Neutron count in time interval $\begin{array}{l}\tau = [\tau_1, \, \tau_2]\end{array}$

Neutron Porosity

(1)	$\begin{array}{l}\displaystyle N_{near}[\tau] = \int_{\tau_1}^{\tau_2} N_{near}(t) dt\end{array}$

(2)	$\begin{array}{l}\displaystyle N_{far}[\tau] = \int_{\tau_1}^{\tau_2} N_{far}(t) dt\end{array}$

(3)	$\begin{array}{l}\displaystyle N2F = \frac{ N_{near}[\tau]}{N_{far}[\tau]}\end{array}$

Diffusion Correction

(4)	$\begin{array}{l}\displaystyle \phi_T = N2F[\tau] + \Delta_{\tau}(\phi_N)\end{array}$

Neutron Sigma

(5)	$\begin{array}{l}\displaystyle N_{near}(t) = N_{near}(0) \exp ( - t \, \Sigma_{near} )\end{array}$

(6)	$\begin{array}{l}\displaystyle N_{far}(t) = N_{far}(0) \exp ( - t \, \Sigma_{far} )\end{array}$

Diffusion Correction

(7)	$\begin{array}{l}\displaystyle \Sigma_{near} = \Sigma_{frm} + \Delta_{near}(\phi)\end{array}$

(8)	$\begin{array}{l}\displaystyle \Sigma_{far} = \Sigma_{frm} + \Delta_{far}(\phi)\end{array}$

(9)	$\begin{array}{l}\displaystyle \Sigma_{frm} = (1-\phi) \, \Sigma_m + \phi \, ( \Sigma_w \, s_w + \Sigma_o \, s_o +\Sigma_g \, s_g)\end{array}$

(10)	$\begin{array}{l}\displaystyle \delta \Sigma_{frm} \approx +/-1.5 c.u.\end{array}$

(11)	$\begin{array}{l}\displaystyle \Sigma_m = \sum_k \Sigma_k\end{array}$

(12)	$\begin{array}{l}\displaystyle \Sigma_o \approx 18 \quad 11 < \Sigma_o < 21\end{array}$

(13)	$\begin{array}{l}\displaystyle \Sigma_w = 21 + 0.05 * Sal[\rm ppk]\end{array}$

(14)	$\begin{array}{l}\displaystyle \Sigma_g \approx 3\end{array}$

(15)	$\begin{array}{l}\displaystyle \Sigma_{sh} \approx 40 \, c.u.\end{array}$

(16)	$\begin{array}{l}\displaystyle \Sigma_{ls} \approx 7 \, c.u.\end{array}$

In case of two-component sandstone-shale model:

(17)	$\begin{array}{l}\displaystyle \Sigma_m = (1-V_{sh}) \, \Sigma_{snd} + V_{sh} \, \Sigma_{sh}\end{array}$

In case of two-component limestone-shale model:

(18)	$\begin{array}{l}\displaystyle \Sigma_m = (1-V_{sh}) \, \Sigma_{lms} + V_{sh} \, \Sigma_{sh}\end{array}$

TSCN, TSCF, NPHI, SIGMA