Table of Content

01 April 2014, Volume 36 Issue 2

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Gas Sources Condition of Gas Hydrate Formation in
Shenhu Deep Water Sea Zone

Su Pibo1，2, Liang Jinqiang1，2, Sha Zhibin1，2, Fu Shaoying1，2

2014, 36(2):  1-8.  DOI: 10.11885/j.issn.1674-5086.2013.10.16.01

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To further study the gas source controlling factors of gas hydrate formation in Shenhu deep water zone of the northern
in South China Sea，this paper focuses on the survey area of hydrate in Shenhu area，and analyzes the influence of various gas
source supply conditions by the basic survey data and results of drilling in the area. The main results are as follows：（1）in
the shallow area，about 400～1 200 m under the seabed，there are good conditions for biogenic gas formation and the potential
Bio-gas source rocks，and it has great potential for the production of the biogenic methane gas；（2）in the deep area，the early
Tertiary area，Wenchang Formation and Enping Formation are two main source rocks and can provide some thermogenic gas for
gas hydrate formation；（3）Gas hydrate reservoir was formed in the deep areas，where deep thermogenic gas migrates upwards
to shallow ground by faults or diapers，then，biogenic gas and thermogenic gas were enriched in the stability region of hydrate
by lateral migration.

Characteristics of Tectonic Evolution and Distribution and Enrichment
Patterns of Oil and Gas in the Chinese Marginal Basin

Zhang Wei1，2, He Jiaxiong1, Yan Wen1, Zhang Jingru1，2, Li Xiaotang1，2

2014, 36(2):  9-23.  DOI: 10.11885/j.issn.1674-5086.2013.08.22.01

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The Chinese marginal basin is located at the most active Cenozoic era，which is formed by the interaction of Eurasia，
India-Australia and the Pacific plates，and its southern marginal basin is still subjected to the impact of the South China Sea
cracking and expansion and many other factors，so the rift-depression double-layer structure basins have formed，which have
different types，such as extensional or composite strike-slip-extrusion type. The sedimentation has filled in the basin，which
is mid-deep lake face strata and hydrocarbon source rocks in the early phase of the Paleogene rift Valley，coal-bearing strata
and hydrocarbon source rocks in the late phase of the Paleogene rift，and marine strata and hydrocarbon source rocks in the
Neogene depression，which has laid a foundation for oil and gas formation. Due to the impact of the regional geological setting，
the characteristics and thickness of the marginal basin crust has gradually graded features from the continental margin area to
the deep ocean basin area. The basin subsidence deposition center has gradually migrated to the deep ocean basin，which results
in the terrestrial heat flow and geothermal field increasing gradually to the ocean basin，coupled with the space-time mutual
coupling configuration between advanced new tectonic movement and source supply system，which ultimately controls and
restricts the law of oil and gas distribution and enrichment in marginal basin.

Sequence Stratigraphy and Evolution of Sedimentary Facies of
Upper Perma in Jiannan Area

Yang Wei1，2, Hu Mingyi1，2, Gao Yan3

2014, 36(2):  24-34.  DOI: 10.11885/j.issn.1674-5086.2013.04.02.01

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Based on previous researches of sedimentary structure of Changxing Formation，and combining with reorganization
of sequence boundary，logging and lithology data，Changxing Formation in Jiannan Area has been divided into two three-order
sequences and five fourth-order sequences，the development of reservoir and transverse distribution of sedimentary facies within
fourth-order sequence in Changxing Formation have been studied in this paper. According to the calibration of fourth-order
sequence on seismic section and time-slice map of strata，taking system tract of fourth-order sequence as mapping unit，the
evolution of sedimentary facies is also discussed. The results indicate that the lower three-order sequence experienced three
times relative fall of sea level，the organic reef and bank mainly developing in the stage of HST；in the upper three-order
sequence，exposed organic bank with lithology of dolomite is widely distributed，but the scale is smaller than that of lower
three-order sequence and the distribution range moves to the central part of study area gradually.

