In this chapter, I link the information available from seismic
with physical rock models. This enables
me to address an important question that arises after having evaluated
the cause of the BSR and the properties of the sediments across the
BSR: how much
methane hydrate is present in the sediment? This is an essential
question to answer if we are to realistically evaluate the possible
impact methane hydrates might have as a future energy resource. Here, I
provide a theoretical tool for quantifying the amount of gas hydrate and
gas around the BSR at the Blake Outer Ridge. Since there is no direct
well control of the data, all estimations are based solely on
information available from surface seismic. I examine three different
micromechanical models of hydrate formation: (A) hydrate is part of the
pore fluid; (B) hydrate becomes part of the solid frame, thus reducing
porosity and weakly affecting the stiffness of the sediment; and (C) hydrate cements grain contacts and therefore strongly reinforces the sediments. Using
the interval velocities obtained from velocity analysis together with the
rock-physics models, I obtain lateral maps of hydrate and gas saturation
across the BSR. Model A predicts maximum hydrate saturations between 20% and
26%, model B saturations between 15% and 20% and model C saturations
less than 1%. Maximum gas saturation is between 1% and 2%.
Subsequently, I analyze
the stability of these estimates to errors in the interval velocities.
Such errors can cause the estimations to vary as much as 
14% (note
that % refers to the saturation itself and not to the percentage of
saturation). Therefore, accurate velocity determination is crucial for correct
reservoir characterization.
Finally, I validate the technique by using
known well-log velocities and porosities from wells 994 and 995 at the
Blake Outer Ridge.