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Based on outcrop, core, logging and mud logging data, and modern deposition analog, the sandbodies genetic types and spatial distribution in different facies belts of the shallow water delta in the first Member of Cretaceous Yaojia Formation (K2y1) of Qian'an area in Changling sag of southern Songliao Basin were analyzed, and the sedimentary model...
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... Recently, alongside the Ordos Basin, extensive tight sandstone oil reservoirs have been explored and developed in the Bohai Bay, Songliao, and Junggar basins in China [35,[78][79][80]. These tight sandstone reservoirs are predominantly superimposed distributary channel sandstone reservoirs that exhibit low porosity, a complex pore structure, a large distribution area, abundant resources, and low natural productivity. ...
Tight sandstone oil reservoirs in the Upper Triassic Yanchang Formation of the Ordos Basin are the most promising exploration and development fields owing to their huge production potential. Even though they have received considerable attention in recent years, common productivity prediction methods were not well applied during pre-development owing to their strong internal heterogeneity. In this study, the factors influencing oil production of the Chang 9 Member in the Jiyuan area were investigated and summarized based on drill cores, such as sediment characteristic analysis, lithofacies analysis, other analytical tests, and conventional logging curves. The findings show that fine-sandstone reservoirs with smooth sand body architectures are the main types of tight sandstone commercial oil reservoirs. Furthermore, having high porosity and oil content are prerequisites for commercial oil reservoirs, and the cumulative thickness of effective reservoirs serves as a crucial resource base for them. Through the analysis of logging curves, the relative center of gravity, deviation root of variance, petrophysical index, effective reservoir thickness, and evaluation indicator were used to predict daily oil production, thereby establishing the identification criteria for the ranking of tight sandstone oil reservoirs using logging. Then, the productivity of each reservoir in a single well was predicted by processing the log data from each well using the proposed method, and the productivity prediction results agreed well with the tested results of the perforated interval. This approach highlights the integrated influence of geological factors, physical properties, and the thickness scale of an effective reservoir, thereby improving the predictive capacity of logging curves. Additionally, the proposed methods significantly reduce the need for reservoir parameters better than previous ones, streamline operations, and improve practical applications.
... This section has a darker colour and complicated lithological alternance. It has layers of sand that are brownish and grey-green, respectively, showing the development of normal and subaqueous distributary channels, which are typical characteristics of the delta front sub-facies (Zhang et al., 2017(Zhang et al., , 2018aWang et al., 2019). In conclusion, the complex depositional environments and frequent facies alterations in the HX borehole make it difficult to conduct grain-size analyses. ...
For many years, researchers have used the decomposition of grain-size distributions to acquire critical information on provenances, transport dynamics and depositional environments. This study presents a novel decomposition method, termed the universal decomposition model, for analyzing grain-size data. The universal decomposition model unifies single-sample unmixing and end-member modelling analysis approaches and overcomes their respective limitations. To evaluate the effectiveness of the universal decomposition model, an artificial dataset and borehole data from the west Weihe Basin were analyzed. Results indicate that the universal decomposition model algorithm performs proficiently on both datasets. Correlation analysis was employed to compare the abilities of universal decomposition model, single-sample unmixing and end-member modelling analysis to extract minor signals, with universal decomposition model and single-sample unmixing exhibiting greater proficiency. Furthermore, the universal decomposition model provides a broader perspective for contrasting single-sample unmixing and end-member modelling analysis. The study highlights the inadequacy of the statistical method for determining the optimal number of components and summarizes an empirical approach. Moreover, disregarding the potential diversity in component shapes of real-world sediments has been demonstrated to be a sub-optimal design. Finally, this article presents results of a new investigation into the geological significance of sediment grain sizes revealed by various analytical methods that suggest that the universal decomposition model has enormous potential in reconstructing paleoenvironment.
... Earlier studies focused on the establishment of a stratigraphic framework (Ren et al., 2006;Hou et al., 2008;Liu et al., 2008), distribution pattern of sedimentary facies (Wang, 2012;Li et al., 2017;Zhang et al., 2017), and oil accumulation (Lin et al., 2011(Lin et al., , 2016Ge et al., 2012). However, these studies lacked an examination of the influence of diagenesis during the burial history on the K 2 y 1 sandstone reservoir, particularly cementation, which is one of the major factors that control reservoir quality (Gier et al., 2008;Morad et al., 2010;Bjørlykke and Jahren, 2012). ...
