LNG Export Potential of U.S.and Its Effects on World’s Natural Gas Market

By LIANG Kun,ZHANG Guosheng,MENG Hao,ZHAO Lihua,BI Haibin,YUAN Zixue，ZHENG Jing and ZHOU Mingqing

Abstract:The U.S.is on the track to become a net gas exporter thanks to the shale gas revolution.The natural gas export potential and market competitiveness of U.S.will directly influence the world’s natural gas supply and demand pattern.According to system analysis,it is advocated the net export volume of natural gas in North America will increase greatly,the Asia-Pacific Region will be an important market for the LNG in North America in medium and long term,and the access of the natural gas in North America to European market will cause eastward flow of gas from Central Asia,Russia and Qatar and the Asia-Pacific Region will become the focus of all parties.Based on the judgment above,it is suggested that the construction of long-distance pipeline and the distribution of LNG terminal should be re-examined to avoid the huge economic risks of large-scale long-distance pipelines,the formation of China's natural gas benchmark price should be accelerated and the world’s relaxed natural gas supply and demand pattern should be taken advantage of to encourage natural gas consumption and promote the transformation and upgrading of the energy structure.

Key Words:U.S.,economical efficiency of transportation,gas market,gas export,gas price

Geological Characteristics and Potential Resources of Shale Gas in Longmaxi Formation,Zheng’an Block,Northern Guizhou Province

By DENG Lan,ZENG Jiayao and SHI Fulun

Abstract:There is abundant shale-gas resources in Zheng’an block of northern Guizhou province,in which is extensively developed by black carbonaceous shales,resulting in tremendous exploration potential.Based on large amounts of data from Anye1 welland neighboring wells,we analyzed and summed up geological characteristics of shale gas in the LowerSilurian LongmaxiFormation,Zheng’an block.Results show that(1)the shales with high quality is characterized by burial depth less than 3500 m and thickness ranging from 14 m to 25 m;(2)dominated by I and II1 types,the organic matter is in high-to over-matured stages,and the TOC is usually higher than 2.5%;(3)with rich brittle minerals,the shale reservoirs are featured by extra-low permeability and porosity,better gas-bearing property with analytical gas quantity of more than 3.0 m3/t,and better preservation,in generally belonging to a self-source-reservoir-caprock assembly;(4)through probability volume method,the calculated shale-gas P50resources of the Longmaxi Formation is 445.88×108m3;and(5)Anchang Syncline should be taken as the first favorable target belt for next exploration and development.

Key Words:Lower Silurian,Longmaxi Formation,shale gas,geological characteristics

Belt Division of Permian Structures in Western Sichuan Basin and Exploration Prospects

By XIE Geyun,ZHANG Benjian,YIN Hong,MA Hualing,WANG Yufeng and LIU Bai

Abstract:In western Sichuan Basin,the Middle Permian has become the main target.In order to find out favorable belts and evaluate their prospects,it is necessary to implement a structural-belt division.Based on previous achievements,both features and plane distribution of Permian structures were at first summarized;and then,structural belts were divided in the light of feature difference;finally reservoir-forming conditions in various structural belts were analyzed.Results show that there are five favorable belts with better structural trap and reservoir-forming conditions resulting in better exploration prospects,including Zhongba—Shuangyushi and Shejianhe—Tongziguan back thrust subbelts,Lianhuashan—Gaojiachang fault and fold structural subbelt,Jiulongshan uplift structural subbelt,and slope structural subbelt in southwestern Sichuan Basin

Key Words:Middle Permian,zone division,tectonic characteristics,exploration prospect

Characteristics and Genetic Mechanisms of Heavy Oil in Weixi’nan Sag,Beibuwan Basin

By LI Cai,ZHOU Gang,YANG Xibing,DONG Guineng and CHEN Yabing

Abstract:In Weixi’nan sag,northern depression of Beibuwan Basin,heavy oil is mostly distributed in the Neogene Jiaowei and Xiayang formations,and often indicates some features of high density,viscosity,and colloid asphaltene,and low sulfur content.For heavy-oil reservoirs in this study area,the basic characteristics and genetic mode were analyzed according to crude physical properties and geochemical indices,oil source correlation,and regionally geological conditions.Results show that in this area,heavy oil is of secondary genesis;it is just distributed longitudinally at a strong biodegradation belt with well developed microorganisms;and affected obviously by biodegradation,water washing in the process of underground-water flowing may intensify crude-oil thickening.

