226 research outputs found
Diagenesis of the Permian Fengcheng Formation in the Mahu Sag, Junggar Basin, China
No full textThe Fengcheng Formation in the Mahu sag of the Junggar Basin was primarily composed of detritus, pyroclastic material, carbonates, and evaporites. In order to establish the diagenesis pathways of the Fengcheng Formation, some methods of polarized light microscope, SEM, CL, EPMA, LR, and fluid inclusion analysis were applied to discuss the diagenesis process. The results showed the following: (a) The formation of an alkaline lake was the result of the influence of a high concentration of sodium-rich sources, and it led to the preservation of alkaline minerals in the stratum. (b) After the sediments were buried, three mineral assemblages were formed in the Fengcheng Formation, which are carbonate mineral assemblages (i.e., calcite + ferreous dolomite), reedmergnerite and carbonate mineral assemblages (i.e., reedmergnerite + calcite + ferreous dolomite), and reedmergnerite and alkaline mineral assemblages (i.e., reedmergnerite + shortite + trona), respectively. (c) According to the homogenization temperature of reedmergnerite primary fluid inclusions, the alkaline diagenesis of Fengcheng Formation was divided into an early stage (≤100 °C) and a middle stage (>100 °C), respectively. The earlier stage is marked by the formation of ferrous saddle dolomite, quartz dissolution, and the agglutination of laumontite. These processes occurred under normal burial conditions. The latter is marked by the reedmergnerite’s appearance, which is correlated with the deep hydrothermal activity controlled by faults. (d) Based on sedimentary and diagenetic factors, including climate, provenance, diagenetic surroundings, and the action of subsurface fluid, the alkaline deposition-diagenesis model for shale series in four stages of the Fengcheng Formation was established
Fine-grained sedimentary characteristics and evolution model of Permian Fengcheng Formation in Hashan area, Junggar Basin
No full textThe geological conditions of Hashan area on the northwestern margin of the Junggar Basin are complicated and it is difficult to explore. It is of great significance to clarify the sedimentary and evolutionary characte-ristics of source rocks in the Permian Fengcheng Formation in this area for expanding oil and gas exploration on the basin margin. Based on the analysis of whole-rock XRD, elemental geochemistry, organic matter abundance, thin section identification, and lithofacies association characteristics, this paper conducted a comparative analysis of the sedimentary characteristics, lithology, and lithofacies association characteristics of the Fengcheng Formation in the Mahu Sag and Hashan area, restored the ancient sedimentary environment evolution sequence in the study area, and established a model of ancient sedimentary evolution. The research results show that the lithofacies association characteristics and ancient sedimentary environment evolution sequence of the Fengcheng Formation in the Hashan area are highly similar to those in the Mahu Sag, which are generally fine-grained sediments mixed from multiple sources in an alkaline lake with a volcanic background, and various lithofacies associations are developed. The sedimentary paleoenvironment has phased evolution characteristics. The large number of typical alkaline minerals in the second member of Fengcheng Formation in Hashan area reveals the development of another lake basin center in addition to the Mahu Sag. During the deposition of the first member of Fengcheng Formation (P1f1), the lake level was relatively higher, the water salinity was low, the climate was semi-arid, and volcanic sedimentation was developed, with lithofacies mainly composed of organic-rich blocky tuffaceous limestone. In the lower part of the second member of Fengcheng Formation (P1f2), the basin began to shrink, the climate became relatively drier, the water became saltier, the environment became more limited, and the lithofacies were mainly organic-rich layered dolomitic mudstone. In the top of the P1f2 and the lower part of the third member of Fengcheng Formation (P1f3), the environment was relatively closed, the water salinity was higher, a large number of alkaline minerals were developed, and the lithofacies were mainly organic-rich layered alkaline dolomitic mudstone and organic-rich layered mixed shale. In the upper part of P1f3, the input of terrigenous debris increased, salinization weakened, a fan-delta system was developed, and the lithofacies were mainly organic-rich blocky fine sandstone. The sedimentary environment of the Fengcheng Formation has a controlling effect on organic matter enrichment. Overall, a deep-water environment with less input of debris, warm and humid conditions, and relatively lower salinity is more conducive to organic matter enrichment
