Permeability and reservoir pressure from buildup tests

Input(s)

\(\mathrm{t}_{\mathrm{p}}\): Time till which drawdown was done (h)

\(d t_{a}\): Time of shut in 1 from given values or trendline (h)

\(d t_{b}\): Time of shut in 2 from given values or trendline (h)

\(p w s_{a}\): Well flowing Pressure at shut in point 2 from given values or trendline (psi)

\(p w s_{b}\): Well flowing Pressure at shut in point 1 from given values or trendline (psi)

\(\mathrm{h}\): Thickness of Reservoir (ft)

\(\mu\): Viscosity of Oil \((\mathrm{cP})\)

\(\mathrm{p}_{\mathrm{hr}}\): Pressure at \(t=1 \mathrm{~h}(\mathrm{psi})\)

\(\mathrm{p}_{\mathrm{wf}}\): Pressure flowing well \((\mathrm{psi})\)

Ø: Porosity (fraction)

\(c_{t}\): Compressibility \((1 / \mathrm{psi})\)

\(r_{w}\): Wellbore Radius (ft)

Output(s)

s: Skin Factor (dimensionless)

Formula(s)

\[ s=1.151 *\left((p h r-p w f)-\log \left(\frac{\frac{p w s_a-p w s_b}{\log \left(\frac{t p+d t_b}{d t_b}\right)-\log \left(\frac{t p+d t_a}{d t_a}\right)}}{\emptyset * \mu * c_t * r_w^2}\right)+3.23\right) \]

Reference(s)

Pressure Buildup and Flow Tests in Wells, Matthews & Russell, Page: 21.

Permeability and reservoir pressure from buildup tests

Input(s)

Output(s)

Formula(s)

Reference(s)

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