Large hole drilling technology for underground salt-cavern gas storage in Turkey

One underground gas storage is proposed in Tuz G?lü salt field in Turkey; there are two possible risks: deviation between actual depth of salt bed and the planned drilling depth; leaching of CO2 during drilling and cavern building. So there are certain geological and engineering risks in the building of this gas storage. In order to accelerate this project and meet the requirement of well drilling for salt-cavern gas storage, an optimization scheme of a large hole wellbore configuration, which had never used domestically was used for this project. Hydraulic underreamer was used for hole reaming, and supporting techniques for drilling were developed. This paper sets forth the drilling technology for Tuz G?lü underground gas storage in terms of wellbore configuration, bit selection and application of screw drill tool, selection of drilling fluid, cementing and drilling effectiveness, etc. The use of this technology effectively reduces the time rate of drilling troubles, shortens drilling cycle and improves the penetration rate, hence realizing remarkable economic benefits.