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The Synthesis and Evaluation of a High Temperature Organosilicate Polymer with High Inhibitive Capacity
ZHANG Fan, DU Weichao, SUN Jinsheng, LYU Kaihe, LIU Jingping
2022, 39(3): 265-272.   doi: 10.12358/j.issn.1001-5620.2022.03.001
Abstract(88) HTML(14) PDF (4146KB)(46)
Hydrolysis and polycondensation (and hence crosslinking) of the organosilicon functional group in synthesis reactions is a technical problem that is often encountered. To solve this problem, a new organolsilicate polymer (ADMOS) was developed through emulsion polymerization with monomers such as acrylic acid (AA), vinylmethyldimethoxysilane (VMDS) and methacryloxy ethyl trimethyl ammonium chloride (DMC). 2,2'-azobis(isobutyronitrile) (ABIN) was used as initiator in the polymerization reaction. The optimum synthesis conditions are: molar ratio of the monomers AA∶DMC = 3∶1, the concentration of VMDS id 5.0% of the total mass of the monomers, the concentration of ABIN = 0.3%, the reaction temperature = 70 ℃, the total concentration of the monomers = 25%. and pH = 5. Using 1H-NMR, TGA and GPC, the molecular structure of ADMOS was determined. TGA measurement showed that ADMOS has excellent thermal stability. The inhibitive capacity of ADMOS was tested using linear expansion test, hot rolling test and mud ball immersion test. Liner expansion test results showed that the linear rate of expansion of clay cores was reduced from 83.37% measured by immersing the cores in water to 16.57% measured by immersing the clay cores in 3% ADMOS solution. Hot rolling test with water and 3% ADMOS solution showed that the percent recovery of shale cuttings was increased from 11.82% to 92.85%. Mud ball test showed that ADMOS can effectively hinders the invasion of water molecules into the interior of the mud balls, thereby inhibiting the hydration and dispersion of the clays. The inhibition mechanisms of ADMOS were revealed from a microscopic perspective through Zeta potential measurement, XRD, EDS, AFM and combined IR-TGA analyses.
Laboratory Study on Low Temperature Synthetic Based Drilling Fluid
LIU Gang
2022, 39(3): 273-278.   doi: 10.12358/j.issn.1001-5620.2022.03.002
Abstract(45) HTML(7) PDF (2248KB)(27)
Oil based drilling fluid as the first choice of drilling complex formations has unwanted high viscosity and high gel strengths at low temperatures below zero degree Celsius. To solve this problem, a low temperature synthetic based drilling fluid was developed with low temperature emulsifiers, low freezing point gas-to-oil as oil phase, 30% CaCl2 solution as the water phase, and other optimized flow pattern modifiers. This synthetic based drilling fluid has properties that can be as good as those of oil based drilling fluids. At density of 2.0 g/cm3, the synthetic based drilling fluid, after aging at 180 ℃ for 16 hours, still had viscosity, gel strengths, electrical stability and flow property perfectly suitable for normal operation at -10 ℃. The HTHP filtration rate of this drilling fluid was less than 2 mL. This drilling fluid can effectively prevent downhole troubles arising from high equivalent circulating densities (ECD) and pipeline blocking caused by low temperatures.
The Development and Application of High-Temperature and High-Performance Water Base Drilling Fluid on the well Shunbei 801X
LI Ke, ZHAO Huaizhen, LI Xiuling, ZHOU Fei
2022, 39(3): 279-284.   doi: 10.12358/j.issn.1001-5620.2022.03.003
Abstract(53) HTML(4) PDF (2328KB)(38)
The well 801X in Shunbei area is a key exploratory well located in the Shuntuoguole block in Tarim Basin. This well has total depth of 9,145 m, maximum well angle of 71° and horizontal displacement of 1,075.77 m. To deal with the high temperature high pressure problems encountered during drilling, a high performance water based drilling fluid with density of 2.0 g/cm3 was developed by high temperature additive selection and drilling fluid parameter optimization. Laboratory experimental results have shown that this drilling fluid can function normally at temperatures up to 200 ℃. It has good rheology at high temperatures and can effectively plug the microfractures developed in the shale formations. Filtration rate of this drilling fluid at 180 ℃ was 13.8 mL, and the mud cake was thin and tough. This drilling fluid can also stand the contamination from CO32-, HCO3- and salt water. Field application has shown that this drilling fluid had stable properties in drilling the high temperature formations, and its properties were easy to maintain. Tripping of drilling tools was done smoothly, and no downhole troubles were encountered. The well was safely drilled in high rate of penetration. In well testing, the converted oil and gas equivalent was 1,007.6 t. The development of this drilling fluid has provided a useful reference for the optimization of drilling fluids for subsequent drilling operations in the Shunbei block.
