Abstract:
The hydrothermaily worked reservoir rocks have predominantly vertical zoning. Up section through each of the highly permeable members, one observes a complication of the clastic component of the rock. Highly variable wettability of the void surfaces is typical of the very permeable reservoir rock, and is in very large measure uncharacteristic of the rocks in the transition zone. The vertical zoning of the hydrothermally altered rocks contradicts the idea of a direct relationship of the hydrothermal working of the sandstones under consideration to dynamically stressed zones. The transition zone can be regarded as the region where metasomatism associated with hydrothermal processes developed. The stable hydrophobic character of the rocks in the transition zone, and also the presence within it of signs of residual oil-saturation, may with further research shed light on the order in which the above-described oil traps were filled.