How to predict Liquid Rate and Water Cut versus time

[Nasution]

Is there any publised method to predict liquid production
and water cut progression with time ?

Anyone, please help

Thanks and Regards

Nasution

 

[dhayes]

If you have historic production data, you can use a plot of log water/oil ratio (WOR) vs linear cumulative oil production plot to forecast the future WOR as a function of cumulative oil production. There is some theoretical basis for this approach, based on relative permability effects and displacement of oil by water. Also, this technique is usually only applicable when the water cut (% water) is over 80%. I would suggest that you search the literature and I would suggest

http://www.spe.org

as a good place to locate technical papers on this topic. I do not recommend using a plot of log water cut vs cumulative oil, as I have sometimes seen done. Water cut has to approach 100% assymptotically and therefore the projection is inaccurate at higher water cuts. There are also some special plots that can be generated, based on theoretical multiphase flow effects, which do basically the same thing.
Once you have the log WOR vs cum oil relationship, you can use decline curve analysis to forecast future rates. Assuming an economic limit WOR allows you to predict a cumulative oil produced to that economic limit. Of course, all of this is easier said than done. This is a quick and dirty approach, but is common for petroleum engineers to use as a tool. You really need to understand the reservoir and try to understand the source of the water. Is the reservoir relatively homogenous or is it fractured or have high permeability streaks? Is the water influx from the bottom or the edge? Is the water due to a coning of water? Of course the best approach is to build a reservoir model and try to match historic production and pressures to get a handle on what might be expected.