The above image represents the reservoir fluid.

To compute for the reservoir fluid, two essential parameters are needed and these parameters are **External pressure (P _{e}) **and

**Flowing Bottom-Hole Pressure (P**.

_{wf})The formula for calculating the average pressure of the reservoir fluid:

P^{*} = √[^{Pe² + Pwf²} / _{2}]

Where;

P^{*} = Average Pressure

P_{e} = External Pressure

P_{wf} = Flowing Bottom-Hole Pressure

Let’s solve an example;

Find the average pressure of a reservoir fluid with an external pressure of 19 and Flowing bottom-hole pressure is 15.

This implies that;

P_{e} = External Pressure = 19

P_{wf} = Flowing Bottom-Hole Pressure = 15

P^{*} = √[^{Pe² + Pwf²} / _{2}]

P^{*} = √[^{19² + 15²} / _{2}]

P^{*} = √[^{361 + 225} / _{2}]

P^{*} = √[^{586} / _{2}]

P^{*} = √[293]

P^{*} = 17.117

Therefore, the **average pressure** is **17.117 psi;.**

**Calculating the External Pressure when the Average Pressure and the Flowing Button-Hole Pressure is Given.**

P_{e} = √[[P^{*} x 2]² – P_{wf}²]

Where;

P_{e} = External Pressure

P^{*} = Average Pressure

P_{wf} = Flowing Bottom-Hole Pressure

Let’s solve an example;

Find the external pressure of a reservoir fluid with an average pressure of 24 and Flowing bottom-hole pressure is 16.

This implies that;

P^{*} = Average Pressure = 24

P_{wf} = Flowing Bottom-Hole Pressure = 16

P_{e} = √[[P^{*} x 2]² – P_{wf}²]

P_{e} = √[[24 x 2]² – 16²]

P_{e} = √[2048]

P_{e} = 45.25

Therefore, the **external pressure **is **45.25****.**

**Calculating the Flowing Button-Hole Pressure when the Average Pressure and the External Pressure is Given.**

P_{wf} = √[[P^{*} x 2]² – P_{e}²]

Where;

P_{wf} = Flowing Bottom-Hole Pressure

P_{e} = External Pressure

P^{*} = Average Pressure

Let’s solve an example;

Find the Flowing bottom-hole pressure of a reservoir fluid with an average pressure of 34 and external pressure is 17.

This implies that;

P^{*} = Average Pressure = 34

P_{e} = External Pressure = 17

P_{wf} = √[[P^{*} x 2]² – P_{e}²]

P_{wf} = √[[34 x 2]² – 17²]

P_{wf} = √[4624 – 289]

P_{wf} = √[4335]

P_{wf} = 65.84

Therefore, the **flowing button-hole pressure **is **65.84.**

Nickzom Calculator – **The Calculator Encyclopedia** is capable of calculating the average pressure.

To get the answer and workings of the average pressure 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 **Reservoir Fluid Flow **under **Petroleum**

Now, Click on **Average Pressure**** **under **Reservoir Fluid Flow**

The screenshot below displays the page or activity to enter your value, to get the answer for the average pressure according to the respective parameter which are the **External pressure (P _{e}) **and

**Flowing Bottom-Hole Pressure (P**.

_{wf})Now, enter the value appropriately and accordingly for the parameter as required by the **External pressure (P _{e}) **is

**19**and

**Flowing Bottom-Hole Pressure (P**is

_{wf})**15.**

Finally, Click on Calculate

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