ROP enhancing technology for circum-mahu lake depression in Junggar Basin

The circum-Mahu depression of Junggar is a complex pressure system; its regional pressure changes greatly; conglomerates have grown at base of Badaowan Formation with a thicknes of 100-350 m and poor drillability, leading to low ROP and long drilling period, which greatly hinders the exploration progress in circum-Mahu area. Since 2012, according to the drilling geological characteristics of this block, efforts have been made to tackle the technical difficulties in drilling acceleration, and a complete set of techniques have been developed for drilling acceleration through such measures as optimization of wellbore configuration and effective PDC drill bits, using lost circulation prevention drilling fluid system and using auxiliary accelerating tools. In 20 wells to which these techniques have been applied, the average rate of penetration was 6.29 m/h, up by 63.4%; drilling period was 72.29 d, shortened by 37.2%, and downhole trouble rate were 1.13%, down by 72.9%. Field application showed that the techniques for drilling acceleration have improved the ROP, shortened the drilling period and reduced the downhole troube rate. So, the above technical measures are worth promoting.