2006 Vol. 12, No. 1

Display Method:
PROSPECTS OF PETROLEUM EXPLORATION IN THE PALEOZOIC OF CHINA
KANG Yu-zhu
2006, 12(1): 1-5.
Abstract (130) PDF (174KB)(7)
Abstract:
In the past several decades,the marine origin of Paleozoic oil and gas in China has long been an important problem to which petroleum geologists pay great attention.A major breakthrough was made in 1984 when well Shacan 2 encountered Paleozoic oil of marine origin in the Tarim basin,which for the first time demonstrates that "the Paleozoic marine deposits in China contain abundant oil".However,how are the prospects of Paleozoic marine oil and gas in China? Some people think that they are a key strategic substitute area for petroleum exploration,while others consider that they have no broad prospects but are only an auxiliary area for petroleum prospects.From the great advances in Paleozoic petroleum exploration in the past decade,Paleozoic petroleum potentials,favorable tectonic conditions,association of multi-epochal petroleum and wide exploration areas,the author proposes that Paleozoic marine oil and gas in China has great exploration prospects and will be one of the important strategic substitute areas of petroleum exploration in China.
STRUCTURAL SYSTEMS AND OILFIELD GEOLOGICAL HAZARDS IN THE BOHAI GULF BASIN
XU Shou-yu
2006, 12(1): 6-11.
Abstract (142) PDF (221KB)(6)
Abstract:
The Bohai Gulf basin is an important petroleum base of China.Many structural systems of different structural orders are developed in the basin,such as the en-echelon,brush and network structural systems.According to the dynamic setting,characteristics,harm and distribution of geological hazards,the oilfield geological hazards occurring in the basin may be divided into several types such as well casing damage,induced earthquakes,sand blasting and water and oil spouting at the surface and ground cracks,and the characteristics and distribution of various oilfield geological hazards in the Bohai Gulf basin are discussed.The authors think that the formation,distribution and evolution of oilfield geological hazards in the Bohai Gulf basin are controlled by the structural systems and structural stress fields of different orders.The conversion or turning zones of present stress fields such as the converging end of the brush structural system are usually areas where oilfield geologic hazards take place frequently and intensively.
NEW PROGRESS IN THE STUDY OF TECTONIC GEOMETRY OF THE NORTH YELLOW SEA BASIN
LI Wen-yong, LI Dong-xu, WANG Hou-jin
2006, 12(1): 12-22.
Abstract (153) PDF (849KB)(15)
Abstract:
The North Yellow Sea basin is a Meso-Cenozoic sedimentary basin developed in the setting of the Jiaoliao uplift.Study indicates that the basement of the Meso-Cenozoic North Yellow Sea basin consists of Paleozoic sedimentary rocks and Precambrian metamorphic rocks,and that the basin is developed to different degrees in the lower(J3-K1),middle(E2-E3) and upper(N) tectonic layers.Based on petroleum resources and Meso-Cenozoic strata,the North Yellow Sea region may be divided into three first-order tectonic units,namely,the Liaodong-Haiyangdao uplift area,North Yellow Sea basin and Jiabei-Liugongdao uplift area.Of these tectonic units,the North Yellow Sea basin includes six second-order tectonic units and 24 third-order tectonic units.Folds and faults are very well developed in the basin.The former may be divided into regional compressive folds,local associated folds and drape-like folds,and the latter mainly includes the nearly EW-NE set,NW set and NNE set,of which the nearly EW-NE and NNE sets of faults are better developed and control the distribution pattern of uplift and depression and sedimentary features.
SEDIMENTARY SLOPES OF THE BOHAI GULF BASIN AND THEIR OIL POTENTIAL
WANG Hai-chao, WANG Yu-quan, QIN Yun-long, YANG Cai-hong, LI Li, Lu qingling, Fu jianli
2006, 12(1): 23-30.
Abstract (130) PDF (306KB)(6)
Abstract:
Sedimentary slopes of the Bohai Gulf basin may be divided into three types and four kinds according to their structures,and four kinds of corresponding sedimentary sequences are distinguished.The sand bodies may be divided into eight types of reservoir according to the sedimentary facies,with the fluvial delta sand being the best reservoir.Four reservoir distribution models of slopes are constructed and the basic conditions of hydrocarbon accumulation in slopes are summed up.Comparison of the four kinds of slope indicates that the concave slope type is the best oil-bearing one.Suggestions of petroleum exploration in the slopes of the Jizhong depression have been put forward.
