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2019 Vol. 41, No. 4

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2019, 41(4): .
Abstract(430) PDF-CN(150)
Abstract:
Bimodal hydrocarbon generation and immature oil do not exist in the North Jiangsu Basin
LIU Yurui
2019, 41(4): 461-474. doi: 10.11781/sysydz201904461
Abstract(1175) PDF-CN(162)
Abstract:
A contradiction in the "immature oil in North Jiangsu Basin" theory prevails and the results of geological exploration is not consistent with it. After making a thorough analysis of previous work and validating the data, the following problems were noticed:misusing of raw data, taking outliers as evidence; multi-parameter consideration is lacking in the hydrocarbon generation model, which makes the inference invalid; the consistency of reservoir and hydrocarbon maturity was not verified after the oil-source correlation; hypotheses do not stand the test of source rock gas logging data and other prospecting results. These indicate that the "non-kerogen source rock early maturation & bimodal hydrocarbon generation model" could be incorrect, and the "immature oil" may not exist. After using big an extensive data set to analyze errors and exclude outliers, the sterane C29S/(S+R) and C29ββ/(αα+ββ), the terpane C31S/(S+R) and C32S/(S+R), as well as CPI and OEP maturity sensitive parameters of hydrocarbon and rocks were optimized. Crude oil from the thermal degradation of late kerogen can be divided into 3 types:low maturity oil, medium maturity oil and mature oil. It is pointed that the maturity parameters of a large quantity of medium maturity source rocks (Ro>0.70%) could match well with those of medium maturity oil; the maturity parameters of low maturity source rocks (0.60% ≤ Ro ≤ 0.70%) have only some matching relationships with a small number of low maturity oil maturity parameters; no crude oil matched the immature source rocks (Ro<0.60%). The results indicate that the non-kerogen immature oil does not exist. Prominent anomalous data can be detected in the medium maturity and mature source rock gas logging. Hydrocarbon traps with these source rocks usually have good exploration results, and 99.83% of the discovered oil reserves belong to this type. There is little or no anomalous data in the low maturity source rock gas logging. This source rock is unable to form a commercial scale reservoir, and only some shows of hydrocarbon may exist. No anomalous data can be found in immature source rock gas logging. If there is no mature oil supply from other places, reservoirs will not be formed.
Tectonic evolution stages and deformation characteristics in central and western China
YANG Fan, HU Ye, LUO Kaiping, LI Fengxun, PAN Wenlei, CAO Qinggu, LU Yongde
2019, 41(4): 475-481. doi: 10.11781/sysydz201904475
Abstract(904) PDF-CN(170)
Abstract:
Large basins in central and western China have undergone multiple stages of tectonic movement, which played different roles in controlling the formation and evolution of the basins. Since the Late Paleozoic, the development of these basins can be divided into the ‘north convergence and south separation’ transitional tectonic system from the Late Paleozoic to the Early Mesozoic and the intracontinental alteration system since the Mesozoic era. The change period of the basins is controlled by these two structural systems, while there are some differences in the transformation times and deformation characteristics in different structural locations. In general, there are two key periods. The first is from the Late Hercynian to the Early Indosinian period. The movement led to the completion of sea land transformation. The second is from the Yanshan period to the Himalayan period. This is the most intense period of tectonic activity in the central and western regions, and also the main formation period. At the same time, this period also corresponds to the main accumulation stage and transformation stage of clastic strata. The main deformation characteristics are fracturing, folding and differential uplifting.
