ABSTRACTS

OPTIM IZATION AND FIELD TEST OF HYDRAULIC OSCILLATOR PLACEMENT DURING HORIZONTAL WELL DRILLING

OU Yangyong1，2，DUAN Zhifeng1，2，CHEN Chunyu1，2and MA Tianshou3（1.Research Institute of Oil and Gas Technics，PetroChina Changqing Oilfield Company， Xi’an， Shanxi 710018，China；2.State Engineering Laboratory of Low Permeability Oil and Gas Field Exploration and Development，Xi’an，Shanxi710018，China；3.State Key Laboratory of Oil＆Gas Reservoir Geology and Exploitation，Southwest Petroleum University，Chengdu，Sichuan 610500，China），DPT 42（5），2019：1-4

Abstract：High drill string drag，high low-side support pressure in the horizontal section and low ROP are problems often observed during the horizontal well drilling.The hydraulic oscillator is an effective way to solve this kind of problem.Because the conventional drill string drag prediction method hasn＇t considered the hydraulic oscillator’s effects，the best placement of hydraulic oscillators is still controversial.Therefore，considering the influence of axial vibration generated by hydraulic oscillators，a dynamic drill string dragmodel is established based on Dahl dynamic friction model and conventional rigid rod model.The accuracy of thismodel is verified by the hook loadmeasured at wellhead.The characteristics and rules of horizontalwell drag distribution are analyzed，and the placementof hydraulic oscillators is optimized.Finally，field verification tests are carried out.The results show that the dynamic frictionmodel calculated drill string drag iswell consistentwith themeasured data and the precision is high.Themaximum error is 13.19% and the average error is only 4.90%.In Sulige Gas Field，the best position in kickoff section is 60～80 m away from the drill bit，the best position in the horizontal section is60～100m away from the drill bit.The field test results show that the ROP of the inclined section is increased by 39.01% and the ROP of the horizontal section is increased by 41.57%.The dynamic drag／friction calculation model of drill string and the optimization results of the placement of hydraulic oscillators can provide the theoretical basis and support for the rational application of hydraulic oscillators.

Key words：horizontal well，hydraulic oscillator，drill string drag，drag reduction effect，location optimization，test

STUDY ON CASING FAILURE MECHANISM BASED ON INJECTION-PRODUCTION IMBALANCE

LUO Zeli1，LIAN Zhanghua2，LI Changping2，3，LIN Tiejun2and HE Yong2（1.CNOOC Shenzhen Company，Shenzhen，China；2.State Key Lab of Oil and Gas Reservoir Geology and Exploitation，Southwest Petroleum University，Chengdu，Sichuan 610500，China；3.No.3 Oil Production Factory of Dagang Oilfield Company，Cangzhou，Hebei 061035，China），DPT 42（5），2019：5-8

Abstract：Injection-production imbalance often weakens reservoir compaction and causes ground surface subsidence，and then formation deformation vertically or horizontally，and subsequent casing bending，shear or compression failure.Therefore，a 3D finite element model of casing-cement-formation is established based on the field data and reservoir compaction theory to analyze themechanical behavior of casing under the conditions of insufficient reservoir compaction and subsidence which is caused by injection-production imbalance.It is shown that casing became“S”shape in the deficit compaction reservoir and the bigger surface subsidence is，the greater lateral displacement of casing is.What’smore，the stress on the casing at compaction reservoir is themaximum value.At last，the stress and displacement of casing increases with decrease of the Young’smodulus of the formation in deficit compaction reservoir.And the shale hydration will intensify the casing failure.The methods and results in this paperwill provide a useful reference to analyzewellbore integrity and propose preventivemeasures for casing failure in the insufficient-compaction reservoirs.

Key words：injection-production imbalance， weakened compaction，surface subsidence，casing damage，finite element method

EVALUATION AND APPLICATION OF DRIFTING BHA USED IN ACTUAL BOREHOLES

LINing1，DIQinfeng2，TENG Xueqing1，WANG Wenchang2，ZHOU Bo1and ZHANG Tao1（1.PetroChina Tarim Oilfield Company，Korla，Xinjiang 841000，China；2.Shanghai Institute of Applied Mathematics and Mechanics，ShanghaiUniversity，Shanghai200072，China），DPT 42（5），2019：9-11

Abstract：Drifting process is indispensable in well drilling and completion.However，in actual practice，casing running is often stuck downhole，which proves the limitations of the existing driftingmethod.The reason is that the existing stiffness matchingmethod to design and evaluate the drifting BHA cannot reflect the spatialbending characteristics of the actualwellbore and the non-smoothness of the shaft lining，resulting in the poor effect of drifting process.In this paper，based on the principle of bending deformation energy，considering the influence of actual hole trajectory，wellbore diameter and the BHA configuration，the bending deformation energy model of pipe string in actual hole is derived.Based on the calculation of bending deformation energy of BHA and casing in actual hole，an evaluation method based on equivalent stiffness is presented.The theoretical and field application results show that the drift effects of the BHA used in the actual wellbore trajectory can be quickly evaluated by using themethod in this paper.

