ABSTRACTS

RESEARCHONDOWN-HOLEPRESSURE-WHILE-DRILLINGTECHNOLOGY

TANGXueping1, XIONG Zugen2, WANG Peng1, DENG Le1, LV Haichuan1, WNAG Jiajin1, FAN Jinhui1and PENG Hao1(1.CNPC Engineering Technology Research Institute, Beijing 102206, China；2.CCDC Drilling & Production Engineering Technology Research Institute, Guanghan, Sichuan 618300, China),DPT42(4),2019:1-4

Abstract：Down-hole pressure-while-drilling system is a key technology for underbalanced drilling and managed pressure drilling,it plays an important role in the oil and gas exploration and development. In this paper, the pressure-while-drilling system was introduced in details as for its basic structure, working mechanism, in-situ tests and application. On the basis of memory type annulus pressure measurement tools, system optimization design and test research were completed, a new type of real-time down-hole pressure-while-drilling system, named DRPWD system, has thus been developed successfully. The DRPWD system is composed of pressure measurement sub, MWD, and surface system. Parameters such as annular pressure, pressure in pipe, temperature, directional survey and the natural gamma in formation can be measured in real time，and the changes of down-hole pressure in the whole process of drilling can be monitored with DRPWD system. In addition, high temperature pressure-while- drilling tool (175℃) is suggested to develop, so as to meet the field demands.

Keywords：annular pressure, pressure in pipe, MWD, MPD, UBD

RESEARCHONMECHANISMOFWELLBOREINSTABILITYINGRAVELFORMATIONSDURINGAIRDRILLINGANDAPPLICATION

LIUDianchen1,2,HAN Liexiang1,2and YANG Pei3(1. CCDC Drilling & Production Engineering Technology Research Institute, Guanghan, Sichuan 618300, China; 2. CNPC Underbalanced and Gas Drilling Test Base, Guanghan, Sichuan 618300, China; 3. Oil and Gas Engineering Research Institute,PetroChinaTarim Oilfield Company, Korla, Xinjiang, China),DPT42(4),2019:5-8

Abstract: Extremely thick gravel formations (1000～5000m) are distributed in KuchePiedmont in Tarim Basin. The conventional drilling in this areafaces the problems of not much footage per drill bit, low ROP and long well construction periods. After Tarim Oilfield carried out on-site tests of air drilling, ROP improvement is obtained. However, there still are borehole instability, sand settling at the holebottom, and serioussticking accidents. First in this paper the analysis of the traditional wellbore stability model is madeand the influence of pore pressure is removed, and a wellbore stability model suitable for air drilling conditions is obtained. By this new wellbore stability model, the whole process of wellbore instability is studied, the bottom sands is found to be mainly caused by the collapse of the wellbore when the collapse ellipse is formed. The formation of the collapse ellipse is conducive to maintaining thewellbore stability, the large amount and differentvelocitiesof sand settling occurred is then understood. To solve the problem of borehole instability caused sticking, on basis of the above research results, new air drilling candidate selection criteria are proposed. The study shows air drilling is suitable for uniformly distributed small size gravelscontained formations. For the large and medium-sized gravel layers, the influence of cementation strength on the wellbore stability should be considered.

Keywords: gravel formation, air drilling, wellbore instability, sand settling at hole bottom

DRILLINGACCELERATIONCHALLENGESATFULINGSHALEGASFIELDANDSOLUTIONS

SONGBaojian1,SUN Kai2, YUE Shouqun2, LAN Kai3and MING Xin4(1. SINOPEC Zhongyuan Petroleum Engineering Co. LTD, Puyang,Henan 457001, China；2. No.1 Drilling Company, SINOPEC Zhongyuan Petroleum Engineering Co. LTD, Puyang, Henan 457001, China; 3. Drilling Engineering Technology Institute, SINOPEC ZhongyuanPetroleum Engineering Co. LTD,Puyang , Henan 457001, China; 4.Drilling Tubes & Tools Service Company, SINOPECZhongyuan Petroleum Engineering Co. LTD, Puyang, Henan 457001, China),DPT42(4),2019:9-12

Abstract：Phase II Block of Fuling shale gas field is located in the periphery of the main block of Phase I, characterized with reservoir burialdeepened, fault developed, and stratigraphic dip increased, and problems of well caving, deflection, lost circulation, and slow ROPprominent in Phase II drilling. Based on the analysis of the engineering challenges in the process of drilling, the compound drilling by PDC+Ø286mm high-torque motorand preventive measures for loss and collapse are planned to solve the loss-caving inLeikoupo Group at Jiangdong Block. For the high stratigraphic dip and difficult control of well inclination in straight hole section, a deflection-preventive and fast drilling technique for high steep structure is developed.For the poor drillability2nd-spud drilling, anti-impact cone bitsareoptimized to improve ROP by high torque PDM’s plus hybrid bits. For the high friction and serious backing pressure in 3D horizontal borehole, the backing pressure relieving technology has been practiced,ROP is improved by more than 20%. For the circulation loss in the middle and deep formations, plugging technology has been developed. Thesehavebeen test applied in 31 wells of PhaseII atFuling shale gas field. The average drilling cycle has been shortened from 116.18d to 80.65d. The ROP acceleration effect is significant. It has good reference and guiding significance for the improvement of drilling speed in Phase II drilling atFuling shale gas field.