Sedimentary evolution and controls in paleo-Hanjiang delta from 32 to 10.5 Ma
LIU Chensheng, HOU Wenfeng, QIU Zhengke, WANG Tao, ZHANG Xiangtao, WANG Xudong
2019, 41(4): 482-490. doi: 10.11781/sysydz201904482
Abstract(1069) PDF-CN(108)
Abstract:
The paleo-Hanjiang delta has become a focus of petroleum exploration in the South China Sea. The sedimentary evolution analysis of the paleo-Hanjiang delta is helpful to evaluate the potential of petroleum resources in the Pearl River Mouth Basin and predict favorable exploration blocks. The sedimentary facies types and evolution of the paleo-Hanjiang delta in the Lufeng-Hanjiang sags from 32-10.5 Ma were analyzed based on core, logging, drilling and seismic data. The results show that paleo-Hanjiang delta can be subdivided into delta plain, delta front and pre-delta in the Hanjiang-Lufeng sags. The evolution of the paleo-Hanjiang delta has experienced three stages. In the first stage, during the sedimentary period from the Zhuhai Formation to the Zhujiang Formation, the sediments of the paleo-Hanjiang delta were coarse in grain size and extended in the delta, mainly distributed in the Lufeng Sag. In the second stage, during deposition of the lower part of Hanjiang Formation, the paleo-Hanjiang delta gradually had reduced provenance in response to increasing sea level. Shallow shelf and carbonate platform were dominant in the Lufeng and Hanjiang area. The sea level reached its maximum in the lower section of the Hanjiang Formation, and the area of the paleo-Hanjiang delta reached its smallest. In the third stage, during the sedimentary period of the upper section of Hanjiang Formation, the paleo-Hanjiang delta began to advance to the basin as the sea level fell.
Paleogeomorphologic features and their controls on sandbody distribution on basin margin during Late Paleozoic Era and significance for petroleum exploration, Hangjinqi area, Ordos Basin
HU Huarui, XING Fengcun, QI Rong, WANG Chao, LIU Xiaochen, CHEN Lin, CHEN Xiaoquan
2019, 41(4): 491-497. doi: 10.11781/sysydz201904491
Abstract(966) PDF-CN(156)
Abstract:
The paleogeomorphology in the Hangjinqi area of the Ordos Basin during the Late Paleozoic was restored by establishing a high-resolution sequence stratigraphy framework based on seismic data. The paleogeomorphologic features and their controls on sandbody distribution were discussed. When the Carboniferous Taiyuan Formation to the first member of Permain Shihezi Formation deposited, the study area featured by two distinct uplifts and three depressions from east to west. Vertically, three evolution periods were identified. In the first period, incised valleys developed and were overlapped and filled from the Taiyuan Formation to the first member of Shanxi Formation. In the second period, uplifts and depressions were inherited and gradually filled from the second member of Shanxi Formation to the first member of Shihezi Formation. In the last period, paleogeo-morphology was gentle and flat from the second to the third member of Shihezi Formation. Different periods of geomorphological evolution controlled the sandbody structure evolution. At the first period, the Taiyuan Formation distributed in the southern of Boerjianghaizi fault, which indicates the influence of the fault. Sand transported from the incised valleys in the north to deposit in the depressions in the south. Aggradational sandbodies deposited in the incised valleys and depressions. In the second period, the paleogeomorphology gradually became more and more flat, and faults showed weak controls on sandbody distribution. Sandbodies were contiguous with a certain degree of lateral oscillation. The inherited three depressions were the main distribution area of sandbodies. In the final period, sources retreated northward, and the paleogeomorphology was flat which formed the structure of mudstone-enclosed isolated sandbodies characterized by lateral isolation.
Evolution mechanism and hydrocarbon reservoir characteristics of typical slope zones in Jizhong Depression, Bohai Bay Basin
DONG Dawei, ZHAO Li, LI Tingting, SHI Rui, LI Tong, SUN Yifei, SUN Hao
2019, 41(4): 498-507. doi: 10.11781/sysydz201904498
Abstract(902) PDF-CN(125)
Abstract:
The width and gradient of slope zones in faulted basins in China were studied. The tectonic evolution mechanism and hydrocarbon reservoir characteristics of various types of slope zones were discussed from the aspects of structural geometry and kinematics based on the seismic and geological data collected mainly from the Wen'an, Lixian and Shulu West slopes in the Jizhong Depression. According to slope gradient and width, three types of slope zones were classified:wide-gentle type, platform type and narrow-steep type, corresponding to the Wen'an, Lixian and Shulu West slopes, respectively. The wide-gentle type slope was characterized by a single-break and shallow detachment, and was dominated by sedimentation. Oil and gas migrated horizontally for a long distance and was enriched in multiple layers with various trap types. The platform type slope was characterized by double-breaks and medium detachment, and was controlled by both structure and sedimentation. The hydrocarbon abundance in the platform type slope depended on the hydrocarbon-producing subsags in slopes, and the traps were mainly nose-like or lithologic pinch-out types. The narrow-steep slope was characterized by a single-break and deep detachment, and was dominated by structure. Oil and gas migrated vertically and was mainly enriched in structural traps.