DISTRIBUTION AND CONSTRAINTS OF BURIED HILL RESERVOIRS IN THE JIYANG DEPRESSION,BOHAI GULF BASIN
SHOU Hao, HUANG Shi-yan
2006, 12(1): 31-36.
Abstract (156) PDF (269KB)(7)
Abstract:
Buried hill reservoirs in the Jiyang depression have complex types and are widespread,and structural fractures are the main oil accumulation space of buried hill reservoirs.The distribution of buried hill reservoirs in the Jiyang depression is mainly controlled by the process of basin formation.Tectonic movement is the most important factor for controlling the distribution of buried hills.The buried hill reservoirs are highly heterogeneous and there is appreciable difference in reservoir properties of different buried hill reservoirs.The exploitation characteristics of buried hill oil accumulations in the Jiyang depression are complex,the stable production period is short,the production capacities are greatly different and the water content increases quickly.The buried hills formed in or before the Mesozoic are the most favorable exploration target of buried hill oil accumulations in the Jiyang depression.
DISTRIBUTING CHARACTERISTICS OF FLUID PRESSURE IN THE ZHANHUA SUBBASIN, JIYANG DEPRESSION,BOHAI GULF BASIN, AND THEIR INFLUENCE ON OIL AND GAS ACCUMULATIONS
LI Sheng-li, YU Xing-he, CHEN Jian-yang, FENG Dong-jun, WANG Yong-shi
2006, 12(1): 37-42.
Abstract (137) PDF (236KB)(6)
Abstract:
Six types of fluid pressure are distinguished on the basis of integrating measured data and theoretical calculation.Normal pressure is dominant in oil and gas accumulations in the Zhanhua subbasin,but high abnormal-pressure oil and gas accumulations exist in strata at depth.In a plan view,high abnormal pressure mainly occurs in areas of steep slopes or subbasin centers;whereas low abnormal pressure occurs on gentle slopes.In vertical sections,high abnormal pressure mainly occurs in the less compacted zone at depth;both high and low abnormal pressures may appear in the mixed compaction zone at moderate depth;and normal pressure predominates in the normal compaction zone at shallow depth.The target of petroleum exploration in the deep part of the Zhanhua subbasin should be relatively low potential areas in high potential areas or low potential areas near high potential areas,and one of the important problems lies in combining the distribution characteristics of fluid pressure with the potential distribution to look for hidden traps and favorable reservoirs.
MESO-CENOZOIC EVOLUTION OF THE TANLU FAULT AND FORMATION AND DISTRIBUTION OF PETROLIFEROUS BASINS
YANG Zhan-bao
2006, 12(1): 43-48,70.
Abstract (174) PDF (298KB)(14)
Abstract:
A number of Meso-Cenozoic medium and large petroliferous basins in the peri-Pacific region in the eastern part of continental China are distributed on both sides of or inside the Tanlu fault.It is evident that the formation and evolution and distribution of these petroliferous basins are related to the development and evolution of the Tanlu fault.Based on an integrated analysis of the geological and geophysical data,the internal relations between the Tanlu fault and the formation and distribution of petroliferous basins were studied from the aspects of the distribution of petroliferous basins and their structural geometry,kinematics and dynamics.The author thinks that the sedimentary basins on both sides of the Tanlu fault belong to the fault system and is local derivative structures formed during the Meso-Cenozoic evolution of the fault system.
GRAVITY GRADIENT INVERSION OF DEEP STRUCTURE IN THE SOUTHWEST SEA BASIN
TANG Ren-min, ZHANG Jian
2006, 12(1): 49-54.
