Gas hydrates are crystalline molecular complexes formed from mixtures of water and suitably sized gas molecules as a result of the combination of pressure and temperature in the shallow subsurface within marine settings.

Pure hydrates are high resistive. However, in most offshore cases have been formed in solution with salt water and not pose as highly resistive. Free gas underneath the Hydrate Stability Zone (HSZ) may occur, and will normally be expressed as highly resistive, depending on saturation.