Fracture Characteristics and Petroleum Geological Significance of
Lianglitage Formation in Shunxi Area

Ma Zhongyuan1, Huang Wei1, Ren Lidan1, Shang Kai1, Zhang Jie2

2014, 36(2):  35-44.  DOI: 10.11885/j.issn.1674-5086.2012.10.29.02

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Shunxi Area of middle Tarim Basin is located in the northwest pitching end of Katake uplift. Lianglitage Formation
reservoir of Ordovician is mainly fracture-cavity reservoirs. The studies show that cracks can be divided into the structural
ceacks and non structural cracks. The structural cracks can be divided into vertical fractures，oblique fractures（high angle
fractures，low angle fractures）and horizontal fractures；the non structural cracks contain pressure dissolved stitch seam fractures
and diagenetic fractures；the oblique fractures is relatively more than vertical fractures and horizontal fractures，and trend
of oblique fractures is mainly NW，NWW，followed by NE. Structural fractures have three stages of activities：late Caledonian—
early Hercynian，late Hercynian and Indosinian—Yanshan periods. Further studies show that tectonic stress field，
fracture，lithology，physical property and layer thickness is closely related to the crack. The crack growth is conteolled by local
structural high，key parts，turning point，the junction of the brittle fracture，lithology，physical property and thickness of strata.
Cracks in the area have very important significance in petroleum geology，which can not only be used as good reservoirs，and
also favorable channel and in some extent it can expand karst effect；in the oil and gas migration and accumulation process，
cracks are good oil and gas migration channel for karst effect，plays a vital role in oil and gas accumulation.

Physical Simulation of Oil and Gas Backflow and Its
Geological Significance

Wang Yongshi1, Shan Yixian2, Lao Haigang3

2014, 36(2):  45-50.  DOI: 10.11885/j.issn.1674-5086.2012.08.30.02

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The exploration practice proves that the phenomenon of the oil and gas backflow exists in Chezheng Depression，
the physical simulation experiments of the oil and gas accumulation confirmed that there are two types of oil and gas intrusion
in hydrocarbon migration process，i.e. fracture as migration channel and the sand body framework as migration channel，the
former is the important channel of the oil and gas backflow，however molecular replacement is the formation mechanism，and
the oil and gas pool is of small size. the latter in sand body framework for migration of oil and gas intrusion，is that pressure
difference controlling petroleum downward migration is an important driving force. The desired maximum pressure depends on
the related physical property of sandbody，and it can form large-scale oil and gas reservoirs. The research provides theoretical
support for the expansion of deep oil and gas exploration in petroliferous basin.

Research on Chemical Logging Evaluation of Water Flooded
Layer in Sandstone Reservoir

Cai Dongmei

2014, 36(2):  51-56.  DOI: 10.11885/j.issn.1674-5086.2012.10.11.03

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Evaluation on water flooded layer in the sandstone reservoir is a complex and difficult problem which has persecuted
oilfield workers for many years. It is a new field of geochemical investigation for evaluating waterflooded layer by geochemical
logging，which may be an effective and new way for finding residual oil in the secondary development stage. Based on the
depth analysis on the mechanism of the watered-out oil layer，gas chromatogram，pyrolysis chromatography and coring data，
the evaluation model of waterflooded layer and interpretation chart are established by calculating the parameter of porosity，oil
saturation，oil displacement efficiency，and so on，which provides the quantitative calculation and qualitative identification for
the evaluation method of waterflooded layer in the sandstone reservoir. The method is applied in the D group of C area in B
Field of A Basin. The result indicates that the effectiveness is very great，with the agreement rate of 95percent compared with
the result of well testing interpretation. The study revealed that the chemical logging method is applicable with great utilization
value，which lay the foundation for the scheme adjustment and the enhancing oil recovery of the oilfield in the mid-late period
of oilfield development.

