4 Linear Interpolations... I think.

Here are 4 tables of iterated values for bottom hole pressures in CO2 injection wells. I’d like to be able to input a Surface Pressure (Psurf), TD (total depth), average fluid temperature Tavg, and CO2% and have excel go find the best approximation of the bottom hole pressure from the tables. Basically it needs to do 4 interpolations. I am totally stumped. Any help at all would be much appreciated.

Thanks

John

That is helpful, but not exactly what I wanted.

What I would like to be able to do is say something like: Psurf= 2063 pis, TD=4962, CO2 cut=99.34%, and Temp=84 degrees. And have excel approximate that bottom hole pressure. That's where the interpolation comes in

My first thought: Are you married to Excel? IMO, this would be easier in QuattroPro because it has a built in 2D linear interpolation function, which makes each intermediate interpolation easier. I got a rough quattro pro spreadsheet for this put together, but the forum won't let me upload it (and they just might ban me for trying, who knows ).

The strategy I used though goes something like this:
1) Input surface pressure. Interpolate each column of data at that surface pressure. Now you should get one row from each of the four tables
2) Input TD. Interpolate z against TD from the tables obtained in 1. Now you have 1 table with hole pressure at different CO2 compositions, at all the Tave.
3) Input CO2 fraction: Interpolate all the Tave columns against CO2
4) Fiinal interpolation to get hole pressure at the desire Tave.

Originally Posted by shg

This interpolates each of the four tables (using a UDF -- you'll need to enable macros), and then calculates a weight for each value.

This is awesome. IS there a website or book where I can learn how to do this? Thank you so much!

Thanks for the tip, however I do not have access to QuattroPro. I will ask around my office and see if anyone has it installed on their computer. Thanks

build user defined functions and write VBA macros to solve a spreadsheet like this one.