Application of geoelectrochemical method for exploration of petroleum fields on the Arctic shelf

Abstract

Exploration of oil fields on the shelf is carried out by geophysical prospecting, mainly by seismic surveys, for identifying promising petroleum accumulation traps, with knowledge about also the petroleum system of the region. As a rule, geophysical prospecting is an indirect method and does not provide information on the material composition of target objects. For predicting the presence or absence of reservoirs in anticline onshore structures, geoelectrochemical techniques of studying the jet dispersion halos are applied. Ground geoelectrochemical exploration studies the concentration of active (movable) and secondary stable (fixed) forms of heavy metals. Waters, surrounding petroleum, are enriched by of heavy metals and their ions. Jet dispersion halos with high content of heavy metals can be scattered from the depths of oil-and-gas pools along the subsurface through the semi-porous rocks and water layers. The method of ion-selective electrodes presented in the paper allows to detect anomalies of heavy metals concentrations associated with petroleum content in the water layer. This paper experimentally shows the content of “jet” dispersion halos of such metals in the offshore water layers in oil and gas fields, associated with deeply located sources. The equipment and principles of ion-selective electrodes method for identification of these halos have been developed, and application of the new geoelectrochemical technique for prospecting both structured and unstructured oil deposits have been tested. This technique may have optimum effect when combined with other geophysical methods (seismics and electrical survey techniques).