INVESTIGATION OF CHARACTERISTICS OF THE EFFECT OF ANOMALY HIGH PORE PRESSURE ON CLAY LAYERS OF OIL AND GAS FIELDS

Abstract

The physical properties of clayey formations in oil and gas fields, as well as their electrical resistivity, change dramatically in intervals with abnormally high pore pressure. As a result of the research, it can be concluded that when clays containing water and closed porosity (especially clay thickness) are loaded under high pressure, a certain change occurs in their structure, which is reflected in its petrophysical parameters, as well as electrical resistivities. A comparative analysis of well materials from a number of deposits (Bulla-Deniz, Sangechal-Deniz, Bakhar, Karabagly, etc.) shows that this change is gradual in the upper layers and intense in the depth range of 5000-6800 m. The electrical resistivity of clays in the indicated skins is 0. 3-7.0 Ohm.m, and in some wells it even increases to 1.0-12.0 Ohm.m. After a depth of 6800-7000 m, clayey rocks are gradually freed from the effects of HIGH pressure pressure and are subjected predominantly to geostatic pressure. In this case, clay can transform into other petrophysical rocks, such as mudstones. Under such conditions, the HIGH pressure pressure weakens and it becomes impossible to form and maintain it at depths of 7500-8000 m or more.