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

[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

[Shakespear]

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]

Hi Guys,

The idea is to be able to see a new acquisition or merger opportunity and be able to act quick. I am trying to base it on the general kind of information that will be available for such opportunities initially.

like seismic (interpreted)?
maybe a GIIP value?
sometimes a EUR.?

I want to be able to take this information and do a quick and dirty valuation. (This is just to understand potentially if an opportunity exists till the geo, PE and cost engineers can analyse data and come up with a development scenario.)

It also helps me understand whats going on in project meetings and not look completely dumb)))

[link Point to another website Only the registered members can access] Here is a quick cut of what I have done till now. ( I have marked questions in red.) ... maybe this will give a good idea??

[dumdum01]

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?...

[Shakespear]

Hi Guys,

The idea is to be able to see a new acquisition or merger opportunity and be able to act quick. I am trying to base it on the general kind of information that will be available for such opportunities initially.

like seismic (interpreted)?
maybe a GIIP value?
sometimes a EUR.?

I want to be able to take this information and do a quick and dirty valuation. (This is just to understand potentially if an opportunity exists till the geo, PE and cost engineers can analyse data and come up with a development scenario.)

It also helps me understand whats going on in project meetings and not look completely dumb)))

[link Point to another website Only the registered members can access] Here is a quick cut of what I have done till now. ( I have marked questions in red.) ... maybe this will give a good idea??

OK dumdum, from the above I suspect that you are very new to this. Don't take this negatively but just an assessment of what you have said above.

If I was doing a "quick" evaluation than it might look like this in terms of the information I have.

1) I have little, then I need
- a map of estimated reservoir extent
- estimate of Oil/Gas in place
- estimated recovery coefficient (conservative estimate) for the field

From this I can get an idea of how much I will produce from this field. If you want cash flow then you will have a problem as you have no well production data to even get an idea of how a well will produce in this field. So now you will need to do "magic", guess based on near-by fields or doing simple math (drainage radius expected, number of wells that would fit in your map of the field, some decline rate ) of what you think wells will be producing like here.

2) I have info in 1) plus logs and three wells producing.

Now you can get a "type well" for the field. Perhaps do a kh map and tie that to the kh of the producing wells. Using drainage radius, estimate where you will drill additional wells, estimate there the kh, and scale production expected from these well to be drilled to those that are already producing.

3) I have 1) plus 20 wells.

Now you will do what you did in 2) but you will need to look closer at the producing wells to see "what they were doing", well histories. Why did they producing the way they did? Why the down times? What workovers were done? What problems did they have? What is in the well that they lost, because in the details you may find that the wells is down due to junk in the hole, casing collapse, tubing lost in the hole, or corrosion problems...... DETAILS that are important to understand what this field is all about !!!!!! This means READING and understanding intervention reports on wells which are written in "insider" language. Without this you may run into HUGE PROBLEMS !!!!!!

This is needed to see what remaining production you can expect of exiting producers in the future,if something is left to produce from shut-in wells, if workovers will bring production online for wells shut in, if unperfed zones exist that could bring in additional production ....


Material Balance - you need pressure data, but if it exists this is never plug and play. Questions that come up are, when were they taken, how were they taken, with what were they taken, where were they taken .....?

Once you are clear on pressure, you move on to average reservoir properties and PVT properties. More thinking and probable sensitivity studies to see how things change with the input uncertainty. MB is looking at the reservoir as though it was a huge barrel, one porosity, thickness etc.

Doing MB will require more work and requires more data to be good. With two wells MB won't be any better than doing 1) or 2).

Perhaps others can chip in here to suggests other ideas.

But from my perspective "understand potentially if an opportunity exists" requires logs, map of reservoir extent, some wells producing

[vinomarky]

Agree - I think the Bard has outlined a good summary.

[dumdum01]

OK dumdum, from the above I suspect that you are very new to this. Don't take this negatively but just an assessment of what you have said above.

If I was doing a "quick" evaluation than it might look like this in terms of the information I have.

1) I have little, then I need
- a map of estimated reservoir extent
- estimate of Oil/Gas in place
- estimated recovery coefficient (conservative estimate) for the field

From this I can get an idea of how much I will produce from this field. If you want cash flow then you will have a problem as you have no well production data to even get an idea of how a well will produce in this field. So now you will need to do "magic", guess based on near-by fields or doing simple math (drainage radius expected, number of wells that would fit in your map of the field, some decline rate ) of what you think wells will be producing like here.

2) I have info in 1) plus logs and three wells producing.

Now you can get a "type well" for the field. Perhaps do a kh map and tie that to the kh of the producing wells. Using drainage radius, estimate where you will drill additional wells, estimate there the kh, and scale production expected from these well to be drilled to those that are already producing.

3) I have 1) plus 20 wells.

Now you will do what you did in 2) but you will need to look closer at the producing wells to see "what they were doing", well histories. Why did they producing the way they did? Why the down times? What workovers were done? What problems did they have? What is in the well that they lost, because in the details you may find that the wells is down due to junk in the hole, casing collapse, tubing lost in the hole, or corrosion problems...... DETAILS that are important to understand what this field is all about !!!!!! This means READING and understanding intervention reports on wells which are written in "insider" language. Without this you may run into HUGE PROBLEMS !!!!!!

This is needed to see what remaining production you can expect of exiting producers in the future,if something is left to produce from shut-in wells, if workovers will bring production online for wells shut in, if unperfed zones exist that could bring in additional production ....


Material Balance - you need pressure data, but if it exists this is never plug and play. Questions that come up are, when were they taken, how were they taken, with what were they taken, where were they taken .....?

Once you are clear on pressure, you move on to average reservoir properties and PVT properties. More thinking and probable sensitivity studies to see how things change with the input uncertainty. MB is looking at the reservoir as though it was a huge barrel, one porosity, thickness etc.

Doing MB will require more work and requires more data to be good. With two wells MB won't be any better than doing 1) or 2).

Perhaps others can chip in here to suggests other ideas.

But from my perspective "understand potentially if an opportunity exists" requires logs, map of reservoir extent, some wells producing

Hi Shakespeare,

I suspect this is very much based on the 1st scenario you have. From the above analysis you have kindly provided, it seems the second and the third scenario is both out of my reach and time limit for this project.

I would like to know how to create this "magic". If I do know ( the reservoir area, the estimated Oil/Gas in place and finally the recovery coefficient), how can I then figure out a production profile for the field. In a way, is there a way to "optimise" this to say 1. get the most recovery, 2. highest plateau rate etc. (Be able to play around with the number of wells required?)

Many Thanks,

[dumdum01]

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]

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]

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]

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.

[dumdum01]

Haha,

Maybe I have the wrong end of the stick here but I know Chevron already use a similar model to come up with a basic first cut.

As to can I give you a simple spreadsheet that takes into account all fiscal regimes... is a resounding yes. It wouldn't give you NPV correct to two decimal places, it would give you maybe a +- 30% accurate answer. Thats the kind of thing I am looking for. In RE terms that probably is +- 200% but I am willing to live with it. The first estimates on a field before anything is drilled will be wrong anyways. There is no way G&G and RE comes up with a correct view of a green field development in a frontier play without drilling even a well.

And this has been a great process for me to understand things, even basic things like what an aquifier effect means, or what is Gas formation volume factor. Words that are banded around in functional reviews all the time, and I suspect many people understand it outside the function.

Thank you guys for your help so far.)) It has been very very much appreciated. It has helped me a lot to scratch the surface. It is quite otherwise to know what to look at unless there are some nudges in the right direction sometimes. (And I found the formula in the RE handbook vinomarky. Lol.) Now just to understand it. hehe