Keywords：Fuling shale gas field, Phase II, shale gas, horizontal well, drilling acceleration challenge, solution

EXPERIMENTALSTUDYONSUPERCRITICALCO2EXTRACTIONMETHODFOROIL-CONTAININGCUTTINGSDISPOSAL

WUBaoyu1,2, LI Zhihang1,2and JIN Xiangzhe1,2(1. Drilling & Production Engineering Technology Research Institute, CNPC Chuanqing Drilling Engineering Co. Ltd., Xi’an, Shanxi 710018, China; 2. National Engineering Laboratory for Exploration and Development of Low-Permeability Oil & Gas Fields, Xi’an, Shanxi 710018, China),DPT42(4),2019:13-15,39

Abstract: In order to search for the best solution to improve the efficiency of supercritical CO2extraction for oilcuttings, the focus is placed on the influence of temperature, pressure, time,entrainer and other key parameters on extraction efficiency. The experiments are done at different device temperature changes, pressure gradient changes, and three kinds of entrainment agents are introduced.The orthogonal testsare done at different extraction parameters, the oil content of the extracted cuttings and the recovery of the base oil components are measured by infrared spectrophotometry methods and infrared spectroscopic analysis were performed. The experiments show that 2-hour extraction can reduce the cuttings’ oil content to less than 0.2%, when constant pressure at 10MPa, constant temperature at 45°C and the simultaneous addition of 2% non-polar entrainer. And the recovered base oil phase is similar to the white oil component, once used to formulate water-in-oil drilling fluid system, it is found that its performance will not be affectedafter rolling at 150°C for 16 hours.

Keywords: supercritical CO2, extraction, oil-bearing drill cuttings,entrainer

APPLICATIONOFROTARYSTEERINGSYSTEMINDEEPHORIZONTALSHALEOILWELL

MAHongyan1, WANG Daning1, ZHANG Jie1, ZHAO Huizhong1, LI Qingbi1, ZHANG Pengyu1and WANG Wei2(1.Directional Well Technology Services Branch, CNPC Bohai Drilling Engineering Company Limited, Renqiu, Hebei 062550, China; 2.Institute of Geological Technology, Liaohe Oilfield Tarim Project Management Department, Korla, Xinjiang 841000, China),DPT42(4),2019:16-19

Abstract:The exploitation of shale oil has become an important field in the development of unconventional oil and gas resources in the world.Horizontal well is one of the main technologies used in shale oil exploration and development. In order to solve the challenges like trajectory control, high pressure, collision prevention at close distance, backing pressure and lack of actualtarget zone drilling or testing data, a three-dimensionformation model is established according to the principle of azimuthal gamma detection. Based on the log curve while drilling,a methodcalculating the dip angle of reference formationis proposed and the relevant formulae are also derived.The well trajectory is controlled by the combination of rotary steering drilling system and geosteering technology. The field application results show that the rotary steering drilling system can monitor the borehole annular pressure in real time and improve ROP, realizing automatic steering control and formation evaluation.By the formation dip angle of the reference layer, theinclination of "landing" point in the target layer and the distance between the bit and the boundary can be predicted ahead of time, the borehole trajectory will then be much smooth and the target be tapped more accurately. It can also optimizethe casing program and improvethe geosteering model, providing new reference and strategy for thelater shale oil development.

Keywords: shale oil, rotary steering, horizontal well,borehole trajectory control,field application

STUDYONHOWTOPROTECTCEMENTSTONEINHIGHH2SGASENVIRONMENT

ZHAOQiyang1，2，ZHANG Chengjin1，2and YAN Haibing1，2(1.Downhole Service Company,CNPC Chuanqing Drilling Engineering Company Limited, Chengdu, Sichuan 610051, China; 2.National Energy R & D Center of High Sulfur Gas Reservior Exploitation, Chengdu, Sichuan 610051, China),DPT42(4),2019:20-23

Abstract：In order to improve the corrosion resistance of oil well cement in the environment of high H2S gas and improve the cement seal integrity for a long time, by adding inorganic siliceous materials and anti-corrosion polymer materials, the composite anti-corrosion material WJ-1 is formulated. Anti-corrosion performance was analyzed on the base fluid and the required additives of the cement slurry. The ompressive strength and permeability before and after corrosion, microstructure and phases of the cement stone are tested. The results showthat the corrosion in liquid phase is more serious than the corrosion in gas phase, the composite corrosion resistant material WJ-1 can improvethe close packing and compactness of thecement,reducethe Ca/Si ratio and the permeability of cement stone, can significantly improve the H2S corrosion resistance of cement. The cement slurry system has a good performance in rheology, stability, high temperature service, anti-channeling, and low water loss.

Keywords：corrosion, compressive strength, permeability, corrosion resistant material, close packing

BITTYPESELECTIONBYBPNEURALNETWORKMETHODBASEDONROCK’SANTI-DRILLINGPROPERTY

ZHANGHui1,WANG Hao1, JIANG Chang1, XIONG Tianwen2and FAN Guohong3(1.Oil and Natural Gas Engineering College, China University of Petroleum, Beijing 102249, China; 2.Jiangsu Drilling Company, East China Petroleum Engineering Company, China; 3.The Third Drilling Branch of CNPC Bohai Drilling Engineering Company Limited, Tianjin, China),DPT42(4),2019:24-27