The oil-bearing layer in the first member of the Upper Cretaceous Yaojia Formation (K2y¹) in the middle of the Changling Sag of the southern Songliao Basin, northeast China, has low-permeability and is deemed to be an unconventional reservoir. Therefore, better evaluation of reservoir quality and related controlling factors are crucial for the reduction in exploration risk and sustainable development. The current study integrates diagenesis, sequence stratigraphy, and sedimentary facies to decipher their influence on reservoir quality using core and thin section observations, X-ray diffraction, scanning electron microscopy, fluid inclusion, and carbon and oxygen isotope analyses. The K2y¹ is composed of shallow delta sediments of transgressive system (TST) and lowstand system (LST) tracts. The depositional microfacies of the sandstones include TST deltaic front underwater distributary channels and sheet sands, and LST deltaic plain distributary channels, distributary channel intersections, and crevasse splays. The sandstones are dominantly fine-grained moderately sorted feldspathic litharenites and lithic arkoses with silt. Early diagenetic events included compaction, development of smectite, and alteration of feldspar and kaolinite whereas mesogenetic alteration included feldspar dissolution, precipitation of quartz and carbonate cements, and clay mineral alteration. The reservoir quality of the K2y¹ sandstones is generally poor, exhibiting variations among different deltaic depositional facies within the LST and TST. The (underwater) distributary channel (intersection) sandstones, particularly those of the LST, have relatively higher reservoir quality owing to their larger grain size, better sorting, lower carbonate cement content, mixed-layer I/S and illite, and greater occurrence of chlorite.
... Therefore, the conventional research on a small layer-level reservoir cannot meet the production needs. It is urgent to carry out the research on a single sand body-level reservoir [1][2][3][4][5][6][7]. A single sand body refers to its own vertical and horizontal continuous distribution, but it is different from the upper and lower sand bodies. ...
By taking the third member of the Dongying Formation in the Cha71 fault block of the Chaheji oilfield as an example, the single sand body of the deltaic front underwater distributary channel is meticulously depicted by using the data of well logging and performance production. Portrays the vertical separation model, total lateral separation type, vertical type, lateral superposition type, 4 types of single sand body vertical superimposed and bay type, bank contact between docking, instead of four kinds of single sand body lateral contact type, and summarizes its logging facies identification. The quantitative prediction model of the single sand body was established, the characteristics of single sand body plane distribution were summarized, and the identification of the oil-water layer and the lower limit of reservoir effective thickness were studied. And we got the conclusion that based on the fine characterization of the single sand body and the lower limit standard of effective reservoir thickness, the distribution range of the effective reservoir and connecting unit is determined. Finally, the connectivity of the connecting unit is verified by dynamic data.
... The study area is located in the southern part of Daqing Placanticline in Songliao Basin (Figure 1), which is multihigh dome anticline [39]. A series of typical small meandering river deposits with a thickness of about 150 m were developed in the third member of Quantou Formation through long-term filling of the underlying Denglouku Formation [40]. ...
Although stochastic modeling methods can achieve multiple implementations of sedimentary microfacies model in dense well blocks, it is difficult to realize continuous convergence of well spacing. Taking the small high-sinuosity meandering river sediments of the third member of Quantou Formation in Songliao Basin as an example, a deterministic modeling method based on geological vector information was explored in this article. Quantitative geological characteristics of point bar sediments were analyzed by field outcrops, modern sediments, and dense well block anatomy. The lateral extension distance, length, and spacing parameters of the point bar were used to quantitatively characterize the thickness, dip angle, and frequency of the lateral layer. In addition, the three-dimensional architecture modeling of the point bar was carried out in the study. The established three-dimensional architecture model of well X24-1 had continuous convergence near all wells, which conformed to the geological knowledge of small high-sinuosity meandering river, and verified the reliability of this method in the process of geological modeling in dense well blocks.
... The Yaojia Formation is composed of red and green mottled claystones with interbedded fine-grained sandstones and greyish green claystones. The Yaojia Formation is divided into three members from the bottom upwards, and is mainly composed of fluvial to lacustrine deposits in the southern Songliao Basin (Zhang et al. 2017). ...
... In recent years, red paleosols formed in semi-arid palaeoclimate are found in fluvial, delta, and lakeshore deposits in cores of the Yaojia Formation from drilling wells in oilfields (Du et al. 2011;Zhang et al. 2017). The paleosols can provide important evidence for palaeoclimate research (e.g. the International Continental Scientific Drilling Project) in the Songliao Basin (Wang et al. 2013b). ...
