Lithologic Reservoirs

Starting pressure gradient does not truly exist，which is a wrong phenomen0n in exDeriment．Through theanalysis of some mistakes caused by starting pressure gradient，this paper proved that the starting pressure gradient d0es not exist·With starting pressure gradient，pressure can increase automatically without any liquid injection；the e will be n0unique equilibrium pressure in reservoir，but a pressure distribution with a pressure gradient；reserv0ir Pressure can not return to initial value even after a long time；reservoir pressure distribution will evolve a singularity point mathematica11v：migration of oil and gas can not make progress and accumulation of oil and gas can not take place at all；static liquid will have the ability to suffer from shear stress． All the phenomena above do not agree with the Dractice 0f 0it and gas development，and also do not comply with the principle of science． Without starting pressure adient，the science 0f petroleum will be self-consistent．

Determination method of oil—bearing area boundary of the 3P reserves based on SPE—PRM S standard

LI Hongying,SUN Jing

2013, Vol.25(4): 6–10 Abstract ( 562 ) PDF (922 KB) ( 647 )

doi: https://doi.org/10.3969/j.issn.1673-8926.2013.04.002

The basis for the determination of oil bearing area is not clear when use SPE．PRMS standard t0 evaluate 3Preserves．By the comprehensive application of the data of production testing，testing for oil，well logging and reservoir characteristics，combined with the evaluation resuh of 3P reserves in international cooperative block． this paper studied the determination method of oil．bearing area boundary of 3P reserves of different types of reservoirs based on SPE—PRMS standard．The results show that the evaluation method according to the reservoir types to determine oil．bearing area can further improve the credibility of reserves evaluation results，and effectively reduce the risk 0f devel0Dment 0f oil and gas production．

Reservoir formation conditions and mechanism of Chang ₄₊₅ oil reservoir set in Linzhen area，Ordos Basin

XIA Jia,DUAN Yi,GAO Yuan,ZHANG Xiaoli,HE Jinxian,XU Li

2013, Vol.25(4): 11–16 Abstract ( 494 ) PDF (1549 KB) ( 581 )

doi: https://doi.org/10.3969/j.issn.1673-8926.2013.04.003

Based on the research of hydrocarbon generation，reservoir conditions，migration，traps and accumulation，this paper systematically analyzed the forming conditions and mechanisms of Chang 4+5 oil reservoir set in Linzhen area．The result shows that the hydrocarbon of Chang 4+5 oil reservoir set is mainly generated from the Chang 7 source rocks，and the reservoir rocks are mostly delta front subfacies sandstone，which is considered to be low porosity and low perm eability reservoir．The dark mud rock，finer sihstone and sihpelite can effectively provide top cap rock for the reservoir．The anomalous pressure form ed by Chang 7 mudstone provides the force for migration．The hydrocarbon form ed by Chang 7 source rocks migrated into Chang 4+5 reservoir through the vertical folding sand bodies and micro—fractures under the high overpressure，vertically migrated into the traps along the delta front sand bodies and form ing reservoir，and form ed nose·shaped structural reservoir,lithologic reservoir and structural—lithologic reservoir,which are influenced by source rocks，sedimentary facies belt,micro-fractures，nose—shaped structure and overpressure．

Sedimentation and diagenesis of Chang 8 sandstone reservoir of Yanchang Formation in Huaqing area

ZHANG Rui,SUN Wei,REN Dazhong,QU Xuefeng,ZHOU Shuxun,GAO Hang

2013, Vol.25(4): 17–22 Abstract ( 435 ) PDF (958 KB) ( 605 )

doi: https://doi.org/10.3969/j.issn.1673-8926.2013.04.004

The reservoir in Huaqing area is characterized by poor properties and large diferences of properties between adjacent wells．This paper analyzed the major factors of resulting in diferences of reservoir properties from the two aspects of sedimentation and diagenesis．By using core observation，cast thin section and scanning electron microscope，this paper studied the sedimentation and diagenesis of Chang 8 reservoir in Huaqing area．The result shows that multi-source of deposition is an important cause of obvious differences of Chang 8 reservoir properties in Huaqing area,the sedimentary quality from the northeast is better than that flr0m the southwest in respect for sorting coeficient and average pore size．and the effect of diagenesis on reservoir properties is different．Based on the effect of diagenesis on reservoir properties，three combinations of diagenesis are divided as follows：dissolution and chlorite rim cementation is the best combination with relatively high porosity and permeability，the combination of strong compaction and carbonate cementation severely damaged the reservoir properties，and the effect ofthe combination ofkaolinite or illite cementation and dissolution is moderate．

