Lithologic Reservoirs

The exploration of stratigraphic-lithologic reservoirs is discussed by using seismic information in the following four aspects: petrophysics analysis and study, the requirement of seismic data acquisition and processing for lithological exploration, seismic lithologic interpretation parameters and stratigraphic-lithologic trap interpretation. The related techniques are introduced. The purposes and points for attention of the techniques are briefly expounded.

First principle of practice for exploration creativity

ZHANG Xia

2008, Vol.20(4): 9–13 Abstract ( 351 ) PDF (243 KB) ( 305 )

doi: https://doi.org/10.3969/j.issn.1673-8926.2008.04.002

Practice is the basis for the forming of creativity, and the creative talent comes from the accumulation of practice. The courage and wisdom come from the truth of practice. Practice is the key for forming creative thinking, the promoter for improving implementation, the fertile soil for cultivating correct thinking methods. Improving the creativity needs to heighten the level of practice, propose new targets, broaden the practice field, recognize the importance of the exercise of practice and establish the management system of practice motivation.

Sequence stratigraphy framework and lithologic reservoirs prediction of the third and fourth members of Shahejie Formation，Damintun Depression

FENG Youliang

2008, Vol.20(4): 14–19 Abstract ( 414 ) PDF (560 KB) ( 671 )

doi: https://doi.org/10.3969/j.issn.1673-8926.2008.04.003

By using high resolution 3D seismic data, log curves and logging data, high resolution stratigraphy frameworks of the third and fourth members of Shahejie Formation in Damintun Depression are established in order to recognize sequence system tract characteristics. The sy s tem tracts of Sha 3 and Sha 4 members are controlled by synsedimentary faulting. LST delta distributes below the synsedimentary faulting slope break, while fluvial delta and fan delta mainly develope in HST. In lake expanding system tract, deep lake mudstone and oil shale distribute below the slope break, shallow lake sediments distribute above the slope break. LST sand bodies of SSq3-1 and SSq2-1 sequences controlled by synsedimentary faulting slope break spread under the high quality source rocks, just being in the overpressured zones of Sha 3 and Sha 4 members, which is favorable for the lithologic reservoirs formation. The LST sand bodies of SSq2-1 sequence in west slope zone and SSq2-1 and SSq3-1 sequences in Rongshengpu Sag are most favorable for lithologic reservoirs forming.

Fractures distribution characteristics of Kulongshan reservoir in Jiuquan Basin

WANG Chongxiao，TIAN Duowen，WEI Jun，HANG Wei

2008, Vol.20(4): 20–25 Abstract ( 407 ) PDF (404 KB) ( 657 )

doi: https://doi.org/10.3969/j.issn.1673-8926.2008.04.004

The axial direction of Kulongshan anticline in the south thrust belt of Qingxi Sag in Jiuquan Basin is accordance with the regional structural trend of NWW. However, the proved high oil abundance block of the structure spreads in the direction of NNE. The reservoir distribution is greatly dominated by the development situation of the deep fractured reservoir of Lower Cretaceous. Based on the core observation and description, the data of rock thin section, scanning electron microscope, X-CT scanning of whole-core and image logging, the fracture genesis, types and occurrence, including the spreading direction and the group systems of the reservoir of Lower Cretaceous Xiagou Formation are studied. Furthermore, the fractures distribution model is set up by the combination of test analysis data with image logging interpretation result and the seismic attribute analysis.

Main basin and mountain coupling systems and their characteristics in China continent

LI Fengjie，ZHENG Rongcai，JIANG Bin

2008, Vol.20(4): 26–32 Abstract ( 662 ) PDF (412 KB) ( 731 )

doi: https://doi.org/10.3969/j.issn.1673-8926.2008.04.005

According to the prototype basin analysis, the geodynamics environment and plate tectonic setting combining with the basin evolution are applied to analyze the basin and mountain coupling systems. The basins and orogene in China continent could be divided into eight main basin and mountain coupling systems. The characteristics of these basin and mountain coupling systems are studied. The results show that the multi-stage and multicycle of tectonic movement in China continent result in the superimposed basin pattern which has many types of basin and mountain coupling systems with multi-stages.