Key words：actual borehole，casing，drifting，stiffness match，bend deformation energy

EFFECTSOF KILL FLUID LOSSON FLUID ACCUMULATION IN GASWELLBORES

LISanxi1，JIA Hu2and WU Xiaohu2（1.CNOOCShanghai Company，Shanghai200232，China；2.State Key Lab or Reservoir Geology and Development Engineering，Southwest Petroleum University，Chengdu 610500，Sichuan，China），DPT 42（5），2019：12-15

Abstract：Wellbore accumulation effects is sensitive to the well test analysis results.A lot of study has been done on accumulation coefficient and ending time of borehole accumulation，but the effects of kill fluid loss under different well conditions and work conditions is not considered.The study shows that the over high kill fluid density or too long operation time will lead to increase in kill fluid loss，which will affects the borehole accumulation，and the low permeability will affects the accumulation.This study results will provide reference for gas well test and production test analysis.

Key words：borehole accumulation effects，kill fluid，loss，gas well，numerical simulation

STUDY ON PREDICTION OF GAS INVASION RISK DURING HORIZONTAL WELL DRILLING

ZHANG Haolin1，LI Jun2and FAN Guohong3（1.SINOPEC Research Institute of Petroleum Engineering，Beijing，100029，China；2.CCDCDownhole Service Compary，Chengdu，Sichuang 610213，China；3.The Third Drilling Branch of CNPC Bohai Drilling Engineering Company Limited，Tianjin，China），DPT 42（5），2019：16-19

Abstract：With the continuous exploration and development of oil and gas，more and more sour gas reservoirs are being exploited.Especially in the northeastern Sichuan basin and Xinjiang Tarim Basin and othermarine carbonate blocks，the invaded gas often contains H2S or CO2，which will cause casualties once evolved into gas blowoutaccidents.In this paper，the temperature＆pressure fields are coupled to establish an improved two-phase flow model of horizontal well after gas invasion.The BHP variation law in gas invaded wellswith differentgas composition is analyzed.Based on pressure division of underbalanced drilling，the risk of gas invasion can be predicted and graded.Combined with the geologicalmodel data and the real-time logging data，the proposed model can be used to calculate and predict the risk of gas invasion during the horizontal well drilling process.

Key words：horizontal well，gas invasion，gas-liquid two phase flow，well kick，risk warning

EXPERIMENTAL STUDY ONWOB FLUCTUATION CHARACTERISTICS

WEN Xin1，2，GUAN Zhichuan3，LIANG Deyang3and ZHOU Yingcao1（1.CNPCDrilling Research Institute，Beijing，102206，China；2.PetroChina Research Institute of Petroleum Exploration＆Development，Beijing 100083，China；3.School of Petroleum Engineering，China University of Petroleum（East China），Qingdao，Shandong 266580，China），DPT 42（5），2019：20-23

Abstract：By drill string dynamics simulation apparatus，the law ofweighton bit（WOB）fluctuation under different drilling parameters in a highly deviated well is quantitatively analyzed from the aspects of fluctuation frequency and amplitude.The results indicate that the WOB fluctuation curve is generally a sine wave and the phenomenon of random deviation is observed.When the rotary speed increases，the WOB fluctuation frequency increases and is always equal to the drill string rotation frequency，whereas the WOB fluctuation amplitude decreases.In addition，the influence of the nominalWOB on theWOB fluctuation only reflects on the upper and lower translations of theWOB curve，the WOB fluctuation frequency and amplitude will not be changed significantly.

Key words：WOB fluctuation，highly deviated well，drilling parameters，simulation experiment

EXPERIMENTAL STUDY OF HYDRAULIC CASING-CEMENT BONDING STRENGTH UNDER H IGH TEMPERATURE CONDITIONS

ZHANG W andong1，LI Yanjun1，WU Jiang1，YANG Yuhao1and YANG Huanqiang2（1.CNOOC Zhanjiang Branch，Zhanjiang，Guangdong 524000，China；2.College of Petroleum Engineering，Yangtze University，Jingzhou，Hubei，China），DPT 42（5），2019：24-26

Abstract：According to the complex temperature variation in high temperature and high pressure（HTHP）deep water wells，a full-size HTHP experimental device is developed to evaluate the seal integrity of cement sheath.By the device，the hydraulic bonding strength（HBS）between casing and cement is measured and the effects of high temperature and its variation on the HBS are investigated.The results show that the HBS behaves differently to the different cement slurry curing time，different curing temperature and different temperature variation.With the increasing of curing temperature in the same curing time，the HBS increases gradually.While the HBS increases first and then inclines to stable value with the increasing of curing time in the same curing temperature.The temperature variation has significant effects on HBS.HBS increases obviously with the increase of temperature.This study will be a certain guideline for evaluating the sealing integrity of cement sheath in HTHPwells.

Key words：HTHP，cement sheath，hydraulic bonding strength，temperature variation

DOUBLE CASING CEMENTING IN GYPSUM SALT LAYER OF SHULUJINGQIU STRUCTURE

WANG Fuchang，LAN Yan，HUANG Xia，KONG Na and YU Wanbao（No.1 Cementing Branch of CNPC Bohai Drilling Engineering Co.Ltd.，Hejian，Hebei 062450，China），DPT 42（5），2019：27-30

Abstract：In view of the problems of gypsum-salt formation creeping and casing collapse at Shulu Jingqiu structural belt，through research and practice，double-layer casing cementing has been used to solve the casing collapse caused by gypsum creeping.Through the study on flushing space fluid and cement slurry systems，laminar displacement is adopted to ensure the integrity of cement sheath，achieve good sealing along the whole cementing section，ensure the operation safety and cementing quality，and create favorable conditions for the later operations.

