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A Device for Quantitatively Evaluating the Hydration of Cement in Impacting Stability of Hydrate Layers and a Case Evaluation
MA Rui, BU Yuhuan, LU Chang, LIU Huajie, GUO Shenglai, GUO Xinyang
 doi: 10.12358/j.issn.1001-5620.2024.02.015
Abstract(0) HTML(0) PDF (4576KB)(0)
A new device is developed aimed at evaluating the effect of the hydration heat of the cement on the amount of the dissociated hydrate during well cementing operation. In developing this device, the contact manners of the cement slurries with the hydrate are fully considered. Using this device, hydrates at low temperature and high pressure can be generated, the cement slurry can be pumped under pressure into the wellbore while in contact with the hydrate layers, and the effect of the hydration heat of the cement slurry which is directly in contact with the hydrate layers on the formation temperature and pressure is directly measured. By calculating the gas saturation of hydrates and the amount of gas released from the dissociation of hydrates, a method of developing simulated hydrate formation is established taking into account the properties of the device, and a method is formulated for evaluating the effect of the hydration of cement on the stability of hydrate layers. In laboratory experiments, a simulated hydrate formation is constructed based on the geology of the shallower formations in south China Sea, three different cement slurries (a blank class G oil well cement slurry, a low-density cement slurry and a low-heat cement slurry) are pumped into the simulated hydrate formation. The experiment results show that in the setting process of the cement slurries, the quantities of the gas released from the hydrate by the heat from the hydration of the three kinds of cement are 0.7356, 0.1091 and 0.0649 mol/L, respectively. These results show that the low-heat cement slurry can greatly shorten the time required for the cement slurry to set. This study has provided a method of directly testing the effect of cement hydration on the hydrates in the shallower formations, and it also shows that low-heat cement should be used in cementing the hydrate formations in deep water drilling.
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Challenges, Developments, and Suggestions for Drilling Fluid Technology in China
SUN Jinsheng, WANG Ren, LONG Yifu
2024, 41(1): 1-30.   doi: 10.12358/j.issn.1001-5620.2024.01.001
Abstract(197) HTML(39) PDF (12068KB)(146)
The technical problems of drilling fluid in ultra-deep, unconventional oil/gas, deep water, hot dry rock, polar, natural gas hydrate and other complex formations are systematically sorted out. The key scientific problems and core engineering problems are discussed. Combined with the research progress of drilling fluid technology in recent years, the development of drilling fluid technology for ultra-deep, unconventional oil/gas, deep water, hot dry rock, polar, natural gas hydrate and other complex oil and gas is provided.The problems in the drilling of complex formations, such as hightemperature, high-pressure and high- salinity, serious shale hydration, wellbore instability, large temperature difference, loss circulation, formation damage, and low degree of automation of drilling fluid maintenance, domestic and foreign researchers have developed key material, systems and equipments such as high-temperature and high-salinity water-based/oil-based drilling fluid, constant rheological drilling fluid, anti-ultra-high temperature foam drilling fluid, environmentally friendly ultra-lowtemperature drilling fluid, intelligent temperature and pressure response plugging material, degradable reservoirprotection material, drilling fluid online monitoring and automatic feeding system. However, with the increasingly complex formationconditions of drilling, there are still deficiencies in drilling fluid materials in terms of ultra-high temperature resistance, ultra-long-term stability, clay swelling inhibition, and environmental protection performance. Severe/total loss circulation, reservoirprotection, and drilling fluid automation control still face severe challenges. In order to meet the performance requirements of drillingfluid in the process of drilling in complex formations, it is necessary to further study the working/failure mechanism of drilling fluidadditives under complex formation conditions, the structure-activity relationship changes and action mechanism of drilling fluidadditives at different scales such as micro-meso-macro scales, establish a safe and efficient multi-functional integrated controlmethod of drilling fluid, construct intelligent drilling fluid theory and technology, and provide technical support for the development of complex underground resources.
