A model on dual string drilling: on the road to deep waters
As the offshore market is facing the deepwater production challenges, the Oil and Gas Industry is investing in new technologies to bring down costs needed to effectively exploit reservoirs. Therefore, dual string drilling (DSD) can eliminate the marine riser which would result in exploring oil fields in deep and ultra-deepwater economically. In order for controlling fluid contact with a borehole wall during drilling operations include introducing an outer pipe into a borehole and positioning an inner pipe within the outer pipe axially. The method may further include circulating a drilling fluid to a drill bit using inner pipe and the annulus between the inner pipe and outer pipe. The drilling fluid may be separated from the control fluid by using an annular isolator. The results showed that with DSD approach a lot of time will be saved in order to circulate the kick out of the well. Apart from riserless drilling, DSD has an efficient cutting removal capacity, better annular clearance, elimination of differential sticking, better well stability, better well control parameters, reduction of torque and drag, avoid the dynamic equivalent circulating density gradient, and better extended reach drilling. The novelty of the new dynamics model is in the ability to solve narrow operational margin between pore pressure and fracture pressure as we move into deeper waters.
KeywordsRiserless Control fluid Annular isolator Equivalent circulation density Well control
The authors are grateful to Pandit Deendayal Petroleum University for the permission to publish this paper. Authors are thankful to Mr. Gudendrasingh Negi for his technical advice and support.
Compliance with ethical standards
Conflict of interest
The authors declare that they have no competing interests.
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