Table of Content

01 October 2016, Volume 38 Issue 5

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Study of Characteristics of Lateral Vibration of the Riser in Deepwater Drilling Condition

LIU Qingyou, ZHU Junkai, MAO Liangjie

2016, 38(5):  1-8.  DOI: 10.11885/j.issn.16745086.2014.08.05.02

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Study of vibration of riser is rarely about lateral vibration of the riser in deepwater drilling condition. We built the fluid-structure interaction model for lateral vibration of the riser using Newton's method, and solve the model using the differential transform method(DTM). We also analyzed the effects of displacement of drilling fluid, fluid density, tension ratio, the riser's structure and other factors on the natural frequency of lateral vibration of risers. The results show that: the presence of drilling fluid will reduce the natural frequency of horizontal vibration of deepwater riser; natural frequency of the lateral vibration of the riser increases when the density of the drilling fluid decreases and when the tension ratio increase; tension ratio is a very serious impact on the natural frequency of the lateral vibration of the riser. The effect of the drilling fluid displacement and drill string size for the lateral vibration of the riser can be neglected under drilling conditions. The study results can be used to guide the operations and to optimize process parameters of deepwater drilling.

The Lithofacies of Carboniferous Volcanic Rocks in Dixi-Wucaiwan Area

QIN Zhijun, WEI Pu, ZHANG Shuncun, WANG Changwei, ZHANG Shengyin

2016, 38(5):  9-21.  DOI: 10.11885/j.issn.16745086.2014.12.07.04

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The complex volcanic rock types of carboniferous volcanic reservoir in Dixi-Wucaiwan area, Junggar Basin have made further research on the volcanic rock lithology and lithofacies distribution characteristics difficult. Based on the core observation, thin section identification, logging, well logging data, and scanning electron microscopy(SEM), the responses of well logging were analyzed. The methods of lithology identification for volcanic rock were established. Furthermore, by analyzing the features of single well facies of 5 typical wells and section phase, the lithology and lithofacies distribution characteristics were studied. The results revealed that the north of study area is mainly tuff and sand-mudstone intermingled with intermediate volcanic rocks, basic volcanic rocks and volcanic breccia. What develops in the central part are tuff, intermediate volcanic rocks, tuffaceous sand, with crumb acidic intrusive rocks, acidic volcanic rocks and volcanic breccia. In the southern part, sand-mudstone and tuff are distributed, with tuffaceous sand mudstone, basic volcanic rocks, crumby intermediate volcanic rocks and volcanic breccia. Due to the different reservoir performance of different volcanic facies, the research on the plane distribution features is of positive significance to oil and gas exploration.

Influence of Structure of Northwest Guizhou Area on Preservation of Lower Cambrian Shale Gas Reservoirs

FU Jinglong, DING Wenlong, ZENG Weite, HE Jianhua, WANG Zhe

2016, 38(5):  22-32.  DOI: 10.11885/j.issn.16745086.2015.01.08.02

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Tectonic conditions of Northwest Guizhouare highly complex. The preservation conditions of shale gas reservoirs in Lower Cambrian Niutitang Formation are studied and the favorable preservation condition areas of the shale gas reservoirs are divided with reference to shale gas reservoirs' preservation condition evaluation index. Combined with the tectonic evolution, the development and distribution characteristics of folds and faults, the shale sedimentary environment and thickness, the organic carbon content and the organic matter maturity, etc. in Northwest, Guizhou. Preservation conditions of shale gas reservoirs have important reference values in other areas. The folds and faults are highly developed in Northwest,Guizhou. The folds are mainly trough-like folds,and the faults have four groups of fault systems at different stages and trends. The preservation conditions of shale gas reservoirs are destroyed at different degrees by the above reasons. The favorable preservation condition areas of the shale gas reservoirs are mainly distributed in most parts of the Dafang and Qianxi County in Central of Northwest Guizhou, and some parts of the Tongzi County and Renhuai City in the northeast of Northwest Guizhou.