Key Words:Weixi’nan sag,heavy oil,reservoir characteristics,genesis

Gas Components and Isotopic Characteristics of Yuanba Gasfield

By QIN Xuqian

Abstract:After analyzing gas geochemical characteristics of Changxing Formation,Yuanba gasfield,northern Sichuan Basin,it is shown that,natural gases are dominated by hydrocarbon gases in chemical composition with methane the most,and featured by higher drying coefficient,moreover non-hydrocarbon components are mainly composed of sulfur and carbon dioxide;and δ13C value of hydrocarbon gases exhibits a feature of normal carbon isotope sequence due to two effects of high thermal evolution and thermochemical sulfate reduction(TSR).In addition,after a correlation of ethane in natural gas,bitumen in reservoirs,and δ13C of various source rocks,it is deemed that gases in this study area should be originated from Permian source beds.For non-hydrocarbon components in different well blocks,their content varies a lot.Other analysis on gas components,and isotopic correlation and distribution also shows the TSR stronger in Yuanba I well block than in Yuanba II block.

Key Words:Yuanba gasfield,gas component,isotope,thermochemical sulfate reduction

Application of Probability Cumulative Grain Size Curves and Lithofacies Association to Sedimentology

By ZHANG Jieru,YANG Hongfei,HAN Jianbin,LI Qiang and LIU Wenchao

Abstract:Guantao Formation in Jinzhou oilfield,which its sedimentation belongs to braided-river facies,mainly consists of massive sandstones.Core observation displays an obvious difference among grain size in longitudinal direction,also revealing some variations of both depositional environment and hydrodynamic condition.However,smooth box-like natural GR,SP,and resistivity curves demonstrate that conventional logging curves have some disadvantages in depositional environment analysis.Through core analysis,we at first identified five lithofacies,three lithofacies associations,and three microfacies,and then systematically summarized certain characteristics of probability cumulative grain size curves on the basis of plenty of core and sidewall core data,thirdly classified these curves into three types with the help of lithofacies,finally established probability grain size curve plates under various depositional environments in order to assist microfacies classification.

Key Words:Guantao Formation,probability cumulative grain size curves,lithofacies,microfacies

Optimizing Schemes of Potential Productivity in High Sour Gasfields by ANP

By LIANG Ping,HU Lianxing,TAO Jiaming,CHEN Yiwei,FU Xianzhao,SONG Donghan,LI Mengying and DUAN Jiayi

Abstract:In order to boost an exploration and development of natural-gas resources in Sichuan-Chongqing area,it’s very urgent to implement potential tapping of mature gas-producing regions in eastern Sichuan Basin.According to current situation of surface gathering system in these regions,a judgment matrix was developed by an approach called analytical network process(ANP).Furthermore,an optimal mode was established bymeansofSuperDecisionssoftware,and both weight matrix and extreme matrix showing consistency were calculated.The weight factor was obtained;and schemes to newly build desulfurization installations depending on A2 dewatering station were recommended.An application of these optimal schemes to sour gasfields in mature gas-producing regions shows that the potential productivity has been obtained to the most.

Key Words:high sour gasfield,analytical network process,potential productivity,scheme optimization,extreme matrix

Gas-water Transitional Zones and Gaswater Distribution Mode in Dina 2 Gasfield

ByRAN Lijun,BAIRong,YAO Chao,WANG Kaiyu,WANG Weiwei,LI Shaohua and CHEN Yuan

Abstract:Dina 2 gasfield,in which most reservoirs are characterized by poor petrophysical property and strong heterogeneity,is typical of complex gas-water correlation and thicker gas-water transitional zones.It is difficult to identify the transitional zones for these low-permeability gas reservoirs by conventional well-logging interpretation.So,the distribution attributes in these zones were analyzed through two approaches of capillary-pressure curve and relative-permeability curve.Results show that for these gas-water transitional zones,their thickness is respectively 160 m in Palaeogene Suweiyi 3 Member of eastern field,180 m in western field,and 266 m in Cretaceous.And a gas-water distribution mode was also developed,which not only accords with actual testing result but also provides evidence for making water prevention and control measures.

