| 摘要 |
A restrictor device (6) for controlling a return flow of drilling fluid from a borehole (51) where drilling fluid is provided from a surface installation (3) via a drill string (4) to a bottom-hole assembly (45), drill pipes (41) forming the drill string (4) being provided with pipe joints (42) including enlarged-diameter pipe portions (43), and where an annulus (22) is formed between a pipe, for example a marine riser (1), and the drill string (4), and where the annulus (22) is in fluid communication with or forms parts of a drilling-fluid flow path (23), and where the restrictor device (6) is arranged in the annulus (22), the restrictor device (6) being formed of a restrictor pipe (61) anchored to said riser (1) and surrounding at least one restrictor element (64) placed on an intermediate pipe portion (44) that connects two enlarged-diameter pipe portions (43), and the length (L) of the restrictor device (6) exceeding the largest distance (M) between two consecutive restrictor elements (64), the restrictor element (64) being a drill-pipe/casing protector (DPP) with an external diameter larger than a diameter of the pipe joints (42). |
| 主权项 |
1. A restrictor device (6) for controlling a return flow of drilling fluid from a borehole (51) where drilling fluid is provided from a surface installation (3) via a drill string (4) to a bottom-hole assembly (45), drill pipes (41) forming the drill string (4) being provided with pipe joints (42) including enlarged-diameter pipe portions (43), and where an annulus (22) is formed between a pipe, for example a marine riser (1), and the drill string (4), and where the annulus (22) is in fluid communication with or forms parts of a drilling-fluid flow path (23), and where the restrictor device (6) is arranged in the annulus (22), the restrictor device (6) being formed of a restrictor pipe (61), anchored to said riser (1), and surrounding at least one restrictor element (64) placed on an intermediate pipe portion (44) that connects two enlarged-diameter pipe portions (43), and the length (L) of the restrictor device (6) exceeding the largest distance (M) between two consecutive restrictor elements (64), characterized in that the restrictor element (64) has an external diameter that is larger than the diameter of the pipe joints (42). |
