摘要:

About half of the world's oil production is from carbonate formations. However, most of the research in microbially enhanced oil recovery (MEOR), a potentially important tertiary recovery technology, has focused on sandstone reservoirs because, in general, they are geologically simpler than carbonate reservoirs and easier to model in the laboratory. Carbonate formations have a wide range of pore geometries and distributions, resulting in complex flow dynamics. The low matrix permeabilities and the dual porosity characteristics of most carbonate formations, coupled with the chemistry of carbonates, have slowed implementation of enhanced oil recovery methods. A review of the data on carbonate reservoirs in Dwight's Energydata TOTL System indicated that 40% of the oil‐producing carbonate reservoirs surveyed in the United States have environmental, geological, and petrophysical conditions that would make them candidates for MEOR. A review of a number of MEOR field trials showed that rates of oil production could be increased by as much as 200%. Microbial activity in these trials was probably due to that of indigenous populations rather than the microorganisms injected for the trials. Detrimental effects such as loss of injectivity and increased souring were not reported. Based on analysis of the geology and petrophysical characteristics of carbonates, two common mechanisms of MEOR, microbial acid production and microbial gas production, are especially suited for application in carbonate reservoirs.

ISSN:0149-0451    

DOI:10.1080/01490459109385998

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor

摘要:

The vadose zone and its contaminant‐attenuating processes are physically interposed between surface contamination and groundwater supplies. Given the potential role of microorganisms in mediating vadose‐zone chemical processes, it is vital to understand vadose microbial distributions and factors controlling those distributions. Vadose and shallow saturated zone sediments obtained from cores drilled to approximately 8 m below the surface at two hydrogeologically contrasting sites, named Dalmeny and Washington State University (WSU), were examined for culturable heterotrophic bacteria, total organic carbon (TOC), and sediment texture. Pore‐water elutions were analyzed for dissolved organic carbon, sulfate, and inorganic nitrogen species. Numbers of cultured bacteria (103‐107g−1) generally decreased with depth at both sites. The TOC decreased uniformly with depth at WSU where soil processes are the sole carbon source; at Dalmeny, where both soil and kerogen carbon are present, TOC was higher and relatively constant with depth. Numbers of distinct colony types at Dalmeny did not decline below the solum. Bacteria at Dalmeny were more numerous, exhibited greater numbers of colony types, and were metabolically more flexible than those at WSU. The smooth decline of numbers with depth at WSU paralleled and may be caused by the TOC decline with distance from a solum source. Sediment permeability and pore‐water flux did not control bulk populations as suggested in previous studies; this may be explained by bacterial residence on fracture surfaces in low‐permeability materials. Psychrotolerant organisms did not appear to be as abundant as mean ambient temperatures might suggest.

ISSN:0149-0451    

DOI:10.1080/01490459109385999

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor

摘要:

Laboratory experiments were conducted to measure the activity of phosphomonoesterases in various zones of a geological outcrop. The outcrop contained an Entisol and partially weathered carbonaceous shales of Paleozoic age with differentiating zones rich in pyrite and goethite. Goethite is the most commonly occurring iron oxide in soils, and pyrite is often found in reconstructed soils of coal surface mines. The activity of acid phosphatase was significantly elevated in goethite‐rich zones compared to zones where pyrite was present. Alkaline phosphatase activity was reduced significantly in the presence of goethite but was not affected by pyrite. Experiments with pure pyrite and synthetic goethite substantiated the results obtained from the outcrop samples. The enhancing effect of goethite at lower pH values is probably due to chemisorption and removal of mineralized P, which increases the mineralization of organic P. At higher pH values goethite surfaces are negatively charged and repel phosphate anions. The exact mechanism for the inhibitory effect of pyrite on acid phosphatase is not known.

ISSN:0149-0451    

DOI:10.1080/01490459109386000

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor

摘要:

A new heterotrophic, thermophilic, alkaliphilic, facultatively anaerobic, cellulose‐degrading bacterium strain STS1 was isolated from mound soils infested with the higher termiteOdontotermes obesusin the semiarid ecosystem of Delhi (India). The gram‐positive, spore‐forming, catalase‐positive Bacillus sp. grew on natural and raw celluloses. The taxonomic position of the organism was investigated. The guanine plus cytosine content of the isolate was found to be 48.6 mol% (melting temperature profile). Addition of peptone or yeast extract stimulated growth. The isolate did not grow on silica gel plates or on agar media in which the agar was the sole source of carbon and energy. The high growth temperature of 70°C and the pH of 9.0 are characteristic of this species. The role of this bacterium in the semiarid ecosystem is discussed. Because of its high optimum temperature and high optimum pH for growth, the nameBacillus thermoalcaliphilusis proposed.

ISSN:0149-0451    

DOI:10.1080/01490459109386001

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor

摘要:

Arora, Dilip K., Bharat Rai, K. G. Mukerji, and Guy R. Knudsen (Eds.),Handbook of Applied Mycology, Volume 1: Soils and Plants(New York, Marcel Dekker, 1991). 720 pp. $150 (U.S. and Canada), $172.50 (all other countries).

ISSN:0149-0451    

DOI:10.1080/01490459109386002

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor

ISSN:0149-0451    

DOI:10.1080/01490459109386003

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor

ISSN:0149-0451    

DOI:10.1080/01490459109386004

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor

ISSN:0149-0451    

DOI:10.1080/01490459109385997

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor