KB](153)
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.
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