Abstract:

Gas hydrate will be formed in the course of drilling shallow layer gas sand at offshore deepwater. In case of natural gas hydrate formed in drilling fluid, it would block the well bore, annular and blowout preventer (BOP), and endanger drilling operation seriously. With the selfdeveloped tetrahydrofuran (THF) circumvolved curette testing flat, the influence of the common offshore drilling additives on the formation of gas hydrate, including inorganic salt, organic salt and macromolecule polymer has been studied. Results show that inorganic salt and organic salt can efficiently inhibit the formation of natural gas hydrate, and macromolecule polymer is effective only in high concentration. When the concentration of macromolecule polymer is low, it would accelerate the formation of natural gas hydrate.

Key words: deepwater drilling, drilling fluid additive, gas hydrate, THF testing 