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Allan maps and fault juxtaposition diagrams? 
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Joined: Thu Jun 17, 2010 6:22 pm
Posts: 13
Post Allan maps and fault juxtaposition diagrams?

I did not know where to post this but I have a question about fault modeling and determining whether or not faults are sealing. I've read some books on the subject and one of them tells me to construct Allan maps and fault juxtaposition diagrams. They fail to tell me how that is done and I would be very thankful for getting that explained to me here.

Hope you van help,


Thu Jun 17, 2010 6:32 pm

Joined: Sun Jul 04, 2010 3:12 pm
Posts: 1
Post Re: Allan maps and fault juxtaposition diagrams?
Fault seal analysis requires knowledge about strucutal styles, rock properties and fluid flow.
A fault can be a transmitter of or a barrier to fluid flow and pressure communication; fault can act as seals or conduits, which makes it such an important subject for the Oil and Gas industry.

Fault seal behavior isn't random. There is a pattern and once the pattern is understood, seal can be predicted with a high degree of confidence. Acting of fault as a seal depends on its geometry, rocks, and throw and its analysis estimates likelihood of seal or conduit and whether permeable rocks juxtapose each other? Fault gouge can be permeable (sand smear) or impermeable (shale smear). Als you have to take into consideration the reduction in permeabilities due to Cataclasis. Sealing faults may be the main control on the trapping in many hydrocarbon reservoirs and can also make large reservoirs into small compartmentalized reservoirs.

A fundamental step in evaluating fault behaviour and sealing properties is mapping the faults and constructing fault plane throw and juxtaposition maps. These are the Allan diagrams which will help you in quick initial examination and prediction of fault seal capacity.
Resolution also plays important role as mapping of faults whose throw is less than the seismic resolution makes uncertainty in the prediction of such faults. You then prepare SGR(Shale-Gouge-Ratio) and ESGR(Effective-Shale-Gouge-Ratio)’s within the fault zone will permit you to have a greater control on fault transmissibility (Peterl let's you do this, using offsets and vshale from your 3d model).

Software such as Geoframe, Jewelsuite and Petrel can help you achieve all this.

Fri Jul 13, 2012 7:44 pm
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