Diagenesis types and characteristics of Xishanyao Formation in Malang Sag, Santanghu Basin
MA Ling, LI Jie, XU Shenglin, CHEN Xuan, YANG Shuai, LI Fuxiang
2019, 41(4): 508-515. doi: 10.11781/sysydz201904508
Abstract(1091) PDF-CN(112)
Abstract:
There are many large-scale sandstone reservoirs in the Xishanyao Formation of the Malang Sag, Santanghu Basin, with great potential for oil and gas development. The diagenesis types and stages of the reservoir were studied by means of thin section observation, scanning electron microscopy, X-ray diffraction, vitrinite reflectance, etc. Based on this, the influence of diagenesis on the reservoir was analyzed. Eight types of diagenesis were developed in the sandstone reservoirs of the Xishanyao Formation in the study area. Constructive effects include rim chlorite cementation, alteration, dissolution and rupture, while the main destructive diagenesis includes compaction, pressure solution, and siliceous and carbonate cementation. In addition, the cementation and metasomatism will change from constructive to destructive with the backward transition of the diagenetic stage. The sandstones of the Xishanyao Formation in the study area are mainly in the late part of the middle diagenetic A stage. Compaction is the main reason for porosity reduction, while kaolinite and dissolution are the main causes for porosity increase. Chlorite rim cementation developed. The sandstones with remaining primary intergranular pores and dissolution pores are the most favorable reservoirs.
Sedimentology of lower section of third member of Shahejie Formation on western slope of Lijin Subsag, Dongying Sag, Bohai Bay Basin: a case study of Bin 648 area, Binnan Oil Field
CHENG Kenan
2019, 41(4): 516-523. doi: 10.11781/sysydz201904516
Abstract(866) PDF-CN(120)
Abstract:
The Binnan Oil Field tectonically belongs to the western slope of Lijin Subsag, Dongying Sag, Bohai Bay Basin. The Bin 648 area is an anticlinal fault oil reservoir (higher in the north and lower in the south) complicated by faulting. The lower section of the third member of Shahejie Formation is the main oil-bearing series and is in the development stage of medium-low water content and low oil production rate. Based on the standardized processing of logging data, the multi-well edit module of the Direct-Art software was used for stratum division and sand body contrast using the elevation vertical depth contrast pattern. Finally, the lower section of the third member of Shahejie Formation was divided into five sand groups and eleven thin layers. The grain-size cumulative probability curves and C-M chart of well Bin 648 showed coarse to medium size and high density turbidite sediment characteristics. The lower section of the third member of Shahejie Formation is dominated by fan delta front subfacies and pre-fan delta subfacies, including submerged distributary channel microfacies, tributary bay microfacies, channel bar microfacies, frontal sheet sand microfacies and pre-fan delta lacustrine mudstone microfacies. The favorable facies belt for oil and gas reservoirs are the submerged distributary channel microfacies and channel bar microfacies.
Sequence stratigraphy and reef beach distribution of Feixianguan Formation in western Hubei-eastern Chongqing area: a case study of the third member of Feixianguan Formation in Jiannan and adjacent area
WU Nazhu
2019, 41(4): 524-529. doi: 10.11781/sysydz201904524
Abstract(1012) PDF-CN(144)
Abstract:
The sequence boundary identification, sequence unit division, isochronous stratigraphic framework establishment and sedimentary system of bioreef-beach bodies in the third member of the Lower Triassic Feixianguan Formation in and around Jiannan town in the western Hubei and eastern Chongqing area were studied based on drilling, logging, core, outcrop, seismic and testing data. The Feixianguan Formation consists of two third-order sequences, SQ1 and SQ2. The SQ1 was composed of the first and second members of Feixianguan Formation, while the SQ2 was made up of the third and fourth members of Feixianguan Formation. The third member of Feixianguan Formation can be further refined into three fourth-order sequences, which are sq1, sq2, and sq3 from bottom to top. The third member of Feixianguan Formation can be divided into inner, central and outer gentle slope facies, and further divided into 9 beach subfacies, including oolitic, granulated, bean, biodetritus, sandy clastic and inter beaches, and lower slope, upper slope and platform depression. During the deposition of the third member of Feixianguan Formation, the terrain of the study area was high in the west and low in the east. The high-energy shoal was distributed in the central area,while the granulated beach and main reservoirs were mainly distributed in the north and south of the study area.
