Abstract

An important step in the design development of carbonate reservoirs is the understanding and simulation of well flooding mechanism particularly water coning. The significance of coning is due to the fact that an incorrect account of the flooding mechanism may lead to the following negative consequences: overstatement of the target oil production inaccurate forecast of remaining reserves and the mechanism of their production, selection of unsuitable well-workover methods and other negative results.

The paper discusses different approaches to the water coning simulation: local grid refinement; non-neighbour connection with the bottom water; water flooding through a vertical fracture using method of allocating drains; use of additional completions; use of the non-diagonal permeability tensor; the verticallu directed change in rock permeability and pore volume with pressure decreasing; dual porosity model.

It is recommended that in case of the typical orthogonal grid, local grid refinement should be used for hydrodynamic model water coning. It is possible to obtain appropriate results using dual porosity method and non- neighbour connections, but these methods have bad forecasting power.

If water coning were not repeated then:

  • oil production total would increase up to 10-15% (for a 5 year forecast) or up to 5-35% (for a 25 year forecast);

  • water-free period well production would be prolonged;

  • oil production rate would increase.

The implementation of the recommendations made it possible to optimize new wells targeting and well operation, which provided an increase of water-free periods of the wells for the Urals-Volga region oilfields.

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