Research on On-line Detection Method of Marsh Funnel Viscosity Based on Pressure
CHEN Hui, MA Shaohua, HUANG Jinyun, WANG Hanxiang, ZHAO Yuming, GONG Zhaoyang, YANG Jinsong
2022, 39(3): 285-293.   doi: 10.12358/j.issn.1001-5620.2022.03.004
Abstract(28) HTML(3) PDF (3738KB)(19)
An online method of measuring Marsh funnel viscosity was presented and a set of online measurement device developed to overcome the problems existed in field manual measurement of Marsh funnel viscosity, such as heavy workload, low measuring precision and measuring discontinuity. In developing the online measuring method, the online measurement process was studied from several aspects, such as the principle of the Marsh funnel viscosity measurement, the structure of the Marsh funnel and algorithm of calculating of viscosity measured with the new instrument. The relationship between the height of the liquid level in the funnel and the pressure of the liquid column is used to calculate the funnel viscosity. The accuracy of the new instrument was verified through analog and emulation, and field experiment in Zhongyuan Oilfield, the precision of the instrument was determined to be ±1 s. By comprehensive analyses of the factors affecting the measurement of funnel viscosity of drilling fluids, the online measurement method was optimized in several aspects, such as the shape of the outlet, the modification technique of the funnel and detection of the liquid level. Measurement error caused by density of the drilling fluid is less than 3%, and the error by viscosity of the drilling fluid is less than 2%. This method and the instrument can be used to realize online measurement of the viscosity of the liquid drilling fluids, and have good applicability and high degree of automation. Satisfying the need of precise measurement of the funnel viscosity of drilling fluids, the online measurement method and the instrument can be used to replace the manual measurement presently in use, improving the intelligence level of oilfield operations.
A High Temperature Gel Plugging Agent
ZHOU Xinyu, LIU Jingping, LYU Kaihe, SUN Jinsheng, ZHANG Wenchao, TENG Yuxiang
2022, 39(3): 294-300.   doi: 10.12358/j.issn.1001-5620.2022.03.005
Abstract(43) HTML(6) PDF (2676KB)(21)
Gel plugging agents have the characteristics of strong self-adaptation, their use in drilling fluids, on the other hand, has the shortage of poor thermal stability. To overcome this shortage, a new gel plugging agent, PPAA, was developed with poly vinyl alcohol (PVA), acrylic acid (AA) and acrylamide (AM) as the reaction monomers, N, N-dimethyl bisacrylamide (MBA) as the crosslinking agent and ammonium persulphate as the initiator. PPAA functions normally at temperatures as high as 180 ℃. PPAA has low expansion factor, minor effect on the rheology of mud, and is able to control the filtration rate of the mud. A drilling fluid containing 2% PPAA, after aging at 180 ℃, can invade into a 80 – 100 mesh sand-bed by 2.6 cm, and the plugging efficiency of the mud is 60.6% higher than that of a mud treated with conventional plugging agents. Compared with conventional plugging agents, 6% NaCl solution treated with PPAA has efficiency of plugging increased by 48.6%, and the HTHP filter loss through sand plate reduced by 69.7%.
