EXPERIMENTAL MODELING OF THE INTERACTION OF DRILLING FLUID WITH FROZEN HYDRATE-CONTAINING ROCKS
E.M. Chuvilin, E.O. Krivokhat, B.A. Bukhanov, N.S. Sokolova, V.V. Ekimova, A.Z. Mukhametdinova
Skolkovo Institute of Science and Technology, Center for Petroleum Science and Engineering, Moscow, Russia
Keywords: Arctic, permafrost, gas hydrates, cryopegs, well drilling, drilling fluids, pore hydrate dissociation
Abstract
Experimental modeling has been used to analyze the influence of drilling fluid composition and temperature on the destabilization of intrapermafrost gas hydrates. The need for this research is linked to the drilling of oil and gas wells in the Arctic permafrost zone, which, in addition to ice, may contain gas hydrate formations, as well as horizons of saline rocks and cryopegs. Since drilling fluids are an integral part of the well drilling process, studying their interaction with the host ice- and hydrate-containing rocks is essential for preventing various emergency situations associated with the dissociation of pore gas hydrates and the melting of ice inclusions. Experiments have been performed on frozen, artificially hydrate-saturated sand samples exposed to drilling fluids of varying compositions, including those containing contaminated cryopegs. The experimental modeling results suggest that the composition of drilling fluids and their temperature can have a significant impact on the destabilization of intrapermafrost gas hydrate formations, especially those under self-preservation conditions. Contamination of drilling fluids during drilling operations with cryopegs leads to a significant intensification of the decomposition of pore hydrates in the frozen rock strata due to active salt transfer processes.
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