Pore structure characteristics and controls of Lower Cambrian Niutitang Formation, western Hubei Province
HE Qing, HE Sheng, DONG Tian, ZHAI Gangyi, WANG Yi, WAN Kuo
2019, 41(4): 530-539. doi: 10.11781/sysydz201904530
Abstract(1473) PDF-CN(242)
Abstract:
The pore structure features of shale in the Lower Cambrian Niutitang Formation in the western Hubei Province were examined using low-temperature CO2 and N2 adsorption tests, Field Emission-Scanning Electron Microscopy (FE-SEM) observations, TOC content measurements, and X-ray diffraction analyses. The TOC content is high in the Niutitang Formation, and the dominant pore types are organic pores and intra-particle pores, displaying complex pore morphology. XRD analysis suggests that the mineral components are dominated by quartz and clays. The CO2 and N2 adsorption experiments show that the pore size distribution displays multi-peaks, and the size of mesopores was mostly within the range of 2-25 nm. The pore volumes and specific surface areas of Niutitang shale are mainly provided by micropores and mesopores. Three shale lithofacies can be identified including siliceous shale, mixed shale and muddy shale. The role of TOC content and minerals on pore development is different in different lithofacies of Niutitang Formation. The porosity development of siliceous shale is mainly affected by the contents of TOC and biogenic silica. The porosity development of mixed shale is mainly affected by the contents of TOC and clay minerals.
Influence of graptolite debris on shale gas generation and accumulation
SONG Di, XU Chang, YAO Suping, TENGER Boltsjin
2019, 41(4): 540-547. doi: 10.11781/sysydz201904540
Abstract(1075) PDF-CN(162)
Abstract:
As one of the standard fossils of the Ordovician and Silurian, graptolites are widely distributed in the Upper Ordovician Wufeng Formation to the Lower Silurian Longmaxi Formation in the Lower Paleozoic of South China. This stratum shows a good potential for shale gas exploration; however, there is a disagreement about the contribution of graptolite debris to the generation and storage of shale gas. Acid treatment was carried out on shale samples from the Wufeng-Longmaxi formations in well Weiye 1 in the Weiyuan and Changning areas of the Sichuan Basin. Graptolite debris was collected and analyzed with Microscopic Fourier Transform Infrared Spectroscopy, Scanning Electron Microscopy and Transmission Electron Microscopy. The composition and pore development characteristics of the organic matter in graptolites were examined, and the contribution of graptolite bodies to shale reservoir capacity was discussed. The graptolite bodies were mainly composed of organic matter of collagen, which shows a poor gas potential. However, the inner fetal tube of the graptolite body is hollow, and strawberry-like pyrite is developed in the body cavity, which is favorable for the storage of shale gas. The graptolite bodies are superposed on each other to form a multi-layer structure, and the vertical and horizontal stripes and the nano-mineral partitions in the graptolite skin form gaps between the stacked graptolite skins, thereby improving shale gas storage. Therefore, it is believed that the large number of graptolites in the Wufeng-Longmaxi formation shale is one of the important reasons that affect the shale gas enrichment in this segment.
