Lithologic Reservoirs

Sand injectite is a special kind of sand bodies which are formed by the remobilization of the original depositional sand. More attentions have been paid on sand injectites after 1980s by the discovering of series hydrocarbon reservoirs. The research status of sand injectites is introduced. The 3Darchitectural model, the outcrop characters and the recognization cretials of sandstone injectite in cores, well logging and seismic responses are summarized. The trigger mechanism and flowregime of sand injectites are concluded, and its geological significance is discussed. Sand injectites have important impaction for petroleum exploration and development, and it may be a new kind of lithological stratigraphic traps in exploration and development in China.

Analysis on exploration potential of buried hill in southern Niutuozhen uplift

ZHA Ming， WEI Yamin， GAO Changhai， CUI Yongqian

2011, Vol.23(2): 10–14 Abstract ( 551 ) PDF (501 KB) ( 754 )

doi: https://doi.org/10.3969/j.issn.1673-8926.2011.02.002

The buried hill in southern Niutuozhen uplift of Jizhong Depression is characterized by little oil-bearing series and low degree of exploration. The oil sources, reservoir-seal assemblage, migration system and trap types of buried hill are studied. The result shows that the buried hill in southern Niutuozhen uplift has favorable hydrocarbon accumulation conditions, and developed two types of hydrocarbon accumulation models, including weathered crust of buried hill and inner buried hill, and different model has different characteristics of hydrocarbon migration and accumulation. It is believed that the buried hill in southern Niutuozhen uplift has favorable exploration potential. The buried hill monadnock trap in northern Xiong 11 well and the inner buried hill trap in Ba 28 well will be the next preferred exploration targets.

Formation mechanism and distribution prediction of tight sandstone gas in Kekeya-Shanle area, Tuha Basin

HUANG Zhilong， LIU Bo， YAN Yukui， ZHANG Daisheng， TU Xiaoxian， CHEN Jianqi

2011, Vol.23(2): 15–20 Abstract ( 522 ) PDF (946 KB) ( 603 )

doi: https://doi.org/10.3969/j.issn.1673-8926.2011.02.003

There are good conditions for forming tight sandstone gas in Kekeya area, Tuha Basin, including abnormal pressure sealed formation, good conditions of gas source and wide distribution of extra-lowporosity and lowpermeability reservoirs. Because of the unique geological conditions in this area, it developed a set of sealed formation at the depth of about 3 000 m, formed the upper and lower pressure system, and the geochemical characteristics of petroleum are different. The upper tight sandstone gas reservoir has normal pressure system and bottom water structure. The tight sandstone gas reservoir of the lower pressure systemhas the following characteristics: the gas source condition is good and it is typically self-generating and self-preserving; the gas is widespread in the tight sandstone and the “sweet spots” are of industrial value; there are no closed water-oil interface between gas sand and the “sweet spots” gas reservoir except for the higher tectonic position; the gas reservoir has overpressure and gas is well preserved with the sealed formation. According to the forming characteristics of tight sandstone gas reservoir, the range of the tight sandstone gas reservoir in Kekeya-Shanle area is predicted.

Characteristics of basement reservoir in Kunbei fault terrace belt in southwestern Qaidam Basin

LI Jianming，SHI Lingling，WANG Liqun，WU Guangda

2011, Vol.23(2): 20–23 Abstract ( 469 ) PDF (596 KB) ( 515 )

doi: https://doi.org/10.3969/j.issn.1673-8926.2011.02.004

The discovery of basement reservoir in Kunbei fault terrace belt is an important exploring breakthrough in southwestern Qaidam Basin. Based on the analysis of well logging data, core observation, section identification and imaging well logging data, the lithology, reservoir space and influencing factors of basement reservoir in Kunbei fault terrace belt are expounded. The result shows that the lithologies are mainly granite and slate, the reservoir spaces contain tectonic fissure, dissolved fissure and dissolved pore, and the reservoir type is fracture-dissolution. The analysis of physical property and thin section illustrates that basement reservoir has low permeability and complex reservoir space, but the dissolved pore along the fracture has good physical property. Finally, the main factors such as the lithology of basement rock, tectonic movement and diagenesis which influence the development of reservoir space are analyzed.