Abstract: Formation rock’s anti-drilling property is the most important factor affecting the performance of drill bit, but most bit type selection methods only qualitatively rather than quantitatively analyze the relationship between geologic rock’s anti-drilling property and the bit type. On the basis of existing bit type selection methods, a bit type selection method by BP neural network based on rock’s anti-drilling property is proposed, which has been applied in Dagang Oilfield. At first we set up Dagang Oilfield formation rock’s anti-drilling property evaluation model according to logging data and laboratory experiments,at the same time the rock’s mechanics are calculated by this model. Along with abundant field bit job data they have been encoded into neural network training material. Then BP neural network model for the formation rock anti-drilling property and its corresponding optimal bit type is set up. Finally learning samples are input into neural network to complete its training. By predicted rock mechanicsdata, after calculation by the neural network, the model will output the optimal bit type. This bit type selection method works well in WellGangshen 18-17, compared with the offset well, the average ROP is improved about 25% by the chosen bit inShaYi layer inWellGangshen 18-17.

Keywords：bit optimization, anti-drilling property, BP neural network, database

RESEARCHONPLUGGINGTECHNOLOGYFORSURFACECASINGDRILLINGOFCHANGNINGSHALEGAS

WANFulei1,2(1. National Energy Shale Gas Research (Experimental) Center, Guanghan, Sichuan 618300, China; 2. CCDC Drilling & Production Engineering Technology Research Institute,Guanghan, Sichuan 618300, China),DPT42(4),2019:28-31

Abstract: Lost circulations are common when drilling surface casing section atChangning shale gas block. By analysis of the loss dataduring surface drilling, the well loss features at the block are known and the plugging results are evaluated. Suggestions are given regards the EM geologic survey, casing program optimization, optimal drilling pattern, etc., to minimize or control the lost circulations, expecting to provide guide and suggestion for Changning shale gas drilling.

Keyword：Changning shale gas, surface drilling, lost circulation, environmental protection, casing program.

OPTIMALMODELOFINJECTIONPARAMETERSFORAERATEDUNDERBALANCEDRILLINGINHORIZONTALCOALBEDMETHANEWELLS

SUNChenglong(No.1 Drilling Company，Sinopec Zhongyuan Petroleum Engineering Co., Ltd., Puyang, Henan 457001, China),DPT42(4),2019:32-35

Abstract：2-bore coalbed methane horizontal wellsare drilled with tubingin way of aerated underbalance drilling. The gas injection pressure is controlled by the vertical well, a variety of complications during drilling in coal bedscan not only be effectively resolved,but also there are many advantages, including stable gas injection and lower bottom hole under-pressure maintained. Here in this paper aninjection parameteroptimization design model foraerated underbalance drillingin coalbed methane horizontal wells are set up. The effects of different bottom hole pressure differences on the balance pressure limit, collapse pressure limit, cuttingscarrying limit and gas-liquid flow window are evaluated. The study results show that the model is reliable and can be applied in aerated under-balanceddrilling of horizontal wellsin coalbeds.

Keywords：coalbed methane, aerated UBD, injection parameters, bottom hole pressure difference, cuttings carrying performance

HOWTODECIDEOPTIMALRUBBERSEALELEMENTSFORHPHTDOWN-HOLETESTINGTOOLS

HEQiuyun, HAN Xiong and ZENG Xiaojun (Drilling and Production Engineering Technology Research Institute, CNPCChuanqing Drilling Engineering Company Limited, Guanghan, Sichuan 618300, China),DPT42(4),2019:36-39

Abstract: The key specifications of HPHT down-hole testing tools include rated working pressure and rated working temperature, which mainly depend on the rubber seal elements’ performance envelope. Here in this paper the great challenges the rubber seal elements of theHPHT down-hole testing tools face are listed, including long working period、complicated working medium etc. The advantages and disadvantages of three rubber seals used on the HPHT down-hole testing tools are analyzed. And finally some suggestions on the application，research, reliability testing standards of rubber seal elements of HPHT down-hole testing tools are proposed.

Keywords: HPHT, down-hole testing tool, rubberseal element, application

ANALYSISOFSTIMULATIONTECHNIQUESFORDEEPTIGHTSANDSTONERESERVOIRSINYUANBAAREA

DUANHua1，DENG Yan2，LI Mei2，FU Zheyi1and LIU Yuxuan2(1. Sinopec Exploration Branch, Chengdu, Sichuan 610041, China；2. State Key Lab of Oil and Gas Geology and Exploitation, Southwest Petroleum University, Chengdu, Sichuan 610500, China),DPT42(4),2019:40-43

Abstract：The terrestrial sandstone reservoirs in Yuanba area are characterized by deep burial, tight sands, complex lithology, high pressure, high temperature, strong heterogeneity, thin payzones, and generally low gas saturation. Though economic gas production is usually obtained after reservoir stimulation, most gas wells are difficult to stimulate and shows low production after fracturing. In this paper the key points of deep tight sandstone fracturing are analyzed through deep understanding of the reservoir. Combined with the previous theoretical exploration and field practice, a set of fracturing technology suitable for deep tight sandstone gas reservoirs in northeastern Sichuan is built, focusing on solving the problem of high operation pressure, ensuring low damage during fracturing，which has improved the fracturing scale, and effectively promoted the exploration work in the region. It also has important reference significance for similar fracturing in deep tight sands.

