Muddy baffles are one of the major geological factors controlling the underground fluid flow as well as the remaining oil distribution. This study used detailed drilling data from the E1f1 reservoir in the X Oilfield,...Muddy baffles are one of the major geological factors controlling the underground fluid flow as well as the remaining oil distribution. This study used detailed drilling data from the E1f1 reservoir in the X Oilfield, Subei Basin, China, to investigate the hierarchical muddy baffles developed on lacustrine delta fronts and their precise cross-well correlation.According to the theories on allogenic and autogenic cycles as well as the genesis and scales of muddy baffles, five orders of muddy baffles were classified, which provided various degrees of difficulty when attempting interwell correlation. Under the guidance of a reliable stratigraphic model, the precise cross-well correlation of muddy baffles could be achieved and the key point of establishment of this stratigraphic model was to calculate foreset angles of hierarchical muddy baffles during deposition. During calculation, the relationships between sediment flow direction, higher-order strata dipping direction,well types and well trajectory direction should all be taken into consideration and some other angles（referred to here as θ1,θ2 and θ3） should also be measured. Such new methods of cross-well correlation for hierarchical muddy baffles could greatly reduce the uncertainties and multiple solutions, which in turn would be significant for efficient development and oil recovery enhancement in the reservoirs.展开更多
Submarine or sub-lacustrine lobe deposits are important reservoirs,but the fan fringe deposits form heterogeneities within deep water fan deposits.Fan fringe facies records the complex sediment gravity flow types.By u...Submarine or sub-lacustrine lobe deposits are important reservoirs,but the fan fringe deposits form heterogeneities within deep water fan deposits.Fan fringe facies records the complex sediment gravity flow types.By understanding of the bed types and flow mechanisms,we can identify the fan fringe deposit,which aids in the reconstruction of deep water fan and reservoir evaluations.The Jiucaiyuanzi and Dalongkou sections in the West Bogda Mountains preserve well-exposed 536-m and 171-m thick successions,respectively,of a deep water lacustrine depositional system from the Middle Permian Lucaogou Formation.Bed types of the Lucaogou Formation include high-density turbidite,low-density turbidite,incomplete Bouma-type turbidite,hybrid event beds,and slump deposits.The Lucaogou Formation is interpreted here as a fan fringe facies due to the thin bed thickness that characterize turbidites and hybrid event beds,as well as the predominance of the isolated sheet architecture.Previous studies suggest that these deposits were considered as deposited in a deep water setting due to the absence of wave-related structures.The presence of abundant mud clasts in massive medium-coarse grained sandstone beds reflects the significant erosional capability and interactions between high-density turbidity currents and lake floor.The fan fringe facies here contains amalgamated and thick-bedded homolithic facies(~30%)and thin-bedded heterolithic facies(~70%).The examination of the bed type is of wider significance for facies prediction and reservoir heterogeneity in the sub-lacustrine fan fringe facies.展开更多
Based on analysis on X-ray diffraction, the metamorphic grade of coal in southeast Qinshui Basin was discussed, and a precise evaluation of coal rank through XRD analysis was made, in addition, the correlation of coal...Based on analysis on X-ray diffraction, the metamorphic grade of coal in southeast Qinshui Basin was discussed, and a precise evaluation of coal rank through XRD analysis was made, in addition, the correlation of coal rank and vitrinite reflectance （Ro） was compared. XRD spectra of coal shows （002）-band and γ-band, and based on fitting calculation and multi-peak separation methods, the values of 2θ002 and 2θγ can be obtained, as well as corresponding intensities I002 and Iγ, consequently the coal rank can be quantized as the ratio of I002 and Iγ, that is coal rank=I002/Iγ. The research shows that the values of θ002 and θγ increase with the metamorphic grade, and a very good linear positive correlation exists between calculated Coal Rank and Ro.展开更多
Junggar Basin,located in northern Xinjiang,presents continuous and multikilometer-thick strata of the Jurassic deposits.The Jurassic was entirely terrestrial fluvial and lacustrine deltaic sedimentation.Eight outcrop ...Junggar Basin,located in northern Xinjiang,presents continuous and multikilometer-thick strata of the Jurassic deposits.The Jurassic was entirely terrestrial fluvial and lacustrine deltaic sedimentation.Eight outcrop sections across the Jurassic strata were measured at a resolution of meters in southern Junggar Basin.Controlling factors of sedimentary evolution and palaeoclimate changes in Junggar Basin during the Jurassic were discussed based on lithology,fossils and tectonic setting.In the Early to Middle Jurassic,the warm and wide Tethys Sea generated a strong monsoonal circulation over the central Asian continent,and provided adequate moisture for Junggar Basin.Coal-bearing strata of the Badaowan,Sangonghe,and Xishanyao Formations were developed under warm and humid palaeoclimate in Junggar Basin.In the late Middle Jurassic,Junggar Basin was in a semi-humid and semi-arid environment due to global warming event.Stratigraphy in the upper part of the Middle Jurassic with less plant fossils became multicolor or reddish from dark color sediments.During the Late Jurassic,collision of Lhasa and Qiangtang Block obstructed monsoon from the Tethys Sea.A major change in climate from semi-humid and semi-arid to arid conditions took place,and reddish strata of the Upper Jurassic were developed across Junggar Basin.展开更多
基金supported by an Open Fund of State Key Laboratory of Oil and Gas Reservoir Geology and Exploitation (Southwest Petroleum University, PLN1503)the National Natural Science Foundation of China (Nos. 41602145, 41402125, and 41602117)Scientific Research Starting Project of SWPU (No. 2014QHZ008)
文摘Muddy baffles are one of the major geological factors controlling the underground fluid flow as well as the remaining oil distribution. This study used detailed drilling data from the E1f1 reservoir in the X Oilfield, Subei Basin, China, to investigate the hierarchical muddy baffles developed on lacustrine delta fronts and their precise cross-well correlation.According to the theories on allogenic and autogenic cycles as well as the genesis and scales of muddy baffles, five orders of muddy baffles were classified, which provided various degrees of difficulty when attempting interwell correlation. Under the guidance of a reliable stratigraphic model, the precise cross-well correlation of muddy baffles could be achieved and the key point of establishment of this stratigraphic model was to calculate foreset angles of hierarchical muddy baffles during deposition. During calculation, the relationships between sediment flow direction, higher-order strata dipping direction,well types and well trajectory direction should all be taken into consideration and some other angles（referred to here as θ1,θ2 and θ3） should also be measured. Such new methods of cross-well correlation for hierarchical muddy baffles could greatly reduce the uncertainties and multiple solutions, which in turn would be significant for efficient development and oil recovery enhancement in the reservoirs.
