Thermal Stimulation Techniques to Mitigate Gas Hydrate Decomposition Risks During Drilling in Permafrost Regions

This study addresses the critical issue of gas influx during the drilling of intervals containing gas hydrates, a common challenge in drilling operations in hydrate-bearing formations. The primary objective of the research is to determine optimal drilling fluid parameters, specifically temperature and flow rate, to mitigate risks associated with gas hydrate dissociation and ensure wellbore stability. The COMSOL Multiphysics software package was used for the simulation. The model integrates Fourier's law of thermal conductivity and heat transfer correlations to simulate the thermal interaction between the drilling fluid and the wellbore. For the first time in drilling process modeling, the thermodynamic state of gas hydrates under the specific conditions of Gubkinskoye field has been integrated. The decomposition potential of hydrates was evaluated using the GHA350 autoclave. The model accounts for the thermobaric conditions of the formation, as well as the gas composition and water formation of the Gubkinskoye gas-condensate field. The simulation was conducted for the depth interval of 250–350 m, with the rock temperature ranging from 270 to 278 K and the drilling fluid temperature varying between 283 and 298 K. This research contributes to the development of safe and more efficient drilling practices, reducing the risks of gas influx and ensuring the stability of wellbores in gas hydrate reservoir. As a result, it was found that the recommended flow rate of drilling mud should be in the range of 0.030–0.045 m3/s, and its temperature should not exceed 293 K.