Characteristics of micro—pore structure of tight sandstone reservoir：A case study from Chang 7 reservoir of Yanchang Formation in Ordos Basin

HE Tao,W AN G Fang,W ANG Lingli

2013, Vol.25(4): 23–26 Abstract ( 657 ) PDF (537 KB) ( 998 )

doi: https://doi.org/10.3969/j.issn.1673-8926.2013.04.005

Based on reservoir properties，scanning electronic microscope，cast thin section and constant rate mercury penetration，this paper cam ed out quantitative analysis of micro—pore structure of tight sandstone reservoir．The result shows that Chang 7 reservoir in Ordos Basin is typical tight sandstone reservoir,the reservoir permeability is less than0．3 mD，the secondary dissolved pore is the main pore type and average pore radius is 1 62 m，and there is 130correlation with permeability；the average throat radius is 0．33 p,m and has a good positive correlation with permeability．and it is the main influencing factor of permeability；the pore throat radius ratio is large and the average value is 602；the big pore is controlled by small throat，which causes reservoir strong heterogeneity and poor permeability．So，the advanced stimulation technology need to be used for large scale development of tight sandstone reservoir，and need to enlarge the throat radius and lower pore throat radius ratio and improve the permeability．

Quantitative characterizati0n of interlayer heterogeneity of reef flat reservoir

CHEN Peiyuan,TAN Xiucheng，YANG Huiting,WANG Haifang,JIN Xiuju

2013, Vol.25(4): 27–32 Abstract ( 500 ) PDF (976 KB) ( 446 )

doi: https://doi.org/10.3969/j.issn.1673-8926.2013.04.006

Reef flat reservoir is often in fluenced by diagenesis and tectonism，which leads to the extremely strong heterogeneity．Therefore，quantitative characterization of the heterogeneity can effectively guide the reservoir prediction and oil·gas field development．Taking the reef flat reservoir of Pugu ang Gas Field as an example，we selected aggregate index method and permeability diversity coeficient method to characterize the interlayer heterogeneity The result shows that the two methods have consistency in the assessment result，and the assessment result is consistent with geological cognition．The two methods can not only solve the uncertainly problem of single parameter characterization， but also avoid the impact of unbounded parameters．The methods can realize the quantitative characterization of reservoir heterogeneity，and truly reflect the reef flat reservoir characteristic of stronger heterogeneity，which provides reference for similar research．

Oil and gas enrichment law of Jurassic in Pengyang Oilfield，Ordos Basin

YU Lei,CHEN Jianwen,JIN W enhui,PU Lei,GE Shanliang,ZHANG Juan

2013, Vol.25(4): 33–37 Abstract ( 525 ) PDF (1484 KB) ( 345 )

doi: https://doi.org/10.3969/j.issn.1673-8926.2013.04.007

The reservoir of Yan’an Formation in Pengyang Oilfield is dominated by structure and it is characterized by fast lateral variation，complex reservoir formation relation and low degree of exploration knowledge．Based on core， logging and analytic data，this paper discussed the geologic conditions and reservoir formation models in detail by using the theory of sedimentology and petroleum geology．The result shows that this area is rich in 0il and gas．with well reservoir conditions and multiple reservoir-seal assemblages．Oil and gas accumulation is mainly controlled by hydrocarbon source rocks，depositional system，reservoir properties，structure and rock features．The optimization matching of these factors is the key point to find lithologic—structural reservoir of Yan 9 member to Yan 7 member．

Diagenetic environments of Ordovician carbonate rocks in Yuqi area，northern Tarim Basin：Evidence from fluid inclusion analysis