Application of Drilling Fluid Technology in Drilling a Long Horizontal Section Well in Block Fengxi in Qinghai
ZHANG Minli, YUAN Guide, ZHUANG Wei, WANG Wei, LIU Wu, GUO Chao, MING Hongtao, YANG Pengmei
2024, 41(1): 31-38.   doi: 10.12358/j.issn.1001-5620.2024.01.002
Abstract(72) HTML(16) PDF (2058KB)(45)
To obtain high production rate with less oil and gas wells, The Qinghai oilfield decided to drill five long open hole horizontal wells in the Fengxi structure which is located in the Dafengshan area in Qaidam Basin. Water-based and oil-based drilling fluids were to be used to drill these wells, and the results be compared to improve and perfect the technical prototype for future drilling and completion of long open hole and long horizontal section horizontal wells in the same area. This paper summarizes the field engineering of a high-quality compound saltwater drilling fluid on the well Fengxi IH1-5 and analyses are briefly conducted on the application, control of the engineering parameters, rheology and sand carrying capacity of the drilling fluid. The well Fengxi IH1-5, which is 5,487 m in depth, has a length of horizontal section of 2,541 m, the longest horizontal section in the Qinghai oilfield. This well has broken several records in this oilfield, such as penetrating the highest percentage of pay zones (100%), the longest footage (1,566 m) drilled in a single bit run, the longest horizontal section (1,000 m) in which short trips were performed, as well as the first application of casing floatation technology in casing running etc. The success of the drilling operation has milestone significance in applying the ultralong horizontal section well drilling technology in the Qinghai oilfield. Compared with the drilling operation of the offset wells drilled with oil-based drilling fluids, the use of this high-quality compound saltwater drilling fluid has gained better results in drilling than the oil-based drilling fluids previously used in other wells. The success gained in applying the water-based drilling fluid has provided a good guidance for optimizing the properties of water-based drilling fluids for horizontal wells with long open hole and long horizontal sections.
Microscopic Behavior Analysis of Core Components of Water-based Drilling Fluid at High Temperature
2024, 41(1): 39-44.   doi: 10.12358/j.issn.1001-5620.2024.01.003
Abstract(75) HTML(16) PDF (2786KB)(48)
The key to the stable performance of water-based drilling fluid at high temperature is related to the dispersion state of core colloidal particles, but the influence of the dispersion state of colloidal particles is very complicated. For the core components of water-based drilling fluid, the shear stress-strain temperature curve of bentonite colloid was obtained through high-temperature and high-pressure rheological testing, and the particle size distribution of colloidal particles was tested after different temperature effects. The dispersion, flocculation, and aggregation states and formation mechanisms of clay mineral colloidal particles were analyzed within the temperature range of room temperature to 220 ℃. In addition, the high temperature stability mechanism of porous fibrous clay mineral colloid rich in magnesium was revealed from a microscopic perspective by means of SEM test and clay mineral layer structure analysis. At the same time, based on a comprehensive analysis of the changes in rheological properties and filtration loss before and after high-temperature hot rolling, the interaction mechanism between bentonite/composite clay minerals and polymer based treatment agents at high temperatures is revealed from the perspectives of clay mineral structure characteristics, polymer chain breakage, adsorption characteristics, etc. Combined with experimental results, it is clear that low concentration bentonite/sepiolite composite colloids have significant high-temperature stability advantages, which provides theoretical support for the construction of ultra-high temperature water-based drilling fluid.
Key Technologies for Drilling Horizontal Wells in Thin Interbedded Tight Reservoirs with Complex Pressure Systems
WU Xiaohong, LI Yunfeng, ZHOU Yan, KAN Yanna, LI Ran, LUO Cheng
2024, 41(1): 45-52.   doi: 10.12358/j.issn.1001-5620.2024.01.004
Abstract(62) HTML(10) PDF (2562KB)(45)
The Sha-3 member V reservoir in the Gaoliu block, Nanpu sag is a typical interlayered thin sandstone and thin claystone tight reservoir with complex formation pressure systems and densely distributed artificial fractures resulted from many years of fracturing and injection operations. Horizontal drilling in this area is faced with problems such as mud losses, oil and water kicks as well as collapse of borehole walls. This paper describes, based on the formation characteristics of the Gaoliu block, the technical difficulties in horizontal drilling, and points out the causes of mud losses and borehole wall collapse. To solve these problems, an oil based drilling fluid was formulated with a nanometer/micrometer sized emulsified borehole wall collapse preventing agent, graphite microspheres, a micrometer flexible plugging agent and calcium carbonate of ultrafine particles, which render the drilling fluid capacities such as plugging, high pressure bearing and borehole wall stabilizing. The oil based drilling fluid has low filtration rate and has the ability of maintaining the strengths of the claystones that is 5 times higher than other drilling fluids. With this drilling fluid, the pressure bearing capacity of the sandstones of medium and high permeability can be increased to 18 MPa. Bridging and solidification mud loss control techniques were used to control mud losses. Using this drilling fluid, horizontal drilling through the tight reservoirs in the Gaoliu block was safely performed and no borehole wall collapse was encountered during drilling in more than ten wells. In formations where mud losses were encountered, the mud losses were controlled and the pressure bearing capacity of the formation was increased by 5.4 MPa, satisfying the requirement of subsequent drilling.