Fracture Modeling at Different Scales Based on Convergent
Multi-Source Information

2014, 36(2):  57-63.  DOI: 10.11885/j.issn.1674-5086.2012.08.30.11

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For the fractured carbonate reservoir，fractures are effective reservoir space and primary channels. But the development
of fractures is complex and the reservoir has strong heterogeneity. The normal geological modeling methods are
not applicable to the fracture modeling. This paper takes X Oilfield in the Middle East Region as an example and establishes
the technology of fracture modeling on a scale of fracture zones，medium-size fractures，and small-size fractures based on
convergent multi-source information including geology，well-logging，seismic，and dynamic data. It is first proposed by the
authors that the fracture reservoir facies model is established on the combination of the deterministic model and stochastic model
method. Under the constraints of facies model，the development intensity bodies at different scale of fractures are established.
Finally，a discrete fracture network（DFN）model and fracture property model are generated by means of DFN modeling and
parameter field equivalence. In general，this paper discusses and studies a set of fracture modeling method converging with
multi-source information on the basis of different scale of fractures for the complex carbonate reservoir.

Recognition of Single Channel in Composite Sand Body Based on
Well-seismic and Inversion

Xu Liheng, Hao Lanying, Liu Jiangyu

2014, 36(2):  64-70.  DOI: 10.11885/j.issn.1674-5086.2012.08.30.08

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With the well pattern successively infills，the distributing tend of reservoir sandbody is gradually determined，the
distributing characteristics of sandbody in vertical direction can be accurately recognized according to the logging data，but
that in horizontal direction is difficulty to be identified. Aiming at the problems of the heavy tasks and the ambiguity on the
recognition of a single channel on well-tie sections，the technique of well-seismic and inversion to predict the boundary of a
single channel in composite sand body was proposed in the paper，and the river channel boundaries were further proved by
the logging curve characteristics. Four typical indicators of the single river channel in composite sand body are recognized
on the inversion sections，8 synchronous but not simultaneous single channels are identified clearly by sandstone poor belt
conditions of the seismic inversion plan. With the single channel recognition achievement，good effects are obtained on the
injection-production relation and remaining oil tapping，which shows a good application prospect.

Study on Gas-water Layer Identification Model in the Single Well
of Xu 2 Gas Reservoir of Xinchang Gas Field

Pang Heqing1, Kuang Jianchao2，3, Cai Zuohua4, Liao Kaigui4, Wang Zhong2，3

2014, 36(2):  71-78.  DOI: 10.11885/j.issn.1674-5086.2013.08.30.01

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Xu 2 Gas Reservoir，which is in Xinchang Gas Field in western Sichuan Basin，is a typical low-permeability and tight
clastic gas reservoir. Due to the complicated geological conditions and serious heterogeneity in this area，the gas-water layer
distribution is very complicated，and the bound water’s content is high. The boundaries of resistivity between gas reservoir and
gas-water layer are blurred，so that some mistakes arise in log interpretation. We use kernel principal component analysis and
support vector machine，also known as KPCA–SVM model，which is based on particle swarm optimization（PSO），to solve
the problem. Firstly，the model extracts non-linear properties of variables by kernel principal component analysis（KPCA），
and then inputs the properties of a variable into the support vector machine（SVM）. And in the identification process，we
use the particle swarm optimization（PSO）to seek the optimization algorithm. Finally，the gas-water layer identification is
implemented in the SVM. We applied this model to gas & water layer prediction of Xu 2 Member gas reservoir of Xinchang
Gas Field，and the recognition result is in line with the actual situation of the study area.

