Importance

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Abstract

A method of providing a casing in well from a series of casing sections. The first section is provided from the top of the well and the subsequent sections are arranged progressively downwards therefrom. The subsequent section to be fitted is lowered into the well by a suitable lowering tool, such as a coiled tubing runner. The well fluids which are displaced by the lowering of the subsequent section and the lowering tool, passes from the lower portion of the well up through the internal bore of the section to be fitted. The displaced fluids pass out from the internal bore of the lowering tool into an outside annulus between the lowering tool and existing casing through radial closable openings or side valves. A lockable nonreturn valve is provided at the lower end of the section to be fitted and normally permits flow downwardly out of the casing and prevents flow upwardly into the casing but which may be optionally arranged in a locked open position to permit the well fluids to flow inside the internal bore of the section to be fitted.

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First Claim