Evolution of Persian Gulf Basin and formation of super-large oil and gas fields
LI Yunzhen, ZHANG Xin, XIN Shiyin, LIU Wanchun
2019, 41(4): 548-559. doi: 10.11781/sysydz201904548
Abstract(1534) PDF-CN(160)
Abstract:
The Persian Gulf Basin has a large number of super-large oil and gas fields, and their formation is closely related to the evolution characteristics of the basin. The basin is controlled by basement rifting and the opening and closing of the Tethys Ocean.The tectonic evolution has undergone three stages of rift, drift and collision, eventually forming the basement rift, the passive continental margin and the foreland basin. Each evolution stage has different controlling functions on the generation, migration and accumulation of oil and gas. The evolution of the rift stage controls the prototype of a series of large structures and salt domes. The evolution of the drift stage controls the formation of the main source rocks and the Mesozoic-Paleozoic reservoir-seal assemblages. The evolution of the collision stage has an important influence on the definition of traps and the secondary distribution of oil and gas. Through three stages of special tectonic evolution, the Persian Gulf Basin has formed very superior petroleum geological conditions, and there is a good matching relationship among various reservoir-forming factors, resulting in a large number of super-large oil and gas fields with concentrated distribution.
Distribution patterns and geochemical implication of bicadinanes in crude oils from Baiyun Sag, Pearl River Mouth Basin
LU Xiaolin, SHI Ning, LI Meijun, ZHANG Zhongtao, FU Jian, CHEN Cong, LAI Hongfei, DAI Jinhui
2019, 41(4): 560-568. doi: 10.11781/sysydz201904560
Abstract(962) PDF-CN(119)
Abstract:
Bicadinanes (W, T) are abundant in crude oils in the Baiyun Sag of the Pearl River Mouth Basin. The distribution patterns and geochemical implication of bicadinanes in crude oils from the study area were investigated based on the gas chromatography-mass spectrometry of 35 oil samples. The relative content of bicadinanes in crude oils is relatively higher in the north but lower in the east of the sag. Maturity and gas washing exert a minor impact on the relative contents of bicadinanes in mature to high-maturity crude oils, while hydrocarbon sources play an important role. The relative content of bicadinanes is positively related to Pr/Ph and tricyclic terpane (C19TT+C20TT)/C23TT ratios, which shows that an oxidizing environment with high terrestrial input is more favorable for the enrichment of bicadinanes. Therefore, the relative content of bicadinanes can be used to define biological source, depositional environment and oil-source correlations. In addition, bicadinane T/W ratios may serve as an index for evaluating maturity in low to medium-maturity crude oils.
Characteristics of diamondoids in crude oil and its application in hinterland of Junggar Basin
LI Erting, CHEN Jun, ROUZI Dilidaer, GAO Xiuwei, MI Julei, MA Wanyun
2019, 41(4): 569-576. doi: 10.11781/sysydz201904569
Abstract(1074) PDF-CN(115)
Abstract:
The content of diamondoids in crude oil from the hinterland of Junggar Basin was analyzed by GC, MS and GC-MS methods. The applicability of diamondoid indices to identify and evaluate oil maturity was discussed. The diamondoid content in crude oil is (200-500)×10-6. The concentration index of diamondoids can classify oil types effectively, and the adamantane isomerization index can be used to evaluate oil maturity. The oil in the hinterland of Junggar Basin can be divided into two types. Type I oils were generated early with relatively lower maturity and lower content of diamondoids. The content of adamantane is relatively higher. The concentration index A/1-MA ratio is distributed in the range of 0.50-0.71, and the maturity index MAI value is smaller, between 0.41 and 0.50, which is far away from the hydrocarbon source depression. Type Ⅱ oils were generated late with relatively higher maturity and higher content of diamondoids. The content of 1-methyladamantane is higher. The ratio of A/1-MA is in the range of 0.30-0.37, and the MAI value is between 0.52 and 0.69, which fall within the hydrocarbon source depression. The distribution pattern is consistent with the direction of oil migration. That is, the late filling oil displaced the early filling oil away from the hydrocarbon generation depression, which proves that the oil in the hinterland area migrated from the area of the well Pen 1 sag to the north.