Reservoir description of Devonian in BEL structure, Algeria

LI Guobin， SHA Xuemei， FANG Guangjian， ZHANG Jing， WANG Jiangong

2011, Vol.23(2): 24–29 Abstract ( 508 ) PDF (1307 KB) ( 618 )

doi: https://doi.org/10.3969/j.issn.1673-8926.2011.02.005

The Devonian reservoir in BEL structure in Algeria belongs to fractured tight reservoir with medium porosity and extralow permeability and has strong heterogeneity and fast facies change, which results in more difficulties in reservoir prediction. Based on the analysis of characteristics of sediment, structure and hydrocarbon-bearing property, it is considered that the sand body of Siegenian-Low reservoir is well developed and has better continuity, and can form favorable reservoir; the sand body of Siegenian-Med reservoir is less developed with poor continuity, and only several part can form reservoir; the sand body of Siegenian-Up reservoir is relatively developed with better continuity, and can form favorable reservoir. Based on seismic-sedimentary facies analysis, combined with techniques such as multi-attribute optimization, reservoir random simulation, pre-stack fracture prediction and pre-stack seismic attribute hydrocarbon detection, the favorable areas are comprehensively predicted, and appraisal well is proposed, in which good application results have been achieved. These techniques have been the key techniques for the reservoir prediction and description in Algeria, and even Libya and Tunisia.

Sedimentary characteristics of Upper Permian Changxing and Dalong Formation in northwestern Sichuan Basin

LIU Kanglin， WU Xichun， LIU Shugen， LIN Jie， LI Jinxi

2011, Vol.23(2): 30–34 Abstract ( 552 ) PDF (1058 KB) ( 488 )

doi: https://doi.org/10.3969/j.issn.1673-8926.2011.02.006

Based on the measure d profiles , the sedimentary characteristics of Upper Permian Changxing and Dalong Formation are studied. The result shows that since fromthe early depositional stage of Late Permian Changxing Formation, Guangyuan-Liangping area is a gulf which formed by the rifted synsedimentary fault in Upper Yangtze Platform; in Changxing Formation in Yudongliang and Pingshang area in Jiangyou, there developed tidal and open platform, with bioclastic shoal, and there also developed immature sponge reefs in Pingshang area; in Changjianggou area in Jiange, there developed deep water sedimentation in Dalong Formation which is at the same stage with Changxing Formation, and it is rich in calthrop and radiolarians. The main reservoir spaces are intergranular dissolved pore, intergranular pore,fractured cavern, structural fracture and dissolved fracture. In a word, reefs at the margin of Guangyuan-Wangcang gulf are located between Erlangmiao in Jiangyou and Xiasi in Guangyuan, where Changxing Formation is deep buried, and they are the favorable area for exploration of underground reef-beach reservoir.

Pore structure and influencing factors of reservoir of Sangonghe Formation in Baijiahai area, Junggar Basin

LIAN Xiaocui，WANG Zhen-qi， YE Chun， LIU Zuoqiang， LI Shitao

2011, Vol.23(2): 35–40 Abstract ( 464 ) PDF (1591 KB) ( 455 )

doi: https://doi.org/10.3969/j.issn.1673-8926.2011.02.007

The first and second members of Sangonghe Formation in Baijiahai area are the important exploration target zones. The cast thin section, scanning electronic microscope, cast image analysis and mercury injection analysis are applied to analyze the pore structure of Sangonghe Formation reservoir in Baijiahai area. The main pores of Sangonghe Formation are residual primary intergranular pore and secondary dissolved pore. The throat types are lamellar or curved lamellar and bundle tubular. Based on the result of pore structure calculation, the throats are divided into five types. The throats of the second member of Sangonghe Formation are mainly typeⅡ and Ⅲ, and the throats of the first member of Sangonghe Formation are type Ⅲ throat. The main influencing factors of the pore structure are sedimentation and diagenesis, and the cementation and dissolution are dominant factors.