Keywords: Yuanba area, deep formation, tight sand, reservoir stimulation, fracturing

DIAGNOSISOFDOWNHOLELEAKOFFPOINTSANDPLUGGINGTECHNOLOGYFORHIGHSULPHURGASWELLS

LUOWei1,2, WANG Xinhan3, ZHAO Jingwen4, XIANG Dong3, GONG Zhanpeng3and LIN Ruidong3(1.Nanchong Vocational and Technical College, Nanchong, Sichuan 637131, China; 2.Post-doctoral Research Center, Sinopec Southwest Branch Company, Chengdu, Sichuan 610000, China; 3.Tubular Service Branch, BHDC, Renqiu, Hebei 062550, China; 4.Research Institute for Engineering Technology, PetroChina Huabei Oilfield Company, Renqiu , Hebei 062550, China),DPT42(4),2019:44-46

Abstract: Sustained casing pressure caused by downhole leakage and production casing corrosion due to H2S invasion into annulus will seriously threaten the safe production of high sulphur gas wells. Therefore it is especially important to ensure the wellbore’s integrity and reliable service status throughout the life cycle. Firstly, combining the theory chart and the high frequency ultrasonic logging, a downhole leak points diagnosis method is established. This can realize accurate location of downhole leakage. Then, evaluation of the sealing performance of the self-developed differential pressure activated sealant is carried out by the experimental facility. The pressure-loading and thermal stability of the high strength gel formed are also carried out. And combined with the field situation, the precondition and procedures of downhole plugging operation are put forward. The field application shows that the self-developed differential pressure activated sealant and the corresponding plugging process can realize the successful blocking of downhole leak points, and it can be applied in similar high sulphur gas fields.

Keywords: high sulphur content, downhole leak points, diagnosis method, differential pressure activated sealant, plugging technology

ANEWMODELFOROPTIMALFRACTUREPARAMETERSDETERMINATIONFORFRACTURINGINCBMWELLS

ZHAOAifang，LI Ji，LV Wengang，WU Na，JIN Qi and HU Xueheng (Laojunmiao Production Plant, Yumen Oilfield Company，Jiuquan, Gansu 735019，China),DPT42(4),2019:47-49

Abstract:The effects of the fracture permeability produced after fracturing and fracturing scale are not considered in previous fracture parameter optimization methods for CBM wells. For the realization of fracture parameters optimization for fractured CBM wells, based on proppant index method, considering the effects of dynamic change of fracture permeability, a mathematical model is set up which is related with fracturing scale. With the multiple iteration method, the optimal fracture parameters can be obtained under optimal fracturing scale conditions. And fracture parameters optimization chart is drawn for different coal seam permeability and fracturing scale. The result shows that there is an optimal value for proppant volume to gain maximum productivity after fracturing. The more severe non-Darcy flow effect in the fracture, the smaller optimal fracture length is, and the larger the optimal fracture width is. The method is simple to use, and the optimization results are more accurate and reasonable. So it can be used to guide fracturing for CBM well.

Keywords: non-Darcy flow, CBM, fracturing, fracture parameter, proppant index

FEASIBILITYSTUDYOFNETWORKFRACTURINGFORHIGHDIFFERENTIALSTRESSFRACTUREDRESERVOIRANDAPPLICATION

ZHANGYong1, WANG Zhisheng1，GAN Yuming2，HE Jinpeng1，LEI Fengyu1and GUO Ziyi1(1. Drilling & Production Technology Research Institute of Qinghai Oilfield Company, Dunhuang, Ganshu 736200, China; 2. Service Supervision Company of Qinghai Oilfield Company，Dunhuang, Ganshu 736200, China),DPT42(4),2019:50-53

Abstract：Many reservoirs have characteristics of high in-stress difference and natural fracture development in Qaidam Basin. Feasibility study of network fracturing was then proposed for such reservoirs. By analyzing the stress state, the fracture initiation condition of nature fracture are studied, and mathematical model of tensile initiation and shear initiation is established. Principal of stress difference and net pressure effects on shear initiation of nature fractures are obtained by model calculation and uni-variate analysis. When hydraulic fractures encounter natural cracks, increasing the net pressure of hydraulic fracture promoted the opening of natural fractures within a wider angle range. As the maximum and minimum stress differences increase, the fracture net pressure causing shear failure of natural cracks is reduced. According to the above conclusion, multi stage pulse temporary plugging technology was ever used to increase the net pressure of hydraulic fractures. By the G function analysis of the pressure drop curve it is shown that multiple fractures are opened during the fracturing, and the feasibility of network fracturing is verified.

Keywords: high stress difference, fractured reservoir, in-fissure net pressure, network fracturing

STUDYONHOWTOELIMINATEERRORSOFWELLTESTINGINTERPRETATIONCAUSEDBYDIFFERENTDEFINITIONSOFWELLPRODUCTION

NIUXiaoxi(Testing & Logging Technology Service Branch of Daqing Oilfield Co. Ltd., Daqing, Heilongjiang 163000, China),DPT42(4),2019:54-56

Abstract：The rapid development of computer technology and computational mathematics has caused the refinement of well testing interpretation. In the modern well testing interpretation, the well test engineer uses the actual production well history instead of simplified production well history. The history of the production wells obtained by using the daily average total liquid production data provided by the geological department shows a downward trend. The skin factor interpreted increases, and the pollution characteristics appear near the wellbore, which is inconsistent with the actual. The theoretical calculations are used to analyze the influence of different production definitions on the results of well test interpretation, and the reasons for the decline in the production well history of the tested wells are analyzed. The concept of fluid production rate is then proposed and the actual production correction formula is established. The field application shows that by correcting the daily average liquid production of the test well to the liquid production speed during the well test interpretation, the interpretation error caused by the inaccurate definition of the output 24 hours before the well pressure measurement is eliminated, and the well test interpretation accuracy is improved.

