Estimated Ultimate Recovery
EUR = \frac{Q_o}{V_o} = \frac{ (p_i - p_{wf \, min}) \, c_t}{(1-s_{wi})\, B_o} = \frac{ (p_i - p_{wf \, min}) }{(1-s_{wi})\, B_o} \, \big( c_r + s_{wi} c_w + (1-s_{wi})c_o \big) |
The definition of total compressibility
and can be split into rock, water, oil components:
For low compressible oil compressibility can be assumed constant and the volume reduction can be related to pressure decline as:
and
hence
and
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Motivation = maintain formation pressure at sweep interface
EUR = E_S \, E_D = E_{SV} \, E_{SH} \, E_D |
Total sweep | Areal sweep | Vertical sweep | |||
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– sweep volume – pore volume | – sweep area – pore area | – sweep thickness – pore thickness |
E_D = \frac{1-s_{wi}-s_{orw}}{1-s_{wi})} |
Motivation = maintain formation pressure at sweep interface with gas in case of high water mobility which makes watrflood inefficient
Motivation = maintain formation pressure at sweep interface with alternating inejction of water and gas in case of high residual oil to water sweep is high and gas sweep is less than to water sweep .
Motivation = maintain formation pressure at sweep interface with chemical injection and reduce residual oil to EOR sweep .
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