OS6B-2:SCIENTIFIC DRILLING PROJECT OF MK-2 WELL FOR GAS HYDRATE IN MOHE BASI

Youhong SUN， Rui JIA ， Wei GUO， Shengli JI
College of Construction Engineering, Jilin University, CHINA

    MK-2 well is located in Mohe Basin, drilling depth was 2300m. In 2011 -2013, Jilin university finished Scientific Drilling Project MK-2 well for gas hydrate with the organization by the China Geological Survey. This paper would show the research of drilling project of MK-2 well ., and the drilling equipment and processes for gas hydrate were used in the entire construction process. The diameter of well was 77.5 mm, and the well structure was devided into four parts, large diameter rope coring drilling tools were used for the whole well coring. HXY-8 rig, SG-24-type drill tower and BW320 mud were selected as the conventional drilling equipment. The well control system was used to prevent the blowout caused by the production of gas hydrate dissociation, and two platforms were designed for the installation of the control system. The gas hydrate slurry refrigeration system was necessary drilling equipment for gas hydrate drilling. It could cool the drilling mud in the coaxial heat exchanger and keep the well at low temperature, through the refrigeration unit for cooling, refrigerant glycol as a carrier. The solid control system could guarantee the mud performance at low temperature, which is including grit removal equipment and degassing equipment. The drilling parameter detection system was configured to detect the WOB, rotational speed, pump pressure, the pump output, mud temperature, flammable gases in the process of drilling real-time, which could also improve the drilling efficiency, meet hydrate drilling requirements, and predict the layers of gas hydrate position. This research of Scientific Drilling Project MK-2 well would provide the foundation and protection for the drilling procedures of gas hydrate in permafrost.