The Oil Drum: Europe | GHAWAR: an estimate of remaining oil reserves and production decline (Part 1

67 comments on GHAWAR: an estimate of remaining oil reserves and production decline (Part 1 - background and methodology)

Comments can no longer be added to this story.

| Show without comments | PDF version

totoneila on April 25, 2007 - 7:05pm

Hello GaryP,

Thxs for responding. I hope you and the other TopTODers will carefully evaluate North Uthmaniyah [UTMN] with the Voelker PDF page 90, frame 120, in your analysis. IMO, this injector to producer analysis covering over 9,300 ft in roughly 4,000 days right in the heart of N. UTMN does not bode well for the rest of Ghawar. This area of Ghawar should theoretically have the lowest occurence of super-k and DFNs because it is a non-crestal area less prone to tectonic fracture forces.

If I understand the UTMN graphic correctly [left to right Saturation graphical series]:

1. [No fault] Waterfront override predominates the sweep in non-DFN and non-super k gridded blocks. Higher permeability in the upper layers at the detriment of lower porosity/perm in the lower layers largely prevents uniform 'piston sweep' of the payzone layers.

2. [Middle of Blocks] Water quickly seeks the interlayer high perm zones as primary conduits. Zonal thieving may be just as important to optimal sweep efficiencies as gravity drive because of these multi-layers.

3. [Next to Fault] IMO, this clearly shows non-ideal sweep phase separation or non vertical 'piston sweep' due to multilayer differentials, not ideal gravity drive.

4. [Fault Plane] Here the well data seems to illustrate ideal vertical sweep, but as has been previously seen in the earlier graphics-- this amalgamation with data interference caused by the fault or DFN distortion paints a false picture of what really occurred from across the injector to producer distance.

It suggests that Aramco will need to do a lot of down-dip studies to best identify lower perm payzone pockets that were bypassed, then carefully install horizontals or downbore pumps to best extract these payzones at low watercuts. If one considers that they might have been misreading some or much of the reservoir sweep data for thirty or more years because of super-k and DFNs: is it any wonder that Aramco is now struggling with high watercuts and declining production?

I hope the TopTODers can cut my WAG to pieces, for all our sakes. Have at it, Gentlemen. Thxs for any reply.

Bob Shaw in Phx,Az Are Humans Smarter than Yeast?

Comments can no longer be added to this story.

totoneila on April 26, 2007 - 8:07am

Hello TODers,

I done some googling on Fracture Networks that might simplify one's understanding of the problems it presents to optimal reservoir extraction. Hopefully, it will aid in your understanding of Voelker's Motherlode PDF and his voluminous detail on Ghawar Super-k & DFNs.

Are you ready for a 3D fly-thru of Ghawar?
Bring your imagination!

The first link is a supercluster rotational animation of a simulated fracture network in a material. Now use your imagination: picture a 3d graphic of Ghawar spinning slowly instead, and each color spot or squiggle represents a bypassed pocket of oil that can be tapped if it can be identified by Aramco supercomputer simulation [easier said than done]. Imagine this cube being stretched to approx. 170 miles long, 20 miles wide, and 200 ft thick! Each one of those squiggles could represent a supertanker VLCC if they could be tapped precisely. At Ghawar's current advanced age: If the well misses the squiggle target from incomplete or bad data --> then you get a hell of a lot of water instead.

http://www.csm.ornl.gov/images/clusters.gif

The red layer [nearer the bottom of the cube] could be analagous to the bottom layer of Arab Zone D with lower permeability/porosity-->here, as Voelker suggested, horizontal wells will be more effective in sweeping thru this geo-interlayer.

Maybe SS, Euan, and F_F would think it more accurate if you mentally flipped this rotating cube: then the red layer cluster would represent the topmost crestal dry oil in the previously discussed waterflood geo-slices.

The toplink was taken from this source:

http://www.csm.ornl.gov/archive/HL06.html

Here is another rotating simulation showing vertical and horizontal faulting:

http://www.sandia.gov/geostats/flow_model.htm

taken from this source:

http://www.sandia.gov/geostats/site_char_jnc.htm

Again, if you mentally transpose the Shedgum leak area into vertical faulting as illustrated by this simulation--> then you can understand why Aramco doesn't want to just pump water from this area.

Here are some more links with good illustrations to further aid amateur understanding:

http://www.veritasdgc.com/bins/content_page.asp?cid=5-946-2642

http://www.badleys.co.uk/products/pdf/FaultED.pdf

Use the PDF zoom tool to look at the pictures in greater detail.

Hope this helps bring people up to speed so that they have a greater understanding of what the TopTODers are writing about. Cheers!

Bob Shaw in Phx,Az Are Humans Smarter than Yeast?

Comments can no longer be added to this story.