Diagenesis and porosity evolution of deep volcanic reservoirs in Songliao Basin

LIU Chenglin，DU Yunhua，GAO Jiayu，JIN Hui，LIU Renhe，FAN Bojiang，ZHU Yuxin，ZHU Jie

2008, Vol.20(4): 33–37 Abstract ( 634 ) PDF (494 KB) ( 659 )

doi: https://doi.org/10.3969/j.issn.1673-8926.2008.04.006

Based on core description, thin section analysis, pore character and microphotograph, the diagenesis and pore evolution of deep volcanic reservoirs in Songliao Basin are studied. It is believed that the rock types are mainly basalt, andesite, rhyolite, tuff and volcanic breccia. The reservoir spaces include primary pore, primary fracture, secondary pore and secondary fracture. The diagenesis and the pore evolution could be divided into two stages （eruption stage and post-eruption stage） which include condensation phase, thermogenesis phase, hypergenesis phase and burial diagenesis phase. The reservoir spaces are affected by the diagenesis events including metasomatism, faulting, pressure solution, deep denudation and hydrocarbon aggregation.

Depositional system in sparse-borehole areas

LI Zhenxiang

2008, Vol.20(4): 38–42 Abstract ( 485 ) PDF (567 KB) ( 563 )

doi: https://doi.org/10.3969/j.issn.1673-8926.2008.04.007

It is difficult to obtain credible results from the study on the depositional system in sparse-borehole areas. The advanced 3D seismic information is used in the study on detailed depositional system. Based on the regional depositional settings and single well sedimentary microfacies, we apply spectral decomposition data to analyze the sand distribution in the area of about 400 km2, use amplitude slice, waveform analogue slice and reflection section to confirm the main stream channels, and use waveform analogue slice to determine the sedimentary boundary. The groupⅠ in the second member of Sangonghe Formation in the central Junggar Basin is divided into two depositional systems and four stream channels, which provides foundation for the interpretation of the lithologic traps in the study area.

Study on sedimentary microfacies of Chang 2₁³ in ZhangquⅠandⅡ areas,Jing’an Oilfield

CHEN Yongqiao,JIN Wenqi,WEN Zhigang,WANG Lingxia,LI Youqiang

2008, Vol.20(4): 43–46 Abstract ( 467 ) PDF (2227 KB) ( 497 )

doi: https://doi.org/10.3969/j.issn.1673-8926.2008.04.008

Based on the regional geologic background, the rock color and texture, sedimentary structure, sand body distribution and sedimentary sequence combining with logging curves are applied to study the sedimentary microfacies of Chang 213 in Jing’an Oilfield. The result shows that the target stratum in the study area is a suit of braided deltaic plain, consisting of underwater distributary channel, interdistributary bay, natural levee and crevasse splay, and that the underwater distributary channel sand bodies constitute the dominated reservoir, which provides geological foundation for the further exploration and development in the target stratum.

Genetic type and characteristics of micro-pore of Chang 6 reservoir in Yongjin area, Zhidan Oilfield of Ordos Basin

FENG Yongchun，WANG Jianmin

2008, Vol.20(4): 47–52 Abstract ( 407 ) PDF (512 KB) ( 658 )

doi: https://doi.org/10.3969/j.issn.1673-8926.2008.04.009

Based on the rock thin section observation, cast image analysis, scanning electron microscope and capillary pressure curves, pore genetic type and pore structure of Chang 6 reservoir in Yongjin area, Zhidan Oilfield are analyzed and studied. The result shows that Chang 6 reservoir is characterized by low porosity and ultra-low permeability. The pore types mainly include primary intergranular pore, secondary intergranular dissolved pore and intragranular dissolved pore. Feldspar corrosion is the main cause of the forming of secondary pore. Middle-small pore and fine-micro throat are the main pore throat characteristics, which provides the major reservoir space and seepage channel of Chang 6 reservoir. The pore structure is divided into three types. Middle-small pore and fine throat （type Ⅰ） and small pore and micro throat （type Ⅱ） are considered as the dominated reservoirs of Chang 6, and micro pore and micro throat （type Ⅲ ） is non-effective reservoir.