Key Words:Tarim Basin,Dina 2 gasfield,capillary-pressure curve,relative-permeability curve,gas-water transitional zone

Drawdrop Methods to Calculate Geological Reserves and Their Application to Low-permeability Gas Reservoirs

By ZHAO Kunshan

Abstract:Average formation pressure is the key parameter to calculate geological reserves of a gas reservoir by material balance method.However,it’s unrealistic to carry out shut-in furtherto obtain this parameter;moreover,it’s currently deemed that there is big error among well test pressure.Combining with some characteristics of balanced pressure drop under pseudo-steady state,and adopting two equations of both material balance and deliverability,we deduced two methods,containing(1)adopting well test pressure to calculate reserves by drawdrop method underbetterreservoirconnectivity or shut-in test pressure very close to average formation pressure,(2)under poor connectivity,firstly adopting shut-in test pressure to calculate reserves of different belts,secondly summing these different reserves to finally gain the total reserves.In addition,these two methods were affirmed by numerical simulation,showing that all errors are limited to 3%,which meets the demand of engineering precise.

Key Words:gas reservoir,material balance,pseudo-steady state,formation pressure,reserves

Reserve Calculation Methods for Extrahigh-pressure Gas Wells

By LI Xucheng,CAO Jian,LIANG Jing and ZHOU Guangliang

Abstract:For marine gas wells with extra-high pressure in western Sichuan Basin,we implemented a study on empirical calculation formula of gas deviation factor,and analyzed the applicability of various methods to calculate reserves.Results show the smallest error obtaining from HY method through compressibility factor.So,HY method is recommended to calculate the compressibility factor for those extra-high-pressure gas wells.Moreover,a comparison of various calculation methods reveals that(1)both material balance and analytical methods are strict to dynamic monitoring data even better effect gained;(2)cumulative output,oil-pressure decline,and logistic function methods have advantages of less required parameters and convenient calculation whereas disadvantages of offset existing in early calculation,which is not conducive to recognizing reservoir dynamic features;and(3)by material balance method available for fractured and fractured-vuggy gas reservoirs with extra-high pressure,the calculated result is mainly affected by comprehensive compressibility.So,it is suggested to carry out the study on the compressibility.

Key Words:extra-high pressure,deviation factor,reserve prediction

High-temperature Fluid Slug for Plugging Oil and Gas

By WU Yan,WANG Zaiming,XU Ji,SHEN Yuanyuan and LI Yunfeng

Abstract:With developed fractures,most buried-hill oil and gas reservoirs in Nanbao block are typical of high well temperature,narrow pressure window,serious overflow and leakage in the tripping operation or completion.So,two formulas of high-temperature fluid slug were formed after the reaction of sulphonate copolymer to double-stage crosslinking agent,including that(1)under low temperature,it is featured by moderate viscosity,easy to pump,and being capable of cleaning shaft lining;and(2)under high temperature,it is characterized by viscosity of above 40000 mPa·s to plug high-pressure oil and gas and further to prevent them from rising.Moreover,a number of skills to evaluate the slug property were established.Indoor experiments show that the highest temperature resistance and the pressure-bearing are respectively 150℃and 0.03MPa/m.And other experiments on one well in Naobao 2 structure also indicate that these two formulas can successively plug oil and gas below 150℃for 13 days,and provide support for safe and efficient drilling this well with high temperature and narrow density window.

Key Words:plugging high-pressure oil and gas,fluid slug,temperature resistance,pressure-bearing,narrow density window

Well Testing Technologies and Their Application to Sour Gas Wells,Western Sichuan Basin

By YANG Bo,FAN Rong and LUO Lingrui

Abstract:Most marine gas reservoirs discovered in western Sichuan Basin are featured by burial depth varying from 5500 m to 6500 m,high temperature,pressure,and sulfur content,and low formation pressure coefficient.Aftersumming up some experiences and lessons from well testing of sour gas wells in Yuanba area,combining with actual situation in western Sichuan Basin,we developed two technologies containing APR testing combination operation and direct downhole completion tool testing combination operation.It is demonstrated by field application that,(1)the optimized APR testing pipestring is suitable for those marine strata in the basin with special geological conditions(such as low formation pressure coefficient,and high temperature and sulfur content),and has two virtues of safety and fast reservoir evaluation;and(2)to utilize the formed domestic and complex anti-sulfur testing may implement a safe testing in high-sour and high-yield marine strata for a long time.

Key Words:western Sichuan Basin,sour gas well,APR testing,completion tool testing

Improvements of Y241 Packer and Its Application to Western Sichuan Basin

By ZHOU Yijun

Abstract:Y241 packer is extensively used to most shallow Jurassic gas reservoirs,western Sichuan Basin,however presenting some problems like release squeeze and hard to get out tools during multilayer fracturing,packer testing,and leakage detection.So,we analyzed its basic framework and operation principle,and putforward some improvementsagainst these problems.The improved packer has obtained a successful application.

