I thing again the Archie formula is the best in this problem

you can try to use acoustic time for  estimatjng hydrate saturation 

 Look at this paper; it contains details of how to estimate hydrate saturation from resistivity log

I think a combination of electrical, acoustic and possibly nmr logs would offer the most accurate approach to determining hydrate saturation. Keep in mind that hydrate saturation estimates are very sensitive to ion concentration in the formation water, where a dynamic system with dissociation and reformation may be quite challenging to solve. See the attached paper (and also my thesis if interested) for comparison between resistivity and MRI based saturation estimates during growth.

Conference Paper Electrical Resistivity Measurements of CH4 Hydrate Bearing S...

Thanks a lot to everyone!!

Maybe Faust formula can help you.

As you read Knut Arne Birkedal's paper you will realize that the basic Archie model worked well in estimating saturations in pore-filling hydrates. Fracture filling hydrates are a different matter, but you might be able to adjust the various Archie parameters to generate some reasonable results. The Gulf of Mexico project (DOE/Chevron) collected well logs from intervals that contained a large fraction of fracture-filled hydrates. There is an entire volume of J. Marine Petrol. Geol (v.34, no. 1, June 2012) dedicated to the results of this cruise. Note especially the paper by Ann Cook on electrical anisotropy.

Hi Matteo! There are a few papers that compare log and pore water derived saturation values and the archie equation overestimated hydrate saturation. I'll dig these up and email to you. Also read the following:

(1) Estimation of gas-hydrates from seismic velocity-resistivity transformed data in the Krishna-Godavari basin, eastern Indian margin Vivekanand Pandey, Kalachand Sain* and Mrinal K. Sen

(2) Gas hydrate saturation in the KrishnaeGodavari basin from P-wave velocity and electrical resistivity logs Uma Shankar , Michael Riedel

(3) USGS Doc attached

Hi Katie! Thanks a lot!

Archie's equation remains the best option for estimate saturation from resistivity logs

Hello all,

Archie equation entrenched into petrophysical industry since it was formulated. Before applying Archie equation, you know your reservoir and the reservoir should fulfill the per-requisite for being called an Archie rock. Archie's equation is fit for purpose equation and it shouldn't be extended to reservoirs which aren't archie rocks.

Regards,

Syed

Fuzzy logic. The same method used and create by Cuddy. I thnik it's the best method. Have you this paper ?

I think the joint inversion of conventional log data is the best way.

You can find the examples in our papers:

1. Kazatchenko, E., Markov, M., Mousatov, A., 2004b. Joint inversion of

acoustic and resistivity data for carbonate microstructure evaluation.

Petrophysics 45 (2), 130–140.

2. Kazatchenko, E., Markov, M., Mousatov, A., Pervago, E., 2006a.

Simulation of the electrical resistivity of dual-porosity carbonate formations saturated with fluid mixtures. Petrophysics 47 (1), 23–36.