| 摘要 |
In a process of downhole drilling in an open hole, where the drill bit has struck a lost circulation zone in the wall of the formation, and mud circulating through the annulus during drilling has been lost into the zone and therefore circulation of the mud has been lost, the process for reestablishing circulation downhole would include the steps of (b) closing off any flow of mud out of the annulus substantially at the level of the earth's surface; (a) introducing a quantity of lighter fluids such as salt water into the annulus so that the annulus becomes filled with the lighter fluid; (c) pushing a quantity of the mud in the annulus into the formation by the weight of the lighter fluid in the annulus, thus lowering the weight of the column of fluid in the annulus; (d) in calculating the mud weight necessary to circulate out the heavy mud with the lighter fluid; and introducing the lighter weight mud into the hole and into the drill pipe, for allowing the heavier mud to circulate up through the annulus to be replaced by the lighter mud.
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