The total compressibility of oil saturated formation 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 | and can be split into rock, water, oil componentsThe STOIIP can be written as: LaTeX Math Block |
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| cV_tO = c_r +V_o/B_o = s_{wi} c_w +o \, V_\phi = (1-s_{wi})c_o \, V_\phi |
The pore volume reduction due to offtakes is: LaTeX Math Block |
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| \delta V_\phi = Q_o \, B_o |
For low compressible oil, the total compressibility can be assumed constant and the pore volume reduction to due to offtakes 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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