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In order to quantify and define the features of the bottom concave and convex structure of the Yanchang Formation in several key sedimentary periods, four stratigraphic units, namely Chang 10 ~ Chang 8, Chang 7, Chang 6 ~ Chang 4 + 5 and Chang 3 ~ Chang 1, were divided by basin simulation technology based on a large number of drilling data in Ordos Basin. The paleo structural features of the bottom of the lake basin in the Yanchang period at the end of the sedimentary period of each stratigraphic unit were quantitatively investigated. The results show that at the end of the sedimentary period of Chang 8, the structural elevation of the bottom surface of the formation is “high in the east and low in the west, high in the south and low in the north”, and the structural contour of the main lake basin is below - 600 m. At the end of the sedimentary period of Chang 7 Formation, the paleo geomorphology was “high in the south and low in the north”. The main lake basin is mainly distributed in the north of the basin, and the structural elevation is below - 1 150 m. At the end of the sedimentary period of Chang 4 + 5, the depression area is distributed in the northwest area of the basin, and the difference between the distribution range and the structural elevation becomes smaller, about 200 m. At the end of Chang 1 Deposition, the overall structural pattern of the bottom of the basin shows a paleogeomorphic feature of “high in the east and low in the west”, and the elevation difference of the concave-convex structure of the bottom of the basin is 300 ~ 400 m. The structural features of gentle slope on the bottom of each sedimentation period are favorable areas for reservoir distribution. [ABSTRACT FROM AUTHOR]

Copyright of Natural Gas Industry is the property of Natural Gas Industry Journal Agency and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Sub lacustrine fan on the background of fault slope development in the lowstand system tract of the third member of the Shahejie Formation, Laizhouwan sag. It has a clear seismic reflection geometric appearance, but the internal structure of the sub lacustrine fan is chaotic, the vertical stacking relationship and plane enrichment position of the sand body were difficult to predict in the exploration and early evaluation stages. Based on drilling,logging,laboratory date,and three-dimensional seismic data, the principles of rheological properties and fluid concentration classification of gravity flow channels in sub lacustrine fan were applied, the sedimentary transport forms of gravity flow were divided into sliding, collapse, debris flow and turbidity flow. Based on the seismic reflection characteristics of channel sand bodies with different genetic transport mechanisms, five sedimentary structural units were identified and characterized in different facies zones of the sub lacustrine fan,they were stacked channels, composite channels, channel wings, single channels, and inter-channels,in addition, the reliability of different unit classification and the differences in sand content through model forward modeling was verifiem. The results indicate that the superimposed channel of the inner fan has developed multi-stage sliding collapse sedimentation, and the overall thickness of the reservoir is large. The composite channel in the lower part of the middle fan has developed sandy debris flow reservoirs with good physical properties, both of which are favorable locations for oil and gas exploration and drilling. The development level of the outer fan reservoir is relatively low. The highly constructive braided river delta from the Kendong uplift provides a large amount of sandy foundation for the sub lacustrine fan, and the slope break zone and ancient landforms jointly control the sedimentary transport mechanism, channel direction, and channel type of the sub lacustrine fan. [ABSTRACT FROM AUTHOR]

The delta-salt lake system was developed in the sedimentary period of Qianjiang Formation in Qianjiang sag, Among them, many lithologic reservoirs were found in Eq34、Eq 40 and other oil formations in the hollow zone, which has broad exploration potential. This paper analyzes the sedimentary background and reservoir characteristics of Benghu Syncline in Qianjiang sag, and summarizes the reservoir distribution combined with seismic reflection characteristics、attribute analysis、forward modeling and inversion description. Using logging data and seismic data for fine labeling of reservoir, identification and tracking, to predict the favorable sand body distribution area, it is considered that the main controlling factors of reservoir formation in semi-arid period are reservoir and oil source distance, and the prediction results are consistent with drilling and geological laws. [ABSTRACT FROM AUTHOR]

Copyright of Acta Sedimentologica Sinica is the property of Acta Sedimentologica Sinica Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