ZHU Lifen,CHEN Honghan,FENG Yong

2013, Vol.25(4): 38–43 Abstract ( 509 ) PDF (779 KB) ( 692 )

doi: https://doi.org/10.3969/j.issn.1673-8926.2013.04.008

Abstract：The Ordovician carbonate rock is one of the principal producing formations in Yuqi area,northern Tarim Basin．Through the use of fluid inclusion technology，this paper discussed the diagenetic environment and stages of Ordovician carbonate reservoir from the aspects of petrography characteristics，homogenization temperature and salinity． The result shows that three groups of saline water inclusions were detected in pore filling calcite，and the fluid evolutionary trends is I c(1ow temperature and high salinity) ⅡA_H(middle temperature and low to middle salinity) ⅢA(high temperature and low salinity)；there are two episodes offluid activities in fracture filling calcite：II A_H(middle temperature and low to middle salinity)and lI B—c(middle temperature and middle to high salinity)，and both of their salinity decrease with homogenization temperature increase．Combined with burial history and saline water inclusions research in Yuqi area,the evolution of diagenetie environments was determined to trend from marine to continental diagenetic environment． During Caledonian·early Hercynian stage，Yuqi area experienced exposure palaeokarst，and subsequently buried with the Meso·Cenozoic deposition，which constitutes a diagenetie evolution of a mid open—type system．

Reservoir characteristics and influencing factors in the inner Yingshan Formation in Guchengxu uplift，Tarim Basin

TANG Zhaoxing,CAO Zicheng,WANG Xinwen，SHA Xuguang

2013, Vol.25(4): 44–49 Abstract ( 601 ) PDF (1824 KB) ( 493 )

doi: https://doi.org/10.3969/j.issn.1673-8926.2013.04.009

The drilling result of GL1 and GC6 well confirmed that a set of gas-bearing strata developed in the inner Yingshan Formation in Guchengxu uplift．The lithology is mainly composed of limy dolomite and fine—grained dolomite． Through comprehensive use of cores，slices and logging data，the reservoir space mainly comprises dissolved pores， intercrystalline(corroded)pores and cracks，and the reservoir type is fractured and cavernous reservoir．The reservoir of inner Yingshan Formation is mainly affected by the lithology combination，structure crack and buried dissolution in Guchengxu uplift．Lithology combination has an important effect on the buried dissolution．The limy dolomite is conducive to the development of the reservoir，the structural fracturing is the key factor for the reformation of brittle dolomite reservoir，and buried dissolution is important constructive diagenesis by the organic acid and high temperature hydrotherma1．The study will be beneficial to the reservoir favorable area prediction of Yingshan formation in Guchengxu uplift，and has significance for guiding the further oil and gas exploration．

Pore structure characteristics of glutenite reservoir of the second member of Nantun Formation in A block of Huhenuoren Oilfield

WANG Jianfeng

2013, Vol.25(4): 50–53 Abstract ( 579 ) PDF (619 KB) ( 441 )

doi: https://doi.org/10.3969/j.issn.1673-8926.2013.04.010

Based on mercury injection method，this paper studied pore structure，flowing pore volume and reservoirheterogeneity．The result shows that there are three types of pore structure in the second member of Nantun Formation，including type I，type 11 and type 11，and they respectively displays single peak，double peak and flat peak．Single peak was the major type of the pore structure in the study area．Flowing pore volume in the study area is small，and the average flowing pore volume is 26．47％．The uni~rmity coeficient，sorting coeficient and fractal dimension of the pore structure in the study area were analyzed，and the result shows that the pore structure of rock in the study area has strong heterogeneity．

Biomarker characteristics 0f source rock and bitumen and oil—source correlation of paleo—reservoir in northeastern Sichuan