Key Words:Y241 packer,hydraulic pressure,release,locking

PreliminaryAnalysison Interprovincial Gas Pipeline Networking Projects of Zhejiang-Jiangxi and Zhejiang-Anhui

By MIAO Shengtao,CAI Zheng and GE Guobao

Abstract:The interprovincial gas pipeline networking project between Zhejiang and Jiangxi and between Zhejiang and Anhui is conducive to improving the gas supply capacity of Zhejiang,Jiangxi and Anhui provinces,making efficient use of coastal LNG receiving stations and international LNG resources,and constructing a mutually coordinated and beneficial gas supply system among the regions.From the current situation and planning on the construction of the pipeline network in Zhejiang,Jiangxi and Anhui provinces,the paper describes the development condition of the pipeline network in the gas market of the three provinces,analyzes the potential pipeline connection location and the construction conditions of the networking project,and gives reasonable suggestions for the implementation ofthe interprovincialgas pipeline networking project between Zhejiang and Jiangxi and between Zhejiang and Anhui.Due to the constraints of pipeline network planning at Anhui and Jiangxi side and the pipeline transmission capacity,the two pipeline networking projects are in poor construction conditions and it is suggested to strengthen the connection between the gas pipeline networking plans between Zhejiang and Jiangxi and between Zhejiang and Anhui in far term and plan the Changshan-Wuyuan-Leping connection line for Zhejiang and Anhui and Changxing-Anhui connecting line forZhejiangand Anhuiaccording to the gasconsumption growth of the three provinces and the gas supply condition of coastal LNG receiving stations and national trunk gas pipeline.

Key Words:gas pipeline,interprovincial pipeline networking project,analysis on balance of supply and demand

Calculation and Operation of MultiplestagePositiveDisplacementCompressors Under Variable Conditions

By CHEN Xuhua,RAN Dongming,LI Gang and ZHONG Yuanhan

Abstract:Positive displacement compressors have been widely applied to oil and gas industry.It’s necessary to implement some no-load or load commissioning after their installation.Moreover,for multiple-stage positive displacement compressors with invariable size and main parameters along with variable interstage pressure and temperature,it’s essential to carry out calculation in order to guide commissioning.In this study,the whole calculation flow was at first analyzed for piston multiple-stage positive displacementcompressors;and then taken BOG compressor with five stages in one LNG plant as an example,the actual operation of this compressor undervariable conditionswasdiscussed;finally suggestions were made,that operational process under normal conditions is not always available for new conditions and it should be adjusted immediately.

Key Words:positive displacement compressor,variable condition,commissioning debugging,BOG compressor,nitrogen commissioning

Analysis on BOG Generation and Treatment in LNG Stations

By REN Jinping,YU Chunliu,REN Yongping,MA Zhipeng and ZHANG Qi

Abstract:The paper introduces the basic structure of LNG stations,describes and analyzes the three main approaches(introduction of external heat,volume replacement and flashing during loading and unloading,and changes of ambient temperature and pressure around)that generate BOG in the operation process of LNG stations and puts forward a method to treat the BOG.The method advocates that active cooling method should be used and then a low temperature refrigerator should be used to cool the LNG in tank or condense and then re-liquefy BOG.

Key Words:LNG station,BOG generation,BOG treatment,re-liquefaction,active cooling method

Metering ErrorofDiaphragm Meter CausedbyTemperatureandPressure and the Resulting Impact on Economic Benefit

By LI Xingrong,HE Haiyang,QIU Xianzhong and XIA Hongchun

Abstract:With regard to the metering error of the diaphragm meter used in the metering of low pressure natural gas for residents in Nanchong,the paper,based on the metering principle of the diaphragm meter and distribution of users of the diaphragm meter,studies and analyzes the cause of the metering error from two aspects of temperature and pressure,further describes the effects of the metering error on economic benefits and puts forwards that intelligent diaphragm meter should be used and gas meter with temperature and pressure compensation device can be installed for new users or users whose gas meter is expired and should be replaced to reduce the metering error.