This research was conducted using EEI inversion on seismic data in Z Field, Kutai Basin. The EEI inversion is effectively used to determine the reservoir distribution by eliminating the angle limit on the elastic impedance to the Chi angle so that it can be correlated with petrophysical parameters that are sensitive to lithology and fluids. The data used in this study are well data, checkshots, horizons, and partial-stack angle gather 3D seismic data. The data obtained is processed to obtain the target zone first based on log interpretation. Based on data processing, the target zone is obtained at 1513 m to 1531 m. Sensitivity analysis was conducted to determine the sensitive parameters, which can separate the lithology of the formation. In the sensitivity analysis, the most sensitive log to separate lithology is the Vp/VS log, which can separate sandstone, shale, and coal. Furthermore, the EEI inversion analysis was carried out to obtain the most suiTable model for the inversion, the Based Hard Constraint model was obtained with a correlation reaching 0.997 and an error value of 0.078. Based on the EEI inversion, the target zone in the Z-field at a depth of 1258 ms - 1269 ms with a sandstone reservoir in the EEI range of 6000 (m/s)(g/cc) - 7500 (m/s)(g/cc) which spreads from northeast to south. The distribution of the sandstone reservoir is surrounded by coal with a range of EEI 7500 (m/s)(g/cc) - 12000 (m/s)(g/cc), and also the distribution of shale in the EEI range of 7500(m/s)( g/cc) - 9200(m/s)(g/cc).

The study on morphology and distribution of sublacustrine fan are necessary for the exploration of oil and gas, which could help to effectively predict the reservoirs of sublacustrine fans. In this paper, the distribution and geomorphology of sublacustrine fans of Dongying Formation in Liaoxi uplift (Bohai Bay Basin, East China) and their controlling factors (including shape and formations) have been analyzed in detail based on seismic, core, and logging data. The main conclusions achieved in this study are: (1) During the sequence of the third member of Dongying Formation (SQd3), two types of sublacustrine fan, including channelized fan (in channel shape) and non-channelized fan (in tongue shape and lobe shape), developed on the eastern slope of Liaoxi uplift, which inherited the characteristics of sediments structural maturity in braided river delta front (good sandstone sorting and high structural maturity); (2) Steep slope was favorable for forming tongue shape sublacustrine fans with large ratio of length and width, while gentle slope tended to deposit lobe shape fans; high mud content tended to form stable channels with strong erosion on the slope end, while high sand content tended to form continuous lobes with lobe shape; (3) In the basin with uplift, the beneficial combination among provenance, relative lake level change and paleomorphology, determines the development and distribution of sublacustrine fan, and the sublacustrine fan deposits are mainly concentrated in the TST. The Yanshan fold belt in the west provided sufficient sediments to the Liaodong Bay during LST for the development of a sublacustrine fan in the east slope of Liaoxi uplift since the Liaoxi uplift sunk into the water, with the result that the deposition of braided river delta front can overlap the uplift. The incised canyons in the Liaoxi uplift provided the channels for sediments entering into the eastern slope, and the main sedimentary location of lacustrine fans was between two stages of faults. This study could provide a theoretical basis for researching the characteristics and distribution of other sublacustrine fans in similar basin backgrounds. [ABSTRACT FROM AUTHOR]

Copyright of Natural Gas Industry is the property of Natural Gas Industry Journal Agency and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The study on morphology and distribution of sublacustrine fan are necessary for the exploration of oil and gas, which could help to effectively predict the reservoirs of sublacustrine fans. In this paper, the distribution and geomorphology of sublacustrine fans of Dongying Formation in Liaoxi uplift (Bohai Bay Basin, East China) and their controlling factors (including shape and formations) have been analyzed in detail based on seismic, core, and logging data. The main conclusions achieved in this study are: (1) During the sequence of the third member of Dongying Formation (SQd3), two types of sublacustrine fan, including channelized fan (in channel shape) and non-channelized fan (in tongue shape and lobe shape), developed on the eastern slope of Liaoxi uplift, which inherited the characteristics of sediments structural maturity in braided river delta front (good sandstone sorting and high structural maturity); (2) Steep slope was favorable for forming tongue shape sublacustrine fans with large ratio of length and width, while gentle slope tended to deposit lobe shape fans; high mud content tended to form stable channels with strong erosion on the slope end, while high sand content tended to form continuous lobes with lobe shape; (3) In the basin with uplift, the beneficial combination among provenance, relative lake level change and paleomorphology, determines the development and distribution of sublacustrine fan, and the sublacustrine fan deposits are mainly concentrated in the TST. The Yanshan fold belt in the west provided sufficient sediments to the Liaodong Bay during LST for the development of a sublacustrine fan in the east slope of Liaoxi uplift since the Liaoxi uplift sunk into the water, with the result that the deposition of braided river delta front can overlap the uplift. The incised canyons in the Liaoxi uplift provided the channels for sediments entering into the eastern slope, and the main sedimentary location of lacustrine fans was between two stages of faults. This study could provide a theoretical basis for researching the characteristics and distribution of other sublacustrine fans in similar basin backgrounds.

