## How to Calculate and Solve for Semi-Log Pressure-Time Slope, Permeability-Thickness Product, Oil Rate, Oil FVF, Oil Viscosity in Well Testing | Nickzom Calculator

The image above represents semi-log pressure-time slope.

To compute for the semi-log pressure-time slope, four essential parameters are needed and these parameters are Permeability-Thickness Product (kh), Oil Rate (Qo), Oil Viscosity (μo) and Oil FVF (Bo).

The formula for calculating the semi-log pressure-time slope:

m = 162.6QoBoμo / kh

Where;

m = Semi-Log Pressure-Time Slope
kh = Permeability-Thickness Product
Qo = Oil Rate
μo = Oil Viscosity
Bo = Oil FVF

Let’s solve an example;
Find the semi-log pressure-time slope, when permeability-thickness product is 12, oil rate is 17, oil viscosity is 21 and oil FVF is 13.7.

This implies that;

kh = Permeability-Thickness Product = 12
Qo = Oil Rate = 17
μo = Oil Viscosity = 21
Bo = Oil FVF = 13.7

m = 162.6QoBoμo / kh
m = 162.6 x 17 x 13.7 x 21 / 12
m = 795260.34 / 12
m = 66271.69

Therefore, the semi-log pressure-time slope is 66271.69.

Calculating the Permeability-Thickness Product when Semi-Log Pressure-Time Slope, Oil Rate, Oil Viscosity and Oil FVF is Given.

kh = 162.6QoBoμo / m

Where;

kh = Permeability-Thickness Product
m = Semi-Log Pressure-Time Slope
Qo = Oil Rate
μo = Oil Viscosity
Bo = Oil FVF

Let’s solve an example;
Find the permeability-thickness product, when semi-log pressure-time slope is 90, oil rate is 23, oil viscosity is 27 and oil FVF is 14.

This implies that;

m = Semi-Log Pressure-Time Slope = 90
Qo = Oil Rate = 23
μo = Oil Viscosity = 27
Bo = Oil FVF = 14

kh = 162.6QoBoμo / m
kh = 162.6 x 23 x 14 x 27 / 90
kh = 1413644.4 / 90
kh = 15707.16

Therefore, the permeability-thickness product is 15707.16.

Calculating the Oil Rate when Semi-Log Pressure-Time Slope, Permeability-Thickness Product, Oil Viscosity and Oil FVF is Given.

Qo = m x kh / 162.6Boo

Where;

Qo = Oil Rate
m = Semi-Log Pressure-Time Slope
kh = Permeability-Thickness Product
μo = Oil Viscosity
Bo = Oil FVF

Let’s solve an example;
Find the oil rate when semi-log pressure-time slope is 110, permeability-thickness product is 42, oil viscosity is 31 and oil FVF is 11.

This implies that;

m = Semi-Log Pressure-Time Slope = 110
kh = Permeability-Thickness Product = 42
μo = Oil Viscosity = 31
Bo = Oil FVF = 11

Qo = m x kh / 162.6Boμo
Qo = 110 x 42 / 162.6 x 11 x 31
Qo = 4620 / 55446.6
Qo = 0.0833

Therefore, the oil rate is 0.0833.