Characteristics and Genesis of Alkaline Lacustrine Tight Oil Reservoirs in the Permian Fengcheng Formation in the Mahu Sag, Junggar Basin, NW China
No full textThrough optical microscopic examination, scanning electron microscope analysis, whole rock X-ray diffraction analysis, X-ray fluorescence spectrum analysis, carbon and oxygen isotope analysis, and temperature measurement of fluid inclusions, the characteristics and formation mechanism of the alkaline lacustrine tight oil reservoirs of the Permian Fengcheng Formation in the Mahu Sag of the Junggar Basin have been systematically studied, and a genetic model has been proposed. Porosity of tight oil reservoirs of the Fengcheng Formation in the Mahu Sag is mostly less than 4%, with permeability mostly less than 0.1 mD. The lithology of the Fengcheng Formation in the Mahu Sag is mainly tuff, and the authigenic minerals mainly consist of feldspar, quartz, dolomite, and salt minerals (e.g., shortite, trona). The authigenic feldspar and quartz of the Fengcheng Formation in the Mahu Sag mainly originate from devitrification of volcanic glass in pyroclastic rocks. Reservoir space is dominated by dissolution pores of feldspar and salt minerals, followed by intercrystalline pores among feldspar, quartz, and other minerals formed by devitrification. Fractures are mainly comprised of shrinkage fractures, structural fractures, and bedding seans. The Permian Fengcheng Formation was mainly formed in an alkaline lake in the Mahu Sag, and the alkaline lacustrine sedimentary setting plays a decisive role in the formation of the tight oil reservoirs of the Fengcheng Formation. Volcanic glass in the tight oil reservoirs was generally devitrified within the alkaline lacustrine diagenetic fluid in the early diagenetic stage, and the devitrified micropores become an important reservoir space. Feldspars and salt minerals were mainly dissolved by acidic fluids generated by burial thermal evolution of the alkaline lacustrine source rocks of the Fengcheng Formation in the Mahu Sag, which produces the most developed dissolution pores in the tight oil reservoir. The abnormal high pressure formed by the early hydrocarbon generation and expulsion of the alkaline lacustrine source rocks in the Fengcheng Formation is one of the main reasons for porosity preservation. In the alkaline lake sedimentary environment of the Fengcheng Formation, widespread dolomitization and precipitation of a large number of salt minerals in the early diagenetic stage resisted partial compaction, which not only effectively protected early porosity, but also provided material conditions for dissolution porosity enhancement
Characteristics of Hydrocarbon-Generating Pressurization in Shale Series of Fengcheng Formation in the West and South of Mahu Sag, the Junggar Basin, China
No full textFormation overpressure is an important controlling factor for the formation of high-yield oil reservoirs in the shale series of the Permian Fengcheng Formation in the west and south of Mahu Sag, the Junggar Basin. Hydrocarbon-generating pressurization (HGP) is an important cause of overpressure in the shale series of Fengcheng Formation, but the evidence for this viewpoint is insufficient. There is still no systematic study on the quantitative calculation and distribution characteristics of HGP in the Fengcheng Formation shale series. The control effect of HGP on the formation of high-pressure and high-yield reservoirs is still unclear. Therefore, by using the data of mudstone logging and measured formation pressure, the causes of overpressure in the Fengcheng Formation shale series are clarified. The predicted organic matter abundance, the predicted maturity and thickness of source rocks, and the statistical ratios of mudstone thickness to formation thickness in each section of Fengcheng Formation are used for HGP of shale series. Combined with the physical characteristics of reservoir rocks and the geochemical characteristics of oil, the control effect of HGP on the formation of high-pressure and high-yield reservoirs is analyzed. The results indicate the following: (1) The organic matter abundance and the thickness of source rocks predicted by the logging data gradually decrease from the eastern lake basin area to the western slope area. (2) The HGP of shale series in Fengcheng Formation is related to the hydrocarbon generation capacity and the overpressure preservation conditions of the source rocks. The HGP can be quantitatively predicted by comprehensively using the organic matter abundance, the maturity, the thickness of source rocks, and the ratios of mudstone thickness to formation thickness. (3) The HGP in the Fengcheng Formation shale series also gradually decreases in distribution characteristic from the eastern lake basin area to the western slope area. (4) The oil accumulation mode of the Fengcheng Formation shale series is that, with the drive of overpressure, the oil migrates slightly within the layer, and finally accumulates to form the oil reservoir. The research results are helpful to understand the distribution characteristics of HGP and the formation mechanism of high-pressure and high-yield reservoirs in the shale series of Fengcheng Formation in the west and south of Mahu Sag, and are of great significance to guide the exploration and development of shale oil and tight oil
