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The definition of total compressibility | LaTeX Math Block |
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| c_t = \frac{1}{V_{\phi}} \frac{\partial V_{phi}}{\partial p} = c_r + s_{wi} c_w + (1-s_{wi})c_o \big |
and can be split into rock, water, oil components: | LaTeX Math Block |
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| c_t = c_r + s_{wi} c_w + (1-s_{wi})c_o \big |
For low compressible oil compressibility can be assumed constant and the volume reduction can be related to pressure decline as:| LaTeX Math Block |
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| \frac{\delta V_\phi}{V_\phi} = c_t \, \delta p = c_t \, (p_i - p_{wf \, min}) |
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| \delta V_\phi = Q_o \, B_o |
and | LaTeX Math Block |
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| V_o = s_o \, V_\phi = (1-s_{wi}) \, V_\phi |
hence | LaTeX Math Block |
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| \frac{Q_o \, B_o \, (1-s_{wi})}{V_o} = c_t \, (p_i - p_{wf \, min}) |
and | LaTeX Math Block |
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| EUR = \frac{Q_o}{V_o} = \frac{ (p_i - p_{wf \, min}) \, c_t}{(1-s_{wi})\, B_o} |
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Water flooding
Motivation = maintain formation pressure at sweep interface
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EUR = E_S \, E_D = E_{SV} \, E_{SH} \, E_D |
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| LaTeX Math Block |
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E_D = \frac{1-s_{wi}-s_{or}}{1-s){wi}} |
Gas flooding
Motivation = maintain formation pressure at sweep interface with gas in case of high water mobility
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| body | \frac{k_{rw}}{\mu_w} \gg \frac{k_{ro}}{\mu_o} |
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which makes watrflood inefficient
WAG flooding
Water and gas flodding.
Motivation = increas displacement as residual oil saturation to gas 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
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Chemical EOR
Motivation = maintain formation pressure at sweep interface with chemical injection and reduce residual oil to EOR sweep
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| body | s_{or \, eor} < s_{orw} |
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.CО2 injection
Reference
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