Search

After conventional oil recovery operations, more than half of the crude oil still remains in a form, which is difficult to extract. Therefore, exploring and developing new enhanced oil recovery (EOR) technologies have always been priority research in oilfield development. Microbial enhanced oil recovery (MEOR) is a promising tertiary oil recovery technology that has received widespread attention from the global oil industry in recent years due to its environmental friendliness, simplicity of operation, and cost-effectiveness. This review presents the: principle, characteristics, classification, recent development, and applications of MEOR technology. Based on hundreds of field trials conducted worldwide, the microbial strains, nutrient systems, and actual effects used in these technologies are summarized, with an emphasis on the achievements made in the development and application of MEOR in China in recent years. These technical classifications involve: microbial huff and puff recovery (MHPR), microbial flooding recovery (MFR), microbial selective plugging recovery (MSPR), and microbial wax removal and control (MWRC). Most of them have achieved good results, with a success rate of approximately 80%. These successful cases have accumulated into rich experiential indications for the popularization and application of MEOR technology, but there are still important yet uncertain factors that hinder the industrialization of this technology. Finally, based on the extensive research and development of MEOR by the authors, especially in both laboratory and industrial large scales, the main challenges and future perspectives of the industrial application for MEOR are presented. [ABSTRACT FROM AUTHOR]

Monodisperse composite microspheres were prepared of zirconia and urea formaldehyde resin having an average particle size of 2.2 μm. Their surface was modified by silane coupling agent and styrene, and then sulfuric acid assisted with silver sulfate to form solid sulfonic acid based ion‐exchange catalyst (namely, ZrO2‐SIEC) for the alkylation of 2,4/2,5‐xylenol mixture. The selectivities of catalyst ZrO2‐SIEC to produce 6‐2,4‐xylenol and 4‐2,5‐xylenol were found to be 98.9% and 97.9%, with yields of 98.6% and 80.9%, respectively. The optimized reaction conditions were identified including temperature (80°C), catalyst dosage (9%) and reaction time (180 min). In addition, catalyst ZrO2‐SIEC showed good reusability for maintaining stable catalytic performance over 25 cycles of reuse, attributed to its stable mechanical, thermal and chemical properties. Comparison with other four catalysts demonstrated good performance of ZrO2‐SIEC in terms of catalytic activity, operating conditions, separation from products, and environmental friendliness. [ABSTRACT FROM AUTHOR]

It is challenging to separate 2,4‐/2,5‐xylenol isomers with very close boiling points. In the present work, a multistep process for the separation of 2,4‐/2,5‐xylenol isomers from coal tar was investigated, involving alkylation, distillation, and dealkylation. Starting from the selection of suitable catalyst, the operating conditions for alkylation, distillation, and dealkylation were optimized by varying key parameters systematically. Among the four catalysts examined, p‐toluenesulfonic acid (PTSA) showed best performance in terms of conversion and selectivity. Under the optimized alkylation conditions, the yields of 6‐tert‐butyl‐2,4‐xylenol and 4‐tert‐butyl‐2,5‐xylenol were 97.3% and 86.2%, respectively. Following pH adjusted to 7–8 with 10% sodium carbonate and water washing, the minimum reflux ratios during distillation for obtaining 6‐tert‐butyl‐2,4‐xylenol and 4‐tert‐butyl‐2,5‐xylenol were 4 and 12, with product purity of 99.8% and 99.5%, respectively. Under the optimized dealkylation conditions, both yields of 2,4‐xylenol and 2,5‐xylenol reached 99.9%. After recrystallization, the final product purity was over 99.5%. This lab‐scale investigation provides key information for an on‐going pilot‐scale process design. [ABSTRACT FROM AUTHOR]