Abstract (106) PDF (356KB)(8)
Abstract:
The gravity gradient anomaly reflects the change of gravity anomaly,and it has a higher resolution than gravity anomaly.The plot of gravity gradient space parameters can give diagnostic information of dip angles and planes.A geometric model of subsurface structure may be constructed by integrating a gravity gradient section with the gravity gradient space parameter plot,and furthermore some complex structures may be interpreted.The authors used gravity gradient anomalies to interpret the Southwest sea basin of the South China Sea and obtained the domal structure plane with the NE-trending spreading axis of the sea basin as the symmetric axis.This structure plane forms a density interface 6-15 km below the sea basin,which might be caused by mantle uplift during NW-SE-trending sea floor spreading of the Southwest sea basin.
CHARACTERISTICS AND ORIGIN OF TRANSVERSE ACCOMMODATION ZONES IN THE DONGPU SUBBASIN,BOHAI GULF BASIN, AND THEIR ROLE IN REGIONAL SEGMENTATION
SUN Si-min, PENG Shi-mi, HUANG Shu-wang
2006, 12(1): 55-63.
Abstract (161) PDF (422KB)(9)
Abstract:
Through an analysis of the distribution of vertical displacements along the strike of the boundary faults in the Dongpu subbasin in various phases,the authors deduce the growth process of these faults.He thinks that the complex fault system originated from connection of individual fault segments during their growth,each of which controls a half-graben.On that basis,accommodation zones and structures are recognized and distinguished.An accommodation zone consists of several regularly arranged accommodation structures,while the latter formed by overlapping of two fault terminations or separate growth of various segments of a large fault.Two transverse zones are developed in the Dongpu subbasin,each of which comprises several types of accommodation structure.They strike nearly perpendicularly to the strike of the Dongpu subbasin and occur as discontinuous transverse rises between half-grabens,which control the north-south segmentation of the subbasin and separate the subbasin into the north,central and south along-strike areas,each of which has its own structural,sedimentary and petroleum geological characteristics.The along-strike heterogeneous extension is the dominant factor for forming the transverse accommodation zones and the fault segmentation is the direct cause for their formation.Transverse accommodation zones exert great influence on the structure,sedimentation and hydrocarbon distribution of the subbasin.
APPLICATION OF WAVELET ANALYSIS IN HIGH-RESOLUTION SEQUENCE STRATIGRAPHIC DIVISION
LIU Wen-ye
2006, 12(1): 64-70.
Abstract (191) PDF (276KB)(10)
Abstract:
The author introduces the basic principle and procedure of wavelet analysis and discusses the applicability of the log signal wavelet analysis in the high-resolution sequence stratigraphic division.The cycles of various orders may be obtained after multi-scale wavelet resolution of log signals.He made the cyclic sequence boundaries of various orders determined by lithofacies in the borehole correspond to the wavelet cycles of log signals and then selected appropriate scales for determining stratigraphic sequences.The results indicate that wavelet transform is very suitable to the division of cyclic sequences of intermediate order and smaller orders.The method has great significance for the improvement of the precision of cyclic sequence division,reservoir evaluation and prediction of the precision.
NEW TEST METHODS FOR PARAMETERS OF INDIVIDUAL PAY ZONES IN A MULTI-ZONE RESERVOIR: RESEARCH AND PRACTICE
ZHAO Zhong-jian, HE Zhi-xiang, LI Zhi-ping
2006, 12(1): 71-76.
Abstract (137) PDF (187KB)(6)
Abstract:
Conventional pressure buildup/drawdown tests of wells have disadvantages such as long test time,influence on well production and difficulty in obtaining parameters of individual pay zones.In regard to these disadvantages,the authors propose two multi-zone well test methods,i.e.the variable flow rate method and flow-pressure fluctuation curve method,by using flow rate and pressure data of production logging in well tests,the downhole parameters such as formation pressure,permeability and contamination coefficient for each individual interval in the case of normal production of wells have been obtained using the two new methods and the problem of testing parameters of individual pay zones in a multi-pay zone well has been solved.Furthermore,the authors describe details of the test principle of the two new multi-zone well testing methods and cite the cases of field application.
ENTROPY MODEL OF GRAY SYSTEMS AND ITS APPLICATION IN OIL-BEARING AREA EVALUATION
HUANG Shi-yan
2006, 12(1): 77-83.