Super-low permeability reservoir evaluation in Zhenjing area, Ordos Basin

LI Nanxing， LIU Linyu， ZHENG Rui， LU Degen， ZHU Yuqing， SUN Yunbin

2011, Vol.23(2): 41–45 Abstract ( 473 ) PDF (788 KB) ( 396 )

doi: https://doi.org/10.3969/j.issn.1673-8926.2011.02.008

In order to open up a vast range of prospects for oil and gas exploration and development in Zhenjing area, southern Ordos Basin, series of research methods such as rock thin sections, cast sections, scanning electron microscope and mercury penetration of constant speed are used to analyze core hole data for surveying fair reservoirs. The result shows that feldspar lithic sandstone and lithic feldspar sandstone are the main reservoir lithologies, with low compositional maturity and low textural maturity, the main reservoir spaces are intergranular pores and dissolved pores, and the reservoir is characterized by poor-middle property, poor original productivity and strong heterogeneity. Combined with production performance, the evaluation parameters for lowpermeability reservoir such as throat radius, percentage of mobile fluid, start-up pressure gradient and active porosity are selected to evaluate Chang 81 reservoir. According to the result, Chang 81 reservoir can be divided into three types. The typeⅠis better reservoir, type Ⅱ is medium reservoir, and type Ⅲ is poor reservoir. The typeⅡand type Ⅲ are the main reservoir in the study area, while typeⅠis seldom.

Characteristics of Permian-Carboniferous volcanic reservoir in Zhongguai-Wuba area in northwestern margin of Junggar Basin

YAO Weijiang， LI Bing， ZHANG Shuncun， SHI Jian

2011, Vol.23(2): 46–53 Abstract ( 515 ) PDF (1060 KB) ( 769 )

doi: https://doi.org/10.3969/j.issn.1673-8926.2011.02.009

Volcanic reservoir in Zhongguai-Wuba area in the northwestern margin of Junggar Basin mainly developed in Carboniferous and Jiamuhe Formation of Lower Permian. The volcanic rocks are mainly composed of basalt, andesite, eruptive tuff, volcanic breccia, volcanic breccia lava, rhyolite and a small quantity of intrusive rocks such as granite. The reservoir spaces are made up of primary and secondary spaces. The primary space has poor connectivity, while the secondary space developed reservoir with good connectivity, owing to weathering, denudation and leaching. The reservoir rocks have two types of pore texture. The typeⅠhas poor sorting, while the typeⅡ has good sorting and better properties. The volcanic reservoir in the study area belongs to lowporosity and lowpermeability reservoir. Because of the deep buries, the exploration of volcanic reservoir is different. The properties of volcanic reservoir become better while its age becomes younger.

Characteristics and comprehensive evaluation of Chang 4+5₂reservoir in Hujianshan Oilfield, Ordos Basin

DIAO Fan， WEN Zhigang

2011, Vol.23(2): 53–58 Abstract ( 402 ) PDF (1171 KB) ( 575 )

doi: https://doi.org/10.3969/j.issn.1673-8926.2011.02.010

Based on core observation，cast thin section and intrusive mercury curve， the petrology characteristics，pore throat characteristics and diagenesis of Chang 4+52 reservoir in Hujianshan Oilfield are studied, and the reservoir is comprehensively evaluated. The result shows that the lithologies of Chang 4+52 reservoir are mainly fine arkose and lithic arkose, the reservoir spaces mainly are residual intergranular pore and feldspar dissolved pore, and the lamellar throat and curved lamellar throat are the main seepage channel. The diageneses contain compaction, cementation and dissolution. Chang 4+52 reservoir are mainly of typeⅡ and Ⅲ, belonging to lowporosity and extra-lowpermeability reservoir.