ABSTRACT: In May and July of 2017, China Geological Survey (CGS), and Guangzhou Marine Geological Survey (GMGS) carried out a production test of gas hydrate in the Shenhu area of the South China Sea and acquired a breakthrough of two months continuous gas production and nearly 3.1 × 105 m3 of production. The gas hydrate reservoir in the Shenhu area of China, is mainly composed of fine-grained clay silt with low permeability, and very difficult for exploitation, which is very different from those discovered in the USA, and Canada (both are conglomerate), Japan (generally coarse sand) and India (fracture-filled gas hydrate). Based on 3D seismic data preserved-amplitude processing and fine imaging, combined with logging-while-drilling (LWD) and core analysis data, this paper discusses the identification and reservoir characterization of gas hydrate orebodies in the Shenhu production test area. We also describe the distribution characteristics of the gas hydrate deposits and provided reliable data support for the optimization of the production well location. Through BSR feature recognition, seismic attribute analysis, model based seismic inversion and gas hydrate reservoir characterization, this paper describes two relatively independent gas hydrate orebodies in the Shenhu area, which are distributed in the north-south strip and tend to be thicker in the middle and thinner at the edge. The effective thickness of one orebody is bigger but the distribution area is relatively small. The model calculation results show that the distribution area of the gas hydrate orebody controlled by W18/W19 is about 11.24 km2, with an average thickness of 19 m and a maximum thickness of 39 m, and the distribution area of the gas hydrate orebody controlled by W11/W17 is about 6.42 km2, with an average thickness of 26 m and a maximum thickness of 90 m.

Dividing carbonate sequence with natural gamma data is the popular method, while it is not suitable for shallow platform because high gamma of mud flat represent shallow-water environment. Taking Majiagou Formation of Ordovician in Bozhong 21–22 structure of Bohai Sea as an example, a new sequence division method for shallow platform was presented based on natural gamma spectrum data, and the relationship between the sequences and reservoirs was discussed as well in this paper. The high natural gammas in Majiagou Formation of the study area are response for the weathering, uranium element enrichment in reservoirs and argillaceous sediment. The comparison result between well logging parameters and geological data shows that the ratio of Th/K is an effective parameter for sequence division, which can distinguish the origin of different high gammas effectively, even the mudstone from oxidized environment and reductive environment. Based on the ratio of Th/K, five third-order sequences were divided in Majiagou Formation of the study area; among them, all the sequences are developed in well BZ21-B-1, while SQ5 is missing in well BZ22-A-2 for denudation. The corresponding relationship between sequences and reservoirs indicates that the reservoirs of SQ4–SQ5 are dominated by structural fractures, which are mainly controlled by tectonic movement and weathering; while those of SQ1–SQ3 are dominated by dissolved pores, which may be related to the internal dissolution. [ABSTRACT FROM AUTHOR]

Copyright of Natural Gas Industry is the property of Natural Gas Industry Journal Agency and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Natural Gas Industry is the property of Natural Gas Industry Journal Agency and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Natural Gas Industry is the property of Natural Gas Industry Journal Agency and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Abstract Based on core, thin-section, scanning electron microscopy (SEM) and well logging data, the characteristics of the parametamorphic rock reservoirs in the Pingxi area were analyzed by means of whole rock X-ray diffraction and micron CT scanning. The parametamorphic rock reservoirs mainly had three types of rocks: slate, crystalline limestone and calc-schist; the original rocks were Ordovician-Silurian marine clastic and carbonate rocks. The three types of parametamorphic rock reservoirs developed three types and six sub-types of reservoir space. The first type of reservoir space was fractures, including structural, weathered and dissolution fractures; the second type was dissolved porosities, including dissolved pores and caves; the third type was nano-sized intercrystalline porosities. The three types of parametamorphic rock reservoirs were different widely in the quantity, volume and radius of pore-throats, and were strongly affected by the type and development degree of fractures. The parametamorphic rock reservoirs were formed by metamorphism, weathering, structural fragmentation and dissolution. Metamorphism reformed the parametamorphic rock reservoirs significantly, breaking the traditional constraint of finding weathering crust at top. The parametamorphic rock reservoirs experienced five formation stages, and their distribution was controlled by rock type, metamorphic degree, ancient geomorphology, and weathering intensity. [ABSTRACT FROM AUTHOR]

