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?

Hello TODers,

From the Motherlode PDF page 74, frame 104:
------------------------------------------------
The opposite extreme occurs if the intervals are laterally extensive such that both production and injection wells are intersected by them, or if one or more DFNs intersect the intervals at such an orientation as to facilitate the flow of injection water to the interval. The first condition has not been verified in the literature, and in fact
contradicts the prevailing facies distribution model for the Arab-D (Chapter 4).

The second condition, however, may be prevalent. The existence of faults and discrete fracture systems have been confirmed throughout the field.[5] Furthermore, the high conductivity of these systems has been accepted as prevalent,[1],[52],[46],[51] and the orientation of the fracture systems, although becoming better defined with seismic studies currently being conducted over much of the field, may be practically irrelevant, as coning within a DFN has been demonstrated, as cited in the previous section.

Thus, under this condition, a DFN of any orientation, and any appreciable length, for that matter, that has a sufficient vertical thickness to connect a permeable interval intersected by a well, to a region of high water fractional flow, located at a greater depth, may contribute to high water cut at the well.

Thus, the existence of DFNs in the Arab-D favors, and may in fact determine completely, the detrimental effects of
the high permeability intervals.

Note that we have adopted, in the title of this section, the traditional parlance for super-k, as describing only the thin, permeable interval. It must be made clear that
our model of super-k consists of the combination, thin conductive interval and DFN.

Therefore, under our definition, it is concluded definitely that super-k is bad: under waterflood conditions, DFNs provide conduits for water flow, and the conductive
intervals provide connections from DFNs to producing wells.

Al-Ajmi, et al.[54] presented the results of a study of well productivity for 450 wells (over half of the total) in the Uthmaniyah Sector, that clarifies which of the
two classes of wells, those favorably disposed to thin, conductive intervals, and those rendered non-productive by them, prevails.
----------------------------------------

To me, this is very compelling reading: how much worse has DFN coning gotten in the intervening years? There is probably no way to cost-effectively minimize for this geologic effect. Aramco probably has to accept ever-increasing watercuts and declining production.

DFNs and super-k was ideal in the early stages before the application of waterflooding; it allowed very high, dry oil barrels/well. Now the opposite effect is occurring: the easy waterflood flow through DFNs is inhibiting effective and economic sweep efficiencies from the low porosity/permability payrock.

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