Key words：gypsum salt layer，creep，double casing，spacer fluid，cement slurry

PRODUCTION CASING CEMENTING IN HORIZONTAL WELLSAT ZHAOTONG SHALE GASDEVELOPMENT DEMONSTRATION ZONE

ZHANG Yongqiang1，QU Congfeng2，BIAN Weikun1，CHEN Anhuan1，TANG Shouyong1and XU Ming2（1.PetroChina Zhejiang Oilfield Company，Zhejiang，China；2.CNPCEngineering Technology Institute，China），DPT 42（5），2019：31-34

Abstract：The lateral lengths of horizontalwells at Zhaotong shale gas field at Sichuan basin border are getting longer，2810 m at themaximum.How to ensuring safe casing running and improve well cementing quality becomes challenging.The related study and practice show good hole conditions and suitable casing string are all prerequisites for safe casing running.The method of releasing the tension on the casing is effective to prevent casing deformation.Special spacer can improve the interface casing-cement bonding quality.Ductile cement slurry system，balanced-pressure cementing and prestress cementing can improve well integrity.The application of above measures have been proved to be effective in 103 wells，they can be popularized in other shale gas field.

Key words：long horizontal section，ductile cement slurry system，stress cementing，well integrity

HOW TO REDUCE DENSITY AT M ANAGED PRESSURE DURING PRECISE MANAGED-PRESSURE CEMENTING

SHI Rui1，2， XU Bihua1，2， CAI Xiangyu2， ZHENG Yuanyun2and FENG Yuqi3（1.Petroleum Engineering College，Southwest Petroleum University，Chengdu，Sichuan 610500，China；2.CCDC Downhole Operation Company，Chengdu，Sichuan 610213，China；3.Cementing Technology Research Institute，CCDCDownhole Service Co.，Chengdu，Sichuan 610213，China），DPT 42（5），2019：35-38

Abstract：In the oilfield development，to deal with the drilling challenges in multi-pressure system and narrow safety density window formations，precisemanaged pressure cementing is often adopted.It is to reduce the pressure of the hydrostatic column of drilling fluid by using the precise pressure-control equipment to ensure the dynamic well pressure between the formation pore pressure and the breakdown pressure.How to determine the drilling fluid density during casing running and cementing is critical.2 methods have been proposed herein，the advantages and disadvantages are analyzed.The application in two wells on site shows that before the precisemanaged pressure cementing，one-time density reduction and phased density reduction both can ensure a smooth casing running，and can successfully control the pressure and reduce density without causing the lost circulation，to effectively guarantee the success of precise managed pressure cementing，ensuring the cementing quality.

Key words：precise managed pressure，pressure reduction atmanaged pressure

EXPERIMENTAL STUDY ON PROPPANT SETTLEMENT REGULARITY IN FRACTURES DURING VOLUME FRACTURING

LIU Junchen1，PENG Huan2，3，GAO Xinping2，3，LIU Huanjie4，WANG Liang2，3and ZHOU Yuchao2，3（1.CCDC Sichuan Shale Gas Exploration and Development Co.Ltd.，Chengdu，Sichuan 610051，China；2.Engineering Technology Research Institute of PetroChina Southwest Oil＆ Gas Field Company，Guanghan，Sichuan 618300，China；3.Sichuan Key Laboratory of Shale Gas Evaluation and Exploitation，Chengdu，Sichuan 610091，China；4.Development Division of PetroChina Southwest Oil＆ Gas field Company， Chengdu， Sichuan 610051，China），DPT 42（5），2019：39-42

Abstract：With the shale gas exploration and development，the volumetric fracturing plays an increasingly important role in the development of shale gas reservoirs.The slick-water is often used.Due to its low viscosity，poor sand carrying performance，the proppants are subject to settlement at the bottom of the hydraulic fractures，affecting the results of volume fracturing.The proppant settlement rule and distribution in the hydraulic fractures are very important to the successful volume fracturing.The proppant in-fissure flow visualization device is used to carry out experimental study on proppant settlement，the quantitative study of the effects of flow rate，proppant types，proppant pumping program on proppant settlement law is finished.And according to the sensitivity of the affecting factors，the factors are ordered as flow rate，proppant injection process，proppant type.This will be helpful for proppant selection and operation parameter optimization.