Contrast of gravity flows between shallow water and deep water in Pearl River Mouth Basin

QIAO Bo， ZHANG Changmin， DU Jiayuan， ZHU Rui

2011, Vol.23(2): 59–63 Abstract ( 535 ) PDF (956 KB) ( 586 )

doi: https://doi.org/10.3969/j.issn.1673-8926.2011.02.011

Based on core observation, the structural features of the gravity flows in shallow water and deep water are analyzed in the aspects of bedding, biological activity, special structure and Bouma sequence. The external features are contrasted in the aspects of gravity flow type, sedimentary dynamics mechanism and facies model, and the formation mechanisms of the two types of gravity flows are analyzed. The result shows that in the shallow water, there are many beddings, frequent biological activities and tide beddings, the gravity flow type is full and the influences of fluvial, waveness and tide processes are apparent;While in the deep water, there are simple bedding, scarce biological activity and obvious Bouma sequence, the gravity flowtype is simple, and entire fan model and trough model are formed. Based on the formation mechanismanalysis of these two types of gravity flows，it is believed that the main influencing factor for the gravity flows in deep water is slope gradient，and the influencing factor for the gravity flows in shallow water is sediment supply.

Thermodynamic calculation of laumontite dissolution and its geologic significance

ZHANG Xuehua， HUANG Sijing， LAN Yefang， HUANG Keke， LIANG Rui

2011, Vol.23(2): 64–69 Abstract ( 583 ) PDF (403 KB) ( 365 )

doi: https://doi.org/10.3969/j.issn.1673-8926.2011.02.012

Based on thermodynamic calculation, the thermodynamic features of laumontite dissolution in different fluid are disscussed. The result indicates that: ①Gibbs free energy increment （ΔG） of the reactions involved laumontite dissolution is minus, so laumontite dissolution are all spontaneous reactions in diagenesis environment; ②Gibbs free energy increment （ΔG） of the reactions involved laumontite dissolution is plus relativity with burial depth, and the trend of laumontite dissolution in deeper burial depth is less than that in lower burial or the earth’s surface;③Laumontite dissolves easily and forms secondary pore in diagenesis environment of higher P CO2 , lower pH, decrease of Ca 2+ and increase of K + ; ④The reactions involved laumontite dissolution are accompanied by the decrease in the volume of the solids, the decrease in the volume of the solids in the reaction Lm- Ill is the most, and it consumes K + and conquers dynamics balk of K-feldspar dissolution and makes more K-feldspar dissolution to form secondary pore. So the way which laumontite dissolve to form illite and quartz is most profitable to form reservoir.

Diagenesis of Chang 6 reservoir and its influence in Shuangcheng oil region,Hengshan area

LIU Xiuchan， LIU Linyu， CHEN Xipan

2011, Vol.23(2): 70–74 Abstract ( 414 ) PDF (790 KB) ( 452 )

doi: https://doi.org/10.3969/j.issn.1673-8926.2011.02.013

Chang 6 reservoir of Upper Triassic in Shuangcheng oil region is the major oil producing zone in Hengshanarea. Based on the analysis of cast slice，scanning electronic microscope and other test data, combined with sedimentary facies and pore structure, it is determined that the main diagenesis which cause the reservoir compacted are compaction and cementation. The great loss of primary pore and cement filling in intergranular residual pore are the main causes for low porosity and low permeability of the reservoir. The complex reservoir with low porosity and low permeability is dominated by the strong compaction and cementation in the early diagenesis stage. Five types of diagenetic facies are divided, which is helpful for the study on hydrocarbon distribution and enrichment.

