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The southern Junggar Basin, Xinjiang, has abundant coalbed methane (CBM) resources. Currently, the Baiyang River development pilot test area (BYR block for short) in the Fukang east block has achieved large-scale CBM development, but the productivity characteristics and its controlling factor are still unclear. Based on the field production data of the BYR block and experimental tests, this paper summarizes the gas and water production characteristics and presents the analysis results of the geological and geochemical responses to the productivity of CBM wells. The productivity of CBM wells in the BYR block was generally characterized as medium-to-low yield. The productivity was jointly controlled by the burial depth, structure condition, thickness and number of co-production coal seams, and hydrogeological conditions. The gas production first increased and then decreased with the increase in the burial depth of the coal seam, and a burial depth between 750 and 1000 m was the most beneficial to increasing the gas production due to the good gas preservation conditions and suitable permeability and stress conditions. The total thickness of the co-production coal seams had a positive effect on the productivity of gas wells, but the productivity was also affected by the number of co-production coal seams and interlayer interference. In the BYR block, the co-production of the nos. 41 and 42 coal seams was the most favorable combination form for CBM drainage. The productivity of CBM wells had a good response to the Na+, K+ and HCO3− concentrations but a poor response to δD-H2O and δ18O-H2O. Based on the concentrations of the main ions and TDSs of the coal seam water, a productivity response index δ* was established, and there was a good positive correlation between the productivity and δ*. [ABSTRACT FROM AUTHOR]

Fracture system identification of coal reservoirs plays a vital role in evaluating favorable zone of coalbed methane (CBM) development and improving CBM well productivity. In order to identify the fracture system of the No. 2 coal reservoir, and to determine the productivity differences of CBM wells with different coal structures in the Yanchuannan (YCN) Block, Ordos Basin, China, a comprehensive analysis method from macroscopy to microscopy and from static to dynamic was provided in this work. Site observations on coal sections and observations under light microscope and scanning electron microscopy (SEM) were combined to understand the fracture characteristics of the coal seam, and the spatial geological model of fracture development was built. The selected logging data was conducted cluster analysis to identify the coal structures of coring wells and to predict the coal structures of non-coring wells. The analysis results show that the No. 2 coal seam has a high fracture development degree, and is dominated by type II coal structure (cataclastic coals). The coals with different structures show evident zonation on the plane, which is largely controlled by faults. The well-developed fracture system and high permeability zone mainly concentrate on the tectonic rolling areas and the areas with small faults. Furthermore, the output data of coal fine and the drainage curves of CBM wells were performed dynamic analysis to indirectly reflect the fracture system difference and the resulting productivity difference. The results indicate that the wells with poor-preserved coals tend to produce more coal fine, and the gas production has a negative correlation with coal fine amount. The productivity pattern of CBM wells can be divided into “high yield—long-term stable yield” and “low yield—decline quickly”. Almost all CBM wells with type I coal structure and most CBM wells with type II coal structure have the first productivity pattern, and part wells with type II coal structure and all wells with type III coal structure present the second productivity pattern. [ABSTRACT FROM AUTHOR]