Productivity Forecast and Characteristics of the Carbonate Reservoir in H Oilfield in the Middle East

JIANG Junwei, XU Xing

2016, 38(5):  33-40.  DOI: 10.11885/j.issn.16745086.2014.11.24.03

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The lithologies of the MB2 Formation in H Oilfield are mainly composed of grainstone and packstone. The core data are used to analyze the lithology, physical property and pore structure property. The result shows that the carbonate reservoirs in H Oilfield are of complicated heterogeneity. The pore systems are classified into Macro pore, Mezzo pore and Micro pore according to the mercury injection. Marco pores and Mezo pores are predominant in limestone with a grainstone texture in the upper interval of MB2 Formation, and the packstone pore system mainly consists of Mezzo pore and Micro pore. The Nuclear Magnetic Resonance Logging Tool(CMR)has been employed to characterize the pore system of the limestone reservoirs. The results of the CMR pore size distribution agree with the core data in general. The NMR can evaluate the reservoir accurately. Based on the study result, the productivity prediction of the MB2 formation is made.

Evaluating Residual Oil Saturation and Water-flood Degree with Hydrocarbon Ratio Logging

HE Zhongsheng, CUI Zhigang, CHEN Guanghui, HE Yuyang, WANG Xuelei

2016, 38(5):  41-49.  DOI: 10.11885/j.issn.16745086.2014.01.06.06

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R_CH logging technology focuses on carbon and hydrogen ratio in the stratum to get the oil saturation,which mitigates the effect of porosity and is free from the limitation of salinity. The authors analyzed and identified the relation between the R_CH and oil saturation according to the conclusions of the R_CH interpretation and oil testing of 15 wells of five reservoirs types, as well as the data on hermetic core oil saturation. the analysis revealed that the oil saturation, rather than porosity has the prominent effect on the R_CH, which changes along with oil saturation changes; The conclusions of the R_CH interpretation and oil testing are accurate,credible and of good correlation. The test on the five reservoirs types indicated that the R_CH can evaluate waterflood degrees and the residual oil saturation effectively. It can provide reliable data in searching missing oil reservoir and providing measures of water plugging as well. Besides, the R_CH can be widely-used in sand shale profile. It has a remarkably geological effect in sand, mud or low resistance oil reservoir.

Discussion on Several Issues of Integrated Well-to-Seismic Fault Interpretation

WANG Yanhui, SI Li, PIAO Changyong, LI Cao, WANG Yuanbo

2016, 38(5):  50-58.  DOI: 10.11885/j.issn.16745086.2015.05.14.02

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The structure interpretation method based on well-seismic integration gradually grew mature and got promotion and application. But some problems are found in the application process: synthetic seismogram calibration, identification of lowlevel small fault, structure illusion under lower walls of large faults, mismatch of well-seismic breakpoint. According to timedepth relationships of the VSP, the acoustic curve is corrected, thus producing accurate synthetic seismograms. The problem of small fault identification is solved by the forward model and with information of tectonic attribute data such as spectral decompositions. By the technique of pre-stack depth migration(PSDM) with acoustic constraints, the accuracy of structural imaging is further improved, and the problem of the false structure and the mismatch of well-seismic breakpoints of seismic profiles in time domain is solved. The application of integrated well-seismic structure interpretation technique effectively guides the spatial positions of the breakpoints, spatial combinations of faults in the typical block of placanticline oilfield, and further improves the accuracy of fault interpretation, thus deepens the understanding of the faulted structure in placanticline oilfield, effectively guides the deployment of new wells and injection-production adjustment near faults, and provides a reliable basis for effective development of placanticline oilfield.