Theoretical Simulation and Analysis Factors of Resistivity in
Vuggy Reservoir

Zhang Zhaohui1, Gao Chuqiao2, Gao Yongde3

2014, 36(2):  79-84.  DOI: 10.11885/j.issn.1674-5086.2012.08.30.14

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Because of the many factors influencing the resistivity of carbonate reservoir and the complex conductive mechanism，
it is difficult to identify the reservoir and interpret the property of fluids. On the basis of pore-structure physical model，
we simulated the resistivity of reservoir，and analyzed the factors which affect the resistivity of reservoir. The factors include
the throat size，the resistivity of formation water，and the resistivity of matrix，and the vuggy size，and so on. At last，the
influencing degree to resistivity of reservoir is discussed and the reason of abnormal resistivity in carbonate is interpreted in
this paper. The resistivity of reservoir gradually reduces with the throat diameter increasing，and increases as the resistivity of
matrix and formation water increases. Vuggy extension influence on resistivity along the direction of the current is higher than
that along the vertical current direction. With the vuggy size along current direction increasing，the resistivity reduces. The
effect of throat diameter on the resistivity of reservoir is bigger than vuggy size. The effect of throat diameter on the resistivity
of completely water-saturated rocks is bigger than on completely oil-saturated rocks，but for the resistivity of the matrix and
the formation water，the extended direction and size of the vuggy，the condition is opposite.

Optimization Design of Horizontal Wells in Tight Sandstone Reservoir
in Baimiao Condensate Gas

Ma Qingyin1, Li Caixue1, Bi Jianxia2, Su Daomin2, Jiang Senbao2

2014, 36(2):  85-90.  DOI: 10.11885/j.issn.1674-5086.2013.11.05.02

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Baimiao Gas Field belongs to a tight sandstone condensate gas reservoir which is characterized with complicated
structure，deep burial，poor reservoir property，high content of condensate oil，showing small differential pressure，high formation
pressure. Gas well fracturing stage generally has a higher capacity. But with the condensate blockage flow channel in
the near wellbore area precipitation，the production fast declines and the stable production period shortens. The vertical well
technology has been used in the development of the gas field，which is of low recovery degree and poor development effect.
The development of horizontal well can increase the production rate and the recovery of gas reservoir. According to the geological
characteristics of the gas reservoir，and through in-depth study of the geological characteristics，we recognize the local
structure and the distribution rule of reservoir. Horizontal well test was carried out to study the development of this kind of gas
reservoir. We optimized 2 horizontal wells and obtained initial effect which has a certain guiding significance for the rational
development of tight sandstone gas condensate gas reservoir.

Optimization Technology for Horizontal Well Pattern in Ultra-low
Permeable Tight Reservoirs

Zhao Jiyong, He Yonghong, Fan Jianming, Li Shuheng, Wang Shitou

2014, 36(2):  91-98.  DOI: 10.11885/j.issn.1674-5086.2012.05.03.01

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There is abundant petro-resources with great development potential in the ultra-low permeable reservoirs located
in Ordos Basin；however，it is difficult to increase the production rate of single well drastically as the formation is of poor
reservoir properties and strong heterogeneity. According to the characteristics of ultra-low permeable formation，the study is
carried out focusing on horizontal well pattern，well drainage direction，parameters of horizontal section and producer-injector
spacing，to establish the effective displacement pressure system. According to the studies，the research results show that the
well pattern is the crisscross row pattern，which is the joint cloth well for the horizontal and vertical wells；the artificial pressure
crack pattern is the dumbbell-shaped；the density of artificial fracture is 2/（100 m）；the length of horizontal section ranges from
700 to 800 m；the producer-injector spacing ranges from 700 to 800 m；the row spacing is about 150 m. Based on the research
results for the horizontal well pattern design，the average initial production rate of single horizontal well in ultra-low permeable
reservoirs is about 8.0 t/d，which is 4 times of the average production rate of vertical well. This proves that this method can
improve the well production rate of ultra-low permeable reservoirs drastically.