Keywords: well test interpretation, production, liquid production speed, error

EXPERIMENTALSTUDYONREMOVINGFRACTURE-MATRIXLIQUIDLOCKINGBYGAS-WETTINGAGENT

WANGBin1, WANG Jie2,3, YAO Erdong2,3, ZHOU Fujian2,3, ZHANG Le2,3, WEI Huirui4and LI Xiuhui2,3(1. Engineering Technology Institute, Xinjiang Oilfield Company, Karamay, Xinjiang 834000, China; 2. Unconventional Natural Gas Institute, China University of Petroleum, Beijing, China; 3. State Key Laboratory of Petroleum Resource and Prospecting, China University of Petroleum, Beijing, China; 4. Downhole Services Company, Western Drilling Company Limited, China),DPT42(4),2019:57-59

Abstract: Formation condensate and extraneous fluid form a strong liquid-locking effect in tight sandstone condensate reservoirs, reducing the production of gas wells, it is one of the main problems faced in production. The sand-filling pipe model was used to simulate the prop fracture after fracturing and the matrix core displacement experiments was done to evaluate the effects of the gas-wetting reversal agent CRS-850 to remove the fracture-matrix dual media “liquid lock” damage. The following conclusions were obtained. The fluorocarbon gas wetting reversal agent CRS-850 could change the wettability of the core surface from strongly water wetting to gas wetting. After treatment, the average wetting angle of the gas-liquid-solid end face increased from 33.3° to 101.2°, the gas-wetting reversal agent significantly increased the internal liquid-phase percolation capacity of the core, increased the gas-driving permeability, and had a significant recovery effects on the permeability of the gas-flooded core, which was increased by 501.69% to the gas-driven salt water to 673.91%, indicating the gas-wetting reversal agent was beneficial to the release of “liquid-locking” damage in tight sandstone reservoirs. The gas-wetting reversal agent could further relieve the liquid lock in support crack formed by the sand filling model after the fracturing, and the hydraulic permeability of the sand-filled pipe model was increased. The lower the permeability of the sand filling pipe model, the higher the gas flooding rate, and the greater the increase in gas flooding drainage rate after the change in wettability. At the same time, the gas-wetting reversal agent was beneficial to release the liquid phase damage formed by the fracturing in the fracture-matrix core.

Keywords: gas wetting, fracture-matrix, gas permeability, sand-filled pipe

FLOW-BACKSANDREMOVALPROCESSATWEIYUANSHALEGASBLOCK

XIEKui, ZENG Xiaojun and WANG Lei (CCDC Drilling & Production Engineering Technology Research Institute, Guanghan, Sichuan 618300, China),DPT42(4),2019:60-63

Abstract: Presently, shale gas reservoir is mainly developed with the technology of horizontal well completion and bridge plug staged hydraulic sand fracturing. In flow back at the stage of/after sand fracturing, sands may come out in large volume under three conditions: emergency bleed-off in case of screening out during fracturing, flow-backs during plug milling and after fracturing. Solid particles and sands coming out from wellbore may plug wellbore and surface pipe, erode equipment and pipe, and seriously influence flow-back continuity and safety. In this Paper, characteristics and difficulties in shale gas well flowback are analyzed systematically, and surface flowback & well test system is optimized, a series of surface flowback and sand removal equipment are developed, relevant research on sand removal during flow back is conducted, and finally a whole set of surface sand removal technology and equipment with cyclone de-sander/sand filter as the core equipment are developed, which have been applied in the sand removal jobs of a lot of shale gas wells with good and satisfactory results.

Keywords: shale gas, de-sander, flow back, Weiyuan block, de-sanding effects

APPLICATIONOFSTEAMCARBONDIOXIDEHUFFANDPUFFFLOODINGTECHNOLOGYINWELLCHE510OFXINJIANGOILFIELD

LIAOXianyan1, DING Yating1, LI Li1, YANG Xiaoying3, CHEN Zijing2and HOU Junwei2(1.No.1 Oil Production Plant，PetroChina Xinjiang Oilfiled Company, Xinjiang 834000, China; 2.Department of Engineering, China University of Petroleum, Beijing 102249, China; 3.Down-hole operation Branch,Bohai Drilling Engineering Inc, CNPC, HebeiRenqiu 062550),DPT42(4),2019:64-66

Abstract: Well Che 510 in Xinjiang Oilfield is a typical high-porosity, high-permeability and medium-heterogeneous heavy oil reservoir. Only steam is easy to produce steam overburden and steam channeling problems. To solve the above problems, Xinjiang Oilfield No.1 Oil Production Plant has carried out CO2-steam compound stimulation tests to improve the heavy oil thermal recovery in 2015. The parameters of carbon dioxide throughput, such as the steam injection pressure, steam injection volume and procedures were determined. The operation statistics show with the increase of liquid CO2injection rate, the evaporation rate of CO2slows down, leading to the increase in wellhead pressure. During CO2injection process, reasonable injection pressure and speed should be adopted, keeping the bottom pressure slightly lower than the breakdown pressure. Steam-CO2huff and puff technology has better pressurization and profile control effects, which can effectively improve the steam heat efficiency, able to provide reference for other heavy oil blocks.

