clifman wrote:This may be something of a moot/minor point, but everytime I read that while Hubbert was proven right about the US peak, but he was 'wrong' about the global peak (as in today's Trumpet), I can't help but think it. It seems pretty clear to me that the only reason he was 'wrong' about the global peak is that he didn't forsee the demand destruction caused by the OPEC embargo and Iranian supply crunch, both of which were of course political 'peaks' of a sort. If you extrapolate the upslope of Hubbert's curve absent the substantial dip caused by these political disruptions, we'd likely already be past peak - and having to live in the world we all see coming. Again, it may be a minor point, but to me, it gives Hubbert and his theory even more credibility than it already has, and might help in convincing a few more of the optimists, and maybe even some of the sheeple.
nero wrote:I don't understand why people think the only options are a symetrical profile or a peak followed by a cliff. A third option is that the peak is followed by a long slow decline. Too many factors affect the production profile to say which is the most likely.
I don't understand why people think that the oil crisis in the 70s caused oil production to deviate from some 'ideal' hubbert curve. The production profile has always been affected by economics and politics. There is no geological reason why oil production should follow a hubbert curve. No reason at all. The production profile is what it is. If it doesn't follow the hubbert curve, then the hubbert curve was wrong simple as that. It is a crude approximation used only because no one has a better model.
SilentE wrote:Shorter clifman:
Facts which tend to disprove a theory actually prove the theory.
k_semler wrote:SilentE wrote:Shorter clifman:
Facts which tend to disprove a theory actually prove the theory.
Umm, can you say DOUBLETHINK?
Prod oil cons gas cons ratio
1999 8911 1455 4.5 1980.222222
2000 9511 1485 4.8 1981.458333
2001 9263 1500 5.2 1781.346154
2002 8970 1522 5.5 1630.909091
2003 10222 1629 5.8 1762.413793
2004 10584 1728 6.2 1707.096774
hybrid wrote:We found the posting by Smiley in which he or she proposes a simple physical model for Hubbert’s peak to be quite interesting. In the posting, Smiley comments that he or she can solve the model numerically but doesn’t know if there is an algebraic solution. In fact, it is possible to solve the model algebraically and to show that the solution for the volume of liquid extracted follows the s-shaped logistic curve and that the rate of extraction (the derivative of the logistic curve) has the characteristic bell shape with its peak at the halfway point for total volume extracted. This solution requires a specific algebraic form for the area of the hole A(t) through which liquid is being extracted. However, this particular form is quite reasonable. It is itself peaked, with a peak which lags behind the peak in the extraction rate. This can be interpreted as wells being shut down (due to water encroachment, etc.) as production falls. A very rough draft of the details of our solution can be found at http://www.tam.cornell.edu/~dma32/oil/o ... oBookmark3.
I was wondering: is there a link between depth of the oil field and pressure and temperature of the oil and gas?
rockdoc123 wrote:Indeed. Generally speaking hydrostatic or water pressure increases with depth by about 0.45 psi/ft. There are cases of overpressure in real life due to factors such as undercompaction, an isolated reservoir etc. In terms of temperature it depends on where you are drilling. Offshore in ultradeep water it is possible you are drilling into rocks sitting above oceanic crust in which case the geothermal gradient is somewhere around 35 - 45 C/km. If you are drilling onshore on an old cold craton like central US it can be as low as 10 C/km...if you are drilling near a modern rift (eg. East Africa Rift in Uganda) you can have geothermal gradients as high as 60 - 100 C/km locally.
By the way there are a bunch of engineering formulae constructed for these exact issues.....usually allow you to look a single phase or multi phase flow, water drive versus gas depletion drive, input porosity, permeability...etc etc. Not sure if you guys were just interested in modeling to understand how it works (very commendable) or wanting to solve a problem (commendable as well). I can probably dig the relevant stuff up in some of my dusty reservoir engineering texts.
Thanks for the info! so if P= f(depth) and T= g(depth), the initial conditions of the above model can be known and derived from the reservoir depth.
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