Wells – Processes – Cementing – plugging or consolidating
Reexamination Certificate
1999-06-02
2001-05-01
Bagnell, David (Department: 3672)
Wells
Processes
Cementing, plugging or consolidating
C166S386000
Reexamination Certificate
active
06223823
ABSTRACT:
SPECIFICATION
1. Field of the Invention
The invention relates to a method of installing the casing in a well land an apparatus therefor. Casings are required in wells in order to separate the well from the surrounding formations. Typically the casing is provided in sections which are lowered into the well following the drilling of each corresponding section of the well.
2. Background of the Invention
For the casing of a well, each casing section could be installed inside the previously installed section and consequently its external diameter has to be less than the internal diameter of the installed section. Furthermore it was necessary that an annular gap between the internal diameter of the installed section and the external diameter of the next section be sufficient to accommodate the connecting means between the two sections which includes hanging and packing means as well as the additional diameter of the joints between each length of tubing making up each section. The annular gaps between each subsequent casing section determine the size of the first casing section which is required to be sufficiently large to enable all the required subsequent casing sections to be passed through it and installed in the well. The final casing section is of sufficient diameter to carry out all the desired functions in the production zone of the well, which may require over 5 different lengths of casing sections. This results in the first casing section being very large in diameter and therefore expensive and requiring a large diameter hole to be drilled out in order to accommodate it. Furthermore it may be necessary due to the large diameter of the upper sections to extend the smaller diameter lower sections all the away to the surface in order that the required pressure resistance is provided.
OBJECT OF THE INVENTION
The object of the invention therefore is to reduce the required diameter of the sections to considerably reduce the overall costs of the well both in terms of the drilling itself and disposable of the drilled material and in terms of the costs of the large diameter sections.
It has been proposed previously to provide lower diameter sections by reducing the annular space as much as possible, for example in U.S. Pat. No. 5,307,886. The result is a narrow annulus and with the method of installation disclosed in this patent and used conventionally the problem is that the well fluids displaced by the introduction and lowering of the subsequent casing section into the well have to pass up the annular space to exit the well at the surface. This presents considerable disadvantages due to the very high friction pressure which must, be overcome in order for the well fluids to pass up the narrow annular space. Consequently even with high hydrostatic pressures the installation is very slow due to the time taken for the fluids to pass up the annular space. Additionally the circulation of cement is very problematic because it relies on the displacement of the mud fluids in the well. It is difficult to effectively displace all of the mud which causes incomplete cementing.
SUMMARY OF THE INVENTION
According to the invention there is provided a method of installing a casing section in a well, wherein the casing section to be installed is lowered into the well by means of first and second connection means arranged on a tubular lowering means, the first connection means being connected at an upper end of the casing section and the second connection means being connected at a lower end of the casing section, with tubular means extending through the casing section.
Preferably first and second flow paths are provided in each of the first and second connection means to enable fluids from the well to pass through the inside of the casing, as the casing is lowered into the well.
The first and second flow paths may be ports controlled by valves which are held in the in the open position, during the lowering of the casing.
Preferably the first and second connection means are connected by the tubular lowering means which extends through the first connection means to the second connection means. A hollow is provided through the second tool part connecting the inside of the tubular lowering means to the outside of the casing.
Preferably a lockable non return valve is provided in the hollow which when in the locked open position permits the well fluids to flow from inside the internal bore of the tubular lowering means to the well outside the section being installed, and also permitting fluids to flow from the well to the inside of the tubular lowering means and thus back to surface. When the casing to be fitted has been lowered to its installed position the lockable return valve is unlocked thus operating as a conventional non return valve and preventing the unwanted flow of fluids up the internal bore of the section being installed.
This may be done by pressurizing an activating ball, which is of such dimensions that it releases a catch device, which had been holding the non-return safety valve in the open position.
The casing sealing cement is then pumped down through the internal bore of the lowering means through the lowering tool and down through the internal bore of the casing section being installed, out through the bottom end thereof through the open non-return valve and back up to fill the annular space between the casing section being installed and the drilled well.
The well fluids are displaced upwards through the gap between the casing being installed and the existing casing, into the annular space between the tubular lowering means and the existing casing section.
REFERENCES:
patent: 3910349 (1975-10-01), Brown et al.
patent: 4096913 (1978-06-01), Kenneday et al.
patent: 4364432 (1982-12-01), Bass et al.
patent: 5197553 (1993-03-01), Leturno
patent: 5307886 (1994-05-01), Hopper
patent: 5918674 (1999-07-01), Head
patent: 5918677 (1999-07-01), Head
Bagnell David
Dawelbeit Kamal
Dubno Herbert
LandOfFree
Method of and apparatus for installing casing in a well does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Method of and apparatus for installing casing in a well, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Method of and apparatus for installing casing in a well will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2501717