A New Method of Analysis of Low Permeability Reservoir Interwell
Reserves Producing Status

Sun Laixi1，2, Zhang Zonghui3, Wang Shili4, Luo Gang4, Deng Qingyang1

2014, 36(2):  99-104.  DOI: 10.11885/j.issn.1674-5086.2012.10.19.01

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The existence of start-up pressure gradient of reservoir has a great impact on the reservoir producing extent，the
bigger the start-up pressure gradient，the poor the the reservoir producing extent. Based on the mechanism of fluid flow from
the low permeability reservoir，the relationship between the start-up pressure gradient and permeability relationship of the
study area were established by the in-situ early bound water production performance of single-phase data and well test material
and well test method. we also analyze a typical well group pressure driven between the injection wells and production wells
gradient features. By comparing values of reservoir permeability and reservoir fluid permeability values corresponding to the
size，we determine whether the fluid within the reservoir may flow. This quantitative analysis of low permeability reservoir
interwell reserves producing condition provides the reference for determining interwell residual oil distribution provides of
similar reservoir.

Research on the Match Between Lateral Accretion Shale Bedding
of Point Bar and Flood Pattern

Liu Wei1，2, Ding Yajun3, Song Zhicong4, Luo Shuiliang5

2014, 36(2):  105-113.  DOI: 10.11885/j.issn.1674-5086.2013.09.14.02

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Based on the reservoir architecture model of Gangdong Oilfield，the matching between lateral accretion shale bedding
of point bar and flood pattern is analyzed. The effects of different well networks on the development efforts are studied
respectively，including vertical well，horizontal well and sidetracking horizontal well. The results show that，a better development
effect can be obtained with a low ratio of injection-production wells and the line of wells vertical to lateral accretion
shale bedding when row pattern is utilized for exploitation. In horizontal wells development，when the horizontal section is
perpendicular to incident lateral accretion shale bedding，remarkable effects can be achieved. The horizontal section should
be keep away from injection wells when sidetracking horizontal wells were drilled out for potential tapping. In this study，
remarkable potential tapping results were achieved when the horizontal section was three lateral accretion shale bedding away
from injection wells，and horizontal section crossing with lateral accretion shale bedding at a 45-degree angle. The results of
study are applied to completion of injection-production pattern horizontal wells and sidetracking horizontal wells with the good
effect of oil increment.

Study on the Comprehensive Water Control Methods in Sebei Gas Field

Cao Guangqiang1，2, Li Wenkui2, Jiang Xiaohua3

2014, 36(2):  114-120.  DOI: 10.11885/j.issn.1674-5086.2012.07.25.04

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Sebei Gas Field is a thin layer gas reservoir with very complex gas-water relationship. In recent years，the water
and gas ratio increases quickly，and the main gas edge water invasion is very serious in the gas field. Its uneven waterline
propulsion causes internal segmentation affected water，which results significant impacts on gas recovery. In addition，the gas
well production capacity and output dropped sharply，and the sand production increases rapidly. The drainage gas recovery
technique alone is not effective to solve the water problem. The article analyzes the necessity and feasibility of geological
conditions of water conservancy，discusses the feasibility of the overall water control in Sebei Gas Field and puts forward
methods for comprehensive water control. The objective is to effectively prevent further damage of edge water breakthrough to
the inner regions of the gas field，and to solve the problem of gas field water production，and to guarantee continuous and stable
development of gas field，by combining gas reservoir geological description，reservoir engineering，drainage gas recovery and
water plugging technology，from the gas field level adjustment. The comprehensive water control methods have been a pilot
test at some formations with good results.

Study of Identification Method of Transient Flow from Permanent
Downhole Pressure Data

Liu Junrong, Yao Jun, Yu Weiqiang

2014, 36(2):  121-127.  DOI: 10.11885/j.issn.1674-5086.2012.06.01.01

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The real-time monitoring technology of the downhole conditions with permanent downhole pressure gauge is playing
an important role in improving reservoir and well management. During the interpretation of permanent downhole pressure data，
it is vital to acquire a good well-test result that accurately identifies the beginning time of new transient flow. Due to the large
volume of the collected data by permanent downhole gauge，it is impractical to partition and process these data manually. Based
on wavelet transform module maximum theory and noise-robust differentiator，the identification methods of transient flow from
permanent downhole pressure data are investigated with the synthetic data. The results show that the wavelet transform module
maximum method may not identify some key transient flows，and it is sensitive to the noise. The data must be de-noised before
using this method. But with the noise-robust differentiator，the transient flow can be identified accurately and effectively using
its 2nd derivative. It is robust to noise and can be used to identify the transient flow without data de-noising. The study provides
a new automatic method to process the permanent downhole data.

