Water Production Analysis

[Chee Koh Peh]

Guys,

Need your advice please...

I am working on a project determining the likely source of water production in oil wells.

The reservoir has a weak to moderate waterdrive.

I intend to do this by (1) Individual well analysis (i.e. determine if there is coning / flow behind pipe etc..that is water production is a localized well issue) and (2) Reservoir analysis (i.e. look for a uniform rising OWC, pressure depletion etc..that is water production is a general reservoir production issue)

Fellow engineers can you see any weaknesses and/or other things I need to consider here..or any other methods I should use!

Thanks

CKP

[vinomarky]

If you captured the data, you can also look at salinity trends by well. If they are all consistent and stable, then it is not inconsistent with a field wide issue. If it's variable areally and/or with changes over time, then you are more likely to have some local issues.

It could, however, show nothing.... if indeed your different possible water sources have very similar salinities/Stiff plot characteristics..... but worth a look

[Chee Koh Peh]

Good Point! Appreciated....

CKP

[DAH7542]

I've read some articles about this (please check spe 84966 "A strategy for attacking excess water production" which is good), and based on my experience I recommend you to do this:

1. Determine whether water is a problem or not, i.e. before spending lots of time you'll need to distinguish between two types of water (classification given by some authors like Seright): 1. water production due to fractional flow which is water coproduced with oil in later stages of a waterflood for example, by reducing this particular water production you'll get less oil; and 2. Water competing directly with oil, e.g. water coning, high-perm streaks, flow behind casing, etc.... here is where you have to take actions and focus your water control study.
2. Global approach: In order to identify this type of water production (#2) you can use different tools, e.g. check wells that behave in a strange manner in WOR vs Np plots, make water cut maps (different periods of times) to see trends and strange behaviour, etc. This is a screening process where you'll have to select some wells to analyze in step #3, try to make a list in order of importance, for example, wells with significant remaining reserves should be first analyzed in the next step.
3. Detailed study or individual approach: once you have identified these "problem" wells you can conduct a detailed study on each of them to determine the reasons that produce their water production behaviour so different, here you can use Chan's plots (WOR and WOR derivative vs time), coning calculations, completion and workover history, detailed simulation... use whatever information you have at hand first.

Good luck....

[Chee Koh Peh]

Thanks, excellent input!

[LOST]

thanks