Improving efficiency of oil recovery and finding a source of watering in multi-zone deposits by geochemical methods of research

Abstract

One of the strategic ways in the development of multilayer fields is to identify the source of water inflow into the well production and, as a result, to eliminate it with subsequent optimization of the production of non-watered formations. A method for assessing the degree of water cut in formations based on the quantitative characteristics of the composition of the produced water is proposed in this article. The study of a wide collection of produced water samples made it possible to trace the change in its geochemical composition depending on the age of formation of the reservoir in the Volga-Ural region.The microelements and macro element composition of water, as well as its isotopic composition were investigated. The water of different layers differs in some of the elements, which are called «key elements». Using the methods of mathematical statistics at 2 reservoir objects operated by a common filter, the incoming water was divided into fractions depending on the geochemical composition. It is shown which of the layers has more water out. The feasibility of carrying out these geochemical studies was confirmed by blocking one of the production wells operating in 2 layers, the most watered interval according to geochemical studies, as a result of which the water cut of the well production decreased from an average of 75% to 4% and is observed for several months, the oil production rate increased from 1–2 t/day to 2.5–3 t/day and remains at a constant level.

Keywords

• chemical composition of water; isotope study; geochemistry of formation systems; improvement of oil field development; hydrogeology of petroleum engineering