The invaded zone in producing beds |
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| Abstract: | The results of the invaded-zone investigation described in this article revealed that in the producing beds the zone ccnsists of 2 parts-- a part adjoining the wall of the well (which contains considerable amount of filtrate), and a more remote part in which capillary replacement of rock fluids by the filtrate was observed. In the producing beds, the latter part of the invaded zone had a high oil-gas saturation; this phenomenon was related to the spread of the filtrate over the layer as the result of capillary displacement and to the difference in the densities of filtrate, oil and gas. At a high gas-oil saturation of the invaded zone, the producing layers can be separated on the neutron-gamma logs or on electrical logs registered with small size sondes. It was not always possible to evaluate maximum yield of a producing bed according to the residual oil-gas saturation. In order to improve the technique of porosity evaluation or of the evaluation of the residual gas saturation coefficient, according to the geophysical parameters of the invaded zone, it was necessary to account for the nature of filtrate penetration into the producing layers. -- Petroleum Abstracts. |
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