This paper mainly focused on the genesis of coalbed methane (CBM), CO 2 origin and the CBM accumulation mechanism in the southern Junggar Basin using a combination of geochemical and geological analysis methods. From this work, it is found that the degree of early coalification and the current structural and hydrogeological conditions jointly determine the regional differences in CBM genesis, accumulation and gas-bearing capacity. Microbial (biogenic) gases are widely developed in the whole study area, while their generation types and contributions vary greatly in different areas and structural belts. The CBM in the eastern Urumqi (ER) and Jimusaer (JMSE) areas is primary microbial (biogenic gas) that have been generated through CO 2 reduction pathway and mixed with a small amount of early mature thermogenic gas. The Baiyang River (BYR) area has a mixed gas source of early mature thermogenic gas, primary microbial gas and secondary microbial gas. The CBM in other areas is mixed gas of thermogenic and secondary microbial origins. Abnormally high CO 2 concentration and extremely positive δ13C-CO 2 are all related to microbial methanogenesis. The CO 2 in the ER and JMSE areas and partial CO 2 in the BYR area are produced by the microorganism-mediated degradation of sedimentary organic matter. The selective consumption by microbial reduction and differential dissolution of groundwater result in an increase in CO 2 concentration with increasing burial depth in the ER and BYR areas. The CO 2 in other areas is originally derived from the deoxidation reaction of early coalification which then undergoes secondary biotransformation. The CO 2 intervention commonly runs through the whole process of CBM accumulation in low-rank coal in the study area. Due to isotope fractionation caused by groundwater flow and differential modification of microorganisms, the vertical variations of δ13C-CH 4 and δ13C-CO 2 are positively correlated with burial depth, and the genetic types and gas-bearing characteristics of CBM have obvious vertical zoning under the condition of high-dip structures. • Multiple genetic types of gases coexist in the southern Junggar Basin. • The early coalification, structural and hydrogeological conditions control CBM accumulation. • Abnormally high CO 2 and extremely positive δ13C-CO 2 are related to microbial methanogenesis. • The CO 2 in SGR area was originally derived from the deoxidation reaction of early coalification. [ABSTRACT FROM AUTHOR]

Abstract Coalbed methane (CBM) drilling technology is critical in achieving efficient CBM development. The geological conditions for CBM development in China are complex, including special terrain, high-rank coal areas, deep coal seams, multiple superposed coal seams and coal measure gas symbiosis areas, steeply inclined coal seam areas, and tectonic coal seam areas. Therefore, it is critical to apply the optimum drilling technology in each different area. This paper first reviews the current CBM drilling technologies and gas production behaviors in China. It is found that although vertical wells and cluster well groups are common well types for CBM development in China, U-, V- and L- shaped horizontal wells and multilateral horizontal wells have been favored for CBM development in recent years. The paper then discusses the applicability of different well types to geological conditions and proposes a modification method for well design in various geologic conditions. This method uses the coal structure, R o , in situ stress, and ratio of critical desorption pressure to the reservoir pressure as the main inputs. Highlights • The current CBM well technologies and gas production in China were reviewed. • The applicability of different well types to geological conditions was discussed. • An optimization method for well type selection was proposed. [ABSTRACT FROM AUTHOR]

The reservoir physical properties, pore types, diagenetic characteristics and reservoir quality controlling effect of the Xishanyao formation coal measure sandstone in the southern margin of the Junggar basin were discussed in this study based on thin section observation, high pressure mercury injection, low-temperature nitrogen adsorption and scanning electron microscope observation. The result shows that the porosity and permeability of the sandstone are generally low with a medium-high texture maturity and low compositional maturity. The sandstone storage space is mainly composed of residual intergranular pores, secondary dissolution pores, inter-crystalline pores and micro-fractures. The diagenetic stage of coal measure sandstone is in the mesodiagenesis A1-A2 stage, and their diagenetic interaction types mainly include compaction, cementation and dissolution. The reservoir quality of the coal measure sandstone deteriorates by compaction due to high matrix content and plastic debris content. Because of the large amounts of organic acids generated during the thermal evolution of the coal measure source rock, the coal measure sandstone suffers from strong dissolution. The secondary dissolution pores formed by the massive dissolution of feldspar, lithic fragments and early carbonate cementation in the sandstone significantly improved the reservoir quality. In the coal measure sandstone, clay mineral cementation is the most developed cementation form, followed by quartz cementation and carbonate cementation. Although kaolinite cementation and dolomite cementation can generate a small number of inter-crystalline pores, cementation deteriorates the reservoir quality. The Xishanyao formation coal measure sandstone formed in a lacustrine-delta environment, and its composition and texture make it susceptible to the influence of compaction and dissolution during diagenesis. [ABSTRACT FROM AUTHOR]

