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 (Q _{o}), Oil Viscosity (μ_{o}) **and

**Oil FVF (B**

_{o}).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

Q_{o} = Oil Rate

μ_{o} = Oil Viscosity

B_{o} = 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

Q_{o} = Oil Rate = 17

μ_{o} = Oil Viscosity = 21

B_{o} = 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

Q_{o} = Oil Rate

μ_{o} = Oil Viscosity

B_{o} = 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

Q_{o} = Oil Rate = 23

μ_{o} = Oil Viscosity = 27

B_{o} = 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.**

Q_{o} = ^{m x kh} / _{162.6Boo}

Where;

Q_{o} = Oil Rate

m = Semi-Log Pressure-Time Slope

kh = Permeability-Thickness Product

μ_{o} = Oil Viscosity

B_{o} = 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

μ_{o} = Oil Viscosity = 31

B_{o} = Oil FVF = 11

Q_{o} = ^{m x kh} / _{162.6Boμo}

Q_{o} = ^{110 x 42} / _{162.6 x 11 x 31}

Q_{o} = ^{4620} / _{55446.6}

Q_{o} = 0.0833

Therefore, the **oil rate **is **0.0833.**

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

μ_{o} = ^{m x kh} / _{162.6BoQo}

Where;

μ_{o} = Oil Viscosity

m = Semi-Log Pressure-Time Slope

kh = Permeability-Thickness Product

Q_{o} = Oil Rate

B_{o} = Oil FVF

Let’s solve an example;

Find the oil viscosity when semi-log pressure-time slope is 80, permeability-thickness product is 41, oil rate is 50 and oil FVF is 30.

This implies that;

m = Semi-Log Pressure-Time Slope = 80

kh = Permeability-Thickness Product = 41

Q_{o} = Oil Rate = 50

B_{o} = Oil FVF = 30

μ_{o} = ^{m x kh} / _{162.6BoQo}

μ_{o} = ^{80 x 41} / _{162.6 x 30 x 50}

μ_{o} = ^{3280} / _{243900}

μ_{o} = 0.0134

Therefore, the **oil viscosity **is **0.0134.**

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

B_{o} = ^{m x kh} / _{162.6μoQo}

Where;

B_{o} = Oil FVF

m = Semi-Log Pressure-Time Slope

kh = Permeability-Thickness Product

Q_{o} = Oil Rate

μ_{o} = Oil Viscosity

Let’s solve an example;

Find the oil FVF when semi-log pressure-time slope is 40, permeability-thickness product is 26, oil rate is 12 and oil viscosity is 10.

This implies that;

m = Semi-Log Pressure-Time Slope = 40

kh = Permeability-Thickness Product = 26

Q_{o} = Oil Rate = 12

μ_{o} = Oil Viscosity = 10

B_{o} = ^{m x kh} / _{162.6μoQo}

B_{o} = ^{40 x 26} / _{162.6 x 10 x 12}

B_{o} = ^{1040} / _{19512}

B_{o} = 0.0533

Therefore, the **oil FVF **is **0.0533.**

Nickzom Calculator – **The Calculator Encyclopedia** is capable of calculating the semi-log pressure-time slope.

To get the answer and workings of the semi-log pressure-time slope using the **Nickzom Calculator – The Calculator Encyclopedia. **First, you need to obtain the app.

You can get this app via any of these means:

**Web** – https://www.nickzom.org/calculator-plus

To get access to the **professional **version via web, you need to **register** and **subscribe **for** NGN 1,500 **per** annum** to have utter access to all functionalities.

You can also try the **demo **version via https://www.nickzom.org/calculator

**Android (Paid)** – https://play.google.com/store/apps/details?id=org.nickzom.nickzomcalculator

**Android (Free)** – https://play.google.com/store/apps/details?id=com.nickzom.nickzomcalculator

**Apple (Paid)** – https://itunes.apple.com/us/app/nickzom-calculator/id1331162702?mt=8

Once, you have obtained the calculator encyclopedia app, proceed to the **Calculator Map, **then click on **Petroleum **under **Engineering**

Now, Click on **Well Testing**** **under **Petroleum**

Now, Click on **Semi-Log Pressure-Time Slope**** **under **Well Testing**

The screenshot below displays the page or activity to enter your values, to get the answer for the semi-log pressure-time slope according to the respective parameters which are the **Permeability-Thickness Product (kh), Oil Rate (Q _{o}), Oil Viscosity (μ_{o}) **and

**Oil FVF (B**

_{o}).Now, enter the values appropriately and accordingly for the parameters as required by the **Permeability-Thickness Product (kh)** is **12**,** Oil Rate (Q _{o})** is

**17**,

**Oil Viscosity (μ**is

_{o})**13.7**and

**Oil FVF (B**is

_{o})**21**.

Finally, Click on Calculate

As you can see from the screenshot above, **Nickzom Calculator**– The Calculator Encyclopedia solves for the semi-log pressure-time slope and presents the formula, workings and steps too.