Diffusion of Methane and Ethane Through the Reservoir Cap Rock: Implications for the Timing and Duration of Catagenesis: Discussion
| Autor: | Jon S. Nelson, E. C. Simmons |
|---|---|
| Rok vydání: | 1997 |
| Předmět: |
business.industry
Fossil fuel Energy Engineering and Power Technology Mineralogy Geology Mechanics Petroleum reservoir Methane Catagenesis (geology) Natural gas field chemistry.chemical_compound Fuel Technology chemistry Geochemistry and Petrology Natural gas Earth and Planetary Sciences (miscellaneous) business High turnover |
| Zdroj: | AAPG Bulletin. 81 |
| ISSN: | 0149-1423 |
| DOI: | 10.1306/522b42c1-1727-11d7-8645000102c1865d |
| Popis: | In the July 1995 issue of this journal, Nelson and Simmons (1995) presented a computation of diffusive losses from natural gas accumulations. In their contribution they pointed out correctly that oil and gas fields must be considered as dynamic systems. Regrettably, they omitted (almost systematically) all references to earlier work in which the dynamic character of natural gas accumulations on the geologic time scale was emphasized. We acknowledge that the approach is generally well documented and the corresponding computations are consistent with the definitions. We disagree, however, with certain aspects of the approach used by Nelson and Simmons (1995). As a conclusion of their case study on the McClave gas field in southeastern Colorado, Nelson and Simmons (1995) suggested that high turnover rates (less than 1 m.y. up to several million years) due to diffusive losses are a characteristic feature of natural gas accumulations, and they consequently postulated continuous and rapid gas generation as a prerequisite for the persistence of natural gas reservoirs. However, by using a rather arbitrary set of parameters as the basis of their calculations, they depicted a scenario that must be considered as quite exceptional in terms of reservoir geometry and pay zone thickness. Their conclusionsmore » on the dynamics of natural gas accumulations are therefore questionable and must be considered with caution. Before discussing this issue in detail, we address two aspects of the computational approach used by Nelson and Simmons (1995); the definition of the effective diffusion coefficient and the method of calculating the fractional reduction of the diffusion coefficient.« less |
| Databáze: | OpenAIRE |
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