| 摘要 |
<p>METHOD FOR PLACEMENT OF PRODUCTION CASING UNDER OBSTACLE A system and method of installing a production casing along an inverted underground arcuate path beneath and spanning an obstacle such as a river is disclosed. The casing is installed along the inverted arcuate path of a pilot string occupying a pilot hole underlying the obstacle. The pilot hole spans the obstacle from a first position at or near ground level on one side of the obstacle to a second position at or near ground level on the other side. An oversized casing having an inner diameter greater than the outer diameter of the production casing is first advanced into and partially along the pilot hole from one side of the obstacle. The oversized casing is advanced along the path of the pilot hole until it becomes frozen in place or is substantially impeded typically by friction. The production casing is then advanced through the interior of the oversized casing along the extent of the path of the pilot hole occupied by the oversized casing and along the remainder of the path of the pilot hole to the other side of the obstacle. If desired, second oversized casing can be advanced into and partially long the path of the pilot hole from the other side of the obstacle as well. When extremely wide obstacles are to be traversed, it may be desirable in addition to advance secondary oversized casings inside the initial oversized casings and along the path of the pilot hole until they too are substantially impeded by friction. In this manner, the production casing can be installed beneath and spanning extremely wide obstacles.</p> |