Keywords: Xinjiang oilfield, heavy oil reservoir, carbon dioxide -steam huff and puff technology, ODP

RESEARCHANDAPPLICATIONOFVOLUMETRICFRACTURINGINWEIRONGDEEPSHALEGASRESERVOIRS

LINYongmao, WANG Xingwen and LIU Bin(Petroleum Engineering Technology Institute, SINOPEC Southwest Petroleum Branch，Deyang, Sichuan 618000, China),DPT42(4),2019:67-69

Abstract: Weirong shale gas reservoir of Sinopec is buried 3600-3900m deep, the thickness of optimum reservoir is 35.5～46.6m, the porosity 4%-6.6%, TOC 2.2～4.0%, Ro 2.0～2.6%, gas content 2.56～4.88t/m3, ground pressure coefficient about 1.9MPa/100m. Laboratory experiments and core analysis show that Weirong deep shale is brittle minerals and mechanical brittleness index is high, but the biaxial stress difference is between 6～16 MPa, which makes it more difficult to get the complex cracks. According to the difficulties in fracturing transformation, the “variable displacement+dense slug+continuous sand addition” was successfully developed and applied successfully in Wells WY23-1HF and WY29-1HF, with the post-fracturing production tested at 26.01×104m3/d (35.4MPa) and 23.80×104m3/d(22.2 MPa)respectively, a breakthrough in commercial development of Weirong deep shale gas.

Keywords: deep shale gas, near control distant expansion, continuous sand mixing, volumetric fracturing

EVALUATIONOFAPPLICATIONEFFECTSOFNITROGENFOAMFLOODINGINOFFSHOREHEAVYOILRESERVOIRWITHBOTTOMWATERINULTRALOWRELIEFSTRUCTURE

ZHANGJilei1, LI Tingli1, ZHANG Hao2, ZHANG Wei1, HE Yifan1and OUYANG Yuwei1(1.CNOOC Tianjin Branch，Tianjin 300452，China; 2.Directional Well Technology Services Branch, CNPC Bohai Drilling Engineering Company Limited ，Tianjin 300450，China),DPT42(4),2019:70-73

Abstract: Affected by the rhythm of the channeling, the high oil-water mobility ratio and the strong heterogeneity of reservoirs in Qinhuangdao 32-6 oil field, the injection water channels along the high permeability wide pores, resulting in fast increase in water cut, large decrease in production, prominent contradiction between formation layers, and low recovery rate after water flooding. In order to solve the existing problems, laboratory research and pilot test were carried out regards nitrogen foam flooding technology. The laboratory test results show that nitrogen foam flooding can preferentially plug the high permeability formations and stimulate the performance of low permeability layers, making the water injection changed from the “2-polar displacement” to “homogeneous displacement”. The recovery rate can be improved 24.8%. The pilot has achieved obvious effects in water control and oil increment, the well group comprehensive water cut down 5%, cumulative oil increase 4.5×104m3. Successful application of nitrogen foam flooding pilot test for the technology promotion, the application provides a valuable mine Experience has important significance for the further development of water control and stable oil work in offshore heavy oil field.

Keywords: nitrogen foam profile control, offshore oilfield profile control performance, oil displacement performance, pilot test

STUDYONHOWTOPREDICTSHEARFORCEOFSHEARRAMBOP

WANGXudong1，SI Nianting2，FENG Shuo2，LONG Jiangqiao2and ZHANG Chao2(1. CNOOC EnerTech-Drilling & Production Co，Tianjin 300457, China；2. Tianjin Branch，CNOOC (China) Co. Ltd. ,Tianjin 300450，China),DPT42(4),2019:74-76

Abstract: BOP is a safety device that controls the pressure in the well. The installed shear ram needs to cut off the work string in an emergency to ensure safe well shut-in. In order to accurately predict the shearing ability of the shearing ram to the drill pipe, according to the working mechanism and process of the ram shearing drill pipe, considering shear ram structure parameters, drill pipe performance and shear conditions, based on the compressive stress formula a model predicting shear force is established. The shearing test results show that the relative deviation between the theoretic and the actual test data is about 10%, which meets the deviation requirements of engineering practice. This study can effectively compensate for the shortcomings of APISpec16A in terms of prediction and evaluation of shearing force of the ram. It can be a reference for structure design of the shear ram.

Keywords:ram BOP, shearram, shearing force,compressive stress formula

DEVELOPMENTOFPACKERSFORHIGHPRESSUREINJECTIONINTOSEPARATELAYERS

QINShiqun, SONG Baojian, FAN Xiqun, MA Hongwei, LIU Lei and ZHANG Hua (Henan Oilfield Company, Nanyang, Henan 473132, China),DPT42(4),2019:77-79

Abstract: Packers for high pressure injection into separate layers are developed to solve the packer failure at Shuanghe oilfield during water injection and acidizing jobs. Double-piston low pressure setting mechanism and well flushing valve controlled pins are adopted in this packer to realize setting before closing the flushing valve, ensuring a reliable packer setting. Double-layer brass bowl structure is used at the rubber shoulder for protection and rubber formula is optimzed to improve its high temperature and high pressure performance. Experiments and tests show it can set reliably at rated setting pressures. Application in 12 wells prove the packer is effective over 2 years, meeting acidizing and fracturing needs, success ratio 100%, providing a technical support for high pressure water injection, acidizing and fracturing in different layers.