Abstract Paleosols in an outcrop of fluvial–lacustrine red beds have been recognized in the Upper Cretaceous Yaojia Formation in southern Songliao Basin, Songyuan City, Jilin Province, NE China. They are recognized in the field by pedogenic features, including root traces and burrows, soil horizons and soil structures. Root traces are remnants of small herbaceous plants, elongating and branching downwards in the red paleosols. They are filled by calcite, analcime, and clay minerals in spaces created by the decay of the plant roots. Burrows are found near the root traces with backfilled cells made by soil-dwelling insects. Soil horizons include calcic horizons (Bk horizon) with continuous calcareous layers, argillic horizons (Bt horizon) with clay films and dark brown to black iron-manganese cutans, vertic horizons (Bw horizon) with slickensided claystone, and deformed soil structure and gleyed horizons (Bg horizon) with mottles and reticulate mottles. Soil structures of the paleosols include pseudo-anticlinal structures, subangular blocky structures, and angular blocky structures. The micro-pedogenesis characteristics are also observed, including micrite pedogenic minerals and clay skins. Based on the pedogenic features above, paleosols types including Aridisol, Alfisol, and Vertisol are interpreted in the red beds of the Yaojia Formation. Forming in the Late Cretaceous, the paleosols can provide more details about the seasonal climate conditions and terrestrial sedimentary system in lacustrine basin.
... Abundant hydrocarbon reserves of the fluvial-delta strata in the Yaojia Formation are found in the northern Songliao Basin (Fig. 2B) . In the southern Songliao Basin, shallow water sand bodies of the Yaojia Formation were not main exploration targets until the recent breakthrough made in low net-to-gross reservoirs in the first member of the Yaojia Formation, the Putaohua oil layer (Wang, 2012;Jia, 2013;Ge et al., 2013;Zhang et al., 2017). ...
Shallow water delta developed during the Late Cretaceous greenhouse climate depositing in the red bed succession of the Yaojia Formation in the Southern Songliao Basin, NE China. The shallow water delta deposits provide an opportunity to understand the influence of high discharge variability in a semi-arid climate on the fluvial patterns, internal sedimentary details, and reservoir quality of distributary channels. The sedimentary process of the shallow water delta in the Yaojia Formation was controlled by a dual-stage process, including a high-flow stage and a low-flow stage within a semi-arid paleoclimate. During the high-flow stage, crevasse channels formed through avulsion of major distributary channels on the delta plain. Subaqueous terminal distributary channels and mouth bars formed at the delta front during progradation of the delta. During the low-flow stage after flood events, crevasse channels were abandoned and frequently exposed becoming reddish in color. This process can be reason for the classification for two main types of distributary channels: major distributary channels and crevasse channels in the delta plain. Sand bodies in distributary channels are distinguished by sedimentary structures indicate critical and supercritical flow conditions. Based on well logs and 3D seismic data, the sand distribution of was analyzed from the sandstone isopach map of the 2nd sand bed in the first member of the Yaojia Formation. The framework sand belts develop coincides with distribution of the major distributary channels. Based on detailed observational and reservoir test data from cores, the distribution of major distributary channels revealed a belt of high-quality reservoirs in the shallow water delta. This study provides a new perspective on the sedimentary pattern of distributary channels in shallow water deltas with high discharge variability, which has important implications for reservoir exploration in lacustrine basins.
Dispersive soil features rapid disintegration characteristic while interacting with liquid water, which is attributed to the chief culprit for the failure of many earthen infrastructures worldwide. How to quickly identify such a problematic soil in the field relies on the prior knowledge of its failure mode. Take the seasonally frozen semiarid southwest Songnen Plain as investigation background, in this study, five typical failure modes on bare dispersive soil slope are sorted out, including soluble salt crystallization, rill erosion, relaxation tension fissure-associated collapse, subsurface suffosion, and gully erosion, and their formation and evolution features are analyzed. We figured that the silt-dominant soil composition governs the dispersity to a great extent, and the existence of high percentage of sodium ion contributes to reduce the cementation strength of clay particles to silt and sand particles in the presence of water. In addition, analyses indicate that rainfall is the direct trigger factor for failure, and fissures induced by freeze–thaw and dry–wet cycles speed up the water infiltration, enlarge the soil–water interaction surface, and aggravate the bare slope soil destruction in the final. Practices suggest that the adoption of water isolation measures or enhancing cementation strength between soil particles via mixing additives are core failure prevention principles of bare dispersive soil slope.