Key words：shale gas，volume fracturing，proppant，settlement regularity，experimental study

NUMERICAL SIMULATION OF SAND PRODUCTION MECHANISM IN H IGH PRESSURE H IGH PRODUCTION GASWELLS

MA Yaqin1，ZHANG Bao1，ZHONG Jianfang1，YI Jun1and HAO Jian2（1.Petroleum Engineering Institute，PetroChina Tarim Oilfield Company，Korla，Xinjiang 841000，China；2.Oilfield Operation Company，Yumen Oilfield Company，Jiuquan，Gansu 735019，China），DPT 42（5），2019：43-44，58

Abstract：Themechanism of sand production in high pressure and high production gas wells is complex.High production rate will produce a strong turbulence effects in the nearbore region，which is an important cause of formation sand production.Through physical simulation experiment，it is found that the high-speed gas through the holes can produce strong suction force.The relationship between underground gas flow rate and suction force is analyzed with numerical simulation.Considering the additional differential pressure caused by suction force，as well as the impact of acidizing on rock strength，the critical drawdown pressure predictionmethod for sand production in high pressure high rate gaswells ismodified.Thiswill provide a reference for the sandingmechanism and prediction of sand production in high pressure and high productivity gaswells.

Key words：high pressure high-yielding gas well，turbulence effect，sand productionmechanism，suction force，expereimental study，numerical simulation

STUDY ON BI-WAY PROFILE-ADJUSTING AND PLUGGING TECHNOLOGY FOR HIGH WATER CUT WELL GROUP AT HUZHUANGJIOILFIELD

ZHAO Zezong（Pudong Oil Plant，Sinopec Zhongyuan Oilfield Company，Puyang，Henan 457001，China），DPT 42（5），2019：45-48

Abstract：Huzhuangjioilfield is a highly heterogeneous reservoir，with high water cut，deep reservoir burial and high salinity，single profile control is getting poorer results.In order to overcome these problems，a bi-way profile-adjusting and plugging technology is proposed，a new crosslinking polymer system is developed through the indoor experiments.Through evaluation of different profiling-plugging methods，the bi-way profiling-plugging is relatively advantageous，recovery degree can be improved by 3% when compared with single profile control or water plugging.Its field application has obtained remarkable effects in oil recovery increase.

Key words：Huzhuangji oilfield，high water cut，bi-way profile control and water plugging，crosslinked polymer

FRICTION DRAG CORRECTION FOR MULTI FRACTURING-GRAVEL PACKING STRING USED IN CASED HOLES AT BOHAI

XING Xuesong1，2，CHEN Bin1，2，ZHANG Binqi1，GONG Ning1，2，ZHANG Lei1，2，LI Qiang3，XU Fengxiang3and ZHONG Zhaoyu3（1.CNOOC Tianjin Branch，Tianjin 300459，China；2.State Key Laboratory of Offshore Oil Exploitation，Tianjin 300459，China；3.China Oilfield Services Limited，Tianjin 300459，China），DPT 42（5），2019：49-51

Abstract：One-tripmulti-zone fracturing technology iswidely used at Bohai block，drag reduction ratio method was often used to calculate fictional drag for gravel pack fracturing string.But with the technology and tool improvement and upgrading，the bigger errors appear when using conventional calculation method，leading to higher operation difficulty，risk and operation failure of.In order to effectively solve the problems，by field data at Penglai PL19-9 field，correction coefficient and accurate fictional drag calculation formula are proposed.The formula was applied to J21 and good results obtained.And based on the theoretical formula，d7-5／8＂casing one-trip multi-zone fracturing technology is verified，which is an important measure in response to the current low prices for CNOOC，the results show that the new type 7-5／8＂casing fracturing sand control can realize 400m wash-pipe（not considering the lowest perforation）.the technologywill be applied to Bohaion a large scale in the future.

Key words：gravel pack，drag reduction ratiomethod，fictional drag，correction factor，7-5／8″casing

A SIMULATION METHOD FOR INTELLIGENT COMPLETIONW ITH CONSIDERATION OF ICV RELIABILITY

SHANG Fanjie（CNOOC International Company Ltd，Beijing 100028，China），DPT 42（5），2019：52-55

Abstract：In recent years，intelligent completion technology has beenmore and more widely applied across the world.However，there is no specialized intelligent completionmodulewithin the mature commercial simulators，while equivalent simulation methods are not able to realize all intelligent completion control strategies，especially proactive control.Therefore，the potential gains of intelligent completion cannot be fully described.Based on a thorough literature review，here in this paper the simulation of intelligent completion with different control strategieswith help of Petrel-RE andINTERSECT，Schlumberger is realized.In addition，take the reliability problem of ICV into consideration，an ICV reliabilitymodel is introduced to incorporate with the simulationmethod to formulate a comprehensive evaluationmethod for intelligent completion application.Thismethod has been applied in L field，Brazil.

