Subsidence due to uniform pore pressure reduction in free surfaces

Input(s)

cm\mathrm{c}_{\mathrm{m}}: Formation Compaction per Unit Change in Pore Pressure Reduction (ft3/psi)\left(\mathrm{ft}^{3} / \mathrm{psi}\right)

vv: Poisson's (dimensionless)

r: Radius of Area Involved (ft)

D: Depth of Formation in Consideration ( ft\mathrm{ft} )

ΔPp\Delta \mathrm{P}_{\mathrm{p}}: Pore Pressure Change (psi)(\mathrm{psi})

V\mathrm{V}: Volume of Reservoir (ft3)\left(\mathrm{ft}^{3}\right)

Output(s)

uz\mathrm{u}_{\mathrm{z}}: Subsidence in Z\mathrm{Z} Direction (ft)(\mathrm{ft})

ur\mathrm{u}_{\mathrm{r}}: Subsidence Along R(ft)\mathrm{R}(\mathrm{ft})

Formula(s)

uz=(1)(cm(1v)DΔPp Vπ((r2)+(D2))1.5)ur=(cm(1v)rΔPp Vπ((r2)+(D2))1.5)\begin{gathered} \mathrm{u}_{\mathrm{z}}=(-1) *\left(\frac{\mathrm{c}_{\mathrm{m}} *(1-\mathrm{v}) * \mathrm{D} * \Delta \mathrm{P}_{\mathrm{p}} * \mathrm{~V}}{\pi *\left(\left(\mathrm{r}^{2}\right)+\left(\mathrm{D}^{2}\right)\right)^{1.5}}\right) \\ \mathrm{u}_{\mathrm{r}}=\left(\frac{\mathrm{c}_{\mathrm{m}} *(1-\mathrm{v}) * \mathrm{r} * \Delta \mathrm{P}_{\mathrm{p}} * \mathrm{~V}}{\pi *\left(\left(\mathrm{r}^{2}\right)+\left(\mathrm{D}^{2}\right)\right)^{1.5}}\right) \end{gathered}

Reference(s)

Mark D. Zoback, Reservoir Geomechanics, Cambridge University Press, UK, Page: 412.


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