LI Jing,ZHOU Shixin,GONG Shuhua,ZHENG Zhaoyang,FU Deliang

2013, Vol.25(4): 54–62 Abstract ( 537 ) PDF (863 KB) ( 768 )

doi: https://doi.org/10.3969/j.issn.1673-8926.2013.04.011

Northeastern Sichuan is an important gas producing area of China，and its primary origin of gas is the cracking of crude oil of paleo-reservoir．On account of the uncertainty of oil sources of paleo—reservoir．the biomarker of reservoir bitumen of Changxing-Jialingjiang Formation and source rocks of Paleozonic and Mesozoic in northeastern Sichuan was analyzed and contrasted．The result shows that the organic matter of Lower Paleozonic source rocks was derived from hydrobios and algae；the organic matter of Upper Paleozonic source rocks was derived from a mixing source in which hydrobios and algae prevail over higher plants；the organic matter of Upper Paleozonic source rocks was dominated by higher plants．Paleozonic source rocks deposited in reducing to weakly reducing transitional environment with saline water and Mesozoic source rocks deposited in weakly reducing to weakly oxic transitional environment with flesh water． The main oil source formation of paleo—reservoir in Changxin Jialin iang Form~ion is Upper Permian Longtan Formation，

Comprehensive evaluation of tiny amplitude structure in deep formation in western Tahe Oilfield

GE Shanliang,W ANG Ying,CAO Yang,YU Lei

2013, Vol.25(4): 63–67 Abstract ( 420 ) PDF (694 KB) ( 489 )

doi: https://doi.org/10.3969/j.issn.1673-8926.2013.04.012

A series of tiny amplitude structure attracted by the en echelon fault blocks ranged NW—SE is developed in Kumugeliemu group in western Tahe Oilfield．This paper evaluated the hydrocarbon—bearing quality of traps through the muhidisciplinary analysis of hydrocarbon migration and accumulation direction and identifying fluid properties by seismic multi—attributes analysis，evaluated the implementation degree of traps by qualitative trap identification techniques such as geomechanical model and by the quantitative trap interpretation techniques such as seismic time slice，coherency analysis technique and variable velocity mapping．Based on these，a series of comprehensive evaluation technique of tiny amplitude structure was formed to guide the rolling evaluation effectively．The research results show that the oil and gas of Kumugeliemu group reservoirs has the characteristics of“vertical adjustment，lateral migration and reservoir controlled by the fault”．There is a positive correlation between the closed amplitude of tiny structural traps and the development scale offauh．The abnorm al arc length attribute can be reference to discriminate the fluid properties accumulated in the traps．

Well logging interpretation model based on double pores and its application

WANG Bin，PAN Jianguo，YIN Lu，TAN Kaijun，HUANG Yu

2013, Vol.25(4): 68–72 Abstract ( 466 ) PDF (908 KB) ( 440 )

doi: https://doi.org/10.3969/j.issn.1673-8926.2013.04.013

The final purpose of well logging interpretation is to determine the original water saturation in reservoir，and the n define the properties of the reservoir fluids．Most of the current water saturation models are based on Archie formula．Volcanic reservoirs generally develop two types of pores，including fractures and matrix pores．If we simply use the Archie formula to calculate the water saturation，the value will be higher than the real value．This paper amended the Archie formula according to the characteristics of volcanic reservoirs，and then developed a double pores system based on oil—water identification method of volcanic reservoirs by introducing the double pores parameters．The application in Junggar Basin proves the good effect of this method．

Reservoir prediction based on passive seismic data extracted from seismic removal zone

WANG Shujiang，YONG Xueshan，WANG Yuchao，WANG Xiao，GAO Jianhu

2013, Vol.25(4): 73–77 Abstract ( 428 ) PDF (1205 KB) ( 432 )

doi: https://doi.org/10.3969/j.issn.1673-8926.2013.04.014

Based on passive seismic data extracted from a seismic removal zone，the paper studied a processing method of seismic stacking in frequency domain，then proposed an anomaly energy analysis technique by sub—frequency band energy curve，and found a relationship between the passive seismic signal and reservoir by applications in Sahnhu area of Qaidam Basin．So the anomaly energy analysis in frequency domain for the passive seismic data can be used as an important supplementary mean for reservoir prediction，and can cause attention to the preliminary favorable zone with great benefit to seismic data processing and interpretation．

Logging evaluation of organic carbon content of Chang 7 source rocks in Ordos Basin