Shale Characteristics of Shahai Formation in Fuxin and Shale Gas Resource Potential Evaluation

LIANG Bing, LIU Qiang, SHI Yingshuang, SUN Weiji, LAN Bo

2016, 38(5):  59-64.  DOI: 10.11885/j.issn.16745086.2015.04.22.05

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Based on the previous geological work in Liujia Area,Fuxin,we found that there buried large-scale shales in Fuxin Basin,where accumulation of shale gas is of very huge potential for development. After shale core sampling and laboratory tests of the shale of Shahai Formation in Liujia Area, Fuxin, we analyzed the important parameters of distribution, organic matter content, R_o, porosity, brittle mineral content, and fracture characteristics. The research results show that the shale thickness is 500~600 m, with organic carbon content of 2.14%, thermal maturity 0.634%, and the average porosity 3.46%. Among the brittleness minerals, quartz content accounts for 37.21%, and there are many forms of nanoscale porosity and natural fractures proving that fracture development is very good. According to Ro and organic matter content, it is estimated the shale gas in Liujia Area is(72.8~89.05)×10⁸ m³ by resource abundance analogy method. It is provided the necessary basic parameters for the exploration and development of shale gas in Liujia Area by the analysis and resource evaluation of shale gas of Shahai Formation, and Liujia Area in Fuxin can be determined as favorable areas for shale gas exploration and development.

Research Structure of Fault Shadow Zone by Forward Modeling

LIU Nan, LI Xisheng, HOU Yueming, DONG Ming

2016, 38(5):  65-74.  DOI: 10.11885/j.issn.16745086.2015.12.04.02

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Main fault block of Lufeng A Field developed in ancient uplift background, between the south and north fault, located upthrown fault, the main fault block is in the fault shadow zone composed by the two faults, Seismic profiles in fault shadow zone show "pull up" and "sagging". So it is a great structure uncertainty. To solve this problem, need to establish a series of forward modeling, trying to restore the true structure. The paper analyzes the results which cause structure distortion in fault shadow zone is the lateral velocity difference between the upthrow and downthrow, the throw and dip is the key factor that influences the seismic reflection image in fault shadow zone. By analyzing the results of forward modeling and the drilling data, the structure distortion of the law was identified, and the ZJ_1A depth structure of Lufeng A Field was restored.

Difference Analysis of Oil & Gas Reserve Rule Between PRMS and SEC in U.S.

LI Hongxi, ZHANG Peijun, DAI Cheng, ZHANG Qin

2016, 38(5):  75-80.  DOI: 10.11885/j.issn.16745086.2015.07.22.01

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To effectively distinguish and accurately use America PRMS and SEC reserves evaluation rules, we compared and analyzed the two reserve classification systems. The two reserve rules have similarities and differences. The reserves must be found, recoverable, economical and with economic surplus to be confirmed by both PRMS and SEC. The SEC not only evaluates proved reserve as dose PRMS but also evaluates possible and probable reserve. The differences between the PRMS and the SEC include liquid contact, fault upthrow and down throw reserve definition, PUD offset, analogy reservoir, reliable technique, 5 year PUD plan,economic, oil price & cost. The SEC reserve evaluation is based on the present economic circumstance, because it emphasizes oil and gas economical production and the lowest income of the company. The PRMS reserve evaluation is bases on forecasting economic circumstance, as it concerns the commercial value of the reserve and the return of the company's investment.

Hierarchical Control Function of the Paleogeomorphology in Triassic Period to Sedimentary in Mahu Sag