Intercalation pattern and its impact on development of braided river reservoirs: A case of Fengcheng Oilfield, Junggar Basin, NW China
No full textThrough comprehensive analysis of outcrops, core data and well logs, the type, formation mechanism and distribution pattern of intercalations in the braided river reservoirs of Fengcheng Oilfield, Junggar Basin are studied based on the reservoir architecture, and the inter-well distribution is predicted. The intercalations in Fengcheng Oilfield are divided into four types: intercalation in a bar, intercalation between bars, channel-bar transitional intercalation and chute. The intercalations include two lithologic types: argillaceous sandstone and fine grains. The intercalations are recognized in each individual well by core scale logging. Inter-well prediction is achieved by training image of intercalations established by multi-point statistics. The result indicates that the intercalations are not the uniform size and are scattered with lentoid distribution of various thicknesses. The horizontal wells in test area B are designed by the guidance of intercalation 3-D model, and practice indicates that the intercalation prediction is of great importance for improving oil production. Key words: braided river reservoir, intercalation, channel bar, multi-point statistics, inter-well intercalation prediction, Fengcheng Oilfield, Junggar Basi
Classification and Analysis of Dominant Lithofacies of the Fengcheng Formation Shale Oil Reservoirs in the Mahu Sag, Junggar Basin, NW China
No full textThe exploration of the Fengcheng Formation has revealed the characteristic orderly coexistence of conventional reservoirs, tight reservoirs, and shale reservoirs, constituting a full spectrum of reservoir types, and is important for unconventional oil and gas exploration and development. Affected by frequent volcanic tectonic movement, hot and dry paleoclimate, and the close provenance supply distance, unique saline–alkaline lacustrine deposits formed during the depositional period of the Fengcheng Formation. The lithologies of the Fengcheng Formation are highly diverse, with endogenous rocks, volcanic rocks, terrigenous debris, and mixed rocks overlapping and forming vertical reservoir changes ranging from meters to centimeters. Owing to the complexity of rock types and scarcity of rock samples, the evaluation of reservoirs in mixed-rock has progressed slowly. Hence, we aimed to evaluate the characteristics of Fengcheng Formation shale oil reservoirs. Centimeter-level core characteristics were analyzed based on the lithological change and structural characteristics. To investigate the lithofacies of the Fengcheng Formation in the Mahu Sag and factors affecting reservoir development, high-frequency sedimentary structures were analyzed using sub-bio-buffering electron microscopy, energy spectrum testing, and fluorescence analysis. The results showed that the shale oil reservoirs in the study area can be divided into four categories: glutenite, volcanic rock, mixed rock, and endogenous rock. The reservoir capacity has improved and can be divided into eight subcategories. Mixed-rock reservoirs can be further divided into four subcategories based on differences in structure and composition. Differences in the bedding and dolomite content are the main factors controlling the differences in the physical properties of this type of reservoir. This study provides a reference for the classification and characteristic study of shale oil reservoirs in saline–alkali lake basins
Shale dominant lithofacies and shale oil enrichment model of Lower Permian Fengcheng Formation in Hashan area, Junggar Basin
