In http://www.ncpa.org/pub/bg/bg159/index.html#e David Deming writes:
<< Hubbert?s 1980 prediction of U.S. oil production, his last, was
substantially less accurate than his 1956 ?high? estimate.27 In the
year 2000, actual U.S. oil production from the lower 48 states was 1.7
times higher than his 1980 revised prediction [see Figure V]. >>
Figure V shows a higher peak followed by a faster decline.
Technological improvements in oil drilling appear to only speed the rate at
which the finite amount of oil that is in the ground comes up. This is an
observation not a theory. Yibal was the vanguard for technological
improvements such as horizontal infill ("sideways between established wells")
drilling and this is what happened.
definition of "water coning" with diagram:
http://www.glossary.oilfield.slb.com/Display.cfm?Term=coning
definition of "water cresting" with diagram:
http://www.glossary.oilfield.slb.com/Display.cfm?Term=cresting
Matthew Simmons used "channeling" in this interview but I think that "cresting"
would have been the more commonly used term:
http://www.globalpublicmedia.com/TRANSCRIPTS/index.php?name=MATT%20SIMMONS&origin=/INTERVIEWS/MATT.SIMMONS/index.php&transcript=2004/04/MattSimmons.Interview.2004-04-27
<< The relevancy though is what happened at Yibal was that by 1990 they
couldn't drill vertical wells anymore, because the vertical wells would water
up within months, because the oil column was now so thin that you just couldn?t
put a vertical well down low enough. It was either at the top of the reservoir
or - and so they went to - it was the first field in the Middle East that
embraced the use of horizontal drilling, and they thought that was terrific for
the first 2 or 3 years until all of a sudden this long horizontal extension
channeled up as opposed to coned up. Coning is just when it gets the
[inaudible]. Channeling is when it gets the whole extension. So they then went
to the first generation of these extensions coming out, so that you can kind of
hide from the problem of channeling, and for about 3 years, they thought they
had licked it when they got the well productivity back up to 8 to 10 thousand
barrels a day, but what they were doing without realizing it is just shrinking
the oil column till it was gone, and once it?s gone the production drops, the
gas all comes out, the water co-mingles and you have the unbelievable story of
Yibal. >>
see also
http://www.spe.org/cgi-bin/viewpaper.cgi?paper=00084939.pdf
Maximizing Yibal's Remaining Value
F.C.J. Mijnssen, SPE, and
D.G. Rayes, SPE,
Petroleum Development Oman;
I. Ferguson, SPE,
Consultant; and
S.M. Al Abri,
G.F. Mueller,
P.H.M.A. Razali, SPE,
R. Nieuwenhuijs, and
G.H. Henderson,
Petroleum Development Oman
Copyright 2003
Society of Petroleum Engineers
Also see the diagrams about what happened at Yibal in this slide show:
http://www.spe-nl.org/Presentations/SPE_Lecture_Mijnssen.pdf |
