Identification and monitoring of inter-layer crossflows using oil geochemical analysis by the example of Piltun-Astokhskoye field

UDK: 622.276.21.038:556.343

DOI: 10.24887/0028-2448-2025-5-108-113

Key words: oil geochemical analysis, gas chromatography, development object, inter-layer crossflows, dynamic reservoir model

Authors: D.V. Pavlov (SAKHALIN ENERGY LLC, RF, Yuzhno-Sakhalinsk); T.N. Gafarov (SAKHALIN ENERGY LLC, RF, Yuzhno-Sakhalinsk); R.G. Oblekov (SAKHALIN ENERGY LLC, RF, Yuzhno-Sakhalinsk); A.V. Khabarov (SAKHALIN ENERGY LLC, RF, Yuzhno-Sakhalinsk); S.A. Pesotsky (SAKHALIN ENERGY LLC, RF, Yuzhno-Sakhalinsk); N.V. Fedorov (SAKHALIN ENERGY LLC, RF, Yuzhno-Sakhalinsk); R.A. Lazarev (SAKHALIN ENERGY LLC, RF, Yuzhno-Sakhalinsk); I.N. Khaibrakhmanov (SAKHALIN ENERGY LLC, RF, Yuzhno-Sakhalinsk); A.S. Vasiliev (Lomonosov Moscow State University, RF, Moscow); Lee Chun San (SAKHALIN ENERGY LLC, RF, Yuzhno-Sakhalinsk)

There is often a need to combine reservoirs into a single development object during field development, especially in marine conditions with a limited well stock. This imposes additional requirements for well and reservoir surveillance and management using a set of methods, including production logging, hydrodynamic surveys, tracers, geochemical analysis and others. In case of a hydrodynamic connection between reservoirs, through geological bodies and boundaries, and in condition when a pressure drop occurs during development, interlayer crossflows may happen. This can complicate production allocation and remaining reserves localization, history matching of reservoir models and field development management. Identification and monitoring of inter-layer crossflows occurring in the interwell space are associated with certain difficulties in recording them using direct measurement methods, especially if the crossflow occurs within one phase (gas, oil or water). As a rule, indirect signs establish the fact of cross-flows such as atypical behavior of production wells, calculations of the material balance, history matching of dynamic reservoir models. This paper considers the method of identification and monitoring of inter-layer cross-flows using oil geochemical analysis, supplemented by other field surveillance and analytical data, by the example of the Piltun-Astokhskoye oil and gas condensate field. Geochemical analysis enables to determine the presence of oil from another layer in the production and quantifying its share in the well production.

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