No full textCompared with the Mahu Sag in the Junggar Basin, the adjacent Hashan area has undergone multi-stage napping and complicated oil-gas formation and evolution process, making its shale oil exploration facing many challenges, such as unclear dominant lithofacies and enrichment law. In order to optimize the dominant lithofacies of the Lower Permian Fengcheng Formation shale in Hashan area and summarize the enrichment model of shale oil, by taking more than 200 samples from 8 exploration wells in the area, including Hashan 5 and Hashen X1 wells, and using methods such as core and ordinary thin section observation, a systematic classification of shale lithofacies types was carried out based on the study of sedimentary environment and facies. A comprehensive evaluation of reservoir physical properties and oil content was conducted based on lithofacies by combining experimental methods such as XRD, scanning electron microscopy, low-temperature nitrogen adsorption, and pyrolysis. The enrichment law of the Fengcheng Formation shale oil in Hashan area was preliminarily revealed based on the correlation analysis of shale mineral composition, organic matter abundance and oil content. The results show that the Fengcheng Formation shale in Hashan area can be divided into four lithofacies types: terrigenous clastic, dolomitic diamict, alkaline mineral diamict and volcanic clastic diamict. The (argillaceous) siltstone in terrigenous clastic lithofacies, the dolomitic sandstone in dolomitic diamict lithofacies, and the volcanic clastic diamict lithofacies have good physical properties and oil content, which are good shale oil reservoirs. The shale oil enrichment patterns can be divided into three types: in the terrigenous clastic lithofacies of the outer delta front, the shale oil enrichment patterns are mainly migrated from adjacent strata. In the shallow- semi-deep lake section, the dolomitic mixed-deposit lithofacies are mainly the shale oil enrichment model of the same layer fracture migration and adjacent layer migration, while the volcaniclastic mixed-deposit lithofacies are mainly the self-generated and self-stored matrix shale oil enrichment model
Gan fang yan Fengcheng hua wei yi xiang guan de gong neng yu su “de” yan jiu =: A study of the functional morpheme de related to motion events in the Fengcheng dialect
No full textM.Phil.This thesis focuses on a functional morpheme de which is linked to motion events in the Fengcheng dialect belonging to the Gan family and investigates its distribution and functions. Similar markers of motion were found in many Chinese dialects and even ancient Chinese, but there was few detailed description and grammatical analysis. Under the framework of generative grammar, the current study discusses in detail the functional morpheme de occurring with motion events in the Fengcheng dialect. Syntactically, de may occur in directional constructions, locative constructions, dative constructions and control constructions with a directional verb as the secondary predicate. The syntactic environment of de is generalized as this configuration "V + de (+ DP) + Path verb". Semantically, the constructions containing de express dynamic motion events, which are associated with the strong accomplishment meaning and the strong affectedness meaning. This thesis argues that de plays a role in syntax of introducing a TP (tense phrase) without an independent temporal interpretation. Meanwhile, de also plays a role in semantics of indicating the accurate end of the activity. Building up on de and the related constructions in the Fengcheng dialect, the thesis proposes that compound verbs like “V-lai/-zai/-gei” are the equivalent of the Fengcheng de in Mandarin and both De and compound verbs are distinct from the serial verb constructions in having different meaning. Thus, motion events in Mandarin could be expressed by two different means: compound verbs and serial verb constructions. Based on the means of expressing motion events in the Fengcheng dialect and Mandarin, I argue that motion events in Chinese have their own syntactic reflex and have an independent status in syntax, deviating from the resultatives in terms of the syntactic structure.本文主要關注 贛方言 豐城話中 與 位移事件 表達相關 的 功能語素 “得 ”，考察“得在 句法 結構 中的分佈 及 句法語義功能 。 位移事件 表達中出現 專門的 助詞 這一 現象在很多 漢語 方言和古漢語中都 存在， 但描寫常常過於簡單，分析更是寥寥無幾 。 本文在生成語法的框架下，對豐城話 中 出現在位移事件 表達 中的 功能語素 “得 進行 詳細 討論 。從句法分佈上看， 豐城話 中 與位移相關的“得”出現在述趨結構、處所結構、與格結構和以趨向成分為次謂語的兼語結構中， ，“得 所在的句法結構可以統一概括為“ V+得（ （+DP））+位移成分” 。 從語義上看， ，“得”所在的結構 表達 動態 位移事件，對比不帶“得 連謂結構 ，具有強完結義和更強的受影響義。 我們認為豐城話中 這 個 “得 在句法上起著引介缺乏獨立時 態 解讀的時態短語 TP的作用，在語義上則 起著指示 動作明確終結點 的作用 。 從豐城話帶“得”結構出發，我們 認為 普通話中 複合詞 V來 /在/給”等 和豐城話帶“得”結構 對應 ，具有區別於連謂結構的語義 特徵 。 普通話存在複合詞和連謂結構兩種不同的位移表達形式。 結合豐城話和普通話中位移表達的情況，我們認為 漢語 位移 表達在句法系統中具有自身的獨立地位 其涉及的 具體句法結構可以和結果表達不同 。陳芳荣."2020年9月".Parallel title from added title page.Thesis M.Phil. Chinese University of Hong Kong 2020.Includes bibliographical references (leaves 76-83).Abstract also in English.Title from PDF title page (viewed on March 15, 2022).Chen Fangrong
Characteristics and Formation Stages of Natural Fractures in the Fengcheng Formation of the Mahu Sag, China: Insights from Stable Carbon and Oxygen Isotope and Fluid Inclusion Analysis
