Injection fall-off test methods and interpretation

[indianoilman]

Whether anybody has observed effect of falling liquid level inside the well bore on the data recorded by downhole pressure gauge?

if yes, how to identify and interpret such effects?
if no such effects the why it is so...
i am pretty confused...
please comment.

[vinomarky]

This would be quite a common occurrence. The good news is that with BHP gauge you should be able to correct for it reasonably well. PTA simply look at the way a formation's pressure responds to transient production (or injection).

Now, you know what the pressure is at the wellbore (from the guage) - correct?

What about the flowrate; Shutin = zero flow right? Wrong - with a falling fluid level, the 'falling' fluid level is flowing into the formation. At what rate? Well, as long as you know what the casing pressure is at surface (I'm guessing zero), then you can calculate from the BHP what the fluid level is at any given time. From the casing/tubing capacities you should then be able to calculate the volumes and changing volumes with time which yields the after flow (or after injection) rate with time.

So, BHP - Casing Pressure = Fluid hydrostatic
Fluid Hydrostatic / Gradient = fluid height
Fluid height * Tubular capacity = fluid volume

Use your PTA software of choice, using the BHP you've recorded along with the injection rates, then from the time that you calculate the fluid level is dropping, add in a synthetic injection rate = to the change in annular volume over time

Not that difficult really, just think it through.

[indianoilman]

Thanx for the reply.......
My question is.... in case of injection fall-off study whether this falling liquid level can give response different than those without liquid level falling phenomenon..?

[Shakespear]

Have a look at this

[link Point to another website Only the registered members can access]

[link Point to another website Only the registered members can access]

[link Point to another website Only the registered members can access]

[indianoilman]

Have a look at this

[link Point to another website Only the registered members can access]

[link Point to another website Only the registered members can access]

[link Point to another website Only the registered members can access]

Many thanks Shakespeare