REN Benbing, QU Jianhua, WANG Zesheng, QIAN Haitao, TANG Yong

2016, 38(5):  81-89.  DOI: 10.11885/j.issn.16745086.2015.10.16.02

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Exploration practice confirmed that Fan delta deposit has the characteristics of facies control of reservoir and production in the Triassic Baikouquan Formation in Mahu Sag. For the technical problem that the conventional sedimentary facies division technology is difficult to achieve the division of sedimentary microfacies in order to satisfy the demand of exploration. With the paleogeomorphology restoration technology and drilling data, we studied the hierarchical control function of the paleogeomorphology to the Fan Delta sedimentary in Baikouquan Formation, and achieved meticulous depiction of the front facies of Fan Delta. Studies indicate that the Fan Delta sedimentary in Baikouquan Formation hierarchically controlled by the paleogeomorphology in Triassic Period. Mountain pass,grooves,convex controls the main channel of Fan Delta,thus controls the plain facies of Fan Delta and the Mudstone between Fan Delta. The Platform Area controls the front facies of Fan Delta. The mainstream line towards the direction of the larger gradient, thus controls the symmetry of Fan Delta. Multistage slope breaks control the location of the hi-lo shorelines. In the platform area, secondary paleogeomorphology, including secondary groove and slope break, controls the subprime mainstream line direction, thus controls distribution of Lobes body in the front facies of Fan Delta.

Non-Darcy Seapeage Law and its Application in Low Permeability Water-bearing Gas Reservoir

XU Xuan, WANG Jiping, TIAN Shanshan, JIAO Chunyan, ZHANG Yuxuan

2016, 38(5):  90-96.  DOI: 10.11885/j.issn.16745086.2014.09.09.02

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Gas development practices and laboratory experiments show that there is starting pressure phenomenon in gas seepage in low permeability water-bearing gas reservoir. Therefore, it is very important to study the influence factors and change rules of starting pressure gradient in gas reservoir development. Through experimental methods, the change law of starting pressure in gas seepage in low permeability water-bearing gas reservoir was studied, the correlation analysis of this parameter with water saturation and reservoir permeability was carried out, and quantitative characterization method of starting pressure gradient was researched. An applied analysis was carried out on a typical reservoir with the starting pressure gradient calculation method and gas reservoir percolation theory. Effective development radius of wells was calculated, and the relationship of effective development radius with water saturation and reservoir permeability was established. This method provides a technological guidance for the similar gas reservoirs development especially on well pattern deployment in the early period and well pattern infilling in the middle and later periods.

Non-steady Water-flooding Production Model of Areal Well Pattern Based on Flow Line Integral Method

PU Jun, LIU Chuanxi, SHANG Genhua

2016, 38(5):  97-106.  DOI: 10.11885/j.issn.16745086.2014.10.15.01

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The development of low-permeability reservoirs displays non-Darcy flow in the process of water-flooding, which makes the calculation methods based on Darcy's law not applicable. Based on the flow line integral method and considering the threshold pressure gradient,the production calculation formulas of the flow tube before and after water break- through were derived, then the calculation method of startup angle in the water-flooding development of areal well pattern was introduced, and finally the non-steady water-flooding production model of low-permeability reservoirs was established through numerical integration. This model could be used to predict the production of oil wells, and the reliability of the model was approved by comparison between calculation and realproduction. Applying the model to a certain block,we analyzed the effect of threshold pressure gradient,areal well pattern and production pressure drop in oil production. The results show that the threshold pressure gradient had great influence on the production of oil well,so it could not be ignored when predicting the development index;the production of five-spot well pattern was larger than others while its decrease was slow,so the five-spot well pattern is suggested in the oilfield; and the increase in production pressure drop could enhance the rate of production and shorten the development cycle of oilfields.

Numerical Study on the Impact of Shear Thinning Behavior in Well Test Analysis for Polymer Flooding

JIA Zhichun, YAN Shu, DONG Xiaofang, LI Daolun, LU Detang

2016, 38(5):  107-114.  DOI: 10.11885/j.issn.16745086.2014.11.28.02

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Considering the shear thinning effect, adsorption and inaccessible pore volume, a 3-D two-phase four-component well testing model for polymer flooding was established. Based on PEBI grid, the finite volume method was used to solve the polymer flooding model, and a well testing software for polymer flooding was developed. We studied the influence of shear thinning effect on wellbore pressure, and the results show that shear thinning effect may result in a sudden drop of the pressure derivative curves. This discovery accords with the actual measured results of oil field,and is instructive to well testing analysis and formation parameter inversion.

