The paper reflects problems of gas-condensate recovery for the low permeable sands based on laboratory and analytical PVT analysis and 3D modeling approaches.
Gas-condensate recovery factor (CRF) for the gas-condensate fields depends a lot on initial CGR, filtration properties of the reservoir, well spacing and completion, development plan, economical indexes and final (abandoned) reservoir pressure. High CGR content specific for deep and low permeable zones already determine low gas-condensate recovery factor. On other hand, low permeability leads to deep pressure drawdowns and uneven pressure distribution and trigger earlier and bigger condensate losses in the formation.
CRF official approval according to the current Russian regulations is based on the PVT laboratory or analytical data for 100% gas recovery or 1 bar abandoning formation pressure without taking into account reservoir parameters and system of development. At such pressure conditions and without reservoir properties the ultimate approved condensate recovery factors is too high (over 60%) due to evaporation of liquid condensate below the cricondenbara pressure and neglecting condensate drop out around well bore and in the low pressure formation areas. Due to mentioned above factors the actual ultimate CRF is much less than the approved ones that leads to the losses of economical effectiveness of field development.
The paper reflects the problems of gas-condensate recovery for the low permeable reservoirs and the way how to improve it by implementing a gas cycling process for one of the Western Siberian fields with high initial CGR. The main conclusion is made to use 3D modeling for the correct forecast of the ultimate condensate recovery factors and justification of optimal methods to enhance it.