Evaluation Methods of Producing Degree of Heterogeneous Oil Layer
During the Stage of Extra-High Water Cut

Mu Wenzhi

2014, 36(2):  128-132.  DOI: 10.11885/j.issn.1674-5086.2012.11.10.03

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The interlayer and interwell producing degree are very different in the water drive reservoir during the stage of
extra-high water cut. Based on the relational expression of the recovery，the sweep efficiency and the displacement efficiency，
this paper introduces the conception of flushing efficiency coefficient to describe producing degree of multilayer heterogeneous
reservoir and establishes the relational expression of recovery and flushing efficiency coefficient of the multilayer heterogeneous
reservoir. With the result of the numerical simulation，we calculate the flushing efficiency coefficient of every sublayer. We also
find out the difference of interlayer producing degree by analyzing the variation of cumulative distribution curve shapes，and
average values and variability of flushing efficiency coefficient before and after the structural regulation of fracturing，water
plugging，subdivision water injection and so on. The result illustrates that the cumulative distribution curve shifts towards
right whose slope becomes bigger，the variability of flushing efficiency coefficient becomes smaller and the average values of
flushing efficiency coefficient becomes bigger. Those demonstrate that the producing degree of heterogeneous oil layers and
uneven producing condition has been improved，and quantitative analysis of the producing degree of the oil layers has been
achieved. Therefore，this paper provides a new method and theoretical foundation for the producing degree of heterogeneous
oil layers during the stage of extra-high water cut.

Feasibility Assessment of the CO2 Miscible Flooding Process

Tang Yong1, Yin Peng1, Wang Yong2, Sun Bo1, Hou Dali1

2014, 36(2):  133-138.  DOI: 10.11885/j.issn.1674-5086.2013.09.22.03

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CO2 flooding is a win-win measure for enhanced oil recovery and burial of greenhouse gases，which has a widely
applied prospect in China. CO2 miscible flooding feasibility evaluation is an important foundation for the implementation
of the field-scale. On the basis of considerable field application experience and literatures，we analyzed the negative factors
of CO2 miscible flooding and pointed out an important consideration problem of CO2 miscible flooding process，as well as
the development trend，and proposed feasibility evaluation of CO2 miscible flooding including：reservoir screening，laboratory
measurements，reservoir simulation，economic and risk analysis，pilot testing. We hold that the feasibility assessment also needs
to consider the impact of reservoir CO2 injection on spoiler or gas channeling，corrosion，calcium and asphaltene deposition，
and point out that the success of CO2 miscible flooding focus is to ensure a higher mixed level of the reservoir and CO2 sweep
efficiency. Based on the reservoir and engineering programs，the feasibility of CO2 miscible flooding can be ensured by the
economic demonstration.

Calculation of Relative Permeability Curve at Different Position in
Long Core Displacement Experiment

Sun Lei1, Yan Chenghai1, Pan Yi1, Chen Liang2, Li Shilun1

2014, 36(2):  139-144.  DOI: 10.11885/j.issn.1674-5086.2013.03.20.01

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Relative permeability is an empirical parameter，which interprets the complex effects of the flow of the multi-phase
and incompressible fluid in porous media，so as to calibrate Darcy’s single phase flow equation. The relative permeability can
be influenced by many factors，such as fluid saturation，physical rock properties，wettability，saturation history，overburden
stress，clay and fines content，temperature，interfacial tension，viscosity，magnitude of initial phase saturations，and displacement
rates and capillary outlet phenomena. Based on the results of Huan Guanren and Shen Pingping’s derivation of relative
permeability curve and by considering the character in the displacement experiment whose core arrangement is heterogeneous
in one dimension and harmonious arrangement，we got the relationship between cumulative core length and harmonious average
permeability by Matlab. And then we reversely solved the relationship between absolute permeability and cumulative
core length. We also converted the discrete model into the continuous model. By substituting the above results into the single
dimension homogenous model，we obtained the relative permeability curve in different position of the displaced cores in WC
oilfield. The result is reliable except for few points that fitted poorly.