基金The study was funded by National Science and Technology Major Project(Grant No.2017ZX05001-002)National Natural Science Foundation of China(Grant No.41802129)。
文摘Submarine or sub-lacustrine lobe deposits are important reservoirs,but the fan fringe deposits form heterogeneities within deep water fan deposits.Fan fringe facies records the complex sediment gravity flow types.By understanding of the bed types and flow mechanisms,we can identify the fan fringe deposit,which aids in the reconstruction of deep water fan and reservoir evaluations.The Jiucaiyuanzi and Dalongkou sections in the West Bogda Mountains preserve well-exposed 536-m and 171-m thick successions,respectively,of a deep water lacustrine depositional system from the Middle Permian Lucaogou Formation.Bed types of the Lucaogou Formation include high-density turbidite,low-density turbidite,incomplete Bouma-type turbidite,hybrid event beds,and slump deposits.The Lucaogou Formation is interpreted here as a fan fringe facies due to the thin bed thickness that characterize turbidites and hybrid event beds,as well as the predominance of the isolated sheet architecture.Previous studies suggest that these deposits were considered as deposited in a deep water setting due to the absence of wave-related structures.The presence of abundant mud clasts in massive medium-coarse grained sandstone beds reflects the significant erosional capability and interactions between high-density turbidity currents and lake floor.The fan fringe facies here contains amalgamated and thick-bedded homolithic facies(~30%)and thin-bedded heterolithic facies(~70%).The examination of the bed type is of wider significance for facies prediction and reservoir heterogeneity in the sub-lacustrine fan fringe facies.
基金Supported by the National Natural Science Foundation of China （40972106） the Major Projects of the National Science and Technology of China （2011ZX05042-001-002） the Central Universities Fundamental Research Special Foundation of China （292011266）
文摘Based on analysis on X-ray diffraction, the metamorphic grade of coal in southeast Qinshui Basin was discussed, and a precise evaluation of coal rank through XRD analysis was made, in addition, the correlation of coal rank and vitrinite reflectance （Ro） was compared. XRD spectra of coal shows （002）-band and γ-band, and based on fitting calculation and multi-peak separation methods, the values of 2θ002 and 2θγ can be obtained, as well as corresponding intensities I002 and Iγ, consequently the coal rank can be quantized as the ratio of I002 and Iγ, that is coal rank=I002/Iγ. The research shows that the values of θ002 and θγ increase with the metamorphic grade, and a very good linear positive correlation exists between calculated Coal Rank and Ro.
基金supported by PetroChina Xinjiang Oilfield Companythe Chinese National Natural Science Fund Project(No.41072084+2 种基金No.41272132)National Program on Key Basic Research Project(973 Program)(No.2009CB219502-3)the Fundamental Research Funds for the central universities(2-9-2013-97)
文摘Junggar Basin,located in northern Xinjiang,presents continuous and multikilometer-thick strata of the Jurassic deposits.The Jurassic was entirely terrestrial fluvial and lacustrine deltaic sedimentation.Eight outcrop sections across the Jurassic strata were measured at a resolution of meters in southern Junggar Basin.Controlling factors of sedimentary evolution and palaeoclimate changes in Junggar Basin during the Jurassic were discussed based on lithology,fossils and tectonic setting.In the Early to Middle Jurassic,the warm and wide Tethys Sea generated a strong monsoonal circulation over the central Asian continent,and provided adequate moisture for Junggar Basin.Coal-bearing strata of the Badaowan,Sangonghe,and Xishanyao Formations were developed under warm and humid palaeoclimate in Junggar Basin.In the late Middle Jurassic,Junggar Basin was in a semi-humid and semi-arid environment due to global warming event.Stratigraphy in the upper part of the Middle Jurassic with less plant fossils became multicolor or reddish from dark color sediments.During the Late Jurassic,collision of Lhasa and Qiangtang Block obstructed monsoon from the Tethys Sea.A major change in climate from semi-humid and semi-arid to arid conditions took place,and reddish strata of the Upper Jurassic were developed across Junggar Basin.
