An experimental drilling apparatus used for evaluating drilling risks related to natural gas hydrate

Some countries are trying to drill and exploit natural gas hydrate (NGH). However, the disturbance effects of drilling on the stability of NGH-bearing sediments are unclear. There are still few experimental apparatuses on this issue, and existing experimental apparatuses cannot comprehensively simulate the drilling process as well. In order to fill this gap in prior studies, an experimental drilling apparatus used for evaluating drilling risks related to NGH was developed. The apparatus consists of a high-pressure vessel with a drilling system, a drilling fluid injection system, a drilling fluid treatment system, and a data acquisition system. Hydrates can form in the high-pressure vessel placed inside a walk-in cold room. The drilling fluid can be cooled to the desired temperature by the drilling fluid treatment system and be injected into the drilling system by the drilling fluid injection system. The drilling system can simulate the comprehensive drilling process, including drilling feed, trip up & down operations, drilling fluid circulation, etc. 48 thermometers were inserted into the high-pressure vessel from the bottom. The thermometers uniformly distribute in the high-pressure vessel, and they could quickly and accurately measure the hydrate phase change process under high-pressure and low-temperature conditions. Simulate the drilling process in hydrate-bearing sediments. Evaluate the influence of drilling parameters (drilling fluid temperatures, drilling fluid circulation rates, etc.) on hydrate dissociation characteristics around the wellbore. Simultaneously evaluate the heat and mass transfer process in hydrate-bearing sediments during the drilling process. (C) 2020 The Author(s). Published by Elsevier B.V.