The image above represents radius of investigation.

To compute for the radius of investigation, five essential parameters are needed and these **parameters are permeability (k), porosity (φ), viscosity (μ), time (t) and total compressibility (C _{T}).**

The formula for calculating the radius of investigation:

r_{inv} = 0.0325 √[^{Kt }/ _{φμCT}]

Where:

r_{inv} = Radius of Investigation

K = Permeability

φ = Porosity

μ = Viscosity

t = Time

C_{T} = Total Compressibility

Let’s solve an example;

Find the radius of investigation when the permeability is 25, porosity is 18, viscosity is 12, time is 22 and total compressibility is 37.

This implies that;

K = Permeability = 25

φ = Porosity =18

μ = Viscosity = 12

t = Time = 22

C_{T} = Total Compressibility = 37

r_{inv} = 0.0325 √[^{Kt }/ _{φμCT}]

r_{inv} = 0.0325 √[^{25 x 22 }/ _{18 x 12 x 37}]

r_{inv} = 0.0325 √[^{25 x 22 }/ _{7992}]

r_{inv} = 0.0325 √[^{550 }/ _{7992}]

r_{inv} = 0.0325 √[0.068]

r_{inv} = 0.0325 [0.26]

r_{inv} = 0.0085

Therefore, the **radius of investigation **is **0.0085 ft.**

Nickzom Calculator – **The Calculator Encyclopedia** is capable of calculating the radius of investigation.

To get the answer and workings of the radius of investigation 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 **Radius of Investigation**** **under **Well Testing**

The screenshot below displays the page or activity to enter your value, to get the answer for the radius of investigation according to the respective parameter which are the **permeability (k), porosity (φ), ****viscosity (μ), time (t) and total compressibility (C _{T}).**

Now, enter the value appropriately and accordingly for the parameter as required by the **permeability (k)** is **25,**** porosity (φ)** is **18**, **viscosity (μ)** is **12**,** time (t)** is **22**** and total compressibility (C _{T})** is

**37**.

Finally, Click on Calculate

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