Key words：intelligent completion，reservoir simulation，ICV，control strategy，failure rate

RESEARCH ON HOW TO IM PROVE SINGLEWELL OIL PRODUCTION OF SIDE-TRACKED WELLS IN ANSAI LOW PERMEABILITY RESERVOIR

CHANG Du1，2，LU Hongjun1，2，QI Yin1，2，ZHANG Yuchao3，REN Yong1，2and WU Na4（1.Oil＆Gas Technology Research Institute of PetroChina Changqing Oilfield Company，Xi’an，Shanxi 710018，China；2.State Engineering Lab for Low-permeability Oilfield Exploitation and Development；3.No.1 Oil Production Plant，PetroChina Changqing Oilfield Company，Xi’an，Shanxi 710018，China；4.Laojunmiao Production Plant，Yumen Oilfield Compamy，Jiuquan，Gansu 735019，China），DPT 42（5），2019：56-58

Abstract：The low permeability AnSai reservoirs at Ordos basin has entered the double-high development stage due to the long-term water flooding，and the residual oil is highly dispersed.The casing window side-tracking has been successfully used in the old flooded well，and the new wellbores bypass the waterflooded zone and directly go into the residual oil enrichmentarea.The technology is an effectivemethod to control flooding and to exploit the remaining oil.In order to improve the production of singlewells drilled by side-tracking，the drilling targets in the typicalwell group are optimized based on the numerical simulation with consideration of the distribution of the residual oil.The results show that higher cumulative production can be obtained when the targets are located at110～130m away from thewaterline.Through the program study，optimization of operation and the development of the key tools，material，the multi-cluster fracturing technology is formed forØ88.9mm holes.With application of the new technology，the single well production has reached 2.5t／d.

Key words：side-tracking in old well，residual oil EOR，optimization of target，staged multi-cluster fracturing，numerical simulation

METHOD TO PREDICT STOP TIME OF NATURAL FLOW OUT OF GUSHER WELLS AT HALFAYA OILFIELD IN IRAQ

YANG Junzheng1，WANG Qinghua1，CAO Zhenni1and YANG Qianqian2（1.Engineering Technology Center，Oil and Gas Exploration and Development Research Institute，Beijing 100083，China；2.Aobote Petroleum Technology Company Limited，Beijing 100084，China），DPT 42（5），2019：59-61

Abstract：Development of Halfaya oilfield mainly depends on the energy of edge and bottom water in the early stage of production.Artificial lift is necessary at the later stage.Naturalflow stop time needs to be predicted accurately so as to provide basis for the timing of artificial lift in the later period.The conventionalmethods for this has not considered the influence ofwater cut and wellbore flow pattern，which leads to poor prediction results.In this paper，ceasing conditions of natural flow（noflowing pressure under different water content）are forecasted throughmultiphase flow and nodal analysis technique，then relationship between water，formation pressure and time are established by reservoir engineering methods，and finally，based on all of the above results the natural flow-stop time is predicted comprehensively.This method takes into account high GOR，fast increasing water cut and rapidly descending reservoir pressure in Halfaya oilfield，whichmakes the prediction resultsmore accurate and reliable，at the same time provides a strong technical support for no flow time prediction forwells with same reservoir type，similar production characteristics.

Key words：multiphase flow，nodal analysis，water cut prediction，formation pressure forecast，natural-flow stop time prediction

PRACTICE OF FULL BORE STAGED FRACTURING STIMULATION FOR HORIZONTAL WELLS IN TIGHT SANDSTONE GASRESERVOIRS AND KNOWLEDGE OBTAINED

LILingchuan（Petroleum Engineering Research Institute of Sinopec North China Oil and Gas Branch，Zhengzhou，Henan 450006，China），DPT 42（5），2019：62-65

Abstract：During the early stage of tight sandstone gas reservoir development in Northern Ordos Basin，the staged fracturing with preset pipe string and packer in open holes is themain stimulationmodel for horizontal wells，which provides technical support for the rapid and effective production of gas field.But in the later production stage，the inner diameter ofmulti-stage sliding sleeve gradually reduce stage by stage，full bore after fracturing cannot be achieved.Pressure balls cannot be all returned，some ones remaining in thewellborewill affect the latter secondary stimulation.In order to solve these problems，full bore staged fracturing tests based on casing cementing completion and open hole packer completion are carried out step by step.The effects of full bore staged fracturing based on casing cementing completion is not satisfactory，further research is needed.The open hole packer completion combined with staged fracturing by coiled tubing with bottom packer has the advantages of large drainage area and automatic“sweet spot”location in open hole completion，it also has the advantages of full bore formed after casing cementing completion，which is beneficial to gas production by water drainage during secondary stimulation.Through the continuous improvement ofmatching techniques，this technology has becomemoremature，and the success rate of operation has reached 98.6%.It provides a good model of full bore staged fracturing for horizontal wells in tight sandstone gas reservoirs at northern Ordos Basin，and has valuable prospect for application.

Key words：tight sandstone gas reservoir，horizontal well，full bore，open hole packer，coiled tubing with bottom packer，staged fracturing

STUDY AND PRACTICE OF LIQUID LIFTING ON HORIZONTAL WELLSDURING FULL LIFE OF ELECTRIC SUBMERSIBLE PUMPS AT BZ OILFIELD

LI Xiang，CHAI Shichao，XU Yuxia，RUAN Xinfang，YANG Youguo and HE Bin（CNOOC Tianjin Branch，Tianjin 300452，China），DPT 42（5），2019：66-68

Abstract：Changingmore powerful pumps was widely studied and applied in wells at the stage of high water cut.Study and practice of production optimization on horizontalwells during the full life of electric submersible pumps in BZOilfield is presented in this paper.First，according to the practice of BZOilfield development，the life of electric submersible pump was about 4 years.Then，the coming fluid and water-cutwas exactly forecasted by widely adaptive water drive curve.Based on this，the optimization of electric submersible pump and frequency converter cabinetwas studied to choose the best appropriate one for the coming 5 years.This idea has been applied to 14 wells in BZ Oilfield，production practice have verified that the cumulative oil incrementwas 3×104m3，28 million RMB operating cost for changing big pump IS saved.The field practice has proved that themethod in this paper is very successful.

