FIRST APPLICATION OF CASING DRILLING TECHNOLOGY IN CHINA OFFSHORE

The casing drilling (CD) technology was firstly applied in the drilling operation in South China Sea and Bohai Bay,using ?508mm and ?339.7mm casing,with footage of 61.4m and 507.9m,and average ROP of 16.12m/h and 32.77m/h respectively.The CD operations were smoothly carried out,with the following records set,i.e.,first application of CD technology in China offshore with success;first application of CD technology in the exploratory well,simplifying well casing program by eliminating the use of conventional riser pipe;setting the shortest exploratory well construction period records in Bohai Bay and South China Sea.The practice of CD technology was very important for improving the drilling efficiency and cutting down the drilling cost in offshore drilling in China.