I've picked up from several postings that some are saying that the consultants used by OSH assumed a water drive mechanism.   Is that engineering information as to how they arrived at that available anywhere?

If one goes from pure depletion drive to full water drive in a gas reservoir, recovery efficiency can drop by 50+%.  A good reservoir engineer would give you a better number, and that is quite different for fractured carbonates (like here) vs. sandstone depositions.

Production tests are conducted in part to determine the drive mechanism and thus recovery efficiency.  However, that is more difficult to ascertain when the extent of the reservoir boundardies are not well known and the reservoir volume is huge.  A material balance is conducted measuring the reservoir pressure before and after the production test.  This information is used to determine the drive.  However, if the volume of the reservoir is highly uncertain (our case), then the outcome is also highly uncertain.  Since the aquifer presence is well established, then I have to believe that there is some degree of water drive.  The question is how much.

Since relatively speaking, the total volume produced to date is miniscule in reference to the total reservoir volume, I presume we are dealing with tiny, tiny fractions.  After all of these production tests, the reservoir pressure should have sequentially declined in the case of perfect depletion and bubble tight reservoir seals.  The data I've seen (if memory is right) is the pressure decline was a very small fraction of a psi.  In a water drive or partial water drive, reservoir pressure will have recovered vs. time and will not plot on a log/log straight line plot of pressure vs. time.

So the last production tests provided more information along those lines.  When you have a water drive in a heterogenous rock like this, then recovery gets very sketchy.  The type, size, and distribution of the void space (pores and fractures), well type, well placement and production rate will have a major impact on recovery efficiency.   You can design and operate the wells in a way to significantly improve recovery.  Well placement is critical. It is possible to "outrun" the water since gas has much higher mobility and thereby improve revovery.

Reservoir models have to be built to see how this might turn out.  But all it takes is a very conductive fracture through the reservoir down to the aquifer to blow the model away.  So I suspect they are relying heavily on analogue fields to bracket the range of outcomes.  So in summary, there may be a good bit of subjectivity rather than objective analysis in picking the recovery factor.  A probablistic approach for all of the critical variables makes the most sense.  But I am not a reservoir engineer, but just happened to work with some of the best.

'Putncalls' pid='74918' datel Wrote:It's hard to get a straight answer to the size or drive question.

I have posted this information before but some of you might find it of interest.

Go to the 2009 GLJ report at http://tinyurl.com/lrjknkq 

GLJ thinks this is  not a water drive as described on page 27 of 51:

Pet - Based on this statement from GLJ, will Ant-7 likely provide essential information towards defining drive type?

"This second option would require a regional, north-south oriented permeability barrier to the west of the structure. If this was the case, then a strong aquifer would exist."

'petrengr1' pid='74942' dateline='<a href="tel:1469581 Wrote:

'Putncalls' pid='74918' dateline='<a href="tel:1469562 Wrote:It's hard to get a straight answer to the size or drive question.

I have posted this information before but some of you might find it of interest.

Go to the 2009 GLJ report at http://tinyurl.com/lrjknkq 

GLJ thinks this is  not a water drive as described on page 27 of 51:

"If the Elk/Antelope structure was connected to this system, then an infinite-acting aquifer would be expected. However, as shown on Plot 1, the Elk/Antelope aquifer is approximately 460 psi higher in pressure, proving a disconnection. The over pressuring of this aquifer could be related to a sealed fault block or series of fault blocks being elevated during tectonic movement, which would result in a limited water drive, or a higher recharge area (approximately 500+ metres above sea level, which would be in the mountains to the north). This second option would require a regional, north-south oriented permeability barrier to the west of the structure. If this was the case, then a strong aquifer would exist."

Recovery factors  for the Low Estimate, Best Estimate and High Estimate are shown on page 31 of 51. TheLow Estimate was for a strong water drive with 80% water swept volume. The Best Estimate was for a weaker water drive with 50% water swept volume and the High Estimate was for 20% water swept volume or pretty much a depletion drive.

I do not know how this has changed over the years with the GLJ reports since this is the only one that has been published.

I am a believer in the depletion drive simply because the aquifer pressure is 460 psi higher than the regional aquifer. I do not buy the 500+ meters higher recharge area. I think there are too many faults and we are too far from the mountains for this to be the case. We will probably have some water drive due to the expansion of the "sealed up" and over pressured aquifer but this should be minimal since water is pretty much incompressible. If the aquifer is sealed up then the high case becomes the Best or most likely case. In  2009 the "marketable" P-50 gas was 9.08TCF plus 156.5 million barrels of condensate.

At the end of 2015 GLJ had a Gross un-risked 2C resource level of 1,662.6 MMBOe which is equivalent to10.4 TCFe. The Gross un-risked 3C resource level was 2,022.4 MMBOe which is equivalent to 12.13 TCFe. So if we had a perfect depletion drive the recovery should be more than 12 TCFe.

From conference call replay:

Phil believes E/A has "good, strong deletion drives that eventually will add to larger volumes" at material/final certification.

Some other good stuff from the first 8 minutes of the call:

The CRP certification is "highly speculative and subject to manipulation, not necessarily intentionally, it's just a fact of how it occurs in the business."

The problem for new certifiers is that there are "terabytes ...and years and years of research built up and compounded" upon.  Further, when there are "layers and layers of areas where they have no responsibility"… It "skews" their findings.

These are the reasons he recommends choosing from his list of 3 certifiers familiar with the field and a share final/material certification.

If we get GLJ and a 1/2 share of final certification?  I'LL VOTE YES.

'Li'loilady' pid='74967' d Wrote:

From conference call replay:

Phil believes E/A has "good, strong deletion drives that eventually will add to larger volumes" at material/final certification.

Some other good stuff from the first 8 minutes of the call:

The CRP certification is "highly speculative and subject to manipulation, not necessarily intentionally, it's just a fact of how it occurs in the business."

The problem for new certifiers is that there are "terabytes ...and years and years of research built up and compounded" upon.  Further, when there are "layers and layers of areas where they have no responsibility"… It "skews" their findings.

These are the reasons he recommends choosing from his list of 3 certifiers familiar with the field and a share final/material certification.

If we get GLJ and a 1/2 share of final certification?  I'LL VOTE YES.

Well spoken,Lady !

Pet and Kaliboo = Thank you for your posts concerning the E/A reservoir drive . How refreshing to read well-educated,wise words when you are commenting on one of our greatest finds . How tragic that such a Jewel (or Pearl) got caught up in a web of lies and deceit by a bunch of greedy,self-serving individuals . Again,thanks for your unselfish work to help our cause. Per Red,"God bless" .