Pressure significance of gas chimneys |
| |
Institution: | 1. Marine Geology Dv., Geological Survey of Spain, IGME, Madrid, Spain;2. Instituto Andaluz de Ciencias de la Tierra, CSIC-UGR, Granada, Spain |
| |
Abstract: | Analysis was carried out of part of the northern North Sea to test what the presence and style of gas chimneys indicate about fluid pressure (Pf) within hydrocarbon reservoirs. Previous results suggest that broad chimneys above a trap and thin chimneys on the flanks indicate the presence of hydrocarbons, whilst thin chimneys in the crest suggest the hydrocarbons have escaped. Each type of gas chimney is usually associated with overpressure within Mesozoic reservoirs, but the water leg is hydrostatically-pressured in most Cenozoic reservoirs. This indicates: (a) gas leaking from a trap does not necessarily cause Pf to become hydrostatic; (b) overpressure may not be necessary for the expulsion of gasses through seal units to create the chimneys; (c) although gas chimneys indicate the existence of an active hydrocarbon system, their presence does not appear to indicate anything significant about present-day Pf. |
| |
Keywords: | Gas chimney Fluid pressure Overpressure Seal |
本文献已被 ScienceDirect 等数据库收录! |
|