Patent ID: 8590615
Filing Date: 2013-11-26
Classification: E21B

Abstract:
1. A system for drilling and completing an underground borehole extending through a plurality of petroleum-bearing formation zones, the system comprising: a production casing axially extending in the borehole and containing production equipment for producing petroleum from the plurality of petroleum-bearing formation zones; first and second packers on the production casing, both the first and second packers being selectively radially expandable away from the production casing to thereby seal an annulus between the production casing and the borehole so as to prevent flow of production fluid therepast, both the first and second packers further being selectively radially contractible towards the production casing to unseal the annulus and thereby allow flow of production fluid therepast; the first and second packers being axially spaced apart from each other along the production casing such that a portion of the annulus extends therebetween, and at least the first packer being connected to a sliding sleeve that is disposed on the production casing, the sliding sleeve and the first packer being axially movable together along the production casing; wherein the production casing comprises a downhole end, the system further comprising a drilling head that carries out drilling of the underground borehole, the drilling head being located at the downhole end of the production casing; and an inner casing disposed inside the production casing and a return pipe between the inner casing and the production casing, the return pipe carrying drilling fluid associated with the drilling head.