Method and apparatus for cementing a well

Abstract

A method of cementing a well permitting a reduction in the degree of diameter reduction of casing or liners required, and not requiring excessively large initial conductor casing, is described. The method is characterized by provision of an enlarged wellbore and a novel liner structure which is adapted for expansion of a reduced diameter section thereof downhole, providing, before expansion of the section, unimpeded flow of fluid from the enlarged wellbore during cementing and close fit of the expanded section with the casing or preceding liner, after cementing is completed and expansion of the section. A novel well liner structure and novel well liner expansion means are disclosed.

Description

FIELD OF THE INVENTIONThis invention relates to a method for cementing a well and to apparatus useful in well cementing operations.BACKGROUND OF THE INVENTIONIn the conventional drilling of a well, such as an oil well, a series of casings and / or liners are commonly installed sequentially in the wellbore or borehole. In standard practice, each succeeding liner placed in the wellbore has an outside diameter significantly reduced in size when compared to the casing or liner previously installed. Commonly, after the installation of each casing or liner, cement slurry is pumped downhole and back up into the space or annulus between the casing or liner and the wall of the wellbore, in an amount sufficient to fill the space. The cement slurry, upon setting, stabilizes the casing or liner in the wellbore, prevents fluid exchange between or among formation layers through which the wellbore passes, and prevents gas from rising up the wellbore.The use of a series of liners which have sequentia...

AI Technical Summary

Benefits of technology

In yet further embodiments, the invention relates to a novel liner, which may additionally include expansion means therein; to an apparatus or tool for expansion of a liner having a reduced diameter section; and to a novel liner-die assembly or combination which is useful in cementing operations. More particularly, the liner of the invention comprises a wellbore liner having a .[.minor.]. section of reduced external and internal diameter composed of a deformable material and a .[.larger.]. remainder section of increased external and internal diameter. The expansion device or apparatus of the invention comprises unique fluid tight die means adapted for expansion of a liner section of reduced internal and external diameter, and preferably comprises a means for transmitting a fluid, e.g., a pipe; a die member adapted for expanding, at least substantially uniformly, the bore of a liner, on the periphery of said pipe; and sealing means positioned on the periphery of the die member adapted to provide a fluid tight seal between the bore of a liner and said die member. In the preferred arrangement, the pipe is provided at one end thereof with means for connecting the pipe to, or for suspending the pipe from, a drillstring, and is further preferably provided at the opposite end thereof with means for suspending a tool, preferably components used in cementing operations, and, especially, in one aspect of the invention, means to assist in sealing the end of the liner distant from said opposite end of the pipe.

Problems solved by technology

If the driller encounters an extended series of high pressure / low pressure configurations, the number of liners required under such circumstances may be such that the well cannot usefully be completed because of the continued reduction of the liner diameters required.

Again, a further problem of the standard well liner configuration is that large volumes of cuttings are produced initially, and heavy logistics are required during early phases of drilling.

While several approaches to the resolution of these problems have been attempted, none have proven totally satisfactory.

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