Abstract

The Vankor oil field is one of the largest oil fields in the world that was put into production recently. Main reserves are situated in the two thin productive layers. Each of them has active aquifer and huge gas cap. Wells with horizontal section of 1 km are used. Due to high reservoir heterogeneity and variation in permeability, inflow to the horizontal well is not uniform. As a consequence, recoverable reserves are various in different parts of the same well. Development of the approach to selection the best well completion system, its implementation and control were main purposes of this investigation.

The first stage of this investigation includes preliminary estimation of appropriate well completions before field development starts. An NPV criterion is used for comparison. Very limited field data were available on this step. An approximate model and special decision-making procedures were used. According to this estimation the use of ICD in some wells helps in managing inflow profile efficiently.

One of the main issues consists in a forecast of flow profile to a horizontal well. In this research we used LWD data as a source of online information about rock properties distribution in the horizontal section. PLT data were used to select an appropriate inflow model. On this stage, an approximate model was developed and validated using surface measurements of multiphase flow, horizontal part flow and pressure distribution. This model includes reservoir, ICD, horizontal section, inclined wellbore and surface choke.

Last, a design of a completion system (the sand screen with ICD) was made. Different cases were compared using the sector hydrodynamic model. Oil, water and gas flow profiles in the horizontal part at different times were used to select a choke level and swellable packer's positions. So the optimal completion design in terms of cumulative oil, water and gas production from well was selected and installed in the number of the Vankor wells.

In short this paper presents new system approach to the selection of a completion system. Appropriate numerical models (approximate, sector hydrodynamic) are used on each step depending on the available information and its confidence level. This method is used in some typical wells of the Vankor field.

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