Abstract
Extended Reach Drilling (ERD) and Maximum Reservoir Contact (MRC) well design can drastically decrease development costs. A critical ERD and MRC challenge is frictional drag encountered when running long casing and liner strings. If the frictional drag becomes too great the string will stall before reaching total depth (TD), severely compromising the completion of the well. This paper presents the implementation of the casing swivel tool to effectively mitigate this friction risk.
String rotation can provide a large reduction in axial drag by shifting the friction vector to primarily affect the torsional direction. Full string rotation offers the largest benefit, but the torque required often exceeds both the casing connection rating and top drive capability. The use of a swivel enables partial string rotation above the swivel to reduce the torque requirement. With increasing production lateral lengths the swivel was moved from the running string into the liner to increase the rotating length of pipe while managing rotational torque.
The drill pipe swivel has a long history of effectively providing a reduction in axial drag by allowing for the running string to be rotated when running long MRC lower completion liners. As lateral lengths have increased from 10,000 feet up to 20,000 feet in Extended MRC (EMRC) wells, the ratio of liner length to running string length has greatly increased. To accommodate this shift in well design the swiveling point needed to be pushed deeper into the well, from running string to the liner. The fit-for-purpose design of the sacrificial casing swivel allows it to be integrated permanently into the completion and enables increased partial string rotation.
To date the casing swivel has been deployed on eight wells, including a world record single-run 6-5/8″ production liner. In one well, the liner stalled and only reached TD after engaging the swivel. The use of the casing swivel has reduced the required well count and capital investment by enabling lateral sections of up to 20,000 feet while also decreasing drilling risk due to less overburden drilling.
The application of casing swivel in the Giant Offshore Oilfield Abu Dhabi was a first for this size and length of lower completion liner. The casing swivel has become a key enabler to maximizing the length of production laterals resulting in substantial well construction cost savings.
