Deliverability by hand question

[soman703]

Hello everyone,

I have one very basic question.
I have been plotting deliverability plots by hand. I use cartesian plots by taking logs but I am unable to get exact answers.
Does 1/n slope change to n in cartesian plots?

Is equation also linear in cartesian like in log log scale?

Can I only calculate c,n, and AOF on Log log plots?

Thankyou,

[soman703]

On Cartesian the slope depends on the position and is not a fixed parameter.
Can anyone confirm this please?

[FANARCO]

soman,

Can you please post the plot that you generated for more illustration ....

[anindaghosh2207]

soman,

It depends what is your assignment of axes. If you assign y axes to flow rate and x axes to pressure difference then your slope will be n. In case of reverse you slope will be having slope of -1/n.

Since you are taking logs of all your value and then plotting on cartesian (which is perfectly alright) so while calculating C you have to take antilog.

In Excel there is limitation for calculating C,n and AOF in log log plot (If you use trendline approach it will give erroneous result). But the same problem can be bypassed taking logs of all the values and then plotting on cartesian scale.

[FANARCO]

Are you talking about isochronal test

[anindaghosh2207]

Yes.
But in case of Isochronal, Modified Isochronal and Flow After Flow the deliverability equation is same and that is Rawlins and Schellhadt equation. You can use this equation for hand calculation.
Houpert Equation is also there but it is exhaustive and hard to calculate by hand.

[FANARCO]

Yes.
But in case of Isochronal, Modified Isochronal and Flow After Flow the deliverability equation is same and that is Rawlins and Schellhadt equation. You can use this equation for hand calculation.
Houpert Equation is also there but it is exhaustive and hard to calculate by hand.