CO2 Corrosion Resistance Test and Applicability Evaluation
of Rubber O-ring

Zeng Dezhi1, Li Tan1, Lei Zhengyi2, Cao Dayong3, Shi Taihe1

2014, 36(2):  145-151.  DOI: 10.11885/j.issn.1674-5086.2013.09.11.05

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In the high CO2 oil and gas field operations，the applicability of rubber O-ring has a certain effect on the production
safety. Previous studies related to the rubber O-ring is merely in a free state，but in the actual operating condition，the rubber
O-ring is mostly in a compressive stress state. Therefore，we designed a new device for corrosion resistance and sealing property
test of rubber seals in a compressive stress state，in the harsh environment with pressure of 35 MPa，temperature of 140 ℃，gas
phase composition of 5%CO2 and 95%N2，and the CO2 corrosion resistance experiments on the O-rings of four kinds of rubber
materials were conducted. Through comparing the mechanical properties and morphology changes before and after corrosion，
the applicability evaluation of them in the above experiment environments was made. The study found that the mechanical
properties of O-rings after corrosion decreased. The corrosion extent of O-rings was weaker in the compressive stress state than
in the free state，and in the compressive stress state，the liquid corrosion was weaker than the gaseous corrosion，but stronger
in the free state. After corrosion the swelling and aging of O-rings occurred，which caused the seal failure. The study provided
references for the selection and use of rubber seals in the high temperature and high pressure oil and gas field with high CO2
content.

Thermodynamics Study Progress of Wax Precipitation in
Multiphase System

Yang Wen, Cao Xuewen

2014, 36(2):  152-158.  DOI: 10.11885/j.issn.1674-5086.2013.04.23.03

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Wax precipitation in multiphase system was studied with wax thermodynamic models and experiment methods in
view of sea floor transportation system. Based the analysis of the wax thermodynamic models of Won and Ji’s，the consistency
of calculation method selecting of liquid phase fugacity in vapor-liquid equilibrium and liquid-solid equilibrium，solid-solid
transition，the thermodynamic properties of pure components，Poynting correction term treatment，as well as activity coefficient
calculation should be considered when a new model is built. Experimental measurement methods，such as laser method，
ultrasonic method，acoustic resonance method，quartz crystal microbalance method（QCM），high-pressure micro-differential
scanning calorimetry method（HP–µDSC），which can be used to the analysis of the multiphase system. The results show
that quartz crystal microbalance method has good prospect because of its high sensitivity，and high-pressure micro-scanning
calorimetry method because of its easy conduction，small sample consumption，good reproducibility and almost no influence
of human factors in the testing process.

Analysis of Bottom Hole Flow Field Characteristics in Gas Drilling
With Cone Bit

Wen Jiewen1, Xiong Jiyou1, Liang Hongjun2, Yu Jing3, Wang Guohua1

2014, 36(2):  159-164.  DOI: 10.11885/j.issn.1674-5086.2013.09.23.01

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Based on the CFD technique，the bottom hole flow field CFD model is constructed，the bottom hole flow field
of three-cone bit in gas drilling is studied by numerical simulation. We also analyze the impact of nozzle position，side rake
angle，front rake angle and back rack angle on bottom hole flow field. The results show that the setting of three nozzles with
different side rake angles is more conductive to remove rock from bottom of hole than with same side angle，the bottom hole
rock cleaning ability of three nozzles with composite front rake angles is stronger，but cleaning effect on rock cutting structure is
poorer，Under the condition of constant gas displacement，mixing three nozzles with composite front rake angle and back rake
angle enhances cone cutting structure′s cleaning ability and annulus cutting′s carrying capacity，which guarantees a relatively
good bottom hole rock cleaning ability as well. The results of the research provide theoretical guidance for the design and
evaluation of cone bit in gas drilling as well as technical measures for gas drilling.

