Achieving plateau production from a reservoir sim. model with solution gas drive

[devmantic]

Hello All,

I am having some challenges with my master thesis which is related to production optimization. I am trying to get a semi-synthetic reservoir model with 8 years of history operating under solution-gas drive with already implemented voidage replacement (waterflooding) to produce oil at its plateau for an extended period of time. I have tried manipulating the production targets (e,g BHP of producer while subjecting them to BHP-controlled) but it really did not help on the long run. So I wanna know - What production parameters with a high degree of uncertainty are primary drivers that influence oil production rate... Thanks as i await response from geniuses in the house

PS: I had to post this else I risk being banned by the admin

[DAH7542]

I'm not sure of understanding your current situation, I think is one of these two options but I don't know which one it is:

1) Are you trying to history match those 8 years and your question is intended to know what parameters should be modified to get the oil rate matched?, or,
2) Are you running prediction scenarios based on a history matched model so your question is how to control your prediction in order to reproduce an oil rate plateau?

If it's (1), my advice when it comes to history matching is to follow Mattax and Dalton (SPE monoghaph) suggestion in which those reservoir/aquifer parameters appropiate for alteration in first place are the most uncertain; you'll need to have also a good/overall understanding of the reservoir mechanics based on previous analytical studies such as material balance, or valuable tools such as well correlations, etc.

If it's (2), and assuming you have your wells calibrated (i.e. well's BHP matched for the last 3 to 6 months prior to the end of history), you'll need to control your predictions based on existing or expected production/injection constraints, i.e. pump deliveravilities, fluid handling limits of surface facilities, maximum injection pressures, so on and so forth. The idea is not to achieve "any" plateau (to make someone happy) but to predict a reliable forecast. And at the end, if the wells in your model predict a production plateau is due to your constraint definition (e.g. producers reaching maximum liquid rate constraint or injectors (replacement) at maximum BHP), which is somewhat expected in the oil industry since surface facilities are designed based on plateau productions and not maximum pick productions.

[devmantic]

@ DAH7542,

Thanks for your suggestions. Situation 2 is very much similar to my current situation with the exception of history-matched models. History matching is not an integral part of my work and was not really taken into consideration. The field has a history period of 8 years. I intend to optimize FOPT in prediction mode such that I get a plateau production rate for a period of time before a final decline. As suggested, i have manipulated the injectors' and producers' BHP and RATE. This lead to an increment in FOPT but I was unable to achieve the plateau production in prediction mode. The producers are by default controlled by LRAT - and i am guessing this is the amount of volume the surface facilities can handle. The model has no vertical lift performance data (no VFPDIMS, VFPINJ nor VFPPROD). I have also tried using WELTARG to manipulate targets to get the desired plateau production in the prediction phase but to no avail. What would you suggest i do? Thanks in anticipation of your expert advice....

[devmantic]

@DAH7542,

First and foremost, I will start by appreciating your timely response to my question. Situation 2 is very much similar to what I am experiencing with the exception of an history matching. History matching is not an integral part of my work. Like I said earlier, the reservoir drive mechanism is of solution gas drive type. Most of the oil has been produced within the history period of the reservoir (the buildup and plateau period ran for entirely 900days before the decline phase started. I decided to check if it is possible to achieve plateau oil production rate in the prediction phase by manipulating the injectors and producers BHP and RATE as well as control mode. So far, this has not helped much as the reservoir production rate keeps declining. What would you suggest I do? Thanks as i await your response and those of other geniuses in the forum..