| 摘要 |
<p>This invention provides apparatus and methods for controlling the particle size of the solid mass present in the circulating drilling fluid returning from an underwater wellhead during the drilling of a subsea wellbore. The system may include a separator at the sea floor adjacent the wellhead, which separates solids above a predetermined size from the wellstream. The wellstream then enters one or more underwater pumps, which pump the wellstream to the surface. A crusher, as a separate unit, integrated in the separator or in the pump, receives the separated solids and reduces them to relatively small-sized particles. The small particles are then pumped or moved to the surface by the pumps utilized for pumping the wellstream to the surface or by a separate underwater pump. Alternatively, the separated solids are collected from the separator into a container, which container is then transported to the surface by a suitable method. Solids reaching the surface are removed to obtain filtered fluid, which after conditioning by conventional methods is pumped back into the wellbore as the drilling fluid.</p> |
