Shallow Water Flow Planning and Operations: Titan #1 Exploration Well, Deepwater Gulf of Mexico

Shallow water flows (SWF) from overpressured aquifers have been a persistent problem in the deepwater Gulf of Mexico (GOM) and can create significant financial and operational risks for exploration and development drilling programs. For the GOM, shallow water flow intervals typically occur between 300 ft to 2500 ft below mudline (BML) and in water depths greater than 1500 ft. If left unchecked, the disturbance from the water flow can cause loss of soil strength surrounding the wellbore, thereby compromising the structural integrity of the well. In industry, extreme cases have led to collapsed casing and/or total loss of wellbores. The Titan No. 1 exploration well was drilled in Garden Banks Block 785 (GOM), in 4640 ft of water. At Titan, the planning and successful implementation of operational procedures designed to mitigate the risks associated with SWF hazards included: performing a shallow hazards assessment, preparing and implementing SWF contingency plans, identifying the SWF zone quickly, immediately controlling the water flow zone with weighted mud (while drilling riserless), and using nitrified foam cement to seal off the water flow behind 20 conductor pipe. Operations at Titan were based on the philosophy of quickly identifying the SWF, and immediately stopping the flow with weighted mud, as the chance of successfully mitigating the flow and maintaining the structural integrity of the wellbore will likely decrease with time if the sand is allowed to produce water, sand and/or sediment.