Seismic identification and exploration effect of reef-bank facies reservoir in northwestern Ordos Basin

ZENG Lingbang， DUAN Yushun， BI Mingbo， ZHU Wangming， HE Zhengguang

2011, Vol.23(2): 75–79 Abstract ( 401 ) PDF (1244 KB) ( 577 )

doi: https://doi.org/10.3969/j.issn.1673-8926.2011.02.014

The Lower Paleozoic in northwestern Ordos Basin belongs to Qilian marine sedimentary province, in which Carbonate platform margin is inferred to be present from regional geology. Previous drilling confirms that there may be reef-bank facies in carbonate reservoir in Kelimoli Formation. However, the seismic attributes and distribution scale of the reef-bank facies in this area are not fully recognized. Based on known seismic attributes of reef-bank facies and experience of external exploration area, it is summarize that the seismic attribute of reef-bank facies is mainly hummocky reflection with relative strong attributes. Several technologies such as seismic facies analysis, seismic attribute analysis and seismic inversion are applied to predict the distribution of reef-bank facies in the study area. The actual data shows that in Qitan 1 well there are bioclastic limestone, algal limestone and sandy sparite limestone in Kelimoli Formation, and there are indications of gas-bearing property.

Using logging methods to calculate organic matter abundance of source rocks and its influencing factors

QU Yansheng， ZHONG Ningning， LIU Yan， LI Yuanyuan， PENG Bo

2011, Vol.23(2): 80–84 Abstract ( 464 ) PDF (725 KB) ( 795 )

doi: https://doi.org/10.3969/j.issn.1673-8926.2011.02.015

In recent years, combining abundant geophysical information with geochemical experimental data to study source rocks can effectively overcome the weakness of poor continuity and high costs in conventional formation sample analysis, so it is widely applied. However, it is not found with high accuracy in the practical application. TakingWestern Sag in Liaohe Basin as an example, based on the geochemical and well logging data of source rocks in SG1 well, the log responses of source rocks with different maturity are contrasted. The factors influencing the accuracy of TOC calculation are discussed, and the least square method and ΔlgR method are compared. The result shows that the three constant in least square fitting formula contain various factors which can influence the calculation result. Therefore, the least square method could reflect the TOC changes in source rocks better and it is easy to be applied.

Logging evaluation methods of water flooded layer in Niuquanhu Oilfield

PAN Youjun， XU Ying， ZHANG Zhongjin， WU Meie， XIE Jun， WEN Jing

2011, Vol.23(2): 85–89 Abstract ( 382 ) PDF (608 KB) ( 581 )

doi: https://doi.org/10.3969/j.issn.1673-8926.2011.02.016

The reservoir ofXishanyao Formation in Niuquanhu Oilfield is characterized by lowporosity, lowpermeability and lowpressure. Because the injection water is fresh water and the original oil saturation is low, the resistivity of water flooded layer is high. The water flooded layers are often wrongly interpreted as oil layers by using conventional log interpretation, which results in high water cut after the perforating operation. The conventional logging data combining with oil testing data and core analysis are applied to study the geophysical characteristics and quantitative interpretation model of water flooded layers, and establish the interpretation method for water flooded layer in Niuquanhu Oilfield. The field application proves the good effect.

Sedimentary facies prediction of braided channel of the third member of Shihezi Formation in Daniudi Gasfield, Ordos Basin

XU Jie， DONG Ning， NING Junrui， ZHANG Yonggui， ZHOU Xiaoying， SHE Gang

2011, Vol.23(2): 90–94 Abstract ( 428 ) PDF (1449 KB) ( 475 )

doi: https://doi.org/10.3969/j.issn.1673-8926.2011.02.017

The reservoirs of the third member of Permian Shihezi Formation in Daniudi Gasfield in Ordos Basin are braided channel sediment. The reservoir prediction of channel sand is uncertain because of seismic resolution and overlying sandstone of upper Shihezi Formation. Under the constraint of high resolution sequence stratigraphic framework, and based on the comprehensive analysis of synthetic seismogram and seismic reflection characteristics, it is recognized that there are four geologic implications of seismic reflected wave T9 f at the top surface of the third member of Shihezi Formation. The waveform seismic facies analysis method combining with comprehensive study on seismic facies, electrofacies and sedimentary facies are applied to predict the sedimentary microfacies distribution of braided channel and favorable areas for channel sand development. The prediction result has a consistent rate of 90% with the actual data in D66 well field. So the waveformseismic facies constrained by sedimentary facies and sediment features can be used to accurately predict the complex geologic body.