Key words：full life cycle of electric submersible pump，widely adaptive water drive curve，liquid lifting in oilwells，optimum electric submersible pump selection

FIELD PRACTICE OF HORIZONTAL WELL DEVELOPMENT IN YANCHANG OILFIELD

SHI Lihua1，2，3，4，CHENG Shiqing1，CHANG Yuwen3，ZHANG Xichuan5，WANG Xianxian4，SHI Bin4，FENG Xiaowei6and XUE Ying7（1.College of Petroleum Engineering，China University of Petroleum（Beijing），Beijing，102249，China；2.OEKey Laboratory of Petroleum Engineering，China University of Petroleum，Beijing 102249，China；3.CNPC Research Institute of Petroleum Exploration ＆ Development， Beijing 100083，China；4.Research Institute of Yanchang Petroleum（Group）Co.Ltd，Xi’an，Shanxi 710075，China；5.CCDC Geological Exploration ＆ Development Research Institute，Chengdu，Sichuan，China；6.Qilicun Production Plant，Yanchang Oilfield Incorporated Company，Yan’an，Shanxi 717111，China；7.Xi’an Sitan Instrument Co.Ltd，Xi’an，Shanxi，China），DPT 42（5），2019：69-72

Abstract：Yanchang oilfield is located in the northern Shaanxi slope of Ordos basin and the uplift belt ofWeihe river，with shallow oil layer，insufficient formation energy，diverse reservoir microscopic pore configuration，strong heterogeneity，complex oil-water relationship，and extra-low and ultra-low permeability reserves accountingfor 85% of the total proven reserves，development is very difficult，the average single well oil production is only 0.4 t.The conventional verticalwells can＇t be very effective，complex reservoir geology and surface conditions have decided that the horizontalwellsmust be drilled to increase single well production and whole oil field production.According to the characteristics of the different types of reservoirs，the introduction of shallow arch type horizontalwell trajectory control，different edge-bottom water control and network fracturing technology in field practice shows that horizontalwell development is remarkable in results，the horizontal well production is about 5 times thatof the conventional oilwell at the same period and decline rate lower than that of conventional well，greatly improved the reserve recovery degree.

Key words：horizontalwell，developmentmode，field practice，Yanchang oilfield

DEVELOPMENT AND APPLICATION OF SPIRAL CENTRALIZER FOR EXTERNAL CASING CORROSION PREVENTION

CHEN Pengwei1，2，ZHAO Mifeng3and WANG Hua3（1.CCDC Drilling＆Production Engineering Technology Research Institute，Xi’an，Shanxi 710018，China；2.State Engineering Lab.of Low Permeability Oil and gas Field Exploration and Development，Xi’an，Shanxi710018，China；3.Oil and Gas Engineering Technology Research Institute，Tarim Oilfield Company，Korla，Xinjiang 841000，China），DPT 42（5），2019：73-75

Abstract：Spiral centralizer for external casing corrosion prevention is a cementing accessory integrating high temperature sacrificial anodematerialwith cementing centralizer structure.It can not only replace conventional casing centralizer in cementing operation to realize casing centralization，improve displacement efficiency，butalso to protect the outerwall of casing string after cement bonded，which can effectively reduce outer casing wall corrosion.Considering the safety of tripping in，the convenience of field operation，and ensuring good anti-corrosion effects，the structural scheme is optimized.The mechanical properties of three kinds of spiral centralizers for outer casing wall anticorrosion were evaluated indoor by simulating the downhole stress environment.It has been applied in 4 wells in the field，and good test results have been achieved.The purpose of reducing cost and increasing efficiency has been achieved economically，which fills in the blank at home and abroad.

Key words：casing anti-corrosion，centralizer，structural design

DESIGN OF SPLIT CROSSING SEALER FOR HIGH TEMPERATURE HIGH PRESSURE CHAMBER OF EXPERIMENTAL EQUIPMENT

CHAI Yanqiang1， ZHAI Tingting1， XU Yongfeng1，WANG Yunchuan2，SU Huanzhong1and SHENG Hui3（1.Erlian Branch of Huabei Oilfield Company，Xilinhot，Inner Mongolia 026021，China；2.Sinopec Shengli Oilfield Company，Dongying，Shandong 25700，China；3.School of Earth Science and Technology，China University of Petroleum（EastChina），Qingdao，Shandong 266580，China），DPT 42（5），2019：76-78

Abstract：The split crossing sealer is the core component of the communication equipment inside and outside the HTHP chamber of the petroleum exploration and development experiment equipment.The traditional cable through sealer can not meet the needs of oil and gas exploration experiments.A new type of split sealer and its sealingmaterial have been developed.The new three-stage split structure adopted by the sealer is connected to the high-pressure tank at the lower end，the seal gasket is used for themiddle section，and the upper end is used to strengthen the fixing effect.Different materials have different shape variables in high temperature and high pressure environment to realize the triple sealing of the sealer.The new corssing sealer has a pressure error of±0.5 MPa in the 24-hour normal temperature high pressure and high temperature-high pressurepressure holding tests.The new crossing sealer can work in 300°C and 70 MPa environment，fullymeeting the needs of oil and gas exploration experiments.The above experimental results show that the designed three-stage sealing structure of the new split type crossing sealer is reasonable，the selected sealingmaterial is appropriate，and has a high promotion value.