Synthesis and Application of an Environmentally Friendly Modified Bio-Peptide Shale Inhibitor for Water Based Drilling Fluids
XU Yi, XU Guili, JIANG Guancheng
2022, 39(3): 301-306.   doi: 10.12358/j.issn.1001-5620.2022.03.006
Abstract(39) HTML(6) PDF (2410KB)(27)
As more and more attentions have been paid to environment protection, the conventional polymer-sulfonate drilling fluid additives are gradually inevitably replaced by environmentally friendly additives. An environmentally friendly modified bio-peptide shale inhibitor, WNGT, has been developed based on molecular structure design of the bio-peptide gelatin. NMR spectrum of the modified gelatin has shown that two distinct new characteristic peaks appeared at the chemical shifts of 3.19 ppm and 4.12 ppm, respectively, indicating that the target product was successfully prepared. Results of the linear expansion test showed that the expansion length of the core tested with WNGT was shorter than two other additives, which were KCl and polyetheramine (PEA), at the same concentration, indicating that WNGT had the best inhibitive capacity in the three shale inhibitors. WNGT has the excellent clay hydration suppressing ability; at a concentration of 2%, the expansion length of the clay core in 24 hours was only 1.60 mm. Percent shale cuttings recovery of the modified gelatin was at least 95%, 46.05% higher than that of the non-modified gelatin. A bentonite slurry treated with 2% WNGT had its Zeta-potential decreased to −11.7 mV, meaning that WNGT can effectively neutralize the negative charges of the clay, thereby compressing the electric double layer and reducing the Zeta-potential of the clay. This WNGT shale inhibitor has been used on a well located in Chuanyu area, where the well penetrated the Shaximiao sandy shale formation. When the drilling fluid was treated with WNGT, its viscosity and gel strengths were reduced to some extent, and this effect was maintained for a long time, ensuring the successful drilling of the sandy shale formation with the water based polymer drilling fluid and the reducing of drilling cost.
A Strongly Adsorptive Hydrophobically Modified Nano SiO2 Plugging Agent
TENG Chunming, ZHEN Jianwu, LUO Huiyi, JIANG Sichen
2022, 39(3): 307-312.   doi: 10.12358/j.issn.1001-5620.2022.03.007
Abstract(37) HTML(4) PDF (2519KB)(27)
Downhole troubles such as borehole instability and mud losses are frequently encountered when drilling formations with poor stability and low pressure bearing capacity. Study and evaluation of new nano plugging agents have recently been performed to solve these problems. Study on these issues gave birth to a strongly adsorptive hydrophobic nano plugging agent. Measurement of the particle size distribution, adsorptive ability and wettability of the plugging agent, as well as plugging capacity test performed on sand-bed have shown that the particle sizes of the plugging agent was distributed in a range of 100-150 nm. The plugging agent has good adsorptive ability; it can increase the contact angle of water on the surfaces of shale to 80.7°. A mud sample treated with 2.5% of the plugging agent had its filtration rate through a sand-bed tester reduced to 5.0 mL. The plugging agent has little, if any, effect on the rheology of the drilling fluid. The API filtration rate of the drilling fluid was reduced by the plugging agent from 4.4 mL to 1.0 mL, and the HTHP filtration rate was reduced from 16.2 mL to 6.2 mL. At concentrations in a mud above 3.0%, the permeability of the mud cakes was reduced to 2.8 μD. PPA plugging efficiency test has shown that the plugging agent can form a plugging layer on a ceramic filter disk, the filtration rate was reduced to 0.45 mL/min1/2, and the spurt loss was reduced to 2.58 mL. The study has demonstrated that the strongly adsorptive hydrophobic nano plugging agent can enhance the plugging capacity of the drilling fluid, reduce the amount of filtrate invasion of the drilling fluid into the formation and effectively help stabilize the borehole wall.