Hydrocarbon source rock characteristics and exploration direction in Xingrenpu Sag, Liupanshan Basin
PENG Cuncang
2019, 41(4): 577-582. doi: 10.11781/sysydz201904577
Abstract(962) PDF-CN(109)
Abstract:
The Xingrenpu Sag is located in the southeast of Liupanshan Basin, which is a Mesozoic basin in the early evaluation stage with only limited exploration. The geochemical parameters of hydrocarbon source rocks such as organic matter abundance, type and maturity and the favorable factors for reservoir formation were discussed based on drilling, outcrop core, two-dimensional earthquake and magnet data. The source rocks of the Triassic Yanchang Formation in the sag are medium source rocks, the organic matter belongs to type Ⅱ-Ⅲ, and the maturity is low-mature to mature, which show a certain exploration potential. The exploration of self-generated and self-reservoired resources should be focused on in the future. The Jurassic Zhiluo Formation source rocks are good hydrocarbon source rocks with typeⅠ-Ⅱ organic matter, and the maturity is low-mature to mature, providing exploration targets for structural and lithologic traps.
Geochemical characteristics and geological significance of calcite filled fractures and caves in Middle-Lower Ordovician, northern Shuntuoguole area, Tarim Basin
WANG Yuxiang, WANG Bin, GU Yi, FU Qiang, WAN Yanglu, LI Yingtao
2019, 41(4): 583-592. doi: 10.11781/sysydz201904583
Abstract(1156) PDF-CN(140)
Abstract:
Micro-element cathodoluminescence and in situ elemental analysis were used to determine the trace and rare earth elements in calcite samples from the Middle and Lower Ordovician in the northern Shuntuoguole area of the Tarim Basin. The content of rare earth elements in calcite particles was not high, ranging from 0.735 to 24.538 μg/g, with an average of 4.963 μg/g. An obvious enrichment of light rare earth elements and a relative depletion of heavy rare earth elements was observed, with an obvious differentiation between them. There was a slight positive Ce anomaly and an obvious positive Eu anomaly. The Sc, Th contents and the Fe/Mn values were low, while the U/Th and Sr/Ba values were high, indicating that the calcites were deposited in a dry and reducing environment. The comparative geochemical analyses of different occurrences and different periods of calcites and surrounding rock particles were carried out. It is clear that the reservoir geological fluids in the study area mainly came from the formation water of seawater nature, and there were mixed sources of atmospheric water and silicon-rich hydrothermal fluids. It was confirmed that rare earth elements in the original sedimentary wall rocks were relatively rich, and the rare earth elements in calcite grains inherit from the surrounding rocks nearby, but were controlled by the strength of diagenetic fluid transformation.
Porosity measurement error and its control method
BAO Yunjie, LI Zhiming, YANG Zhenheng, QIAN Menhui, LIU Peng, TAO Guoliang
2019, 41(4): 593-597. doi: 10.11781/sysydz201904593
Abstract(1922) PDF-CN(213)
Abstract:
With the expansion of oil and gas exploration, the lithology and morphology of porosity test samples show diverse development trends. Porosity measurement faces new challenges because the same sample may have different laboratory porosity measurement results, limiting the application of porosity data. Starting from two key parameters of the total volume and skeleton volume of the rock sample, the influence of test error on the porosity measurement results was analyzed. It is found that when the relative error of the test is 0.5%, 1.0% and 1.5%, the absolute error of porosity is 0.5, 0.9 and 1.4, respectively. The test error of the two has similar influence on the accuracy of porosity measurement, and should be effectively controlled. The current situation of error control of rock sample skeleton volume and total volume was analyzed. Volume testing relies on more mature methods and devices, and its test error can be effectively controlled. The development of total volume testing technology lags behind. The acquisition of key parameters in the measurement process is affected by random human factors, resulting in differences between different operators and different laboratory results. The method for effectively controlling porosity measurement error was discussed. A total sample volume measurement system for rock samples based on the fluid density determination principle was introduced, which has no restrictive requirements on the lithology and morphology of the sample, and automates the determination of the total volume of rock sample. The influence of human factors on the test can be reduced. The average relative error of the total volume of rock sample is 0.5%, and the absolute error of porosity measurement can be controlled to about 0.5, which can be used to narrow the difference of measurement results in different laboratories.
