| 摘要 |
<p>A method and system for controlling drilling mud density in drilling operations. The mud required at the wellhead is combined with a base fluid of a different density to produce diluted mud in the riser. By combining the appropriate quantities of drilling mud with base fluid, riser mud density at or near the density of seawater may be achieved, thereby permitting greater control over the pressure in the wellbore and various risers. Blowout preventers may also be used in combination with the process to control these pressures. Concentric risers are disclosed, wherein an annulus defined within one riser is utilized to carry the different density base fluid to the inj ection point for inj ection into the drilling mud, while an annulus defined within another riser is utilized to carry the combination fluid and cuttings back to the drilling rig. Cuttings are separated in the usual manner at the surface. The diluted mud is passed through a centrifuge system to separate drilling mud from the different density base fluid. The centrifuge system may also be utilized to separate the recovered drilling fluid into a substantially barite portion and a substantially drilling fluid portion, wherein the two portions are stored locally at the rig and recirculated during drilling operations.</p> |
