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APPROXIMATION OF SPONTANEOUS POTENTIAL LOGGING DIAGRAMS BY ANALYTICAL FUNCTIONS FOR RAPID DETERMINATION OF FORMATION WATER SALINITY

A. V. Glinskikh, M. I. Epov

Trofimuk Institute of Petroleum Geology and Geophysics SB RAS, Novosibirsk, Russia

An approach is proposed to determine the salinity of formation water by approximating diagrams of spontaneous potential logging (SP) by analytical functions. The method is based on the representation of SP diagrams in the form of a superposition of sigmoid functions. Their parameters are associated with the geoelectric parameters of the medium, and are also used to correct SP signals depending only on the salinity of formation water and the degree of the reservoir layer clay content. The clay content is taken into account by a method based on the assumption of a monotonous dependence of formation water salinity on the depth. The applicability analysis of some sigmoid functions to take into account a wide range of geoelectric conditions is carried out. The effectiveness of the proposed approach is shown on synthetic SP diagrams calculated using a numerical modeling algorithm, as well as on practical data of SP logging materials in the intervals of sandyclayey reservoirs in West Siberia.

Keywords: SP logging, approximation, sigmoid functions, salinity of formation water, West Siberia.

DOI 10.20403/2078-0575-2024-4a-46-55

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