WANG Yanru,LIU Luofu,YANG Liping LI Wei，LIU Xianyang,WANG Ke

2013, Vol.25(4): 78–82 Abstract ( 505 ) PDF (1267 KB) ( 575 )

doi: https://doi.org/10.3969/j.issn.1673-8926.2013.04.015

Chang 7 source rocks of Triassic Yanchang Formation in Ordos Basin are the main resources for oil and gas of Mesozoic in Ordos Basin, so it is very important to study their organic matter abundance for the evaluation of the source rocks. By using ΔLogR technique, one TOC computational model can be obtained by using multi-linear regression analysis of the acoustic time logging curves, resistivity logging curves, density well logging curves and TOC of the source rocks from the experimental analysis. The result shows that the model can reflect the change trend of TOC of Chang 7 source rocks precisely. And the calculation is simple and convenient, so this model can be widely used in the recovery of TOC of Chang 7 source rocks in Huachi-Qingyang area.

Application of facies—controlled modeling technology to gas reservoir of Jia 2 member in Moxi Gas Field

RUAN Jifu，LI Xinling，TANG Qingsong

2013, Vol.25(4): 83–88 Abstract ( 476 ) PDF (1656 KB) ( 679 )

doi: https://doi.org/10.3969/j.issn.1673-8926.2013.04.016

The Jia 2 member in Moxi Gas Field is a structure-lithology trap gas reservoir, with strong heterogeneity and complex gas-water relationship because of double control of sedimentary microfacies and early diagenesis. In order to deploy well site scientifically and make reasonable gas reservoir development adjustment scheme, it must make clear the three-dimensional distribution of the reservoir property and formation water. Reservoir characteristics research shows that sedimentary microfacies is the main controlling factor of reservoir development for Jia 2 member in Moxi Gas Field. Facies-controlled modeling is a method which restrains stochastic modeling based on sedimentary facies distribution characteristics in time and space domain, and the model can reflect the real spatial distribution characteristics of geologic body underground. This paper built three-dimensional sedimentary microfacies model based on facies analysis results of each well and three-dimensional seismic structure interpretation, and built every reservoir section three dimensional petrophysical model by means of facies-controlled sequence Gaussian method based on reservoir property interpretation of each well. The real drilling data show that the model is with high reliability, it provides support for the development of gas field, and it has certain reference significance for the application of facies-controlled modeling in similar area.

Application of time—frequency analysis technique to recognition of fluvial facies sequence

FU Bin,YANG Yingzhou,ZOU Lirong

2013, Vol.25(4): 89–94 Abstract ( 481 ) PDF (955 KB) ( 518 )

doi: https://doi.org/10.3969/j.issn.1673-8926.2013.04.017

The sedimentary facies of Upper Paleozoic Shihezi Formation in Sulige Gas Field are fluvial facies. Traditional stratigraphic division is generally using the principle of formation thickness, which always does not have isochronous. Under the guidance of high resolution sequence stratigraphy principle and Milankovitch cycle theory, based on core and logging data, this paper established isochronous stratigraphic framework of Shihezi Formation in Sulige Gas Field by using time-frequency analysis technique, and divided four middle-term cyclic sequences, nine short-term cyclic sequences and 22 super-short term cyclic sequences, which provides a new method for fluvial sequence division, has significant guideline for dividing sequence of fluvial reservoir, and further certifies the Milankovitch cycle theory.

Research on reservoir prediction of T5B sand in W oilfield，South America

HU Junfeng，XU Shenghui，FENG Fang，LI Dongmei

2013, Vol.25(4): 95–100 Abstract ( 453 ) PDF (1270 KB) ( 581 )

doi: https://doi.org/10.3969/j.issn.1673-8926.2013.04.018

T5B sand reservoir in W oilfield of South America has the characteristics of rapid variation of lateral thickness and lithology and complicated vertical overlap relationship. Thus, it is very difficult to identify and characterize T5B sand. This paper carried out integrated researches including semi-quantitative analysis of the seismic RMS amplitude attribute, constrained sparse spike inversion and pseudo acoustic impedance inversion trying to resolve two specific problems such as poor drilling effect of W-7KH horizontal well and oil-water interface confliction between W-7C well and W-7D well. As a result, amplitude and impedance value of effective T5B sand has been established and the boundaries of T5B sand body have been characterized, and the overlap relationship of sand bodies have also been described so as to resolve the oil-water interface confliction of T5B sand between W-7C well and W-7D well. The research method and result may have good guidance for step out development, horizontal well design and fine reservoir characterization of W oilfield.