Ultra-High Temperature Drilling Fluid Technology for Second Sidetracking of the Well Shunbei-16X
YU Deishui, WANG Lu, LIU Shiyin, WU Xiuzhen, WANG Xu
2024, 41(1): 53-59.   doi: 10.12358/j.issn.1001-5620.2024.01.005
Abstract(69) HTML(12) PDF (2170KB)(43)
The well Shunbei-16X is a well drilled in the #16 fault zone in Shunbei area by Sinopec Northwest Petroleum Bureau. This is a four-interval deviated exploration well drilled to the Yingshan formation of the Ordovician system. The temperature at 6,680 m was predicted to be 168.9 ℃. After drilling to the designed depth of 6,777 m, decision was made to deepen the well with a high performance drilling fluid ENVIROTHERM NT. The drill pipe got stuck and the well was plugged, then sidetracked with an oil -based drilling fluid. Well test showed no industrial oil production. The well was then re-plugged and sidetracked again with a high temperature drilling fluid. The second sidetracking of the well was done to 7,533 m MD/7,417 m TVD, the bottom hole temperature measured was 209 ℃, and the maximum mud density was 1.75 g/cm3, indicating that the formation at the total depth of the well is an extremely high temperature ultra-high pressure formation. The high performance drilling fluid used to drill the sidetracked section of the well had excellent rheology and settling stability at extremely high formation temperatures as well as excellent resistance to CO2 and formation water contamination. The second sidetracking was successful, and no downhole troubles were ever encountered.
First Application of the Synthetic-Based Drilling Fluid BIODRILL S in Block Kenli of Bohai Oilfield
PENG Sanbing, LI Bin, HAN Dongdong, XU Lei, CHENG Longsheng, HUANG Xianbin
2024, 41(1): 60-67.   doi: 10.12358/j.issn.1001-5620.2024.01.006
Abstract(51) HTML(11) PDF (2177KB)(46)
Drilling operation in the Block Kenli 9-1 of the Bohai Oilfield has long been faced with high risks of borehole wall collapse resulted from complex formation lithologies, fault zones, shales that are easy to hydrate and disperse, as well as sandstones in which tight hole problem is frequently encountered. To deal with the borehole wall collapse problem a BIODRILL S synthetic based drilling fluid has been formulated. The BIODRILL S synthetic based drilling fluid is formulated with a base oil which is synthetic oil of choice, a composite plugging additive PF-MOSHIELD, as well as other drilling fluid additives, taking into account the formation lithology and environmental protection requirement. The BIODRILL S drilling fluid has good rheology , and is resistant to 26% calcium contamination and 15% cuttings contamination. Furthermore, it has excellent plugging capacity, settling stability and lubricity. The HTHP filter loss tested on a sand plate tester is 3.2 mL. The sag index of the mud after standing for 7 d is 0.53, and the extreme coefficient of friction is 0.082. BIODRILL S was first used in the Block Kenli 9-1. The application showed that: 1) the BIODRILLS can be used to solve the shale hydration problem and the tight hole problem in the sandstone formation encountered previously in this block; the drilled cuttings produced in drilling the formations in and above the third section are intact, with sizes distributed between 4 cm and 7 cm. 2) Hole cleaning is well done with the BIODRILL S drilling fluid, the ratio of YP/PV is greater than 0.59 Pa/mPa∙s, the φ6 and the φ3 reading are all greater than 9, and the drilling fluid has good shear thinning property. All these properties result in good hole cleaning and the prevention of the occurrence of cuttings bed. 3) The drilling fluid has excellent lubricity, making possible the direct tripping (out of hole) through the high angle (55°, 70° and 67°) well sections.