Analysis of Mechanical Strength of Buried Pipelines
in Landslide Areas

Lian Zhangfu1, Li Fenglei2

2014, 36(2):  165-170.  DOI: 10.11885/j.issn.1674-5086.2013.11.18.02

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Aiming at the actual work environment of buried pipeline in a certain landslide areas in the west，we carried the
theoretical analysis of the forces of buried pipeline. Because the forces of buried pipeline in landslide areas are very complicate，
the finite element mechanical model between the earth and the buried pipeline was constructed with finite element method
（FEA）. The model can simulate conveniently and accurately the stress and strain of the pipeline under different work conditions
and different mechanical boundary conditions as well as the interactions between the buried pipeline and the earth. Based on
the model，the changes of the maximum stress and strain of the pipe under the different angles of slope and different lengths of
the landslide were analyzed and studied in detail. When the buried pipeline is with 20℃ angle of landslide，the relationship of
the maximum stress of the buried pipe varies with the length of the landslide. The research provides the theoretical supports for
the safety length of the landslide segment. The results of the research can be applied in the analogous buried pipeline.

Safety Evaluation of Production Casing Considering Corrosion in Gas
Well with Sustained Casing Pressure

Zhang Zhi1, Huang Yi2, Li Yanjun2, Zhang Chao2, Zeng Chunmin2

2014, 36(2):  171-177.  DOI: 10.11885/j.issn.1674-5086.2013.09.23.02

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In the high temperature and high pressure（HTHP）gas wells with CO2 and H2S，once sustained casing pressure
builds up in the annulus of tubing and production casing，the production casing above packer will be exposed to the corrosive
environment. Because of the interaction of corrosion and sustained casing pressure，production casing will face big challenges.
A model of the max sustained casing pressure has been established；and based on the corrosion rates of casing，this paper
predicts the safe service life of casing. Meanwhile safe service life has been predicted considering the sustained casing pressure
and corrosion. The paper provides casing residual strength and its safety situation in limited production cycle by casing service
life design，which will not only ensure the safety of casing but also cut the cost of production. For the HTHP sour gas wells，
if the production casing is carbon steel，the performance of annulus protection fluid needs to be tested，and annulus protection
fluid needs to be optimized；and in order to avoid casing security risks，it is necessary to strengthen security supervision annulus
over protection fluid.

Drillng and Completion Fluids for High Permeability Sandstone
Reservoir Protection in Horizontal Well

Kang Yili1, Liu Yanying1, You Lijun1, Niu Xiao2, Luo Faqiang2

2014, 36(2):  178-184.  DOI: 10.11885/j.issn.1674-5086.2012.04.05.01

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The Triassic reservoir with medium porosity and medium-high permeability in the Tarim Basin，exhibits intensively
heterogeneous pore structure，and serious potential damage of solid invasion，particle migration，sanding，fluid sensitivity.
After completion，horizontal wells can not produce through natural power or gas-lift. The results of granularity analysis and
dynamic damage evaluation experiments present that the original drilling and completion fluids can not protect the reservoir
with permeability of more than 100 mD，while the percentage of regained permeability is less than 50%. According to the
mechanism of shielding temporary plugging technology，the original drilling and completion fluids are optimized，and the
granularity analysis and dynamic damage evaluation experiments of optimized fluids are carried out. The structure of filter
cakes，both the original and optimized drilling and completion fluids，are observed through the FEI Quanta 450 environment
scanning electron microscope，then the porosity，pore size and fractal dimension of the filter cakes are analyzed with fractal
geometry theory. All results indicated that the optimized drilling and completion fluids can form tight filter cakes，plug the
pore of reservoir effectively，and enhance the percentage of regained permeability of core samples up to 90%. After applying
optimized drilling and completion fluids，horizontal wells achieved production through natural power and got high production
after completion.