Application of Ultra-low Friction Wwater-based Ddrilling Ffluid in Shale Gas Horizontal Wells
ZHOU Shanshan, ZHONG Chengbing, LIU Jie, DAI Yiqin, XU Mingbiao, HAN Yinfu, SONG Jianjian
2022, 39(3): 313-318.   doi: 10.12358/j.issn.1001-5620.2022.03.008
Abstract(35) HTML(8) PDF (2386KB)(28)
Oil-based drilling fluid has excellent inhibition, blocking and lubrication properties, and it is currently the main type of drilling fluid for shale gas well operations. With the increasing pressure on environmental protection and waste mud disposal, shale gas drilling has put forward an urgent demand for water-based drilling fluid. Four horizontal wells are deployed in Fuling Jiao Shi, and the drilling target formation is Longmaxi Formation-Wufeng Formation. The target formation contains large sections of mud shale and fracture development, which is easy to hydrate and disperse, and has high risk of collapse and leakage. In response to the low friction requirement of the Fuling horizontal well and the vulnerability of the formation mud shale to well wall destabilization, an ultra-low friction water-based drilling fluid system was developed. The field application shows that the ultra-low friction water-based drilling fluid has achieved efficient and safe operation of the horizontal section of shale gas wells, with a 24.7% increase in mechanical drilling speed and a 6.2% reduction in drilling time per meter compared with oil-based drilling fluid in the same block. record. The successful application of this ultra-low friction water-based drilling fluid in Fuling shale gas is expected to realize the replacement of oil-based drilling fluid by water-based drilling fluid in shale gas.
Research and Application of Triassic Anti-collapse Drilling Fluid in Yueman Block on The South Bank of Tahe River
ZHU Jinzhi, YANG Xuewen, LIU Hongtao, YANG Chengxin, ZHANG Shaojun, LUO Chunzhi
2022, 39(3): 319-326.   doi: 10.12358/j.issn.1001-5620.2022.03.009
Abstract(29) HTML(3) PDF (9284KB)(26)
Studies on the mechanisms of borehole wall collapse and the drilling fluid capable of controlling the borehole wall collapse were performed to solve the problem of bad borehole wall collapse happening in drilling the Triassic System in the Yueman block, south bank of Tarim river. The Triassic System is mainly composed of mudstones and sandy mudstones containing 28.6% clay minerals in which 45% is the mixed layer of illite and montmorillonite. When in contact with water the formation rocks absorb the water, and the compressive strength of the rocks decreases. On the other hand, the density of the drilling fluid used is less than the equivalent density calculated from the collapse pressure of the formations. These are the the immanent causes resulting in borehole wall collapse. In field operation, the drilling fluid used had high filtration rate, leaving a thick mud cake with poor toughness. Laboratory test with the drilling fluid showed that the percent recovery of shale cuttings is low, while the linear expansion rate is high. Other shortages of the drilling fluid include poor plugging capacity and bad particle size distribution. A new drilling fluid was formulated based on these findings using optimized filter loss reducers, compound inhibitive additives such as FTDA. This drilling fluid has low API and HTHP filtration rates, and the mud cake is thin and tough. The percent recovery of shale cuttings with this drilling fluid was increased by 15.7% compared with the old mud. Plugging test on sand-bed showed that the plugging capacity of the new drilling fluid was increased by at least 50%, indicating that the drilling fluid has reasonable particle size distribution. In field application, the new drilling fluid had stable rheology and low filtration rate, no pipe sticking and borehole sloughing were encountered. The average rate of hole enlargement was 10.35%, which is 50.24% lower than the average rate of hole enlargement of the wells drilled in the same block. The application of the new drilling fluid has provided a new technical clue for stabilizing the borehole wall of the wells penetrating the Triassic System in the Yueman block.
Response Surface Optimization of Biosafety Disposal of Waste Water Based Drilling Fluids for Deep Drilling
SUN Lulu, GENG Xiaoguang, SONG Tao, ZHANG Yang
2022, 39(3): 327-333.   doi: 10.12358/j.issn.1001-5620.2022.03.010
Abstract(17) HTML(7) PDF (3293KB)(18)
Water based drilling fluids have been used to drill deep tight gas wells in Daqing Oilfield. In the treatment of the waste drilling fluids, it was found that the solids and the liquids were difficult to be separated from each other, the mud cakes had water-cut of greater than 80%, and secondary contamination existed in future operations. A study on the bio-safety disposal of waste water based drilling fluids was conducted to solve these problems. Based on the analyses of the characteristics of and difficulties in the treatment of the water drilling fluids, the Box-Behnken Central Composite Experiment and Response Surface Method were chosen as a means of study. By exploring the effects of the optimum ratio of gel breaker, coagulant aid and flocculant on the solid-liquid separation efficiency of the waste water based drilling fluids, a new mathematical model was established describing the relationship between the water-cut of mud cakes for solids-liquid separation and the treatment recipe parameters. A method for the biosafety disposal of waste water based drilling fluids was developed, with destabilization and flocculation as the core technique. Using the mathematical model and the biosafety disposal method, a destabilization-flocculation-solid-liquid separation technique was established. Field test results have shown that a waste water based drilling fluid, after treatment with the technique, formed a mud cake with water-cut of 47%, the suspension content in the mud cake leachate was 63 mg/L. Nine major pollution indices such as COD etc. of the waste drilling fluid conform to the requirements of the national standard GB 8978—1998 and the local standard DB23/T 693—2000, namely, “Waste Drilling Fluid Treatment Specification of Heilongjiang Province”. This technology provides an effective solution to the poor gel breaking and destabilization efficiency of the water based drilling fluids for deep hole drilling in Daqing Oilfield and has good promotion and application values.