Calculation and application of plane pressure decrease gradient
FENG Yuelin, LIU Hua, SONG Guoqi, YUAN Feifei
2019, 41(4): 598-605. doi: 10.11781/sysydz201904598
Abstract(770) PDF-CN(96)
Abstract:
As a driving force for oil and gas migration, the overpressure change rate has a relationship with oil and gas migration mode. In order to quantitatively identify the hydrocarbon migration modes in overpressure basins, some calculation ideas and methods of the application of formation pressure decrease gradient were established, and were applied in the Bonan Subsag, Zhanhua Sag, Bohai Bay Basin. Based on measured pressure and single well predicted pressure, the pressure distribution characteristics of the main hydrocarbon migration layer were analyzed. According to the characteristics of overpressure genesis, sedimentary facies and faults, different pressure drop gradient calculation methods were applied to the uniform pressure attenuation zone, the inhomogeneous pressure decrease zone of sedimentary facies transformation and the inhomogeneous pressure decrease zone of the faulted zone. The results show that the pressure decrease gradient is the highest in the deep sag of Bonan Subsag, followed by the fault step, steep slope and gentle slope zones, and the pressure decrease gradient near the vertically connected faults is higher. The variation characteristics of oil and gas migration mode under overpressure control were quantitatively explained so that the location of hydrocarbon enrichment can be effectively judged.
Quantitative evaluation of vertical fault transport in Daliuquan area of Langgu sag, Bohai Bay Basin
LIU Junqiao, WANG Wei, LÜ Yanfang, FU Guang
2019, 41(4): 606-613. doi: 10.11781/sysydz201904606
Abstract(942) PDF-CN(112)
Abstract:
The ability to transport oil and gas shows differences for different faults or different parts of the same fault. The vertical transportation of oil and gas through faults was evaluated quantitatively and the controls on oil and gas distribution in the Daliuquan area of the Langgu Sag of the Bohai Bay Basin were discussed. Various factors were considered including migration dynamics, hydrocarbon source, and the kinematics and geometric characteristics of faults.Based on confirming source faults, four geological parameters were summarized, including fault activity intensity, abnormal pressure, "transfer station" scale and fault convex ridge scale, all of which have a positive correlation with reserve abundance and can be used to fit a quantitative characterization formula of fault vertical transporting ability as quantitative indexes. Using this formula to evaluate the vertical fault transport ability of the Daliuquan area, this method indicates that the quantitative evaluation results are consistent with the actual geological conditions, which shows that the quantitative characterization method has a good applicability.
Reef control factors and new seismic prediction techniques of Changxing Formation, east of Kaijiang-Liangping trough, Sichuan Basin
PENG Cai, ZHENG Rongcai, CHEN Hui, WANG Lanying, LUO Jing, LIANG Hong
2019, 41(4): 614-620. doi: 10.11781/sysydz201904614
Abstract(1410) PDF-CN(176)
Abstract:
The sedimentary characteristics, main controlling factors and reef reservoir facies of the Upper Permian Changxing Formation reef on the eastern side of the Kaijiang-Liangping trough in the northeastern Sichuan Basin were studied using comprehensive seismic prediction technology.Through the study of single well sedimentary facies, it is found that there are two stages of longitudinal development of the reefs in this area. The paleogeomorphology of the Changxing Formation has a controlling effect on the development and migration of the reefs:the larger the slope, the thicker the reefs.Early paleo-geomorphology controlled the development of reefs. In the northern steep slope zone, early reef strips developed, while in the southern gentle slope zone, late reef blocks developed. Late paleotopography controlled the migration of reefs to the platform, resulting in the second row of reefs.Targeted prediction techniques were used to account for differences in sedimentary environments in different regions. In the central transitional belt, the amplitude property on the top of Changxing Formation on the platform margin was optimized to predict reef thickness. In the southern gentle slope sedimentary zone, the bioreef is predicted by the seismic-based interpretation technique. The predicted results have been confirmed by actual drilling, and many wells have obtained high-yield gas flow.
2019, 41(4): 621-621.
Abstract(468) PDF-CN(158)
Abstract:

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