Accumulation patterns and controlling factors of “Sweet Point” in low permeability reservoir：A case study from Fuyang reservoir in southern Songliao Basin

XIAO Zhihua，ZHONG Ningning，ZHAO Zhanyin，HUANG Zhilong，SONG Lizhong，ZHANG Zhenying，TAN Jianbo

2008, Vol.20(4): 53–58 Abstract ( 560 ) PDF (403 KB) ( 442 )

doi: https://doi.org/10.3969/j.issn.1673-8926.2008.04.010

Based on the geologic dissection of Fuyang reservoir in southern Songliao Basin, the accumulation pattern of “sweet point” is divided into “Directly expulsion” type and “Fault supply oil” type. The source rocks, reservoir，sedimentary source and fault are considered as the main controlling factors for the formation of “sweet point”. High quality source rocks supply abundant oil sources, and anomalous pressure is the major driving force for hydrocarbon expulsion. Oiliness of the sand group Ⅰand Ⅱis better than that of group Ⅲ and Ⅳ in Quan 4 member. The reservoir thickness is more than 3 meters. The main sedimentary facies are river channel and flood land. The oiliness of the main river channel sand body in Tongyu sedimentary source is better than in Baokang sedimentary source.

Structural features and evolution in the piedmont belt in the middle segment of Longmen Mountains

GUO Bing，LIU Shugen，LIU Shun，LI Zhiwu，SUN Wei，TIAN Xiaobin

2008, Vol.20(4): 59–64 Abstract ( 511 ) PDF (599 KB) ( 816 )

doi: https://doi.org/10.3969/j.issn.1673-8926.2008.04.011

The basic structural features in the piedmont belt in the middle segment of Longmen Mountains and the geological evolution are discussed. The research shows that the piedmont belt in the middle segment of Longmen Mountains is composed of Beichuan-Yingxiu fault, Anxian-Dujiangyan Dam fault and the nappe between them.Beichuan-Yingxiu fault was weakly thrusted in the early stage and was deformed in the late stage. Anxian-Dujiangyan Dam fault was deformed. Thrust plane developed well in the nappe, which was thrusted from NW to SE. The geological evolution displays that it is stable continental margin environment from Sinian to Middle Triassic and is continental clastic sedimentary stage in Late Triassic, and the foreland basin associated with the thrust tectonic appeared at the end of the Xujiahe Formation in Upper Triassic, the thrust activities further developed and entirely uplifted, which finally formed the current complex structure pattern.

Pore structure and influencing factors of Lower Karamay Formation in Hongshanzui area of Junggar Basin

ZHOU Fengjuan，WANG Zhenqi，ZHI Dongming，GUAN Lijun，HU Qingqin，WU Xuewei

2008, Vol.20(4): 65–70 Abstract ( 453 ) PDF (583 KB) ( 654 )

doi: https://doi.org/10.3969/j.issn.1673-8926.2008.04.012

The cast thin section, scanning electronic microscope, cast image analysis and mercury injection analysis are applied to analyze the pore structure of the Lower Karamay Formation reservoir in Hongshanzui area. The main pore type of the Lower Karamay Formation reservoir is secondary dissolved pore. The throat type is lamellar or curved lamellar, mainly of moderate and fine throat. The Lower Karamay Formation is mainly composed of type Ⅲ-Ⅳ reservoirs. The main influencing factors of the pore structure are sedimentation and diagenesis, and the cementation and dissolution are dominant factors.