Keywords: high pressure, separate layer, injection packer, reliable sealing, effective period

DEVELOPMENTOFANNULUS-PRESSURE-OPERATEDINTEGRATEDPRODUCTION-COMPLETIONTOOLANDFIELDAPPLICATION

PANGDongxiao, JIA Hai and HAN Xiong (CCDC Drilling & Production Engineering Technology Research Institute, Guanghan, Sichuan 618300, China),DPT42(4),2019:80-83

Abstract: To improve the reliability of integrated testing and completion job in high temperature and high pressure gas wells, an annulus pressure operated switch valve is developed, by which the process of close to release-reset to open the well is upgraded to a process of close-pressure test-release-reset-pressure test-well opening. Additional two pressure testing links are planned compared with the conventional integrated oil testing and completion technology, ensuring every step can be checked and returned, avoiding complex downhole problems caused by the unexpected release or sealing failure of the resetting tool, to improve the integrity of the field processes. The tests at Moxi-Gaoshiti block show that this technology can effectively improve the reliability of integrated testing and completion in high temperature and high pressure gas wells, worth a wide application prospect.

Keywords: integrated testing-completion，APR tools，high temperature and high pressure gas wells，testing string

DEVELOPMENTOFANEWFISHINGTOOLFORDOWNHOLETHROTTLEANDTESTS

MAShengji(CCDC Downhole Service Company, Chengdu，Sichuan 610051, China),DPT42(4),2019:84-86

Abstract: In order to achieve economic recovery and increase gas production rate, special tools should be used to remove the throttle or replace the throttle. The existing fishing tool for downhole throttle is not easy to control by coiled tubing, no flush circulation passage and with low fishing success ratio. A new fishing tool has been designed with a release fishing barrel, connected with six brass pins. The tensile and shear tests of the pin and fishing tool show that the design scheme is feasible, able to meet the needs of coiled tubing operation on site, and the success rate of fishing is improved.

Keywords: downhole throttle, fishing tool, structure design, test

RESEARCHANDAPPLICATIONOFNEWTYPEMUDCAKESCRAPER

HUChenbin1, ZHANG Rui2and XIE Hongqiao3(1.Sinopec Shengli Oilfield Hekou Oil Production Plant, Dongying, Shandong 257200, China; 2. Shengli Oilfield Sennuo Engineering Co. Ltd.; 3.Sinopec Petroleum Engineering Technology Research Institute),DPT42(4),2019:87-88

Abstract: Shengli Oilfield has been developed over 50 years, the downwhole environment has been increasingly complicated. Therefore, the produce requirement of the residual oil rhythm layer and the low permeability & difficult production reservoir must be in excellent cementing quality, especially for the interfacial cementing quality. In order to improve the interfacial cementing quality, the new type mud cake scraper had been developed as a patented product on the basis of the research on the similar foreign cementing tools.Field application results showed that mud cake scraper could effectively remove the empty filter cake and improve the cementing quality between cement and wellbore . So far, the mud cake scraper has been popularized energetically in the Shengli Oilfield.

Keywords: interfacial cementing quality, mud cake scraper, research, application

R&DOFCOMPOSITESYNERGISTICFRACTURINGFLUIDFORSHALEGASANDAPPLICATION

ZHOUZhongjian1,2, YU Shihu2and ZHANG Xiaohu2(1.School of Petroleum and Natural Gas Engineering, Southwest Petroleum University, Chengdu, Sichuan 610500, China; 2.CCDC Downhole Service Company, Chengdu, Sichuan 610051,China),DPT42(4),2019:89-92

Abstract: Due to the poor sand carrying capacity of the slick water, the crack proppant filling rate is low, the conductivity is limited, and it is difficult to obtain the optimal production capacity. The compound synergistic fracturing fluid is formed and optimized by the existing slick water and linear glue. The fracturing fluid has the advantages of both low friction of slick water and high viscoelasticity of linear glue, which can meet the requirements of “large SRV” and “high filling rate”. The viscosity of the composite fracturing fluid is 2～22mPa.s, with a wide range of controllable viscosity and suitable for a variety of reservoirs. It has lower friction，the friction reduction rate is 63～73%，the sand carrying capacity is obviously better than the slick water, the average residue is below 20mg/L, the damage is lower than linear glue. It can be adjusted in real time to meet various needs and complex situations. The composite fracturing fluid shows good sand carrying capacity in field applications. It is a convenient, environmental and cost-effective fracturing fluid for shale gas.

Keywords: shale gas, composite fracturing fluid, slick water, friction reduction rate, sand carrying capacity

PREPARATIONOFAHIGH-PERFORMANCELUBRICANTFORWATER-BASEDDRILLINGFLUIDANDAPPLICATION

ZHAOZezong1, ZHUO Ran2, LI Hexiang3, CAO Hongyan4, LIU Changzhu5, LI Weiran5and LI Jin5(1. Pudong Oil Mining Factory, Sinopec Zhongyuan Oilfield Branch, Puyang, Henan 457010, China; 2. Xinzhou Company，PetroChina Coalbed Methane Company Limited, Taiyuan，Shanxi 030032，China; 3. Second Oil Mining Factory，North China Oil Field Co. Ltd., Bazhou, Hebei 065799, China; 4. Xi’an Changqing Chemical Group Co. Ltd., Changqing Oil Field Branch Xi’an, Shaanxi 710018, China; 5. Directional Well Technology Service Branch, CNPC Bohai Drilling Engineering Co. Ltd., Tianjin 300000, China),DPT42(4),2019:93-96