Abstract (111) PDF (203KB)(6)
Abstract:
The resolution of evaluation results is sometimes low when using the present gray association analysis to evaluate the geological models of lithology,physical properties,oil potential and oil-bearing area.In regard to this problem,a new gray fine evaluation model has been constructed using the Lagrange multiplier method on the basis of the Jaynes maximum information entropy principle and definition of gray association in the information theory and structural target function.A case study is given to explain how to use this model.A comparison of this new evaluation model with the original gray association analysis shows that their results are in the main consistent and the resolution is markedly raised.This model is strictly derived and has higher sensitivity and reliability.
CHARACTERISTICS OF FLUID INCLUSIONS AND THEIR SIGNIFICANCE FOR RESEARCH ON OIL ACCUMULATION IN THE CENTRAL BOHAI DEPRESSION
YIN Xiu-lan, ZHOU Dong-sheng, LÜ Jie-tang, MENG Yuan-lin
2006, 12(1): 84-90.
Abstract (163) PDF (252KB)(8)
Abstract:
On the basis of intensive observation of a part of the core of well BZ25-1-7 in the Central Bohai depression and a full understanding of deposit fillings,the authors studied the fluid inclusions in a key core interval.The results show that secondary fluid inclusions mainly occur in micro-fractures of quartz,cements of carbonates or calcite veins.There are four types of fluid inclusion in the area:pure liquid inclusions,pure vapor inclusions,two-phase vapor-fluid inclusions and saline inclusions.Measurements of homogenization temperatures of most fluid inclusions display three stages of fluid flow:88-100℃,115-140℃ and 140-155℃,suggesting that there were at least three stages of oil/gas migration and accumulation in the Central Bohai region.According to the above-mentioned study,combined with an analysis of the burial history and thermal history,the authors think that the oil accumulation in the Central Bohai region occurred relatively late,and that the main oil migration and accumulation stage occurred since the late Guantaoan period(13 Ma).
SEDIMENTARY MICROFACIES AND HETEROGENEITY IN FAULT BLOCK RESERVOIR SHU266, SHUGUANG OILFIELD, BOHAI GULF BASIN
CHEN Zhan-kun, YU Xing-he, LI Sheng-li
2006, 12(1): 91-95,83.
Abstract (173) PDF (215KB)(7)
Abstract:
The Dujiatai pay zone of the Shu266 fault block reservoir consists of fan-delta front deposits,which may be divided into seven microfacies: subaqueous distributary channel,subaqueous interdistributary embayment,mouth-bar,distal-bar,front sheet sand and prodelta mud,of which subaqueous distributary channel sands are the main genetic type of reservoir in the area.In a plan view,the Dujiatai pay zone is highly heterogeneous,while the inter-reservoir and within-reservoir heterogeneities are moderate-high.Microscopically,it is characterized by high coordination numbers and thin throats.The reservoir heterogeneity in the area is mainly controlled by the sedimentary environment.
UNMANNED IN-SITU STRESS MONITORING STATIONS ALONG THE QINGHAI-TIBET RAILWAY
PENG Hua, WU Zhen-han, MA Xiu-min
2006, 12(1): 96-104.
Abstract (122) PDF (455KB)(7)
Abstract:
The paper introduces a new type of unmanned automatic in-situ stress monitoring station installed along the Qinghai-Tibet Railway.By using the wireless GPRS communication technology,the station is linked through Internet to the central server located in the LAN for in situ stress monitoring in the Institute of Geomechanics,Beijing to achieve data exchange and telecontrol by the monitoring stations.This network overcomes the shortcoming of conventional in-situ measurements needing artificial in-situ information collection and uses the data terminal to realize the automation of stress monitoring.The monitoring stations can monitor deep-hole stresses in the Kunlun Mountains,Amdo and Yangbajain along the Qinghai-Tibet Railway and displacements of the Central Kunlun fault at Xidatan,Kunlun Mountains.Through continuous monitoring of the geophysical,geological disaster and geo-environmental data and geodynamic process along the Qinghai-Tibet Railway,the stations can offer basic data for the study of geological disasters occurring along the railway and tectonic deformation dynamic process of the Qinghai-Tibet Plateau,earthquake forecast and plateau environment.Additionally,they can enhance the early-warning ability for geological disasters and earthquakes on the Qinghai-Tibet Plateau.