production profile- reservoir model and well decline profile in excel.

**vinomarky** · 08-19-2010, 08:29 AM

1. This is related to the richness of the gas in heavy ends - its not something you can calculate from properties such as viscosity (although I'm sure there is some relationship). You really need to have some understanding on how rich or lean the gas is likely to be
2. Using wellhead abandonment pressure, and correcting back to the sandface pressure taking into account friction and head is an appropriate way of dealing with this
3. If you need to be able to incorporate number of wells required and timing etc, then you need to step up the complexity of your model. The number of wells required is related to not only individual well deliverabilities, but also structure size and continuity. The simple rate potential equation is suitable if you are modeling the field as a tank with one (set of) offtake(s).

General (simple) equation for well deliverability is rate = C(Pr^2 - Pwf^2)^n. You'll have to find your own values of C and n depending upon your reservoir

**Shakespear** · 08-19-2010, 04:28 PM

dumdum

CGR can be obtained from production history (good luck on this one), analog field/reservoir in your area or a PVT study.

Can you tells us more about what your are doing and for what purpose? This may help us to perhaps give you better council :-)

"evaluate field opportunities" to do ....... ????

**dumdum01** · 08-20-2010, 11:06 AM

Also,

If there is an opportunity that has an exploration well already drilled in (or maybe even appraisal wells drilled in)... then... should I use the material balance method?

It seems very complex to model.....?? or does the volumetric method suffice?...

**dumdum01** · 08-24-2010, 06:18 AM

Originally Posted by vinomarky

1. This is related to the richness of the gas in heavy ends - its not something you can calculate from properties such as viscosity (although I'm sure there is some relationship). You really need to have some understanding on how rich or lean the gas is likely to be
2. Using wellhead abandonment pressure, and correcting back to the sandface pressure taking into account friction and head is an appropriate way of dealing with this
3. If you need to be able to incorporate number of wells required and timing etc, then you need to step up the complexity of your model. The number of wells required is related to not only individual well deliverabilities, but also structure size and continuity. The simple rate potential equation is suitable if you are modeling the field as a tank with one (set of) offtake(s).

General (simple) equation for well deliverability is rate = C(Pr^2 - Pwf^2)^n. You'll have to find your own values of C and n depending upon your reservoir

Hi Vinomarky. Thank you for the above, could you please elaborate what each of the symbols (C, Pr, Pwf, n) mean in this instance. As you have already guessed, I am very new to this. Some elaboration will be kindly appreciated.

**Shakespear** · 08-24-2010, 10:15 AM

By "magic" I meant your experience. You have little data but you need to say more than the data allows. Hence you, with your 15-20 yr. experience act like the almighty magician. To do this you need GOOD arguments regarding why you assumed what you assumed.

In your case you will have to wait for this phase to kick in. Your just a novice magician.

**dumdum01** · 08-24-2010, 11:56 AM

Originally Posted by Shakespear

By "magic" I meant your experience. You have little data but you need to say more than the data allows. Hence you, with your 15-20 yr. experience act like the almighty magician. To do this you need GOOD arguments regarding why you assumed what you assumed.

In your case you will have to wait for this phase to kick in. Your just a novice magician.

Haha... Can you help this novice with some behind the scenes magical notions. For example. (how do I assume a given number of wells? what factors do I need to look into for this?)

I am an economist, intend to be an economist. But I would still like to be able to understand and appreciate the work of PE because it is integral to the value of a project. You guys rule!! lol.

**vinomarky** · 08-24-2010, 04:40 PM

How about this Mr Economist - can you tell me how to make a simple spreadsheet which I can use in all fiscal regimes to quickly get the jump on other economists and value opportunities? ;-)

Your answer would of course be no, but you'd be able to on a case-by-case basis generate rapid valuations based upon your judgment - simplifications as needed and plain old experience, that'd get you a 90% solution

I draw this rather simple analogy to illustrate what you are asking of us.... like the various fiscal regimes, there really is no single set of assumptions that will keep you out of trouble when predicting how a reservoir will produce - how many wells you will need over the life etc.... I'm afraid you will have to be stuck with dealing with one of us as required when looking at your new field.

Having said that, if you do sit down with a capable PE/RE to look at a new field, it really shouldn't take very long (hours) to come up with something that'd work as a first pass.