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](703) [PDF 1051KB](946)
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](666) [PDF 540KB](276)
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](470) [PDF 2843KB](225)
页岩具有极低的渗透率和极小的孔喉尺寸,传统封堵剂难以在页岩表面形成有效的泥饼,只有纳米级颗粒才能封堵页岩的孔喉,阻止液相侵入地层,维持井壁稳定,保护储层。以苯乙烯(St)、甲基丙烯酸甲酯(MMA)为单体,过硫酸钾(KPS)为引发剂,采用乳液聚合法制备了纳米聚合物微球封堵剂SD-seal。通过红外光谱、透射电镜、热重分析和激光粒度分析对产物进行了表征,通过龙马溪组岩样的压力传递实验研究了其封堵性能。结果表明,SD-seal纳米粒子分散性好,形状规则(基本为球形),粒度较均匀(20 nm左右),分解温度高达402.5℃,热稳定性好,阻缓压力传递效果显著,使龙马溪组页岩岩心渗透率降低95%。
Synthesis and Evaluation of A Primary Emulsifier for High Temperature Oil Base Drilling Fluid
QIN Yong, JIANG Guancheng, DENG Zhengqiang, GE Lian
2016, 33(1): 6-10.   doi: 10.3969/j.issn.1001-5620.2016.01.002
[Abstract](1085) [PDF 4926KB](500)
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。
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](706) [PDF 2528KB](592)
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](347) [PDF 4562KB](387)
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](326) [PDF 11047KB](195)
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。
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](258) [PDF 2049KB](155)
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](496) [PDF 6834KB](238)
针对顺南区块超深高温高压气井固井面临井底温度高、气层活跃难压稳的问题,研究了胶乳纳米液硅高温防气窜水泥体系。通过将纳米液硅防气窜剂与胶乳防气窜剂复配使用,协同增强水泥浆防气窜性能;不同粒径硅粉复配与加量优化,增强水泥石高温稳定性;无机纤维桥联阻裂堵漏,抑制裂缝延展,提高水泥浆防漏性能和水泥石抗冲击性能。该水泥浆体系具有流动性好、API失水量小于50 mL、直角稠化、SPN值小于1,水泥石具有高温强度稳定性好、胶结强度高、抗冲击能力强的特点。密度为1.92 g/cm3的水泥浆体系在190℃、21 MPa养护30 h后超声波强度逐渐平稳,一界面胶结强度达12.6 MPa;水泥石弹性模量较常规低失水水泥石降低52%,抗冲击强度增加了188%,且受霍普金森杆冲击后仅纵向出现几条未贯穿的裂纹。该高温防气窜水泥浆体系在顺南5-2井和顺南6井成功应用,较好地解决了顺南区块超深气井固井难题。
Temporary Plugging Diverting Test with Fuzzy Ball Fluids in Non-Water Producing Coal Beds in Re-fracturing Well Zheng-X
ZHENG Lihui, CUI Jinbang, NIE Shuaishuai, LIU Bin, FU Yuwei, LI Zongyuan
2016, 33(5): 103-108.   doi: 10.3969/j.issn.1001-5620.2016.05.022
[Abstract](507) [PDF 1759KB](489)

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

Status Quo of Water Base Drilling Fluid Technology for Shale Gas Drilling in China and Abroad and Its Developing Trend in China
SUN Jinsheng, LIU Jingping, YAN Lili
2016, 33(5): 1-8.   doi: 10.3969/j.issn.1001-5620.2016.05.001
[Abstract](703) [PDF 1051KB](48)
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](447) [PDF 2116KB](21)
This paper discusses the instruments and procedures available presently for evaluating fltration property, sizes of pore throats, thickness and compressibility of mud cake. Analyzed in this paper are the status quo of using SEM and energy spectrum in studying the microstructure of mud cake and the distribution of mud cake constituents. Studies presently conducted were focused on the observation of surface topography, while knowledge about the interior microstructure of mud cake is still in demand when optimizing the quality of mud cake. The spatial distribution of the microstructure of mud cake needs to be extensively studied in the future to further understand the mechanism of fltration control and the way of reducing fltration rate. These studies are of help to the development and perfection of the basic theory of controlling drilling fluid fltration and ability of building mud cake, and will provide guide and technical support to the development of new high performancemud additives and to the improvement of drilling fluid technology.