Seepage Flow Discipline and Production Performance of Long-term Shutdown Oilfields

FENG Min, WU Xianghong, MA Kai, HUANG Qizhi, YANG Shenglai

2016, 38(5):  115-121.  DOI: 10.11885/j.issn.16745086.2015.01.05.01

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The seepage characteristics of underground fluid and the formation energy of an oilfield shutdown for over 15 months were studied focusing on underground fluid distribution,formation energy recovery and field production after shutdown period. Physical modeling experiment and numerical simulation were synthesized and applied in this study. The results indicates that the micro movement and redistribution of oil and water were observed, and the reservoir pressure gradually rose again with the gradual recovery of formation energy under the shutdown. Therefore, the well production first increases and then decreases, and the water cut first decreases and then increases after long-term shutdown. It is provided a new angle for studying the seepage characteristics and development laws of long time wide-range shutdown oilfields.

Back-leaching Technology in The Construction of Underground Salt Cavern Gas Storage

LIU Jiqin, JIAO Yujia, LI Jianjun, SHI Xilin

2016, 38(5):  122-128.  DOI: 10.11885/j.issn.16745086.2015.02.24.02

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In order to improve the economic efficiency, the developer always requires to maximize the net volume of the underground gas storage facilities on the premise of operation safety. However,due to geological reasons,engineering failures and inadequate comprehemsion, some salt layers often fail to dissolve during the storage-building process. To make the best use of the increasingly deficient salt formations suitable for underground gas storage facilities, back-leaching can be used to optimize the volume of the gas storage facility. After gas-injection and debrining, fresh water is injected by tubing strings to push the interface of the brine and gas at the designed depth. By doing that the salt formations below the interface can be leached again, which will enlarge the volume of the leached caverns. We established the back-leaching mathematic models and wrote calculation program. The pilot back-leaching in well-L in Jintan project shows the effective volume of the cavern can be raised by 13.04 percent. This research is important for enhancing the efficiency of the use of salt formations and will improve the effective volume of the built caverns.

Establishment of Energy Consumption Index on Water Injection System in Different Reservoir Type Block

RUAN Yan, CHENG Weibin, LUO Hailong, ZHANG Dayi

2016, 38(5):  129-134.  DOI: 10.11885/j.issn.16745086.2016.07.03.01

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In order to solve problems including lack of underground system energy consumption index on oil field water injection system and deficient over ground system energy consumption index, this article puts forward the energy consumption index of underground water injection system according to water injection effectiveness in different reservoir types and blocks. Major Reservoir parameters including permeability, porosity, saturation pressure, formation water salinity were analyzed to find relationships with essential standard unit energy consumption parameters on ground water injection system as well as the pressure and quantity of flow on wellhead. The research synthesizes the effectiveness assessment systems of ground water injection and reservoir water inject and recovery; oil field exploration profit is maximized with water injection energy consumption substituting water injection quantity. By adding station effectiveness and pipe network energy efficiency as energy consumption index on ground water injection system, a completed ground and underground water injection assessment index were established. Such index assists to evaluate the energy consumption of the whole water injection system and provides guidance for evaluating energy consumption condition of water injection system.

A Study on Pressure Transmission of Unsteady Fluid Flow in Banded Fault Block Reservoir

LIU Hailong, WANG Guan, WU Shuhong

2016, 38(5):  135-142.  DOI: 10.11885/j.issn.16745086.2014.08.26.02

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There is a shortage of researches on pressure transmission in banded fault block reservoir. In view of this,this paper develops mathematical models by using steady state replacement method and material balance law based on two-parameter continuous model to study pressure transmission in low permeability reservoir under constant production rate and constant pressure. The research not only presents the law of pressure transmission of banded fault block reservoir,but also fills the blank in researches on one-dimensional unsteady seepage pressure transmission law in the low permeability reservoirs. The model was applied and the influencing factors were analyzed, and conclusions were drawn that in both constant yield model and the constant pressure model,time is quadratic polynomial of transmission distance. The pressure transmission velocity is positively correlated with the yield, but negatively correlated with the bottom hole flowing pressure. In addition, the model of optimum bottom hole flowing pressure corresponding to the maximum output was obtained.