Influence of chlorite film on reservoir porosity：A case study from the second member of Yanchang Formation in Ordos Basin

LI Hong，WANG Furong，DAI Shili，FAN Hao

2008, Vol.20(4): 71–74 Abstract ( 546 ) PDF (314 KB) ( 531 )

doi: https://doi.org/10.3969/j.issn.1673-8926.2008.04.013

Chlorite film developed well in the reservoir sandstone in the second member of Triassic Yanchang Formation in Ordos Basin. According to the regional geologic information and core slice observation, it is concluded that chlorite film formed in the early diagenetic stage, and the porosity increased with the increasing of chlorite film content. So chlorite film takes a constructive diagenesis on the reservoir porosity in this area. This effect is manifested mainly in three aspects: repressing the quartz overgrowth, enhancing the mechanical strength of rocks and resistance to compaction, and repressing the pressure solution by occupying the space of carbonate cement.

Study on lithologic reservoirs in Yuanyanggou area of Liaohe Depression

XIEWuren，NIU Jiayu，WANG Hongliang，LIU Baohong

2008, Vol.20(4): 75–79 Abstract ( 525 ) PDF (447 KB) ( 501 )

doi: https://doi.org/10.3969/j.issn.1673-8926.2008.04.014

With the difficulty increasing of the structural reservoir exploration, lithologic reservoir s become the emphasis of the exploration in Yuanyanggou area of Liaohe Depression. Based on the sequence stratigraphy researches and the theory of sequence and paleogeomorphology controlling sand bodies, the lithologic reservoirs in Yuanyanggou area are studied by using seismic attributes analysis and seismic inversion techniques. The results show that the sand bodies are mainly controlled by paleogeomorphology. the favorable reservoir is fan delta that develops three secondary pore belts with well properties，which is advantageous to the forming of lithologic reservoirs in Yuanyanggou area of Liaohe Depression．

Gas reservoir characteristics of Permian Changxing Formation in Maobachang structure

LIN Hui，ZHOU Kai

2008, Vol.20(4): 80–85 Abstract ( 393 ) PDF (512 KB) ( 388 )

doi: https://doi.org/10.3969/j.issn.1673-8926.2008.04.015

The characteristics of structure, fault, sedimentary facies, four properties, gas component, calculation of reserves and gas reservoir types of Permian Changxing Formation of Maobachang structure in Daxian-Xuanhan area in northeastern Sichuan are analyzed. It is believed that the reservoir of Permian Changxing Formation in Maobachang structure is organic reef. The reservoir is mainly controlled by sedimentary facies, diagenesis and tectonism. According to the gas component analysis and calculation of reserves, the gas reservoir is characterized by a medium-small gas reservoir with rich CH4 , high component of CO2 , low temperature, high pressure and low abundance.

Oil accumulation factors of Chang 4＋5 and Chang 6 reservoirs of Upper Triassic Yanchang Formation in Hejiaji area

GUO Yanqin，YUAN Zhen，LI Keyong，LIANG Jiwei

2008, Vol.20(4): 86–91 Abstract ( 396 ) PDF (740 KB) ( 389 )

doi: https://doi.org/10.3969/j.issn.1673-8926.2008.04.016

The reservoirs of Chang 4+5 and Chang 6 members in Hejiaji area are characterized by thick sand body, fine grain, faster change of sedimentary facies, and reservoir physical property has obvious heterogeneity in both the vertical and horizontal direction. Further research shows that reservoir factors that affect oil accumulation include petrological component, sedimentary facies, sand body distribution, diagenesis and physical property, etc., among which sedimentary facies is the most important one. Distributary channel sand bodies in deltaic plain are the main reservoirs. It is suggested that the next exploration should be in distributary channel sand bodies.

Sedimentary characteristics of lacustrine carbonate rocks of the first member of Shahejie Formation in Banqiao-Beidagang area

ZHANG Di，HOU Zhongjian，WANG Yahui，WANG Ying，WANG Chunlian

2008, Vol.20(4): 92–97 Abstract ( 476 ) PDF (515 KB) ( 527 )

doi: https://doi.org/10.3969/j.issn.1673-8926.2008.04.017

Carbonate reservoir develops well in the first member of Shahejie Formation in Banqiao-Beidagang area. The lithologies are mainly composed of biogenic limestone, oolitic limestone, dolomitic limestone and marlite, which formed carbonate-siliciclastic mixosedimentite not only in the component but also in the vertical sequence. The sediments in the north mainly have terrigenous clastic, and the mixosedimentite are composed of carbonate rocks, sandstone and mudstone, with the main component of lime-siltstone and lime-sandstone. the mixosedimentite in the south are formed by the carbonate rocks, mudstone and shale, with the main component of limestone shale. The sedimentary facies include shore-shallow lake, shallow lake, semi-deep lake, while the microfacies of biology bank and oolitic beach are more valuable for the oil and gas exploration.