Drilling Fluid Technology for “Three High” Wells in Qaidam Basin in Qinghai
WANG Xin, ZHANG Minli, WANG Qiang, ZHUANG Wei, ZHANG Weijun, WANG Zhibin, LI Yifeng
2016, 33(6): 45-50.   doi: 10.3969/j.issn.1001-5620.2016.06.008
[Abstract](325) [PDF 729KB](14)
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.
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](706) [PDF 2528KB](44)
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.
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](501) [PDF 2831KB](26)
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](417) [PDF 2703KB](16)
Perforation well completion is a widely used completion method, and is of great importance to oil and gas well stimulation. With more and more wells completed with perforation, more attentions have been paid to the sealing integrity of cement sheaths after perforation, especially the perforation of wells with thin pay zones. Research work presently done has been focused on the effects of perforation on casing strings, while little attention has been paid to the damage of cement sheath. Oil and gas well perforation has characteristics such as being powerful, short time, high temperature, and being highly destructive. It is pointed out in this paper, based on analysis, that the diffculties in studying the failure of cement sheath mainly lie in laboratory simulation, determination of the degree of damage to the cement sheath, determination of the cement sheath's resistance to impact under practical conditions, and ascertaining the effects of perforation parameters on the integrity of cement sheath, etc. Researches presently done on the topics such as perforation simulation methods used both in China and abroad, integrity of cement sheath after perforation, shock or impact resistance of cement sheath, and the effects of perforation parameters, are summarized in this paper. Defciencies of the researches are also discussed herein. Also included in this paper are technical measures concerning self-healing cement, cement slurry and set cement performance designs, optimization of perforation parameters, and prediction of dynamic damage to downhole cement sheath etc.
A Temperature Sensitive Expanding Microcapsule Anti-Gas-Channeling Cement Slurry
ZHANG Xingguo, YU Xuewei, GUO Xiaoyang, YANG Jixiang, YAN Rui, LI Zaoyuan
2018, 35(1): 71-76.   doi: 10.3969/j.issn.1001-5620.2018.01.014
[Abstract](249) [PDF 4092KB](12)
A temperature sensitive expanding microcapsule anti-gas-channeling agent has been synthesized with acrylonitrile (AN), methylmethacrylate (MMA) and methyl acrylate (MA) as the wall material, and iso-butane as the core material. The effects of the amount of iso-butane used in the synthesis on the performance of the anti-gas-channeling were studied, and the performance of the temperature sensitive expanding microcapsule anti-gas-channeling cement slurry in controlling gas channeling was evaluated. The studies and the evaluation results showed that the temperature sensitive expanding microcapsule anti-gas-channeling agent can be obtained under the following conditions:in 100 g of deionized water add AN, MMA and MA in a ratio of 3:0.4:2, 30% iso-butane, 1% lauroyl peroxide (LPO, as initiator), 0.1% 1, 4-butanediol dimethacrylate (BDDMA, as crosslinking agent), 20% nano silicon dioxide (as dispersant), and react these substances at 65℃ with the protection of nitrogen. The anti-gas-channeling agent has initial expansion temperature of 65℃, optimal expansion temperature of 83℃, and is resistant to temperature as high as 120℃. Rate of expansion of the anti-gas-channeling agent is 50. Stimulation of water-channeling/gas-channeling in oil well cement and test of cement slurry condensation and contraction indicated that volumetric contraction of cement slurry can be made up for with less than 2% of the synthesized anti-gas-channeling agent, meaning that this anti-gas-channeling agent has good gas-channeling prevention ability.