Coal seams are typically self-sourced reservoirs. However, in certain special cases, the coal seams also contain large amounts of external gas from other source rocks. Successful development strategies in relation to Jurassic coalbed methane (CBM) in recent years have confirmed the presence of large amounts of external gas within the coal seams of the Baijiahai Uplift, Junggar Basin, China, which has important exploration and development prospects. However, the genesis and source of Jurassic CBM in the area remain unclear, limiting our understanding of its formation and accumulation as well as the planning of further development strategies. Based on a comprehensive analysis of the geochemical characteristics of Jurassic CBM, combined with research on the burial and thermal evolution history of the Jurassic coal seams, this study discusses the production curves of typical wells as well as regional tectonic styles, genesis, source, and accumulation of Jurassic CBM in the Baijiahai Uplift. Depending on the genesis, Jurassic CBM in the study area is divided mainly into coal-type (humic-type) gas, oil-type (sapropelic-type) gas, and mixtures of them, all of which are thermogenic gases of medium to high maturity. There are two main sources of Jurassic CBM in the Baijiahai Uplift. On the one hand, it comes from the vertical migration of gas generated by Permian and Carboniferous source rocks in the Baijiahai Uplift directly. On the other hand, it comes from the regional lateral migration from the Dongdaohaizi and Fukang Sags. Gas generated by source rocks in the Dongdaohaizi and Fukang Sags is driven by pressure, migrates towards the Baijiahai Uplift through sandstone channels, and accumulates in the Jurassic coal seams through faults. Compared with common self-sourced coal seams, enrichment of the coal seams with large amounts of external gases requires two necessary conditions: (1) Other layers of gas-generating source rocks are present at levels deeper than those of the coal seams, constituting additional gas sources for the coal seams, and (2) an open fault system is developed regionally, providing pathways for gas from other layers to enter the coal seams. • The genesis and source of external gas in deep coal seams are explained. • Identification methods of the gas originates from multiple source rocks. • Reveal the migration and accumulation of external gas in deep coal seams. • The necessary conditions for the formation of external gas are determined. [ABSTRACT FROM AUTHOR]

Psoriasis is a chronic autoimmune disorder related to abnormal keratinocyte proliferation. Long noncoding RNAs (lncRNAs) are significant regulators in the progression of skin diseases. In this study, we explored how lncRNA MALAT-1 controls the pathogenesis of psoriasis by examining its impact on keratinocyte proliferation, inflammation, and apoptosis. A psoriasis cell model was established by treating HaCaT keratinocytes with the inflammatory factor, IL-22 (100 ng/ml), for 24 h. The MALAT-1 and S100A7 levels in psoriatic lesions, normal skin tissues, and IL-22-stimulated HaCaT cells were determined by RT–qPCR and western blotting. Cell proliferation, inflammation, and apoptosis were detected by the MTT assay, western blotting, and flow cytometry analysis, respectively. Bioinformatics analysis was used to identify the miRNAs that bind to MALAT-1 and S100A7. The relationships between MALAT-1 or miR-330-5p and S100A7 were assessed using a luciferase reporter assay. The MALAT-1 and S100A7 levels were upregulated in both psoriatic lesion samples and IL-22-stimulated HaCaT cells. Silencing MALAT-1 significantly reversed the IL-22-stimulated promotion of HaCaT proliferation and changes in Ki67 and KRT5/14/1/10 protein levels, and MALAT-1 deficiency also reversed the upregulation of TNF-α, IL-17, and IL-23 protein levels as well as suppression of cell apoptosis. As a ceRNA, MALAT-1 competed with S100A7 to prevent miR-330-5p-induced inhibition of S100A7 expression. There was a negative correlation between miR-330-5p and MALAT-1 (or S100A7) expression in psoriatic lesion tissues. In response to IL-22 treatment, miR-330-5p silencing eliminated the effects of MALAT-1 knockdown in HaCaT cells. Thus, these findings demonstrated that MALAT-1 modulates the IL-22-induced changes in HaCaT cells through the miR-330-5p/S100A7 axis. [ABSTRACT FROM AUTHOR]