Using time-frequency characteristics to analyze sedimentary cycle

FENG Lei

2011, Vol.23(2): 95–99 Abstract ( 482 ) PDF (976 KB) ( 597 )

doi: https://doi.org/10.3969/j.issn.1673-8926.2011.02.018

Seismic data contain abundant information on underground sedimentary body. Using wavelet transform timefrequency analysis can allowone-dimensional time domain signal expand to two-dimensional seismic wave time-frequency domain, and then the spectrumcan more clearly depict the sedimentary cycle structure of the internal body. Through the establishment of different types of sedimentary models, the change lawof the sedimentary body corresponding to seismic signal in the time-frequency map in progradation, aggradation and retrogradation sedimentary environment is analyzed. The actual data show that the energy group moving direction in the time-frequency map is consistent with petrophysics variation. This method provides a newway of thinking and approach in studying sedimentary cycle in non-drilling area.

Application of response surface regression analysis technique to numerical simulation

WANG Tao， YAN Ming， GUO Haibo

2011, Vol.23(2): 100–104 Abstract ( 654 ) PDF (475 KB) ( 1798 )

doi: https://doi.org/10.3969/j.issn.1673-8926.2011.02.019

The response surface regression analysis technique is an integrative method for optimization procedure. It not only can build continuous curved surface model, but also can form response surface to estimate the interaction of the influence factors, which can make up the shortage of traditional single factor experiment. This technique is firstly applied to carbon dioxide drive numerical simulation, and the influencing factors are analyzed. The good result shows that response surface regression analysis technique can be used for experiment design and analysis in petroleum research.

Genetic analysis and evaluation of low resistivity reservoir in block S

LI Jun， ZHANG Zhansong

2011, Vol.23(2): 105–108 Abstract ( 423 ) PDF (397 KB) ( 396 )

doi: https://doi.org/10.3969/j.issn.1673-8926.2011.02.020

Agreat deal of lowresistivity reservoirs are discovered in block S. The lowest resistivity of the reservoir is only 1.7Ω·m, corresponding to the resistivity ofwater layer, which makes it extremely difficult to recognize the property of the fluid. Based on scanning electronic microscope, claymineral analysis, capillary pressure and formation water property, the genetic mechanism of the lowresistivity in block S is analyzed. It is believed that the lowresistivity is mainly caused by highly mineralized formation brines and lowoil saturation. An evaluation method for lowresistivity reservoirs of different genesis is proposed, which combines apparent formation water resistivity and movable fluid analysis. The actual processing data of 36 wells prove the good result.

Method of determining clay mineral content by using conventional logging data

CHEN Ganghua， YANG Ye

2011, Vol.23(2): 109–113 Abstract ( 590 ) PDF (645 KB) ( 1777 )

doi: https://doi.org/10.3969/j.issn.1673-8926.2011.02.021

Based of X-ray analysis, conventional logging data combined with multielement nonlinear regression and grey theory analysis are applied to determine the clay mineral content in the area where is poor in natural gamma ray spectrometry log. The result shows that the method is accurate for determining the clay mineral content, so it can provide theory foundation for reservoir evaluation and sensitivity analysis.