Research on Cementing and Loss Prevention Drilling Fluid Technology During Drilling in the Sea Basin
HE Yinbo, XU Jie, CUI Guojie, ZHANG Lei, LIN Hai, CHEN Zhuo, JIN Jingyang
2024, 41(1): 68-75.   doi: 10.12358/j.issn.1001-5620.2024.01.007
Abstract(73) HTML(12) PDF (3718KB)(35)
This paper analyzes the geological features and drilling fluid loss situations in the China's Sea Basin, identifying the challenges in leak prevention and plugging technology in this area. These include prevalent formation fractures with micro to millimeter-scale multi-scale cracks, and even the coexistence of fractures and cavities, which pose difficulties in choosing appropriate plugging materials and lead to a low success rate for first-time plugging. Moreover, there are extensive sections of weathered crust in the formation, coupled with highly developed fractures and severe fragmentation in some strata, resulting in secondary development of fractures, critical fluid loss or even non-return fluid loss. In response to these challenges, this paper synthesizes a type of gelation plugging agent, BFD-1, using polyvinyl alcohol, polypropylene acid, and organics with hydroquinone structures as raw materials. Experimental results show that the compressive strength of the artificial loose rock core increased by 19.34% after being soaked in 4% BFD-1 aqueous solution. Based on BFD-1, field plugging materials were combined to create drilling fluid systems for leak prevention and plugging for lost channels with different size. The drilling fluid exhibits excellent circulation-lost-control and cementing capabilities, and effectively prevents pressure transmission. The research results provide support for the subsequent lost-circulation control technology in this area.
Mechanisms and Inhibition of Borehole Instability Encountered in Drilling the Shiqianfeng Formation – Shihezi Formation in the East of Yan’an Gas Field
WANG Bo, WU Jinqiao, WANG Mengyu, LI Wei, YANG Chao, MA Zhenfeng, YANG Xianlun, LI Cheng
2024, 41(1): 76-83.   doi: 10.12358/j.issn.1001-5620.2024.01.008
Abstract(72) HTML(18) PDF (3845KB)(40)
To find out the inherent causes related to the borehole wall collapse in drilling the Shiqianfeng formation – Shihezi formation in the east of the Yan’an gas field, samples were taken from the rig-sites and were studied for their mineral composition, physical-chemical features and mechanical characteristics. Based on the study a measure dealing with the borehole wall collapse, which is to inhibit the self-imbibition of liquid into the formation rocks, is presented. From the study it was found that the Shiqianfeng formation – Shihezi formation in the east of the Yan’an gas field contain 15.44% – 47.52% clays, and are a formation with weak expandability and moderate dispersibility. The rock samples are developed with micro-fractures and micro-fissures which are the main causes for the invasion of liquids and hence the collapse of borehole walls. The percent cuttings recovery of the samples tested on hot roller tester in distilled water is less than 67.2%, and the linear percent expansion of the cores made of the samples in distilled water is less than 8.14%. The Shihezi formation shows stronger dispersibility and stronger hydrophilicity than those of the Shiqianfeng formation. After soaking in a drilling fluid, the triaxial compressive strength of the Shiqianfeng sample is reduced from 186.04 MPa to 98.13 MPa, and the triaxial compressive strength of the Shihezi sample is reduced from 90.09 MPa to 49.21 MPa, indicating that the invasion of the drilling fluid into the rocks along the micro-fractures and micro-fissures causes the strengths of the formations to reduce. Using 0.3% self-imbibition inhibitor ZXS-1, the degrees of saturation of water phase and oil phase in the rock samples can be reduced from 72.6% and 86.6% to 4.7% and 33.5%, respectively, and the ZXS-1 additive can form a dense layer of adsorption around the surfaces of the rocks, thereby turning the wettability of the rock surfaces from hydrophilicity to hydrophobicity. By inhibiting the water imbibition into the rocks, the micro-fractures and micro-fissures are plugged and the liquid can no longer invade into the rocks, and the borehole walls are thus stabilized.