Coal permeability has been identified as one of the key factors affecting coalbed methane (CBM) extraction. CBM drainage and hydraulic fracturing usually lead to coal fines output. Some of these coal fines passed through wellbore discharged of coal bed, and some of them were compacted in fractures during the closing of fractures (or cleats) under the confining pressure. The pore distribution and seepage path of those compacted coal fines are different from natural coal. In this study we used reconstituted coal as a research material to study porosity and permeability characteristics of compacted coal fines in coal reservoir fractures. We use different macrolithotype coal particles with size of 0.2–0.4 mm, a heat-shrinkable tube and two guide blocks to make a reconstituted coal sample. In order to investigate the behavior of reconstituted coal permeability changing with effective stress and the influence of lithotype effect on permeability of reconstituted coal, reconstituted coal cores porosity and permeability test with helium gas in net confining stress were measured in laboratory. And pore distribution of different macrolithotype natural coals and reconstituted coals were analyzed by low-temperature nitrogen adsorption experiment and low-field nuclear magnetic resonance (NMR) measurement. Both porosity and permeability of reconstituted coal decrease exponentially with the increase of effective stress. Initial permeability and permeability damage rate of reconstituted coal have a negative correlation and a positive correlation with quality proportion of clarain and vitrain, respectively. The proportion of seepage channels of dull reconstituted coal is larger than that of bright reconstituted coal. [ABSTRACT FROM AUTHOR]

Organic-rich mudstone, whose formation and accumulation are strongly related to the depositional environment, is a potential source of natural gas. Here, geochemical tests (including total organic carbon (TOC), rock pyrolysis, X-ray diffraction (XRD), and main and trace element analyses) were carried out on mudstone samples from two boreholes in the Jixi Basin to reveal the paleoenvironment and its control on organic matter enrichment. The results show that type III kerogen dominated and that all samples entered the maturity stage with good hydrocarbon generation potential. Generally, the TOC content tended to increase with increasing depth, and the mudstone in the middle (K 1 ch 2) and lower (K 1 ch 1) segments of the Chengzihe Formation was characterized by good quality with TOC > 2.5%. In the Jixi Basin, two common types of mudstones (silica-dominated mudstone and silica-rich argillaceous mudstone) were mainly composed of quartz and clay minerals. These mudstones were rich in Na 2 O, MnO and several trace elements (e.g., Zn, Mo, and Bi) and depleted in other elements (e.g., MgO, CaO, Cr, Co, and Ni). The rare earth element and yttrium (REY) distribution patterns normalized by North American shale compositions (NASC) were flat, with slight negative Ce and Eu anomalies. The ratios of Sr/Cu, Rb/Sr, Sr/Ba and V/(V + Ni) in mudstones indicated a warm-humid paleoclimate, a suboxic environment and a marine-continental transitional fresh-brackish water mass. From the K 1 ch 1 to Muling Formation (K 1 m), although the paleoclimate was more arid and paleosalinity increased gradually, depositional environments were in fresh-brackish water. The paleoclimate and clastic influx are the keys to controlling the enrichment of organic matter. The paleoclimate indirectly affects the preservation of organic matter by influencing the aquatic environment and controlling the level of paleoproductivity, while the strong clastic influx rate directly dilutes organic matter preservation. • Geochemical characteristics of the mudstones from the coal-bearing strata in the Jixi Basin are determined. • Mudstones in the coal-bearing strata were deposited under warm-humid paleoclimate with increasing water salinity. • Mudstones show stable suboxic depositional environment. • Paleoclimate and clastic influx are the keys to controlling the enrichment of organic matter. [ABSTRACT FROM AUTHOR]