Movement of Pulverized Coal in Sucker Rod Pump in Coalbed Methane Well

MO Rihe, ZHANG Fenna, QI Yaoguang, HE Yongjie, ZHANG Guofu

2016, 38(5):  143-150.  DOI: 10.11885/j.issn.16745086.2014.10.31.05

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Based on the solid-liquid two phase flows theory, the mathematical model of coal particles in sucker rod pump was built, and the motion law of coal particles in sucker rod pump was analyzed. Through the model and simulation analysis of the solid-liquid two phase flows in sucker rod pump, the influence of the parameters, including the diameter of coal particles, the inlet velocity of well fluid, and the concentration of coal particles in well fluid, on coal particles deposition in sucker rod pump was obtained. Based on the wearing character of solid particles in the space between pump barrel and plunger, the influence of coal particles on service life of sucker rod pump was analyzed and the measures to prolong the detection period and service life of pump was given. The results show that the concentration of coal particles in the bottom of pump is relatively big and the distribution is very uneven. In sucker rod pump, the velocity distribution of coal particles is uneven and the turbulence is obvious, with coal particles mainly depositing along the entrance of the standing valve. A smaller diameter of coal particles, bigger inlet velocity of well fluid, and smaller concentration of coal particles in well fluid can reduce coal particles deposition in sucker rod pump. In the process of production, a continuous, stable and slow depressurization can reduce the production of coal particles. The reasonable adjustment of stroke and rate of production system and improvement of inlet velocity by changing pump capacity can reduce the coal particles deposition in sucker rod pump, making the coal particles in sucker rod pump discharged into the annulus between pumping rod and tubing, and the influence of coal particles on the pump can be significantly reduced.

Research on The Toughening Mechanism of Fiber/Whisker on Oil Well Cement Stone

LI Ming, DENG Shuang, YAN Ping, JIN Jianzhou, YU Yongjin

2016, 38(5):  151-156.  DOI: 10.11885/j.issn.16745086.2015.01.16.03

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Information such as the microstructure of cement stone cross section can be accurately, speedily and intuitively, provided by SEM when used in the research of cement-based materials. Oil well cement stone easily caused the micro-fracture and micro-annulus under the complex downhole stressed to decrease the sealing integrity between the cement sheath and the casing or formation. Whisker,fiber,and hybrid fiber are incorporated to strengthen and toughen the cement stone. Microstructures and micromechanical behaviors are investigated using scanning electron microscopy. The experimental results show that the toughness of the hybrid fiber cement stone was better than that of the single fiber cement stone. The toughening mechanisms of cement stone contains bridging, crack deflection and fiber pull out and the improvement could be correlated to energy-dissipating processes at the crack tips for different size and structure between the whisker and fibers and different load phases.

Variation of Key Parameters of Reservoir Characteristics by ASP Flooding

ZHAO Fenglan, LI Zihao, LI Guoqiao, SONG Zhaojie, HOU Jirui

2016, 38(5):  157-164.  DOI: 10.11885/j.issn.16745086.2015.04.03.13

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The important prerequisite ensuring the application effect of ASP flooding is determined by the extent of the impact of characteristic parameters variations of reservoir. The variations of the characteristic parameters such as wettability, sensitivity, porosity, permeability of cores, which were drilled before and after ASP flooding in Daqing Oilfield, are analyzed systematically by core-flooding experiments and AFM. The measurement results of relative permeability show that the wettability of reservoir core will change from oil wet to water wet after ASP flooding. The sensitivity experiments indicate that ASP flooding will lead to different influence on types of sensitivity, mainly including the increase of water sensitivity, but the decrease of sensitivity of velocity,acid and alkali. Statistical analysis of the reservoir porosity and permeability shows that both the absolute value of porosity and permeability of core increase and they relatewell with each other. The observations of AFM for microscopic pore structure of core further validate the understanding of the porosity and permeability improvement.

