Drilling difficulty analysis and rate increasing techniques in Halahatang area

Halahatang area is one of the main blocks for black oil reserve increasing in Tarim Oilfield, CNPC. The reservoir depth is usually around 6 800 m. the drilling process is troubled by pipe freezing in middle-upper formations, balled bit, weak wellbore stability in formations of Permian System and Carboniferous System, prone to collapse, poor drillability of deep reservoir formations, low rate of penetration, super-long open hole with more trouble, hydrogen sulphide bearing target, leakage and blowout coexisting, etc. Oil field reserve increasing pace is constrained by super-deep reservoir, complex formation, difficult drilling, long drilling period, etc. According to these difficulties, a series of studies are conducted, such as optimizing hydraulic drilling parameters, selecting bit and turbine, accident prevention, super-long open hole wellbore stability, and carbonate formation safe drilling, and good benefit has been obtained, with average individual drilling period shortened by one month, and good control of accidents happening. The objective of safe and fast drilling was obtained and the difficulties of low drilling rate and accidents prone are solved.