Key words：crossing sealer，split，experiment chamber，cable

DEVELOPM ENT AND APPLICATION OF GASAVOIDED OIL PUMP FOR ULTRA-DEEPWELLS

LIYongbing1，WANG Zexiang1，BI Linlin1and WANG Bo2（1.Bohai Petroleum Equipment Manufacturing Group，New Century Manufacturing Co.Ltd.，Tianjin 300280，China；2.Institute of Technology，No.7 Oil Production Plant of PetroChina Changqing Oilfield，Xi’an，Shanxi 710200，China），DPT 42（5），2019：79-80

Abstract：In view of the gas and sand content in some ultra-deep oilwells in Tarim oilfield，low pump efficiency and frequent sand sticking found in the conventional oil pumps，the anti-gas pump for ultra-deep oil wells is developed by optimizing the design of the self-exhaust structure of the pump barrel，plunger anti-gas structure and sand sinking fixed valve.The pump has the characteristics of safety，reliability，high strength，improving pump efficiency and reducing the probability of sand sticking.Field application in more than 20 wells proves the average service life of the pump more than 7 months，the deepest pump setting depth at 3803.83 meters，and the pump efficiency were all above 56%.

Key words：ultra-deep well，anti-gas pump，development，application

DEVELOPMENT OF QC／ZS 106-54 SLIM HOLE CORING TOOLS

YAO Kunpeng，YAO Jianlin and HE Chao（CCDCDrilling＆Production Engineering Technology Research Institute，Guanghan，Sichuan 618300，China），DPT 42（5），2019：81-82，86

Abstract：Themain development formation of Well XX-1X in Tahe oilfield is Aotao-Yingshan formation，about 7000 m deep，with broken stratigraphic lithology.Influenced by factors such as formation lithology，stratigraphic dip，using existing coring tools in the formation the core recovery is generally not high enough.To solve this problem，to obtain a more complete and reliable geological data，through the optimization of existing coring tools in terms of size and special flow improvement，a new type of s slim-hole coring tool is develooped.The field test shows that the new slim-hole coring tool is used very well，has significantly improved the core recovery at this block.Ithas important guiding significance for the coring planning for adjacent wells at this block.

Key words：broken，slim-hole，coring，core recovery rate

EXPERIMENTAL STUDY ON POLYMER PROPERTIES IN DRILLING FLUID ENVIRONMENT

LIANG Jiabo（Oil Well Operation Center，CNOOC Iraq Limited，TianJin 300192，China），DPT 42（5），2019：83-86

Abstract：Drilling fluid and cementing materialsmixed together are inevitable in the cementing process.If the cementing material performance does not meet the requirements，the cement sheath may be defective or even cause cementing failure.In recent years，geopolymers have gradually become a substitute for Portland cement，a conventional cementingmaterial.However，scholars have little research on the performance of geopolymers in the presence of drilling fluids.In this paper，geopolymers were used as research objects.The rheological properties，compressive strength and water loss of geopolymers were tested in drilling fluid contained environment.The properties of geopolymers and Portland cement under the same conditionswere compared.The results show that with the drilling fluid content increased，the viscosity and shear stress of geopolymer decrease gradually，the viscosity and shear stress of Portland cement increase gradually，and the compressive strength of geopolymer and Portland cement gradually decrease.The polymer exhibits better performance than Portland cement in the presence of drilling fluid and can be used as a substitute for Portland cement in cementing operations.

Key words：drilling fluid，geopolymer，Portland cement，cementing，viscosity

RESEARCH AND APPLICATION OF MULTIVARIATE SYNERGISTIC CLEANUP ADDITIVE

YU Shihu3，ZHOU Zhongjian1，2and ZHANG Xiaohu1（1.CCDCDownhole Service Company，Chengdu，Sichuan 610051，China；2.School of Petroleum and Natural Gas Engineering，Southwest Petroleum University，Chengdu，Sichuan 610500，China），DPT 42（5），2019：87-90

Abstract：A single surfactant is difficult tomeet the fracturing cleanup needs of low pressure，low permeability，high temperature，high salt reservoirs.Based on the synergistic effects principle of different surfactants，the self-made Gemini surfactant，non-ionic surfactant and fluorocarbon surfactantwere compounded at a ratio of6∶2∶0.1 to form amultivariate synergistic cleanup additive GF-S1.GF-S1 has the advantages of strong foaming ability，good foam stability，low surface tension and interfacial tension，good temperature and salt tolerance，and good compatibility with fracturing fluid and acid fluid system.GF-S1 has been successfully applied in high temperature wells and high saltwells in Sichuan and Chongqing，low pressure and low permeability reservoirs in Sulige，and its application effects are better than that ofmost similar products.

