Managed Pressure Drilling

High-Temperature High-Pressure (HT/HP) deep gas requires past technical obstacles to be overcome with a more integrated approach to well control. Developments in underbalanced drilling technology have spawned new techniques and equipment for bottom hole circulating pressure (BHCP) control and hence well control. High-pressure wells have traditionally been drilled with large overbalanced margins to minimize the risk of unplanned reservoir inflow. The high pressures associated with these influxes can result in large kick volumes, reduced reaction time and greater risk. Challenges associated with these narrow margins between equivalent circulating density (ECD) and frac gradient serve to increase loss circulation risk, resulting in high pressures, differential sticking and wellbore damage.

A new technique for dynamic well control addresses the need to control BGP quickly and accurately from the bottom of the wellbore and avoid the need for high surface pressure and time-consuming increases in drilling fluid density. U.S. Patent 6,457,540 B2, foreign PCT filings pending titled "Method and System for Hydraulic Friction Controlled Drilling and Completing Geopressures Wells Utilizing Concentric Drill Strings" is a proven control of critical high-pressure wells while drilling. It employs a combination of fluid injection down the drill pipe annulus and concentric casing annulus to create friction pressures on the return annulus and establish the desired ECD at depth to drill near balance, at balance or underbalanced in the formation. During connections, the normal standpipe injection volume is added to the normal annulus injection volume so the ECD remains constant, thus eliminating the bottom hole pressure surges associated with connections and minimizing connection gas influx.

The method employs a "continuous circulation system" and meets all the "technical obstacle requirements" previously listed. Average cost reduction in rig time saved could be as much as $1.0 million for an offshore well.

• Expands the operating window between ECD and Frac Gradient
• Reduces the excessive cost of circulating out connection gas
• Creates near constant and controllable ECD pressures
• Added well control during trips
• Continuous circulation during connections
• Can be run with all down hole deployment casing valves
• Contains all working pressures below rotary table not on rig floor
• The system has an attached whip stock (up stock) for multilateral deviation or re-entry
• The system can be run in open or cased holes
• The system can be stripped out of hole to keep UB environment at TD
• The system can be run in straight, deviated or horizontal configured well bores
• The system is designed for all MPD situations, under-balanced or tight ECD environments