Imbibition is not caused by capillary pressure

LI Chuanliang， LI Dongmei

2011, Vol.23(2): 114–117 Abstract ( 622 ) PDF (395 KB) ( 826 )

doi: https://doi.org/10.3969/j.issn.1673-8926.2011.02.022

Imbibition is an effective method to flood the oil in matrix pores of reservoirs. However, the mechanism of imbibition is not understood properly and correctly. A study was made about the mechanism of imbibition with the principles of flow in porous media. The driving force of imbibition is buoyancy rather than capillary pressure. On the contrary, capillary pressure is the resistance of imbibition. Surfactants added to injection water can reduce capillary pressure and increase the efficiency of oil recovery. The mechanismof imbibition is the gravity separation of oil and water in pores, which needs long time to finish the process. Interval water flooding, periodical water flooding and low speed water flooding are good methods to recover oil by imbibition.

Advances in deliverability analysis of horizontal well

WANG Dawei， LI Xiaoping

2011, Vol.23(2): 118–123 Abstract ( 693 ) PDF (425 KB) ( 1039 )

doi: https://doi.org/10.3969/j.issn.1673-8926.2011.02.023

Deliverability analysis of horizontal well is the basic work of getting economic benefits, and it provides basis for horizontal well optimization, perfecting work system, production dynamic analysis and adjustment. At present, there are twomethods of deliverability calculation for horizontal well, namely analytical method and simulation method. The deliverability prediction methods for conventional horizontal well, multilateral well, fractured horizontal well and horizontal well pattern are summarized. The birth and development of deliverability analysis theory are reviewed, the new advances at home and abroad in the deliverability analysis theory and methods are introduced, the problems exists are expounded, and the development direction is pointed out, which will be helpful for improving the application of horizontal well in oilfield development.

New method for calculating in-situ stress profile and its application

DENG Yan， GUO Jianchun， ZHAO Jinzhou

2011, Vol.23(2): 124–127 Abstract ( 475 ) PDF (360 KB) ( 364 )

doi: https://doi.org/10.3969/j.issn.1673-8926.2011.02.024

Loggingmethod can be used to continuouslymeasure the rock mechanics characteristics, but when used to calculate stress, the data error is large. The mechanical characteristics measured by core testing are accurate, however, the amount of the core testing is little. The fracturing testing technique is taken as the best method to directional survey the in-situ stress, but due to the conditions, it is seldom applied which restricts this method to calculate continuous stress profile. The triaxial stress experiment in high temperature and high pressure is carried out to test the rock static mechanical behavior, and logging data are used to calculate the rock dynamic mechanical behavior. The relation of the static and dynamic parameters is established, and then the static rock mechanical characteristics in longitudinal can be obtained. Combined with the layered stress profile model from the fractured testing, the in-situ stress profile can be obtained. The layered stress profile model is established in XX block in Erlian Basin, and the calculated result coincides with the actual measurement，so using the method to predict the in-situ stress profile is feasible, which provides effective parameters for the further development.

Laboratory study on oil displacement with active water in Longhupao Oilfield

CHE Hongchang， REN Yaoyu， LIU Hanping， LIU Zhao

2011, Vol.23(2): 128–132 Abstract ( 477 ) PDF (388 KB) ( 391 )

doi: https://doi.org/10.3969/j.issn.1673-8926.2011.02.025

Aimed at the problems ofwater injection displacement for lowpermeability reservoir in DaqingOilfields, such as high water injection pressure, lowwater injectivity and lowoil recovery, a laboratory experimental study is conducted for displacing crude oil in LonghupaoOilfield by active water flooding. Surfactant screening result shows that the interface tension of active water/crude oil system, where sodiumdodecyl benzene sulfonate （SDBS） is used as surfactant, can reach 2.041×10- 1 mN/m. SDBS has good compatibilities with formation water and the active water flooding can reach an oil recovery increment of 16.6% higher than that ofwater flooding. The result of oil displacement experiment shows that active water injection rate, activ e water concentration and active water injection amount have effects on oil displacement efficiency, of which the optimal values are 1.0 mL/min, 0.3% and 0.3 PV respectively. Active water injection timing also has some influence. Oil production wells with lowwater content should be chosen to carry out active water flooding in situ and active water concentration should be augmented when water content increases.