The Successful Application of One Run Drilling Technology in Big-Thickness Halite Formation of Ultra-Deep Water

Abstract The drilling operation in the more than 2000m thickness pre-salt formation with more than 2000m water depth faced great challenges from the beginning in X. Project of Atlantic due to drill string stuck caused by salt creeping and low ROP, so efforts were concentrated to obtain a better drilling performance as a consequence of the high daily rates of drilling ships. In this paper, we look for a combination of high performance PDC bits, near bit reamer stabilizer, synthetic based-based mud, MPD, RSS and LWD systems to increase the drilling performance, both in ROP and salt creeping control in salt formations. ROP has been increased by more than three hundred percentages by high performance PDC bits. Near bit reamer stabilizer and synthetic based-based mud made drill string stuck frequency decrease drastically. The combination of MPD, RSS and LWD systems has improved drilling performance. The above-mentioned integrated drilling technology has been successfully applied in two pre-salt wells in one run whose halite formation thickness is 1870m and 2062m respectively in 2016. The drilling duration for 2062m salt section has decreased to from 14 days to 7 days which saved about 14 millions dollars for the two wells. The average ROP record of the two wells by use of the integrated drilling technology is 24.6 m/h that has been improved 3.4 times comparing the completed four wells in 2015 in X. Project. The NPT caused by drill string stuck has been decreased from the average 11.7 days to zero that can save about 12 millions drilling cost. So the integrated halite drilling technology can not only solve the drilling problems in halite formation in ultra-deep water such as bore hole collapse and drill string stuck but also increase the ROP. The drilling performance in halite formation has been improved and the integrated halite drilling technology has been widely applied in big-thickness pre-salt formation Santos basin and will decrease the drilling duration of ultra-deep water pre-salt reservoirs wells and lower the oil cost per barrel in ultra-deep water development. The method to increase drilling efficiency in halite formation of this paper presented will make a reference for deep water salt formation drilling and offshore oilfields high efficiency development. Also the method to control salt creeping and drill string stuck might give a light to the drilling operation in gypsum formation in onshore oilfields.