Practice of drilling engineering incomplex formation of nappe structures in blocks

Burma M block belongs to tertiary nappe structure.During drilling process,there exist such problems as serious borehole sloughing,formation pore pressure reaching 2.38 g/cm3,and severe shrinkage of soft mudstone.To increase drilling speed of the area,all these technical problems must be solved.Taking RM19-3-1 as an example,research on the mechanism of increasing ROP of nappe formations is conducted based on the prediction of formation pore pressure,the optimal design of hole structure,the development of new drilling tools and systematic drilling equipments.The ROP of RM19-3-1 well is increased by 20% compared with that of similar wells by employing the well control technology for shallow oil and gas layers,the anti-sloughing technology for nappe formations,the drilling technology for soft mudstone,the drilling technology using high density drilling fluid,the cementing technology using high density cement,the hole deviation control technology,and the technology recycling weighting agents.The practice of drilling engineering shows that prediction of formation pressure,hole structure,drilling tools,and drilling fluid are major factors restricting drilling speed.Research in this paper may be a good reference to the drilling operation in complex nappe formations in near future.