Research On Deep-water Top Tension Risers Selection And Initial Design

Riser is an important component in the oil and gas resources development system, but also is one of the weakest members. So the safety of deep water riser design plays an important role in oil and gas production systems. This paper focuses on deepwater TTR system selection and initial design problem, considering the factors of the oil and gas pipeline transportation capacity and casing strength.The multiphase flow theory is used to calculate the pressure drop and riser transportation capacity. Based on it, this paper finishes the iterative calculation and selection of tubing and casing size, and ultimately checks the tubing and casing wall thickness.Firstly, this paper describes the design criteria for deepwater riser systems, including design principles, the design phase, the design process and the design basis document content; lists the commercial design software and design specification that are used for dynamic rigid riser design, and describes the study content and research progress about TTR riser system design. Secondly, based on the National863Program "top tensioned riser (TTR) design theory research and software development," This paper establishes a TTR production riser design basis documents, including the TLP principal dimensions, the reservoir and the wellhead data, and marine environmental data.Based on the API specification, this paper proposes the TTR front initial design process, considering the relationship between the tubing and casing. This paper uses the theory of vertical riser multiphase flow pressure drop calculations. According to the reservoir and the wellhead data, it finishes the tubing hydraulic analysis to calculate the corresponding pressure gradient and pressure drop at different flow rates, and selects the smallest pressure drop corresponding to the inner diameter of the tubing that is tubing as the initial diameter. And then according to API SPEC5L and API SPEC5CT, it determines the size and the material of casing and tubing. Finally, for the selected riser size, according to API RP2RD, the minimum wall thickness is calculated by using the simplified method and checked by the wall thickness analysis.