Reservoir sedimentology of Paleogene Zhuhai Formation in Baiyun Depression

GENG Wei，ZHENG Rongcai，WEI Qinlian，DAI Zhaocheng，DONG Xia

2008, Vol.20(4): 98–104 Abstract ( 514 ) PDF (522 KB) ( 482 )

doi: https://doi.org/10.3969/j.issn.1673-8926.2008.04.018

Based on core description, sample and section structure analyses, and petrology characteristics, the sedimentology characteristics of sandstone reservoir of Paleogene Zhuhai Formation in Baiyun Depression are studied, taking BYT well as a representative. The reservoir is divided into two sedimentary systems: marine delta and continental shelf, of which the characteristics are discussed. Two kinds of deltaic sedimentary evolutionary sequences are recognized, including progradation and retrogradation, and the deltaic depositional model of Zhuhai Formation is established. The pore types and reservoir controlling factors are analyzed, and the sandstone reservoir of Zhuhai Formation is divided into four types. Subaqueous dist r ibutary channel is the most favorable facies belt, followed by frontal sheet sand, subaqueous main channel, mouth bar and distal bar. This study on the reservoir sedimentology of BYT well in Pearl River Mouth Basin is of advantage to the exploration of oil and gas resources in South China Sea.

Controlling factors and evaluation methods of cementation factor

LI Xianpeng

2008, Vol.20(4): 105–108 Abstract ( 490 ) PDF (264 KB) ( 647 )

doi: https://doi.org/10.3969/j.issn.1673-8926.2008.04.019

When Archie formula is applied to calculate water saturation of the reservoir, the cementation factor is usually taken a fixed value. In fact, the cementation factor of different reservoir is not the same, and it changes with the pore structure and shale content. As the cementation factor is controlled by pore structure and shale content, first of all, we must make use of core-analysis data and GR or SP to establish the formula that can calculate the cementation factor, and then use the well logging data according to this formula to determine the cementation factor in each reservoir. In this way, making the calculated result approximately the same with the real value of the cementation factor could make sure that the Archie formula can be used to calculate water saturation of reservoir with high accuracy.

Seismic data processing techniques of carbonate rocks in Tarim Basin

WANG Xiaowei，LV Lei，LIUWeifang，QIE Shuhai，TIAN Yancan

2008, Vol.20(4): 109–112 Abstract ( 544 ) PDF (400 KB) ( 771 )

doi: https://doi.org/10.3969/j.issn.1673-8926.2008.04.020

Ordovician carbonate rocks in Tarim Basin are typical karst reservoirs. For the little difference of wave impedance in the formation interface of the carbonate rocks, the reflection information from the Ordovician is obviously poor. The development of karst fracture on the seismic profile displays a string of beads, which is a significant method for identifying karst. According to the characteristics of Tazhong area, we should place stress on the optimization of the relative amplitude preserved processing and denoising method in seismic processing and choose advisable deconvolution technique to improve the resolution of Ordovician. The application of prestack time migration technique is an effective approach to stand out the reflectance signature of Ordovician in Tazhong area.