A novel 3D coordination polymer {[Cu4.5 (BTZE)1.5 (μ3-OH)3(μ-OH)(SO4)(H2O)1.5·4H2O]}n (1) was synthesized by a solvothermal reaction of 1,2-bis(tetrazol-5-yl) ethane (BTZE) with copper sulfate. Compound (1) contained triangular [Cu3(μ3-OH)] cluster based magnetic Δ-chains linked with in situ generated μ2-BTZE ligands to form a 2D cyclic annular layer. This 2D layer structure was further modified with sulfate and symmetry-related μ3-OH groups, extending to a 3D coordination framework structure. The magnetic performance of (1) was characterized in the temperature range of 2–300 K in terms of direct-current and alternating-current magnetic susceptibilities, revealing that (1) was a canted ferromagnet with a critical temperature (Tc) of 9.5 K. Notably, (1) behaved as a hard magnet with a coercive field of 2.3 kOe at 2 K, showing significant unique characteristics compared to those of the reported spin canting systems based on pure Cu(II) ions. [ABSTRACT FROM AUTHOR]

In the present research, a bioremediation process was developed using solid complex bacterial agents (SCBA) through a combined two-step biodegradation process. Four isolated strains showed high efficiency for the degradation of total petroleum hydrocarbons (TPH) and the reduction of COD of the oily sludge, at 96.6% and 92.6%, respectively. The mixed strains together with bran prepared in form of SCBA exhibited improved performance compared to individual strains, all of which had an optimal temperature of around 35 °C. The use of SCBA provided advantages over commonly used liquid media for storage and transportation. The two-step process, consisting of firstly biosurfactant-assisted oil recovery and secondly biodegradation of the remaining TPH with SCBA, demonstrated the capability for treating oily sludge with high TPH content (> 10 wt%) and short process period (60 days). The large-scale (5 tons oily sludge) field test, achieving a TPH removal efficiency of 93.8% and COD reduction of 91.5%, respectively, confirmed the feasibility and superiority of the technology for industrial applications. ga1 • Four strains showed high efficiency for degrading TPH and reducing COD of oily sludge. • Solid complex bacterial agents were developed for the treatment of oily sludge. • A 2-step process was used to treat oily sludge with high TPH within a short period. • The technology demonstrated potential and superiority for industrial application. [ABSTRACT FROM AUTHOR]

Industrial application of microbial enhanced oil recovery (MEOR) has been hindered by a lack of large-scale data-based guidelines for process design and operation. In the present work MEOR was investigated in both laboratory and large-scale oilfield studies. Six microbial strains were initially isolated from Baolige Oilfield in China. Laboratory based investigation showed that all six strains were able to decrease the oil viscosity. Two mixtures of strains exhibited greater reduction effects, i.e., 35% and 56%, respectively. The optimal nutrient concentration was found to be 1.0%. The mixtures of strains tested in laboratory core flooding based MEOR also confirmed their greater MEOR performance, i.e., MEOR levels of 9.1% and 13.2%, respectively, compared to that of any single strain ranging from 7.0% % to 8.7%. Using the strain mixture that had been selected under the laboratory based conditions, the pilot field study achieved a significant MEOR: 210,000 tons of crude oil produced over 43 months from 169 production wells. The research results obtained in this work including both laboratory and field studies can be potentially applied in other oilfields with similar geological and physical conditions, for large-scale MEOR process design and operation. [ABSTRACT FROM AUTHOR]

The title compound, [Mn(C7H3NO4)(C12H6N2O2)(H2O)2]·2H2O, is a neutral mononuclear MnII complex. The Mn—N bond to the pyridine-2,6-dicarboxylate ligand lies along a crystallographic twofold rotation axis. The Mn2+ cation has a distorted pentagonal–bipyramidal configuration, coordinated by three N atoms, one from the pyridine-2,6-dicarboxylate ligand and two from the chelating 1,10-phenanthroline-5,6-dione ligand. The remaining four coordination sites are occupied by O atoms, two from the pyridine-2,6-dicarboxylate ligand and two from water molecules. The asymmetric unit also contains a solvent water molecule. The crystal structure is stabilized by a network of O—H...O hydrogen-bonding interactions in a three-dimensional supramolecular structure. [ABSTRACT FROM AUTHOR]