Stability Analysis of Drilling Pipe and Subsea Wellhead for Riserless Drilling in Deepwater
- Yuhan Liu (China University of Petroleum) | Honghai Fan (China University of Petroleum) | Deqiang Tian (China University of Petroleum) | Zixiang Wen (China University of Petroleum) | Wenlong Jiang (China University of Petroleum) | Yuguang Ye (China University of Petroleum) | Longteng Yu (China University of Petroleum)
- Document ID
- International Society of Offshore and Polar Engineers
- The 28th International Ocean and Polar Engineering Conference, 10-15 June, Sapporo, Japan
- Publication Date
- Document Type
- Conference Paper
- 2018. International Society of Offshore and Polar Engineers
- vortex-induced vibration, stability, deepwater, riserless drilling
- 2 in the last 30 days
- 72 since 2007
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With the development of drilling in deep water, the Riserless Mud Recovery System (RMR) shows the huge advantage. Relative to the riser drilling, there is less research of analysis for the string and wellhead stability. This paper analyzes the whole loading of the drilling pipe and shallow casing in riserless drilling. An integral static model of the string and the wellhead and a dynamic model of drilling pipe are established respectively in this paper. Some useful conclusions are summarized after computing, such as: the shallow layer of deep water drilling should focus on the influence of vortex-induced vibration; the increase of the velocity of tidal current on the surface of sea and the offset of the drilling platform will increase the displacement and bending moment of the wellhead.
Most of the world's land and shallow offshore oil and gas development has entered the middle and late stage, and the development of oil and gas resources is gradually turning to the deep sea. Drilling in deep water faces huge challenges: because of the narrow gap between pore pressure and fracture pressure, multi-layer system of casing is indispensable, and drilling depth is limited by many factors; the load of large and long riser system under the harsh marine environment is very complicated, which is easy to cause the drilling accident (Choe, 1999). In the dual-gradient drilling technology, the Riserless Mud Recovery (RMR) System carried out by Norwegian AGR Company can effectively solve the various problems caused by the use of riser system and shorten the construction cycle (Stave, 2005). Through field test, this technology has already promote industrial applications, which show a significant economic impact.
As the name implies, the main characteristic of riserless drilling is no riser used during the whole stage of drilling operation: the drilling pipe is directly contact with the water in the sea section, the Suction and Centralizing Module (SCM) is installed at the wellhead to separate the wellbore and water, and the drilling fluid and cuttings are returned to the drilling platform from the wellhead through another reverse line. The schematic diagram of riserless drilling system is shown in the figure 1.
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