Application of seismic attribute analysis technique to the identification of mudstone interbeds

GAO Lei，MING Jun，YAN Tao，ZHAO Haifeng，LI Bin

2013, Vol.25(4): 101–105 Abstract ( 626 ) PDF (1194 KB) ( 719 )

doi: https://doi.org/10.3969/j.issn.1673-8926.2013.04.019

The development of mudstone interbeds affected the high-efficiency development of sand 4-1992 in Bozhong 26 oilfield of Bohai. In order to predict the lateral distribution of mudstone interbeds, we used the method of integrative analysis of strata slice and seismic attributes to study the interbeds genesis based on the fine analysis of interbeds geophysical response. Based on the different seismic attributes calculation methods for several experimental analyses, we optimized three kinds of seismic attributes: RMS amplitude, sum negative amplitude and energy half time. We used the method of seismic attributes cluster analysis to identify and depict the lateral distribution of interbeds. It is considered that mudstone interbeds in the study area are mainly developed in the central part of sand body and presents unstable transverse distribution characteristics. This research idea has certain referential significance for identifying and characterizing the interbeds in complex fault block oilfield, and can provide technical assurance for the efficient development of similar oilfields.

Application of box-wave technology to investigation of interference wave in Qiangtang Basin

LEI Yang，WU Wenjing，LIANG Zhenghong，CHEN Bing，LIU Yuanzh

2013, Vol.25(4): 106–110 Abstract ( 444 ) PDF (1021 KB) ( 740 )

doi: https://doi.org/10.3969/j.issn.1673-8926.2013.04.020

Multiple plateau uplift movement leads to fast lateral lithology variation, strong heterogeneity and development of underground fracture in Qiangtang Basin. The signal-to-noise ratio of seismic data acquired in earlier days is low, and the type of interference wave that often cover the effective wave is various in the single shot record. In order to suppress the interference wave in the process of seismic prospecting by seismic combination method, it is necessary to understand the propagation and attribute character of interference wave completely. Firstly, used the single shot record and radar chart technology to analyze the style, direction of propagation, velocity, frequency and wavelength characteristics of major interference wave in the prospect area, and then analyzed the effect of suppressing interference wave by sorting common-receiver-point gathers with different pattern length. The result shows that: when the detector array is just a single point, it is invalid to suppress the interference wave in the prospect area; as the pattern length increase, the effect of suppressing interference wave with high frequency, low velocity and short wavelength is better; when the pattern length reaches 160 meters （maximum pattern length）, it has a good effect to suppress the interference wave with high frequency, low velocity and short wavelength and improve the quality of original data, but the maximum pattern length has a poor effect to suppress the interference wave with high velocity and long wavelength. In order to suppress the interference wave with high velocity and long wavelength well, larger pattern length or multi-channel mixing process is necessary. The box-wave technology is suitable for investigating the interference wave in low signal-to-noise ratio prospect area, and it is beneficial to suppress the interference wave in the process of seismic prospecting and multichannel mixing process, and then improve the signal-to-noise ratio of original data.

Study on influencing factors of swelling capacity of swellable particle

ZHANG Yu

2013, Vol.25(4): 111–115 Abstract ( 458 ) PDF (346 KB) ( 657 )

doi: https://doi.org/10.3969/j.issn.1673-8926.2013.04.021

Through the experiment, this paper studied the main influencing factors of swelling capacity of swellable particle. The result shows that for the same kind of particles, the smaller the particle size is, the stronger the water swelling capacity is; for different types of particles, the water swelling rate is quite different. Temperature has little effect on the swelling capacity of swellable particle. With the pH value increasing, the water swelling capacity of swellable particle is enhanced. The influence of salinity on water swelling ability of swellable particle is mainly reflected in the concentration of Ca2+ and Mg2+. The greater the concentration of Ca2+ and Mg2+ is, the weaker the water swelling capacity of the particles is. The polymer concentration has no significant effect on the water swelling capacity of swellable particle, but for the same type of particles, if added polymer, the water swelling rate slows down, and the suspending ability is enhanced. The higher the concentration of the polymer is, the greater the water swelling rate declines, and the stronger the suspending ability is. This result can provide experimental basis for the use of profile control agent by swellable particle for deep profile control.

