VBA code to interpolate values between two worksheets

[brandon20]

Hi,

I have a question that is kinda complected. But can definitely be done in VBA.

I have data that gives a well name and a depth in one worksheet, and I have other data that gives a well name and a depth in the other worksheet.

The second worksheet has Surfaces associated with its depths. The first worksheet has pressures associated with its depths.
The pressure depths are rarely exactly equal to the well top depths but the pressure depths always fall within the interval of the shallower surface to the deeper surface.

What I need is to fill a column with the Surface name associated with its pressure depth. (ie, if a specific wells pressure falls within that wells surface interval I need that pressure to have the name of the shallower surface.)

As seen below it is a little easier to understand. The first excel sheet is the well, MD, and Surface. The second sheet is the Well, MD, Pressure, (THEN it has a surface column which I filled in two surfaces that would show up if the VBA code ran.) As you can see, Z51CH is at a depth of 9220 in the second worksheet, this is because that depth falls between Z51CH (9204.9) and Z51 (9232.9).

Well	MD	Surface
RA-0074	9204.9	Z51CH
RA-0074	9232.9	Z51
RA-0074	9237.3	Z48CH
RA-0074	9250.93	Z48
RA-0074	9313.2	Z46CH
RA-0074	9415.6	Z46

<tbody>
</tbody>

Well identifier	MD	FPRESS	SURFACE
RA-0074	8953	4185.8
RA-0074	9000	4220
RA-0074	9028	4245
RA-0074	9110	4292
RA-0074	9165	4244.7
RA-0074	9166	4244.6
RA-0074	9182	4220.4
RA-0074	9220	4238.1	Z51CH
RA-0074	9350	4270.5	Z46CH
RA-0074	9447	4312
RA-0074	9539	4352
RA-0074	9570	4372.8
RA-0074	9641	4539
RA-0074	9666	4834

<tbody>
</tbody>