Key words：surfactant， cleanup additive， synergistic effect，performance evaluation，salt tolerance

PERFORM ANCE EVALUATION AND APPLICATION OF HIGH TEMPERATURE MOLECULAR FILM FLOODING AGENT

WANG Pengtao1，ZHAOQi1，WANG Xiaojun1，ZHANG Xu2，WANG Yong3，LIU Xuewei4and ZHAO Yudong4（1.Xingzichuan Oil Plant，Yanchang Oilfield Co.Ltd.Yan’an，Shanxi 717400，China；2.No.4 Oil Plant，QinghaiOilfield Company，Mangya，Qinghai816400，China；3.No.1 Oil Plant，Qinghai Oilfield Company，Mangya，Qinghai 816499，China；4.Research Institute of Petroleum Engineering，PetroChina Dagang Oilfield Company，Tianjin 300280，China），DPT 42（5），2019：91-94

Abstract：The surface activity，temperature tolerance，adsorption property，wettability and anti-swelling property of temperature-tolerantmolecular film flooding agentwere evaluated indoor.On the basis of this，oil recovery after flooding was studied.The results show that the temperature-tolerant molecular film flooding agent has a certain surface activity；and after aged at120℃for 24 hours the cationic degree changes little which indicates that it has good temperature tolerance；the molecular film flooding agent can make the core slice surface from oil wet to hydrophilic，the surface can be processed into a strong lipophilic core slice（contact angle 103.51°）surface into a weakly hydrophilic（contact angle 49.52°）；molecular film concentration at 3000mg／L，the saturated adsorption capacity at15mg／g or more，the anti-swelling rate reaches more than 90%，the increase of oil displacement efficiency is more obvious，which can increase oil recovery by 11% ormore.Field application results show that the liquid production and oil production have both significantly increased，and the effective period is longer，and a good oil driving effect is achieved.

Key words：molecular film，heat tolerance，wettability transition，flooding effect，enhanced oil recovery

FAST CULTURING OF AEROBIC GRANULAR SLUDGE TO TREAT SHALE GAS RESERVOIR FRACTURING FLOWBACK LIQUID

BAO Jin and CHEN Yexi（CCDC Downhole Service Company，Chengdu，Sichuan 610051，China），DPT 42（5），2019：95-98

Abstract：In order to treat the large amount of fracturing flowback fluid produced by the development of shale gas efficiently and environment friendly，anaerobic granular sludge from Upstream Anaerobic Sludge Bed Reactor（UASB）was inoculated to an aerobic SBR，where actual flowback fluid was used as the inletwastewater，CH3COONa was used as the carbon source and NH4Cl was used as the nitrogen source.Anaerobic granular sludge was turned into aerobic granular sludge in 3 stages，domestication stage，transformation stage and mature stage in 24d.Eventually the formed aerobic granular sludge had stable shape and size，particle size 3.6mm，MLVSS／MLSSvalue 0.82，SVI 30m l／g.Usingmature aerobic granular sludge to treat shale gas reservoir fracturing flowback liquid，the removal rate of COD reached 70～80%，the removal rate of SS reached above 85%and the removal rate of total iron reached above 90%.

Key words：fracturing flowback liquid，granular sludge，chemical oxygen demand，total iron，suspended solid

RESEARCH ON ION CONTENT CHANGE IN FRACTURING FLUID AFTER FRACTURING AT CHANGNING BLOCK

WANG Liang1，2，HU Rende3，YANG Jian1，2，PENG Junliang1，2，HAN Huifen1，2and YANG Bin4（1.Engineering Technology Research Institute of Southwest Oil＆ Gas Field Company，PetroChina，Guanghan，Sichuan 618300，China；2.Key Laboratory of Sichuan Province of Shale Gas Evaluation and Exploitation，Chengdu，Sichuan 610051，China；3.CCDC Chuandong Driling Co.；4.State Key Laboratory of Oil and Gas Reservoir Geology and Exploitation，Southwest Petroleum University，Chengdu，Sichuan 610500，China），DPT 42（5），2019：99-102

Abstract：In the development of shale gas，the flowback after fracturing is highly regarded，and to know the drainage features is a key part of later production.The flowback system at Changning block ismademainly through the experiencemethod or the flowback data of the adjacentwells，the characteristics of the flowback are not theoretically understood.At present，the study of flowback fuild ismainly focused on the environmental protection，disposal of the return fluid，and the changes of ion content in the flowback fluid are rarely paid attention to.In order to explore the ion source of flowback fluid to further understand the interaction mechanism of the shale and fracturing fluid，the ion source and ion content change in fluid flowback are studied，the results show that，①the change of ion contentafter the interaction between shale and fracturing fluid ismainly derived from the dissolution or cation exchange in shale itself，partly from proppant and clayminerals；②the contentof Na+，K+，Ca2+，and Mg2+in the flowback fuild increase with the increase of the flowback time，and the change of ion content tends to be stable after4～10 days；③the change of ion content can reflect the interaction between the fracturing fluid and the shale and the proppant，and provide the theoretical basis for the optimization of soaking time.

Key words：Chang-ning block，shale fracturing fluid flowback，fluid ion source，soaking time