Development and Performance Evaluation of a High Performance Drilling Fluid Viscosifier
SUN Zhenfeng, YANG Chao, LI Jie, ZHANG Jinghui, ZHAO Kaiqiang, WANG Chen
2024, 41(1): 84-91.   doi: 10.12358/j.issn.1001-5620.2024.01.009
Abstract(60) HTML(12) PDF (2992KB)(34)
A high performance viscosifier DV-1 has been developed to solve the problem of degradation and losing effectiveness of drilling fluid viscosifiers in high temperature and high salinity conditions. VD-1 is synthesized through free radical copolymerization with monomers such as MAPS, MAC and NVP. The initiator of the polymerization reaction is AIBA. The optimal reaction condition, determined through orthogonal experiment method, is as this: reaction temperature is 50 ℃, concentration of the monomers is 40%, concentration of initiator is 0.4%, and reaction time is 4 h. The reaction product was characterized using FTIR, 1H-NMR and TG-DTA, and the viscosifying capacity, high temperature high salinity performance and the ling-term effectiveness of the synthesized product were evaluated. The evaluation experimental results show that 1% water solution of DV-1 has apparent viscosity of 44.7 mPa∙s. After aging at 180 ℃ for 16 h, the viscosity of the water solution is still maintained at 53.2% of its original viscosity. DV-1 is resistant to the contamination of salts. DV-1 also has good long-term effectiveness; after aging at 180 ℃ for 72 h and 120 h, the viscosity of the solution is still maintained at 50.5% and 40.7% of its original viscosity. DV-1 has EC50 of 30 200 mg∙L−1, meeting the standard of discharge in offshore area. The viscosifying mechanisms of DV-1 are studied by observing the spatial 3D morphology and by analyzing the Zeta potential of DV-1 in solution, it is concluded that DV-1 viscosifies in solution because the molecules of DV-1 have stable main chains and rigid side chains, the amphoteric ionic structure inhibits the continual curling of the side chains, thus effectively improving the salt resistant performance of DV-1 as a viscosifier.
Ultra-high Temperature Resistant Cement Slurry and Its Application in Hot Dry Rock
XIAO Jingnan, LI Xiaojiang, ZHOU Shiming, WEI Haoguang, YANG Hongqi
2024, 41(1): 92-97.   doi: 10.12358/j.issn.1001-5620.2024.01.010
Abstract(45) HTML(16) PDF (3444KB)(25)
It is easy to cause the strength retrogression of cement sheath, especially at the long-term high temperature condition of dry hot rock. At present, the method of adding sand to strengthen cement is widely used in high temperature cementing operations. However, the strength retrogression of cement still exists when the temperature is above 200 ℃, resulting in casing collapse and annular flow, which seriously affects the wellbore safety. To solve the problem of cement strength retrogression at the ultra-high temperature, a new high-temperature stabilizer (SCKL) was developed by optimizing the phase composition of cement based on the enhanced effect of silica aluminum bonding. The effect of SCKL on the inhibition of set cement strength retrogression at high temperatures was evaluated. The results showed that the compressive strength of set cement was 18.2 MPa at 48-hour age for 300 ℃ curing temperature. And the strength reached 23.2 MPa after 30 days, which inhibited the strength retrogression of cement under long-term high temperature conditions. The influence of temperature on the microstructure and hydrates of set cement was revealed based on the XRD and SEM tests. Finally, a new durable heat-resistant cement system was developed. The cement slurry had very good settlement stability and could meet the requirement of safe cementing in DHR wells at a temperature difference of 100 ℃. The durable heat-resistant cement system has been successfully applied in five wells in Gonghe Basin, Qinghai Province. The cementing qualities are very good, which provides a guarantee for the integrity of cement sheath sealing in dry hot rock.
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](1787) [PDF 1051KB](1099)
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](2147) [PDF 4926KB](600)
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](1153) [PDF 2843KB](252)
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%。
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](775) [PDF 2049KB](175)
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](1219) [PDF 4562KB](448)
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](1928) [PDF 2528KB](706)
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](1377) [PDF 540KB](307)
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](964) [PDF 11047KB](213)
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。
Research on Safe Drilling Technology for Ultra Deep Ultrahigh Pressure Saltwater Zones in Piedmont Area, Kuche
ZHOU Jian, JIA Hongjun, LIU Yongwang, LI Weidong, DENG Qiang, YANG Yanming
2017, 34(1): 54-59.   doi: 10.3969/j.issn.1001-5620.2017.01.010
[Abstract](719) [PDF 922KB](299)
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](787) [PDF 7874KB](234)
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](6189) [PDF 5710KB](352)
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](1787) [PDF 1051KB](355)
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](1237) [PDF 2116KB](289)
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](1928) [PDF 2528KB](374)
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](1054) [PDF 729KB](288)
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](1347) [PDF 604KB](351)
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.
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](1193) [PDF 963KB](318)
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.
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](1246) [PDF 2831KB](277)
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](1165) [PDF 2703KB](274)
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](1193) [PDF 4092KB](316)
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