No full textThe Fengcheng Formation of the Mahu Sag is an unconventional reservoir that is of paramount importance for exploration and development of hydrocarbon resource. However, current research on natural fractures in the Fengcheng Formation remains limited, posing challenges for exploration of hydrocarbon resource in the region. This study is based on core observations, thin section identification, geochemical testing and the evolution of regional tectonic movements to investigate the characteristics and periods of formation of natural fractures to address this gap. According to the characteristics of natural fractures in the drilling core samples and microsections, the natural fractures in the Fengcheng Formation can be grouped into structural fractures and atectonic fractures. Structural fractures can be further divided into three subtypes: high-angle interlayer shear fractures, along-layer shear fractures, and tensile fractures. Additionally, non-tectonic fractures in this studied area are primarily bedding fractures, hydraulic fractures, and hydrocarbon-generating overpressure fractures. Vertically, fracture development is more prominent at the bottom of Feng #2 Formation and at the top of Feng #3 Formation. Results also indicate that natural fractures primarily formed during three distinct tectonic movement periods. The initial stage of fracture evolution pertains to the Late Permian period (243–266 Ma), filled with fibrous calcite, and exhibiting a uniform temperature of 70–100 °C. The second stage of fracture evolution occurred during the Late Indosinian to Early Yanshanian period (181–208 Ma), mostly filled or semi-filled with calcite, with a uniform temperature of 110–130 °C. The third stage of fracture development happened during the late Yanshanian to early Himalaya period (50–87 Ma), predominantly filled with calcite, and presenting a uniform temperature of 130–150 °C. Among the various types of structural fractures, the density of high-angle interlayer shear fractures demonstrates a positive correlation with daily gas production, indicating their vital role in promoting hydrocarbon resource production and transportation. Furthermore, microfractures generated by hydrocarbon-generating overpressure fractures exhibit small pore sizes and strong connectivity. These microfractures can create an effective permeability system by connecting previously isolated micropores in shale reservoirs, thus establishing interconnected pore spaces in the shale formation
Troglocoelotes ruanxiaowu Lin & Li 2024, sp. nov.
No full text<i>Troglocoelotes ruanxiaowu</i> Lin & Li, sp. nov. (Figs 2, 3B) <p> Etymology. The species is named after Ruan Xiaowu, a character in the classic Chinese novel <i>Outlaws of the Marsh</i>; noun in apposition.</p> <p> Diagnosis. The female of the new species resembles <i>T. liangensis</i> Zhao & Li, 2019 by the epigynal teeth directed mesially and oval spermathecae, but it can be distinguished by the strongly procurved posterior margin of the atrium (<i>vs.</i> slightly recurved) and middle part of copulatory ducts expanded (<i>vs.</i> unexpanded).</p> <p>Description. Female (holotype). Total length 4.72, carapace 2.65 long, 1.78 wide, opisthosoma 2.05 long, 3.08 wide. Eyes absent. Chelicerae with 3 promarginal and 2 retromarginal teeth. Leg measurements: I 11.24 (2.88, 3.70, 2.78, 1.88), II 10.60 (2.76, 3.36, 2.72, 1.76), III 10.04 (2.63, 2.97, 2.75, 1.69), IV 13.25 (3.24, 4.10, 3.85, 2.06).</p> <p> <i>Coloration</i> (Fig. 3B). Carapace yellow-brown. Cephalic region brown to yellowish brown, thoracic region pale yellow. Cervical and radial furrows distinct. Chelicerae brown. Endites and labium brown. Sternum yellowish brown. Legs yellow with black setae. Opisthosoma oval, gray, without any pattern. Spinnerets yellowish brown.</p> <p> <i>Epigyne</i> (Fig. 2). Epigynal plate as long as wide. Epigynal teeth finger shaped, located over the atrium, about 2 times wider than long. Atrium inconspicuous. Median plate strongly procurved. Copulatory ducts partially oval, then spiraled and attached to the anterior part of spermathecae. Spermathecal heads obvious. Spermathecae oval. Fertilization duct directed at 1:00-o’clock-position from spermatheca.</p> <p>Male. Unknown.</p> <p>Material examined. Holotype ♀ (IZCAS-Ar44791), China: Guangxi, Fengshan Co., Fengcheng Town, Songren Vil., Xi'an Cave (24.5657°N, 107.04108°E, elev. 574 m), 12.III.2007, Jie Liu and Yucheng Lin leg.</p> <p>Distribution. Known only from the type locality.</p>Published as part of <i>Lin, Yejie, Li, Shuqiang, Mo, Haolin & Wang, Xihao, 2024, Thirty-eight spider species (Arachnida: Araneae) from China, Indonesia, Japan and Vietnam, pp. 4-98 in Zoological Systematics 49 (1)</i> on pages 11-12, DOI: 10.11865/zs.2024101, <a href="http://zenodo.org/record/10941018">http://zenodo.org/record/10941018</a>
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