Abstract: Aiming at the excessive friction and torque problems appeared in horizontal wells in A oilfield, a new high-performance lubricant CRH-1 is developed by environmental base oil and lubrication modifier. Experimental results show that CRH-1 exhibits good stability, good low-temperature fluidity and low foaming rate. The lubrication coefficient of bentonite slurry was ever reduced by 85% when 0.5%wt lubricant CRH-1 contained, the working temperature up to 150℃, lubrication performance better than conventional lubricants, and compatible with drilling fluids. Lubricant CRH-1 was successfully used in the horizontal parts of two wells in southern block in A oilfield. The results show that lubrication performance of field drilling fluid improved obviously, pipe stuck and back pressure problems effectively avoided, much less lubricant CRH-1 used, and the purpose of reducing costs and increasing efficiency been achieved.

Keywords: lubricant, friction and torque, lubrication performance, water-based drilling fluid, A oilfield

APPLICATIONOFALL-OILSYNTHETICDRILLINGFLUIDINWELLYONG3-CEPINGX

SUNRonghua(Sinopec Xinjiang Xinchun Oil Development Co. Ltd, Dongying, Shandong 257000, China),DPT42(4),2019:97-99

Abstract: Yongjin Oilfield is located in the southern margin of the Junggar Basin, in the western section of Changji Sag in the central depression of the Junggar Basin. During the exploration and development, wellbore instability in Qingshuihe Formation and Xishanyao Formation is prominent. Several wells have been drilled with accidents like collapse, reaming, and sticking. An all-oil synthetic drilling fluid system was formulated, suitable for Yongjin Oilfield. It has been successfully applied in Well Yong 3- Ceping x，wall instability, suspension carrying, lubrication and sticking problems are solved, It provides the successful experience for exploration and development of Yongjin Oilfield and technical support for adjacent well drilling.

Keywords: all-oil base, synthetic base, drilling fluid, borehole wall stability, yongjin oilfield

DRILLINGFLUIDTECHNOLOGYFORCOMPLEXWELLSINGALGINESHGASFIELDINTURKMENISTAN

DENGShikui1, CHEN Xin1,2, GAO Lihua1,2, YANG Xiaobing1,2and LI Huakun1,2(1. CCDC Turkmenistan Branch, Chengdu, Sichuan 610000, China; 2. CCDC Drilling & Production Engineering Technology Research Institute, Guanghan, Sichuan 618300, China),DPT42(4),2019:100-103

Abstract: For different complex problems at Galginesh Gasfield in Turkmenistan, different drilling fluid technologies are developed and used. Zwitterion polymer and polymer-sulphonated drilling fluid system are used for 444.5mm large bore to inhibit and to avoid bit ball, well caving and trip sticking. Saturated brine poly-sulphonated system and plugging technology are used to overcome gypsum creeping, undergauging and brine invasion. Anti-sloughing plugging system is used in 3-high carbonate reef zones which are subject to well caving, with narrow safety window, developed pores and cracks, and kick-loss problem. And we have helped Company to solve other kinds of downhole accidents.

Keywords: anti-sloughing, zwitterion polymer, high pressure gypsum bed

DEVELOPMENTANDEVALUATIONOFULTRA-LOWCONCENTRATIONGUARGUMFRACTURINGFLUIDSYSTEMINDANIUDITIGHTGASRESERVOIR

LILei1，QIU Xiaoqing1，FANG Yanming1，FU Na2, LIU Xuewei3and ZHAO Jing2(1.Institute of Engineering Technology, SINOPEC Gas and Oil North China Branch, Zhengzhou, Henan 450006, China; 2.Dalian Chivy Biotechnology Co., Ltd., Dalian, Liaoning 116023, China;3.Research Institute of Petroleum Engineering, PetroChina Dagang Oilfield Company, Tianjin 300280, China),DPT42(4),2019:104-107

Abstract：Fracturing is an effective method to improve the single well production in Daniudi gas field due to its low-porosity and tight properties. In order to meet the demand of green gas field construction in Daniudi, it is necessary to reduce the reservoir damage and cost-effective fracturing fluid system. In this paper, an ultra-low concentration guar gum fracturing fluid system suitable for low-porosity and tight gas reservoirs was developed, which was characterized by the introduction of independently developed super-delayed crosslinking agent, which reduced the amount of hydroxypropyl guar gum to 0.25 %～ 0.30%, compared with the conventional 0.45% hydroxypropyl guar gum dosage decreased by 30%～44%. The cross-linking time of the ultra-low concentration guar gum fracturing fluid system was 35～45 s, meanwhile the viscosity of crosslinked jelly was more than 100 mPa·s under 90℃, 170 s-1after shearing 120 min and it still had fine prop-carrying ability under 38% high sand concentration. Applying APS and FANTA enzyme coupled-breaker technology, the gel-breaking time was 120 to 240 min, and the viscosity of gel breaking liquid and residue value was less than 3 mPa·s and 200 mg/L, respectively. The characters of the fructuring fliud made flowback easily and decreased the formation damage. Ultra-low concentration guar gum fracturing fluid system could both reduce costs and meet the technial requirments for the field operation, which has great prospects for development.

Keywords：tight gas reservior, ultra-low concentration guar gum fracturing fluid system, delayed crosslinking, rheological properties, proppant-carry capacity, gel-breaking performance