In the energy transition context, basin modelling, initially dedicated to the understanding of oil and gas systems, can address several challenges that the sustainable energy sector faces, such as identifying large storage volumes for carbon sequestration, determining the thermal recharge sources for geothermal exploration, or characterising the generation, migration, sink, and accumulation of critical element resources. In this regard, there is a need for spatiotemporal information on the mineral reactions that control the petrophysical properties of the rocks in order to map the best locations in the basin for capturing geothermal energy or storing carbon in basin-wide reservoirs for CO 2 mitigation. Hydrothermal dolomitisation is one of these well-known diagenetic reactions that can enhance or destroy reservoir porosity. It has been extensively characterised by static reactive transport modelling, but not kinematic ones, due to the high computational cost of such reactive transport simulations. To address this issue, we built a machine-learning-based (ML) surrogate geochemical model for hydrothermal dolomitisation valid over a broad range of physical and chemical conditions encountered in such a context with the end goal of developing a generic exploration tool to be deployed in the basin calculator ArcTem for emerging energy needs. We train and test five regression algorithms (Random Forest, Gradient Boosting, AdaBoost, Support-Vector Machine, and Multilayer Perceptron) upon a synthetic dataset to predict the dissolved/precipitated amount of calcite and dolomite (referred to as δCaCO 3 and δCaMg(CO 3) 2 , respectively). The dataset contains 370 × 103 samples and six features (T, pH, NaCl, Ca, Mg, C) generated by a Latin Hypercube Sampling (LHS) between two end-members: (1) the modern seawater composition and a temperature of 80 °C for the lower bound and (2) a highly saline mantle-derived fluid and a temperature of 250 °C for the upper bound. The target values, i.e. dissolved/precipitated mole number of calcite/dolomite, are obtained by performing thermodynamic equilibrium calculations with the LHS samples as the initial unequilibrated solutions. Our results show that the artificial neural network (ANN) model best performs among the algorithms with rmse of 0.007 mol on δCaMg(CO 3) 2 prediction and 0.0084 mol on δCaCO 3 prediction, R2 values above 0.99, and APE smaller than 0.3%, indicating its good generalisability to provide accurate predictions on unseen data in the studied range. Further, the ANN model is ∼1000 times faster than the geochemical calculator when solving the same system at once, illustrating the great potential of ML methods in emulating computationally intensive components of the numerical simulations. • Machine learning is applied to reproduce hydrothermal dolomitisation equilibrium reaction under non-isothermal conditions. • Five algorithms are evaluated, and their performance is compared. • Neural network is the best-performing surrogate geochemical model with an average per cent error of <0.3% on the predictions. • Applicable on a broad range of physical and chemical conditions encountered in basin modelling. • The surrogate model results in a generic exploration tool for the pre-assessment of sedimentary basins' storage capacity. [ABSTRACT FROM AUTHOR]

The Cambrian carbonate & evaporite paragenesis system in the Sichuan Basin is made up of the Longwangmiao, Gaotai and Xixiangchi Fms. So far, great breakthrough has been made only in the Longwangmiao Fm instead of the latter two, and the Anyue Gasfield was discovered in the center of this basin. In this paper, therefore, the Cambrian carbonate & evaporite paragenesis system in the Sichuan Basin was analyzed in terms of its structural–sedimentary setting, sequence stratigraphic framework, sedimentary facies and the distribution of evaporites by using various geologic, logging and seismic data. Then, the geological model of sedimentary facies was established and the distribution range of favorable reservoirs was predicted. Based on these studies, the following results are obtained. Firstly, the palaeotectonic framework is characterized by the style of “one depression between two uplifts” in the setting of a large SE dipping slope, and the stratigraphic filling is in the structure of “onlapping at the bottom and truncation at the top” which is thin in the west and thick in the east. Secondly, three third-order sequence cycles which, on the whole, become shallow upward are developed from bottom to top, and gypsum-salt rocks are mainly located at the high system tract (HST) of third-order sequences and concentrated in the Wanzhou–Yibin sag. Thirdly, the geological model of sedimentary facies is composed of three major sedimentary structural layers from bottom to top, namely the evaporative carbonate ramp, the evaporative diamictic restricted platform and the evaporative restricted platform. The sedimentary environment changes from the open to the closed and the penesaline for a long time, and then back to the open. The distribution of shoals changes from the pattern of “dual banks” in a large area to more scattered shoals and banded shoals, while the evaporative lagoon and tidal flat shrink. Fourthly, the reservoir distribution is complicated and mainly controlled by the sedimentary pattern of palaeotectonics, the grain shoals and the exposed surfaces of sequences with different orders. The favorable areas for reservoir development are located above the paleo-uplift and its surroundings, at the slope-break belt in the platform and in the periphery of platform margin.

