Wells – Valves – closures or changeable restrictors – Longitudinally movable operator
Reexamination Certificate
2000-03-17
2001-07-31
Suchfield, George (Department: 3672)
Wells
Valves, closures or changeable restrictors
Longitudinally movable operator
C166S242100, C166S242900, C166S378000, C166S334400
Reexamination Certificate
active
06267181
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to a method for cementing a well and to apparatus useful in well cementing operations.
BACKGROUND OF THE INVENTION
In 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 sequentially reduced diameters is derived from long experience and is aimed at avoiding problems at the time of insertion of casing or liner installation in the wellbore. The number of liners or casings required to reach a given target location is determined principally by the properties of the formations penetrated and by the pressures of the fluids contained in the formations. 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.
The present invention is directed to a well lining and cementing technique or procedure, and means to carry it out, which would eliminate or significantly reduce the degree of diameter reduction required when a series of well liners must be inserted.
SUMMARY OF THE INVENTION
There is thus provided, in one embodiment, a method or process, useful in cementing a well, especially a hydrocarbon well, which is characterized by the use of increased external and internal diameter liners, i.e., by a reduction in the degree of diameter reduction of the liners required, and which does not require excessively large initial conductor casing or surface pipe. Accordingly, in this embodiment, the invention relates to a method of cementing a wellbore in which a casing or first liner is provided in a wellbore. As utilized herein, the terms “first” and “second”, etc., in relation to the casing or liners mentioned, are relative, it being understood that, after the initial “second” casing or liner is cemented, it may become a “first” liner for the next cementing operation as such operations proceed down the wellbore. Moreover, the “first” liner may actually be at a location down well if previous liner techniques have been utilized in “upper” liner sections. Regardless, the bottom end of the casing or a designated “first” liner is provided with or terminates in a specially shaped joining section (or joint) of somewhat reduced or decreased internal diameter (compared to the normal internal diameter of the casing) adapted to stabilize and/or provide support for an additional section of liner, as described more fully hereinafter.
Further drilling operations are then conducted, preferably after cementing the casing or first liner, to provide an enlarged wellbore. As used herein, the term “enlarged wellbore” refers to a wellbore or borehole having a diameter greater than that of the normal internal diameter of the casing or preceding liner, preferably greater than the largest external diameter of the casing or preceding liner, such a wellbore being provided or drilled in a manner known to those skilled in the art, as also described more fully hereinafter. At a desired depth, or when it is otherwise decided to line and cement the enlarged wellbore, there is provided in the casing or liner a liner-tool assembly which comprises a wellbore liner, having at least one port for wellbore fluid flow, and a novel fluid circulating tool disposed in the liner. The liner-tool assembly is adapted to provide a first fluid flow path for transmission of a fluid through the fluid circulating tool and the liner and into a wellbore, and a second separate fluid flow path for transmitting fluid received from exterior or outside the liner through the port or ports and through the fluid circulating tool in a direction opposite that of the first flow path. For simplicity, as used hereinafter, except where inconsistent with clearly intended meaning, e.g., in describing specific embodiments where a plurality of ports is illustrated, the term “ports”, will be understood to include a single port, the requirement of the invention being simply that sufficient flow opening or aperture be provided, although a plurality of openings is preferred. Preferably, the greatest external (outside) diameter of the liner or second liner of the liner-tool assembly approximates, i.e., is only slightly smaller, than the normal or smallest internal diameter of the casing or first liner provided. In a preferred embodiment, the liner or second novel liner comprises a minor section or segment whose outside diameter may closely approximate the normal internal diameter of the previous casing or liner and a major portion or section having an external -diameter which approximates that of the joining section or segment. The minor and major sections of the liner are joined or coupled in suitable manner, communicating preferably through a tapering section, and the liner portion or junction where they join is preferably of unitary or integral construction. The size differential between the segments permits provision of the length of the major section of the liner through the aforementioned bottom joining section and into the wellbore while retaining the minor section in the previous casing or liner in or above the bottom joining section or segment.
According to the invention, therefore, the liner-tool assembly is then positioned in the wellbore so that the ports are positioned proximate and beneath the casing in the enlarged wellbore. In the case of the preferred embodiment, the liner or second liner is positioned in relation to the enlarged wellbore, with the ports placed as mentioned, so that the minor section or segment is located or positioned in the lower portion of the casing or first liner and in such manner that the weight of the second liner may be supported by the upper or first casing or liner.
To position the liner or second liner, as described, there is disposed or provided on the drill string or tool, as part of the liner-tool assembly mentioned, inside the bore of the liner or second liner, as more fully described hereinafter, a movable, fluid circulating tool of appropriate dimensions, preferably positioned in said liner distant from the bottom of the major segment and disposed or partly disposed in the major and minor sections or segments, and which, after initial positioning or installation by the string, is fixed thereby in relation to the wellbore. The fluid circulating tool comprises a member appropriately sized and adapted or shaped to allow a separate or first fluid flow path or passage(s) for transmission of a fluid or fluids through a liner into a wellbore and, in conjunction with ports and means provided, a second fluid or flow path or passage(s) for transmission of wellbore fluid in a direction opposite that of the first fluid flow path. The invention thus provides flow without substantial or significant impediment from the annulus formed by the liner and the enlarged wellbore to the interior or bore of the casing or first liner, and up the well. The novel fluid circulating tool may further comprise or contain appropriate sealing means on the member for preventing significant passage of fluid past that portion or portions of its peripher
Milne Arthur W.
Pessin Jean-Louis
Prouvost Laurent P.
Rhein-Knudsen Erik
Vercaemer Claude J.
Mitchell Thomas O.
Nava Robin C.
Schlumberger Technology Corporation
Suchfield George
LandOfFree
Method and apparatus for cementing 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 and apparatus for cementing a well, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Method and apparatus for cementing a well will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2518457