Development of Extreme Pressure Anti-wear Lubricant MPA for Water Base Drilling Fluids
QU Yuanzhi, HUANG Hongjun, WANG Bo, FENG Xiaohua, SUN Siwei
2018, 35(1): 34-37.   doi: 10.3969/j.issn.1001-5620.2018.01.006
[Abstract](338) [PDF 963KB](27)
An extreme pressure organic sulfur anti-wear additive has been developed for use in water base drilling fluids. Structural characteristics and extreme pressure anti-wear performance evaluation showed that the organic sulfur compound is a saturated alkane, with sulfur content as high as 35.49%, and has good extreme pressure anti-wear property. An extreme pressure anti-wear additive, MPA, was developed with a modified vegetable oil as the base oil, the extreme pressure organic sulfur anti-wear additive and surfactants. The components of MPA are all environmentally friendly. Performance evaluation showed that MPA has good compatibility with other additives, and is completely dispersible in fresh water or drilling fluids. It helps optimize the properties of drilling fluids and has excellent lubricity.
A New Fracturing Fluid with Temperature Resistance of 230℃
YANG Zhenzhou, LIU Fuchen, SONG Lulu, LIN Lijun
2018, 35(1): 101-104.   doi: 10.3969/j.issn.1001-5620.2018.01.019
[Abstract](404) [PDF 604KB](60)
The natural vegetable gum fracturing fluid presently in use works effectively at temperatures up to 177℃. To fracture formations with higher temperatures, a fracturing fluid with temperature resistance of 200-230℃ has been developed with ultrahigh temperature thickening agent, high temperature resistant zirconium crosslinking agent, high temperature stabilizer and efficient gel breaker through large quantity of laboratory experiments. The experimental results showed that, under the synergetic effect of these additives, the fracturing fluid is suitable for use in fracturing formations whose temperatures are higher than the temperature limit of conventional gels. The fracturing fluid has good shear-resistance property at high temperatures up to 230℃, and the polymer consumption for formulating the fracturing fluid is obviously reduced. Complete gel breaking can be realized with the fracturing fluid, and damage to the fluid conducting formations with proppants is low.
Progress on Drilling Fluid Technology for Hot Dry Rock Drilling
2018, 35(4): 7-13.   doi: 10.3969/j.issn.1001-5620.2018.04.002
[Abstract](296) [PDF 535KB](21)
Two key issues encountered in hot dry rock drilling are high temperature and lost circulation. This paper introduces the analyses made on the geological characteristics of hot dry rock and the drilling fluid technology required for drilling the hot dry rock, and surveying performed on drilling fluid system for hot dry rock drilling and the field applications of the drilling fluids. New technologies for hot dry rock drilling found both in China and abroad suitable for different formation conditions are summarized. Problems found of the hot dry rock drilling fluid are also presented with the prospecting for the development of the technology. Presently, polymer sulfonate water base drilling fluid is mainly used for hot dry rock drilling, however, some other drilling fluids, such as high temperature foam mud, aerated drilling fluid, liquefied nitrogen fluid etc. are also prospective fluids for hot dry rock drilling. These new hot dry rock drilling fluids have been successfully applied in field operation with good results; they impose low formation damage, and are high temperature and salt resistant. Other advantages include good adaptability to different formation conditions and performance in environment protection, all of which represent the future of the development of the hot dry drilling fluid technology.
Competent Authorities:China National Petroleum Corporation Ltd
Sponsored by:CNPC Bohai Drilling Engineering Co. LtdPetroChina Huabei Oilfield Company
Editor-in-Chief:Shi-chun Chen
Address: Editorial Department of Drilling Fluid and Completion Fluid, Bohai Drilling Engineering Institute, Yanshan South Road, Renqiu City, Hebei Province
Postcode: 062552
Tel:(0317)2725487 2722354