Key Words:temperature,pressure,diaphragm meter,metering error,economic benefits

Analysis on Gas Loss Control of LNG Station

By LIHuailei,SHANG Feifei,LIMing,ZHOU Xiaoli,QIANG Long,LIU Xiaojie and BAO Xizhong

Abstract:Reducing gas loss is one of the key measures to save energy in LNG station.From the aspects of the metering error,equipment maintenance,application of process technology and special work type and technological type of LNG filling station,the paper analyzes the causes of the gas loss and proposes to reduce the gas loss in LNG station by taking measures like having reasonable selection and installation and regular calibration of measuring instruments,strengthening equipment maintenance at the station,optimizing the process and promoting the use of new technologies,so as to provide an energy-saving,loss-reducingand safetechnicalfoundation and running environment for future construction and operation of LNG filling station.

Key Words:LNG station,gas loss,metering,control,LNG storage tank

Analysis on Natural Gas Peak Shaving in North China

By WANG Duo

Abstract:In order to study the natural gas supply characteristics and laws in North China,ensure the safe and stable supply of natural gas and provide reference for the study on peak regulation of natural gas in the future,analysis and calculation are carried out for the gas consumption rules of users,the gas supply characteristics and gas supply capacity of gas supply facilities according to the gas supply data over the years.The analysis results show that there is a huge difference in users’gas consumption in North China,some gas demands are restrained and there is a huge potential for natural gas demand.LNG,gas storage reservoirs and natural gas pipelines are all important means for the natural gas peak shaving in North China.It is suggested to speed up the construction of peak shaving facilities and ensure the supply of LNG in winter.

Key Words:gas supply,gas demand,peak shaving,pipeline,gas storage reservoir

Strategy Study of Urban Gas Enterprises Developing Natural Gas Storage Facilities

By LI Zheng and CAI Xinlei

Abstract:Urban gas enterprises are an important part of the natural gas industry and a key link in the construction and operation of natural gas storage facilities.As problems of urban gas enterprises in the aspect of development of gas storage facilities,such as low development speed,single gas storage measures,insufficient capital investment and weak technical force have seriously restricted the reasonable development of gas storage facilities,urban gas enterprises should take targeted measures,such as strengthening the construction of gas storage facilities,developing various forms of gas storage facilities,widely absorbing various kinds of funds,and improving technical strength in an all-inclusive way to continuously enhance the enthusiasm of enterprises in gas storage facilities and achieve the specified gas storage scale.

Key Words:urban gas,natural gas,gas storage facility,gas storage reservoir,development strategy

A Study on Economic Boundary Model of Overseas Single Shale Gas Well

By YAN Na and XING Shubin

Abstract:With the rapid descent of shale gas output,a large number of new wells are expected to be drilled to offset the output decline of old wells.In the operation of overseas shale gas blocks,new technologies should be used to continuously improve the shale gas development efficiency and benefits on one hand,and a scientific planning on production should be made under the constraints of the contract clauses to obtain the best benefits on the other hand.Therefore,the economic frontierofoverseassingle shale gas wellisstudied and based on the dynamic input and output evaluation of single well,the maximum or minimum limit value that affect the economic benefit of single well are defined. Technological schemes are continuously optimized within this range to realize maximum profits.

Key Words:shale gas,economic boundary of single well,oil and gas contract

Discussion on Improvement of HSE Management System Quantitative Audit

By TIAN Yanliang and LIU Xiaoying

Abstract:On the basis of describing the necessity of the quantitative audit of HSE management system,the paper analyzes the problems in current quantitative audit of HSE management system and main reasons and suggests to take means like making a systematic planning of HSE audit,strengthening the management of the audit process,strengthening the use of audit techniques,paying attention to the application of the audit results and conducting big data analysis to improve the quantitative audit of the HSE management system.

Key Words:HSE management system,quantitative audit,audit quality improvement,traceability audit

Application of Resource Flow Cost Accounting in Natural Gas Enterprises

ByPENG Wanling,LIAO Danfeng,SUN Mulan,ZHANG Yan,YANG Lan and ZHONG Keran

Abstract:As the main creator of social value,enterprises bring environmental pollution and ecological damage while having production and operation.As existing traditional cost accounting method failed to meet enterprises'requirements on environmental cost,the resource flow cost accounting,as a result of the development of environmental management accounting,provides a new environmental management technology for enterprises.On the basis of expatiating the conceptual system of the resource flow cost accounting,the paper has preliminary discussion on the application of resource flow cost accounting of a natural gas enterprise in China and thinks the resource flow cost accounting can make the resource waste information accurate to every process,reduce the environmental load fundamentally and improve the resource utilization.

Key Words:resource flow,cost accounting,natural gas enterprises,environmental cost