Well Test 1

[john1964]

Hello all fellow engineers,
My problem has been the accuracy in well testing at the offshore location & this has resulted in problems with forecast's.
The oil producer via the test header is lined to a 2 phase separator & the outlets join each other ( Gas phase + oil & water) before exiting to the oil manifold. This increases the back pressure by around 20 psi which is not accounted for in the test.
Another problem i face is the water cut measurements.(for high water cut wells how do you measure the BS& W? Our guys have been using a measuring cylinder instead of a spinner.As the fluid cools down the volume change sets in. Also how do we compensate for the temperature changes.

Do we have any formula's or software for compensating the pressure increase & temperature changes????

Yet another one is the well test frequency & how long should the test be performed?? Like we do 4 hours test every week.

 

[DrillEng]

John,

Bottom line your Production or Reservoir Engineers need to answer this.
However as long as you have the test separator pressure and basic PVT analysis Pressure, GOR, expansion factor, Bo etc. you should be able to work everything out.

Not sure that I follow on your BSW readings. Yes they need a spinner and also as water is virtually incompressible at the temperatures you will be at (200 psi test separator ?) this should be so small as negligible.

As for software - PETEX (Petroleum Experts) have a good package that does just about everything around thsi (and a lot more).

 

[drillhouston]

John,

You can use the RedEye water-cut meter (Near Infra Red technology) to measure the BS&W in the liquid leg of the 2 phase separator. This meter has great accuracy in the higher water-cut range and works in the 0-100% water-cut range.

Now, you would also need a flow meter (turbine meter should be OK, if your separator works fine), as the water-cut is a flow-rate weighted quantity. This set-up should help you with better well-testing and production forecasts.

As for the Pressure (20 psi) and temperature effects on your test volumes, it should not be much. Hoe much difference are you seeing in your test volumes and real volumes?

8 hrs test once a week should be fine. If you are seeing big differences in the volumes, just have that well tested for continuously (4 tests) for 48 hours and look at the numbers you get.

Hari Aum