William,
Thanks for the useful insight (as usual). Maybe is worth for me to explain a bit more the detail of my problem.
Let�??s take a coarse approach (I don�??t need to model this is detail, so I don�??t need a full 3D model).
Assume a confined, water saturated geological unit in which a fluid that is immiscible with water is also present (its density being lower than water�??s). Physics tells me that this fluid would tend to migrate upwards within the geological horizon until a barrier (caprock) is met. Here the fluid will accumulate. I�??m trying to predict (roughly) where the accumulation areas may be. For this I want to consider the geometry of my geological setting (in my case the geometry of the contact between the geological unit and the caprock). I�??d also like to consider the hydro-geo dynamic of the geological setting, though I�??m not sure how yet (I thought about fluid potential, but did not test this yet).
OK, now let�??s concentrate on the geometry of the geological setting only. As I said I�??d like to use the Particle Track tool to identify possible migration paths and accumulation areas. My problem is that I don�??t have a velocity necessarily associated to this (in the end I�??m not even interested in how long will it take for the fluid to reach an accumulation zone) and, as for my previous post, was wondering if I could �??substitute�?� the local velocity with another �??magnitude�?� such as slope values of the caprock/geological unit contact.
I hope this would clarify a bit better.
Many thanks.
Paola