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Optimal massive gas injection conditions for oil recovery enhancement by diffusion in fractured and heterogeneous reservoirs



The objective of this project is to provide the oil industry with guidelines to determine the optimum conditions, estimated on a technical/economic basis regarding the gas injection
pressure, to recover oil from either fractured or
heterogeneous reservoirs. More precisely, the ultimate goal of this project is to provide the oil industry with a
guideline for developing a gas injection process which,
knowing the reservoir characteristics (pressure,
heterogeneities, fracture distribution, fluid properties) will allow definition of the best operating conditions (maximum of oil produced at the lowest price). The purpose of the project is to determine a gas injection condition that optimizes
technically and economically the recovery factor of a
fractured/heterogeneous oil reservoir.

Technical Approach

High efficiency is evidenced when gas is injected under
immiscible conditions in thick reservoirs for which gravity
drainage operates, and when gas is injected under miscible or partially miscible conditions in fractured or heterogeneous
reservoirs under secondary or tertiary conditions. In such
reservoirs, the expected high efficiency should be due to
(1) mass transfer (diffusion) which occurs between the
injected gas and the oil trapped in the matrix blocks or the low permeability regions, and (2) capillary phenomena
(capillary pumping) which enhance the mobilization of the oil phase. An experimental, numerical and theoretical study of
flow mechanisms will be performed. For injection of a lean gas, the injection pressure, the mass transfer occurring by
vaporization and/or swelling between the injected gas and oil in place, and the reservoir characteristics constitute the
main parameters to be investigated in order to determine the optimal recovery efficiency. The study will involve the
following scales: interconnected pore scale, core scale and
reservoir scale. On both pore and core scale, experiments
will be conducted in order to assess the validity of the
modelling. A physically relevant upscaling technique will be proposed. Relevant physics developed at pore and core scale will be incorporated into a reservoir scale model to define
gas injection optimal conditions. The project will adopt a
multidisciplinary approach.

Expected Achievements and Exploitation

The deliverables of the project are the specification of:
- gas injection pressure efficiency (miscible conditions
versus immiscible conditions)
- the quality of injected gas (rich or lean gas),
- the influence of the reservoir heterogeneities,
- technical/economic conditions for optimal oil recovery.

This will be achieved by developing in three years a
comprehensive study, from pore scale to reservoir scale via
core scale, and by comparing theory with experiment at each

Funding Scheme

CSC - Cost-sharing contracts


18,Instituttveien 18
2027 Kjeller

Participants (3)

Institut Français du Pétrole
1&4,Avenue De Bois Préau
92500 Rueil-malmaison
Institut de Physique du Globe de Paris
4,Place Jussieu
75252 Paris
Aghia Paraskevi Attikis
15310 Athens