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This case study aimed to isolate and identify methanogenic bacteria from landfill soil, mud, and leachate samples to assess their role in anaerobic digestion and biogas production. Anaerobic digestion involves the breakdown of organic matter by a diverse group of bacteria under oxygen-free conditions, resulting in the production of methane and carbon dioxide. The collected samples from the landfill were cultured in a modified mineral salt medium (MSM). Microscopic observations revealed distinct coccus and bacillus morphologies of the isolated methanogenic bacteria. Gas production experiments and substrate utilization studies identified two types of methanogens. Methanosarcina sp., which utilized acetate and methanol for methane production, and Methanobacterium sp., utilizing hydrogen and carbon dioxide, as well as acetate. Scanning electron microscope (SEM) analysis confirmed the different morphotypes of the isolated methanogens. The study findings demonstrated the presence of diverse methanogens in the landfill environment, contributing to anaerobic digestion and biogas production. [ABSTRACT FROM AUTHOR]

Sand production is a serious problem while oil and gas producing from unconsolidated formation. The reasons for such damage are the loss of the balance of the rock's stress in a drilling situation, create a momentum in the grain by fluid movement, reduction in reservoir pressure, and fatigue formation in the rock. Therefore, it is significant to forecast and evaluate the sanding onset of the wells with the intention of drilling and production condition optimisation. In this study, first, a geo-mechanical model based on the reservoir and petro-physical properties was established. Then, a new analytical shear failure sanding onset prediction model was derived on the basis of the three-dimensional Hoek–Brown failure criterion. Furthermore, the developed model was applied to the prediction of the critical drawdown pressure causing sand production in one of the wells drilled in one of the fields located in southwest Iran. Finally, the sensitivity of the relevant parameters with respect to the sanding onset in this well was evaluated. The results showed that the three-dimensional Hook–Brown model was a good fit with well number 19 of the Asmari field. Therefore, this criterion was recommended for the sand production analysis in this oil field. [ABSTRACT FROM AUTHOR]

This study concerns the absolute LA ICP-MS U-Pb dating of hydrothermal cementation, particularly in tectonically controlled fractures filling saddle dolomites and blocky calcites in the carbonate succession of Bekhme Formation (Campanian–Maastrichtian). Dating of multiphase hydrothermal cementation combined with δ18O and δ13C analyses, petrography and field observations shows two major episodes of hydrothermal fluid circulation. The first was measured at ~73.8 Ma and is associated with the Zagros folding-faulting tectonic event (Late Cretaceous) and with the depositional age of the Bekhme Formation (75.1 Ma), and the second was at 30.3 Ma and is associated with the second folding-faulting tectonic event during the Tertiary. The δ18O and δ13C values grouped into two populations corroborate the two episodes of hydrothermal fluid flow. Late Cretaceous folding and faulting tectonics and reactivation during the Tertiary in the study area provided conduits for the hydrothermal fluids along deeply seated faults. This work shows for the first time through U-Pb dating that the hydrothermal diagenetic processes in Upper Cretaceous Bekhme Formation are directly linked with the timings of the major regional tectonics in the Zagros Fold-Thrust Belt (ZFTB) through the flow of hot fluid fluxes in a fractured sedimentary basin. [ABSTRACT FROM AUTHOR]