Well Program

[Malkara]

I mean by the well eveluation review of production data of the well in order to make a new production program. I wonder how I could eveluate the well and prepare a production program.

I was asked the eveluate a well that is at rest by the year 2000.

Data: Well depth:1166 m, has six perforations.... Also there was wax problem during production.

Sincerely yours...

 

[ppata]

Malkara,
I'm a reservoir engineer, and what I can tell you is to analise at the level of reservoir, otherwise you can generate a good production program for your well that can be bad for reservoir. Also, the production history of other wells on the same field can help.
I can be more specific if you'll detail your issue.

Best regards,
Andrei

 

[Malkara]

Thanks Andrei, first of all!

In fact, my job seems to be hard. This well is one of the two oil wells; the others are CO2 wells. Also, other oil well produced for a short time, in deed. The well, I must prepare a program, has a production history like : 13454 Bbl(in 1993 year, totaly), 12932 Bbl (in 1994), 12115 Bbl (1995), 8515 Bbl (1996), 5575 Bbl(1997), 3240 Bbl (1998), 2670 Bbl (199). And, I don't have exactly the data about how many days the well produced..

Also I must decide acid type to be used in the stimulation program. May be the most important question, will wax problem be rally a problem, after the well has started producing. At the moment I suppose pumping condensate in to the well will be a practical solution for wax problem!

Thanks....

 

[DrillerNic]

First I think you need to understand why the well declined... then you can do something about it! Assuming that the rates you've given us were gross rates (ie there was no water cut), possible reasons the well declined would include:

- wax/ ashphaltine in the tubing. Can you do a drift run on slickline to se if there is an obstruction? If there is, get a sample of the stuff in the tubing, analyse it and see if there's a solvent you can pump down the well (diesel usually works!)

- scale in the tubing (or even in the near wellbore region).... Unlikely if you were producing dry oil... Drift run again (scale is often deeper than wax, often near the perforations). Or if it could be scale in teh near wellbore region, do a welltest to measure the skin factor, hich should give you some idea if that's the problem. If it is scale, you're looking at a scale squeeze (and periodic treatments in the future to stop the problem from returning)

- Fill in the sump, obscuring the perforations...is there a sand control problem in the field? Were you producing any sand? Again, do a drift run, to see what the PBTD is, and see if it's different from the TD of the well when it was completed. If there is fill, see if you can get a sample of the fill with a dump bailer. The only real solution to fill is coil, I'm afraid, which is expensive (or lots and lots and lots and lots of dump bailer runs which is very very painful). And add sand control to future wells!

- Pressure decline in the reservoir...what's the drive mechanism? Maybe you've got a small drainage area...run an omega gauge and get an idea of the static BHP, and then compare that pressure with the original pressure. You might need some kind of pressure support from water injection wells or retrofit some kind of artificial lift.

- Problems with the reservoir- perhaps you've got a dual porosity or dual permeability system. Review all the reservoir evaluation data to see if this is the problem. Maybe do a well test to check? If so, start looking at acidising/ fraccing/ acid fraccing.

-cross flow in the reservoir...do you have different perforated intervals in the well? If this is la possible cause, ring up Schlum and do a spinner survey... then start looking at zonal isolation (straddles, plugs, even coil to cement squeeze and reperforate) and get your perforation strategy right on the next well!