Copyright of Petroleum Geology & Recovery Efficiency is the property of Petroleum Geology & Recovery Efficiency and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The Middle Triassic Leikoupo Formation in the northern Sichuan Basin is a new discovery sequence for strategy replacement in the gas exploration field. The carbonate paleokarst reservoirs of the Middle Triassic Leikoupo Formation in the northern Sichuan Basin provide a case study of gas exploration in carbonate paleokarst reservoirs. By conducting a comprehensive study of well drilling, drill cores, well loggings, and test data, combined with the analysis of geological background of the Sichuan Basin, it is considered that syndepositional, supergene, and burial paleokarstification can be identified in the Leikoupo Formation, and these types of karstification were vital for reservoirs formation. Syndepositional karstification controlled the formation and distribution of early reservoirs. This type of karstification was limited to high-energy grain shoals, and therefore its horizontal extent was limited by the distribution of this facies. During temporary episodes of relative sea level fall, carbonate shoals were exposed subaerially or within the fresh water lens, and significant selective dissolution occurs, forming moldic pores and intragranular dissolved pores. The reservoirs related to supergene karstification mainly occurred in the area of the buried hill containing carbonate rock at the top of the Leikoupo Formation, and are vertically limited within a depth of 70-90 m under the carbonate corrosion unconformity plane of the Leikoupo Formation. The reservoirs related to supergene karstification formed mainly in limestone breccia and vuggy limestone in surface karst zone, and the high-angle dissolved fracture and medium- and small-scale corrosion holes in vertical vadose zone, and medium and small corrosion holes, dissolved fractures, roof fracture-caves in horizontal karst zone. The karst monadnocks within karst slope are the most favorable microgeomorphic units for horizontal distribution of reservoirs. Burial karstification was related to dissolution of carbonate minerals by organic acids, and was the key factor in optimal transformation of reservoirs. Burial karstification corroded and expanded the pore system left after infilling of the earlier pore system, and mainly was to optimize the transformation the reservoir space redistribution of earlier pore system. The compact carbonate layers related to burial karstification only can be dissolved along the early cracks in the channel and formation cracked reservoirs, but development of this type of reservoir was limited. The reservoirs were influenced by syndepositional, supergene, and burial paleokarstification in the Leikoupo Formation, and carbonate paleokarst reservoirs were formed finally. [ABSTRACT FROM AUTHOR]

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Strike-slip faults imaged on seismic reflection data from the central Tarim Basin clearly illustrate the spatial and geometrical characteristics of deeply buried (>6.8 km depth) stepovers and their influence on reservoir distributions in fractured Middle Ordovician carbonates. Characterization of along- and across-strike seismic profiles demonstrates that restraining and releasing stepovers characteristically produce pop-up and pull-apart structures, respectively, defined by systems of high-angle subsidiary faults with down-dip reverse or normal displacements. Along-strike vertical displacement and damage zone width measurements reveal that restraining stepovers typically exhibit much wider deformation zones and higher densities of fractures compared to releasing stepovers. Core samples and well logs show that the fractured reservoirs in restraining stepovers comprise stylolite meshes and mosaic breccias. Damage zones in narrower releasing stepovers are more prone to the development of cavities, dilational breccias, and high-angle open fractures. Both restraining and releasing stepovers are strongly asymmetric in the across-strike direction, except in the central part of fault overlap zones where the maximum vertical displacements are symmetrical. Restraining stepovers can typically be subdivided into four sectors separated by helicoidal intermediate-scale linking faults: two in the hanging walls and two in the footwalls. Hanging walls are normally wider, intensely fractured and exhibit better well performance compared to footwalls. Strain compartmentalization with localized zones of upward and downward displacement exist both within, and adjacent to releasing stepovers. The localized extensional zones are where cavities and open fractures are most likely best developed. Seismic reflection profiles and well logging show that certain intraclastic grainstone and packstone horizons in the Middle Ordovician carbonate host rock sequences are more favorable for fracture development. This leads to vertical partitioning of local fractured reservoirs due to the development of down-dip stepovers or bends localized close to major lithological boundaries. Thus interactions between lithological layering and tectonic processes cause further three-dimensional complexity in the reservoirs. • Restraining stepovers exhibit higher structural complexity and stronger damage than releasing stepovers. • Restraining stepovers can be divided into hanging wall and footwall damage zones due to its asymmetric geometry. • Internal strain compartmentalization within releasing stepovers greatly enhances reservoir distribution. • Fracture-cavity reservoir exhibits distinct vertical partitioning. [ABSTRACT FROM AUTHOR]