Study on coalbed methane peak production fitting and production forecast by diferent dynamic analysis methods

ZHANG Hairu,LIHao

2013, Vol.25(4): 116–118 Abstract ( 478 ) PDF (169 KB) ( 881 )

doi: https://doi.org/10.3969/j.issn.1673-8926.2013.04.022

Coalbed methane iS unconventional natural gas．Its production iS influenced by many factors．and the numerical simulation process is complex and the data is dificult to obtain．This paper selected three kinds of dynamic analysis methods to predict the production，including W eibull model，generalized Weng model and H—C—Z mode1．The result shows that the linear relationship of the H—C—Z model does not match the coalbed methane exploration mechanism，and the prediction error is large；the generalized Weng model can predict the peak production with high accuracy，but the time prediction error is large，SO it is dificult to meet the accuracy requirements；the W eibull model can predict both the peak production and the appearance time accurately．Therefore，the W eibull model is more suitable for the prediction of coalbed methane production．

Characteristics of foam driving and profile controlling in heter0gene0us sand pack tube

LI Aifen,TANG Jianjian,CHEN Kai,TANG Peizhong

2013, Vol.25(4): 119–123 Abstract ( 494 ) PDF (321 KB) ( 673 )

doi: https://doi.org/10.3969/j.issn.1673-8926.2013.04.023

In order to solve the problem of low steam sweep efficiency of heavy oil reservoir in Shengli Oilfield, foam is used as profile control agent during steam flooding. The resistance factors in heterogeneous rock （two sand pack tube in parallel having different permeability） saturated with water, the flow rate change with injection time, and the oil recovery factors by foam flooding in these rocks were measured under 90 ℃. The results show that, the foam resistance factor of foaming agent FCY increases with the permeability at the beginning and then decreases. Due to the high flowing resistance in high permeable rock, the flow rate in high permeable rock is greater then that in low permeable rock. In the condition that foam driving oil in this anisotropic rocks, the resistance in high permeable tube increases after total foam injection mount is greater than 0.85 PV, and injection pressure decreases with the permeability ratio increases. The recovery factors of high permeable tube and low permeable tube increase at the same time. But with the permeability ratio increases, the final recovery factors in high permeable tube increase and in low permeable tube decrease slowly.

Research and application of liquid—carrying model for low permeability and water production gas reservoir

ZHOU Ruili，ZHOU Jian，LUO Yi，LI Xuan，LIU Yuxiang

2013, Vol.25(4): 123–128 Abstract ( 453 ) PDF (654 KB) ( 801 )

doi: https://doi.org/10.3969/j.issn.1673-8926.2013.04.024

Accurate prediction of the critical liquid-carrying gas flow is very important to optimize work systems and exclude wellbore effusion for gas well. The currently used liquid-carrying models generally fail to comprehensively consider the influence of liquid droplet deformation and size for the critical liquid-carrying gas flow, and critical Weber number is taken as a given value or critical liquid-carrying gas flow has nothing to do with the Weber number, which is certainly lack of theory. Considering the droplet size and droplet deformation characteristics, and combined with the critical Weber number algorithm of Tatterson and Azzopdiar, based on the liquid droplet partial force equilibrium theory and energy conservation principle, we deduced a new model to predict the critical liquid-carrying gas flow. The new model coefficient varies from 1.92 to 5.3, which becomes larger with the pressure gradually, and it is to make up a defect on a given value of the coefficients of the currently used liquid-carrying models. Field application shows that the predicted effusion status of the vertical wells by this new model is agreed with actual effusion status, which can meet the production requirements.