Study on The Dynamic Characteristics of Vibratory Screen with Rigid-flex Coupling

FANG Pan, HOU Yongjun, LONG Xiaokang

2016, 38(5):  165-172.  DOI: 10.11885/j.issn.16745086.2014.11.11.04

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The key in the new type vibrating screen development is the study of the dynamic characteristics of the vibrating system. It is a new approach to estimating dynamic characteristics and structural strength of the vibration system considering the characteristics of induction motors and the coupling between rigid bodies and flexible bodies. The Lagrange-Max equation was applied to compute the rotation characteristics of the motor rotor first; the main bodies of the vibration screen were then considered as flexible bodies with FEM. By combining the flexible bodies with rigid bodies, we established the rigid-flexible coupling model. Finally, acceleration responses of the system were measured with testing instruments to verify the correctness of the new method. The results proved that the elastic vibration of the structure of the vibrating screen would influence the dynamic characteristics under the effect of vibration force;the rigid-flex coupling method can accurately forecast the dynamics characteristics of vibratory screens considering the inherent properties of the elastic material; therefore, this research method can also be applied to the dynamics study of rotation and other precision machineries.

Geometry Parameter Optimization of the New Flow Conditioner Wavy Pipe

ZHU Yiliang, WEI Fei, MA Yunlong, RAO Danjiao, JI Peng

2016, 38(5):  173-178.  DOI: 10.11885/j.issn.16745086.2014.10.09.03

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This paper simulates the gas-liquid multi-phase flow in the wavy pipes. The effects of the wavy pipe on the laminar flow behavior and the accuracy of the numerical model are investigated. The effects of the bend angle, the ratio of the bend radius to pipe diameter and the number of bends on the flow behavior are analyzed. The geometry parameters of wavy pipes are optimized. The results show that the wavy pipe is effective in regulating the flow pattern and in mitigating severe slugging. The larger the bend angle, the more effective regulation of the flow pattern. The reasonable range of the bend angle is 90°~130° and when the bend angle is 90° or 120°, the wavy pipe is easier to process. Increasing the bend radius and reducing the internal diameter of the tube can increase the ratio of the bend radius to pipe diameter and enhance the regulation effect. With consideration of the investment, reducing pipe diameter is more suitable. With the increase of the number of bends, the wavy pipe regulates the flow pattern more effectively. The number of bends should be determined according to installation space and investment.

Theoretical Analysis of Sphere to Cone Sealing Performance for Tubing and Casing Premium Connection

XU Honglin, LI Tianlei, YANG Bin, SHI Taihe, ZHANG Zhi

2016, 38(5):  179-184.  DOI: 10.11885/j.issn.16745086.2014.07.28.01

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To study the sphere to cone surfaces sealing structure in tubing and casing premium connection,on the basis of Hertz contact mechanics and considering the sealing surface makeup torque, the sealing contact stress model has been established in this paper. The effects of the spherical radius, elastic modulus of sphere and the sealing surface makeup torque on the sealing width and stress were analyzed. And the measures for improving the sealing performance of spherical sealing were proposed. The results show that the contact width increases parabolically,contact stress decreases exponentially and the contact stress tends to be distributed evenly with the increase of spherical radius,the contact width increases and the contact stress decreases with the decrease of the elastic modulus of sphere,both of the contact width and stress increase parabolically with the increase of sealing surface makeup torque. To enhance the sealing performance of spherical sealing structure,we suggest the following measures: a proper larger spherical radius, a lower elastic modulus of cladding alloy sphere and a properly controlled sealing surface makeup torque for sealing width increase and a proper lower sealing contact stress. The obtained results can be of theoretical significance for sealing parameters optimization, makeup torque control and connection sealing integrity improvement.