Reservoir architecture is key in determining reservoir performance and hydrocarbon productivity but varies greatly in deep-water clastic reservoir systems. However, the interpretation of turbidite architectures can be a daunting exercise for non-specialists or those without experience in deep-water settings. Parameters that can be used to make interpretations are copious, vary in usefulness from one system to another, vary in scale and can take a lifetime to master. In this paper we introduce the simple concept of the relative confinement matrix and explain how it can be used by non-specialist geologists to interpret depositional architectures and hence inform all-important forecasts of performance and productivity. We show how any available parameter can fit into this matrix and be used to derive interpretations in a relatively quick manner. Our central concept is the relationship between the size of a turbidity current and the size of the conduit through which it flows and hence the degree of relative confinement to which a flow is subjected, which can in turn be related to depositional style and resulting reservoir architecture. Predictive interpretations can be made by observing patterns at the core and log scale, relating these to relative confinement and thus to larger, seismic-scale architectures. Variations in relative confinement are expressed through lateral bed continuity, vertical connectivity, amalgamation ratio, net:gross, distribution of hemi-pelagics, distribution and uniformity of facies associations, bed thickness frequency distribution, bioturbation diversity and intensity, distribution of sedimentary structures, mineralogical content, variability & textural maturity, grain size and grain size variability. Notionally the expression of the interaction of flow size and conduit size is described for individual turbidity current deposits, but this can also be translated to the bed-set scale, or larger, in genetically similar units. The careful analysis of the parameters described above allows the prediction of depositional architectures through the understanding of relative confinement for use in exploration and development. The architectural predictions in turn provide the basis for understanding permeability length-scales, kv/kh ratios and hence production performance through these heterogeneous reservoirs. • Integrated review of state-of-the-art interpretation methods in turbidite systems. • Simplified interpretation workflows for subsurface professionals working turbidite reservoirs. • The meaning of turbidite flow confinement and introduction of the relative-confinement matrix concept. • Relative confinement matrix allows comparison of different data types at different scales. • Observations of data-type characteristics used to predict reservoir distribution, architecture and performance characteristics. [ABSTRACT FROM AUTHOR]

The Middle Permian Maokou limestone is a major natural gas producing reservoir in the southern Sichuan Basin, China. While matrix porosity is low, bit drops, losses while drilling, blowouts, and extremely high well testing flow rates indicate the presence of a dual permeability system in the form of paleocaves, which were formed by karstification in the late Maokouan Age. A combination of geological, paleogeomorphological and karstic analyses reveal that the development and distribution of the karst features within the reservoir are primarily regulated by shoal facies, paleotopography and syndepositional faults. In our conceptual paleogeomorphological model, the potential cave-bearing zones are located along the rim and outer edge of the Luzhou Paleohigh, which was the highland during the karst. Outside the highland were the karst slopes, and the poljes were on the flanks of the study area. Reservoir performance data suggest, there are two types of sweet spots in the study area. The first corresponds to the syndepositional fault zones along the rim of the karst highland and on the karst slope, where the caves appear to distribute along the faults, impacting the reservoir's vertical permeability. The second corresponds to the shoals of the Mao 2 and Mao 3 members on the lower western karst slope and the upper eastern karst slope, where the caves are widespread, enhancing the horizontal permeability and connectivity of the reservoir. However, the caves are rare in the central karst highland, lower karst slopes, and poljes, which is consistent with the limited gas discoveries. [ABSTRACT FROM AUTHOR]