Application of valve-type continuous circulation drilling technology to the extended reach wells in Panyu Oil field

In Panyu 10-8 Oilfeld, the hole section of Ø215.9 mm in an extended reach well has to run through faults and its safety density window of drilling fuid is narrow (minimum 1.30~1.70 g/cm³). Besides, its angle holding section of Ø311.2 mm in the upper part is long (3 508 m) with high deviation angle (maximum 80°), and cutting tends to accumulate easily. The valve-type continuous circulation drilling technology was introduced in this paper. Its fled application results were analyzed based on case study, and the problems and improvement measures were summarized. The necessity to introduce the valve-type continuous circulation drilling technology was illustrated by analyzing the technological diffculties which were encountered during the drilling of Ø215.9 mm hole section of Well PY10-8-A3 in Panyu 10-8 Oilfeld. Then, the working principles and main equipments involved in this technology were introduced, and its operational characteristics and application effects were analyzed. It is indicated that the variance ratio of drilling fuid ECD (Equivalent circulation density) in the whole well is less than 7.6%, borehole circulation pressure is stable and average ROP is up to 21.7 m/h.Furthermore, borehole is well cleaned and faults are drilled through safely and smoothly without any leak, collapse or sticking.