Application of frequency information to the prediction of hydrocarbon potential in carbonate reef flat reservoirs

CAI Hanpeng，HE Zhenhua，HUANG Deji

2008, Vol.20(4): 113–117 Abstract ( 461 ) PDF (510 KB) ( 672 )

doi: https://doi.org/10.3969/j.issn.1673-8926.2008.04.021

Based on the characteristics of reef flat reservoir and its distribution interpreted by the seismic reflection features, various forms of frequency information are applied to predict the reservoir distribution. The main influencing factors for the change of seismic wave frequency are expounded, and the practicability for identifying the hydrocarbon potantial in carbonate reef flat reservoirs by frequency information is analyzed. Several parameters which could display the frequency features are selected, including single low frequency, dominant frequency, frequency attenuation gradient, high-low frequency energy radio and instantaneous frequency. As a kind of carbonate reef flat lithologic reservoir, the gas reservoir in LY area is characterized by deep burial depth and nonuniform oil and gas distribution. The application shows that the result of oil and gas distribution prediction by using different frequency information is consistent with drilling data, and the reservoir lateral variation could be well reflected.

Logging evaluation for organic reef reservoir of Changxing Formation of Gaofengchang structure in eastern Sichuan

LI Lianxin，HU Hong，LUO Zesong

2008, Vol.20(4): 118–122 Abstract ( 395 ) PDF (711 KB) ( 420 )

doi: https://doi.org/10.3969/j.issn.1673-8926.2008.04.022

Gaofengchang structure is one of the main gas fields in the east of Sichuan. The organic reef reservoir of Changxing Formation found recently is regarded as the highest quality reservoir in Gaofengchang. In the early stage of the exploration, a great quantity of high quality logging data were obtained by using advanced logging instruments. Based on these data, the reservoir division standards, fluid property, productivity prediction of single well of Gaofengchang organic reef reservoirs are analyzed, and the relevant evaluation methods are proposed, which provides foundation for the further development of Gaofengchang organic reef reservoirs.

Numerical simulation of large-scale fracturing low permeability reservoirs in Jing’an Oilfield

WU Xinwei，LI Huaijie

2008, Vol.20(4): 123–127 Abstract ( 432 ) PDF (344 KB) ( 341 )

doi: https://doi.org/10.3969/j.issn.1673-8926.2008.04.023

Aimed at the characteristics of the low permeability reservoirs in Wuliwan area in Jing’an Oilfield of Ordos Basin, the reservoir permeability around the well bottom hole is reasonably adjusted on the basis of well test data and the equivalent percolation resistance law. According to the equivalent connectivity factor method, the fractures produced by the hydraulic fracturing measure are simulated by using interwell communication correction technique and local grid refinement technique. The production technology policies about different production rates and different ratios between injections and productions are studied, and reasonable production technology policies are designed, which provides guidance to the oilfield development.

Two types of dual porosity media

LI Chuanliang

2008, Vol.20(4): 128–131 Abstract ( 513 ) PDF (252 KB) ( 562 )

doi: https://doi.org/10.3969/j.issn.1673-8926.2008.04.024

There are two types of dual porosity media: fracture-pore and fracture-vug, which displays quite different performance. The fracture-pore dual-porosity media are characterized by a “concave” on the well test curve, while the fracture-vug dual-porosity media are characterized by a straight line without a concave. The flow rate of fracture-pore dual-porosity media reservoir declines quite more rapidly than the fracture-vug dual-porosity media. The fracture-vug dual-porosity media reservoir is similar to single porosity reservoir in flow mechanism and production performance, so can be equivalent to single porosity reservoir.

Description method of lateral accretion within point bar of meandering river

WANG Lei，LIU Guotao，LONG Tao，MA Chi

2008, Vol.20(4): 132–134 Abstract ( 357 ) PDF (199 KB) ( 446 )

doi: https://doi.org/10.3969/j.issn.1673-8926.2008.04.025

The description technology of inner lateral accretion within point bar of meandering river under the condition of infill drilling well pattern is introduced. On the basis of fine geologic research conducted in Daqing Oilfield, the reservoir heterogeneity is studied. Based on the analysis of formation sequence and structure elements, the concepts in terms of lateral accretion structure characteristics, as well as description method and prediction method for the interlayer located in point bar of meandering river are proposed. These methods provide effective way for the fine study on sedimentary sand body of meandering river and the further development of remaining oil within thick reservoir. The study results were applied to the locus design of horizontal well in Daqing Oilfield, and good result has been achieved.