Wells – Processes – Cementing – plugging or consolidating
Reexamination Certificate
2001-06-15
2002-05-14
Suchfield, George (Department: 3672)
Wells
Processes
Cementing, plugging or consolidating
C166S117600, C166S242100, C166S313000, C166S380000, C175S061000, C175S080000
Reexamination Certificate
active
06386287
ABSTRACT:
FIELD OF THE INVENTION
The present invention is directed to a borehole drilling assembly and in particular to an assembly for drilling and completing deviated boreholes.
BACKGROUND OF THE INVENTION
Deviated boreholes are drilled using whipstock assemblies. A whipstock is a device which can be secured in the casing of a well and which has a tapered, sloping upper surface that acts to guide well bore tools along the tapered surface and in a selected direction away from the straight course of the well bore.
To facilitate the use of a whipstock, a section of casing is used which has premilled window openings through which deviated well bores can be drilled. The whipstock can be positioned relative to the window using a landing system which comprises a plurality of stacked spacers mounted on a fixed mounting device at the bottom of the casing and defining at the top thereof a whipstock retaining receptacle, or by use of a latch between the whipstock and the casing. A stacked landing system can cause difficulty in aligning the whipstock with the window opening as the distance between the mounting device and the window increases. The whipstock may also turn during the drilling or setting processes resulting in the deviated well bore being directed incorrectly and/or the well bore tools being stuck in the wellbore. Sometimes a latch system is used to overcome some of these disadvantages. However, the latch can sometimes disengage between the whipstock and the casing, allowing the whipstock to turn or move down in the casing. After the deviated wellbore is drilled, it can be left uncompleted or completed in any suitable way. To seal the deviated wellbore hydraulically from the main casing, a liner can be installed and cement can be pumped behind the liner. This is expensive and often creates obstructions in the main casing which complicates removal and run of the tools. When the tools are used in horizontal primary bores, new problems arise. Running and retrieval tools which are useful for vertical tool manipulation are not always useful in horizontal applications.
SUMMARY OF THE INVENTION
An assembly for drilling and/or completing a deviated wellbore has been invented. In one aspect the assembly includes a toolguide which can be positioned relative to a window opening in a casing section and releasably locked in position. The toolguide or portions thereof can have applied thereto a coating which prevents damage to the metal components of the toolguide and facilitates removal of the toolguide from the wellbore after use.
A tool guide for creating deviated borehole branches from a wellbore includes a whipstock including a sloping face portion and a lower orienting section, including at least one latch biased radially outwardly from the orienting section and positioned in a known orientation relative to the sloping face portion and a latch locking means to releasably lock the latch in an extended position, the latch locking means being actuated to lock the latch by torsion of the mandrel within the lower orienting section.
Each latch of the orienting section is selected to fit within and lock into its own latch receiving slot formed in the casing. When the latch of the orienting section is locked into the latch receiving slot the toolguide will be maintained in position in the casing. Preferably, the casing includes at least one premilled window opening positioned in known relation relative to the latch receiving slot. Preferably, a removable liner can be positioned in the casing to close the window opening temporarily and to cover the latch receiving slot.
The orienting section can be releasably connected to the whipstock. Such connection is preferably by connectors such as, for example, shear pins to the whipstock so that these parts can be installed together into the casing. Preferably, the connectors are selected such that the sections can be separated by an application of force sufficient to overcome the strength of the connectors. This permits the whipstock and the lower section to be separated and removed separately should one part become stuck in the casing.
The sections are movable relative to one another and means are provided to translate such movement to actuate such means as a seal.
Preferably, the lower orienting section includes a mandrel engaged slidably and rotatably within an outer housing. The mandrel is releasably connected to the whipstock and moveable with the whipstock. Preferably, the latch locking means is an extension of the mandrel. The extension can be formed to fit behind the latch to lock it in the outwardly biased position.
Another toolguide for creating borehole branches from a wellbore, the toolguide having a longitudinal axis and comprising a whipstock including a sloping face portion, a lower orienting section, the whipstock and the lower orienting section being connected and moveable relative to each other along the longitudinal axis of the toolguide, and an annular sealing means mounted below the whipstock, the annular sealing means being actuatable to expand and retract upon movement of the whipstock and the lower orienting section relative to one another.
The whipstock is attached to a central mandrel of the lower orienting section. The central mandrel is engaged slidably and rotatably within an outer housing of the lower orienting section. The outer housing carries the annular sealing means which is actuatable to expand or retract by movement of the mandrel within the outer housing. Preferably, the outer housing includes a first section and a second section and disposed therebetween the annular sealing means. The first section is moveable toward the second section to compress the annular sealing means therebetween and cause it to expand outwardly. In this embodiment, preferably the mandrel has a shoulder positioned thereon to abut against the first section and limit the movement of the mandrel into the outer housing. Abutment of the shoulder against the first section causes the first section of the housing to be driven it towards the second section and the annular sealing means to be compressed and expanded outwardly.
Previous orienting tools were difficult to use because it was necessary to run the tool to a known depth and then search around for the position of the slot for accepting the latch on the tool. Because the latches of some orienting tools have to be biased outwardly on the trip down into the well, it has been difficult to use the orienting tools in wells, for example, having more than one lateral window and therefore more than one orienting slot for accepting the latch of the tool. To the problem of having the latch lock into the incorrect slot, where multiple slots are present, it has been necessary to shape the slots in the casing such that they will only accept one form of latch. This solution presents logistical problems, however, and limits the number of slots which can reasonably be positioned in the casing.
Thus, in accordance with one broad aspect of the present invention, there is provided an orienting tool for positioning in a well bore casing having a profile positioned therealong, the tool comprising: a body; at least one member mounted on the tool body and biased outwardly, at a selected pressure, therefrom, the selected pressure being great enough to permit determination of when the at least one member has moved past the profile but not being so great as to prevent the at least one member from moving past the profile using normal force.
The at least one member can be a spring loaded dog or an arm such as, for example, a part of a collet, a collar locator or any other means. In preferred embodiment, the at least one member is part of a ring of dogs mounted about a circumference of the tool body and biased outwardly therefrom. The at least one member preferably operates to position the tool at a selected pressure of 20,000 to 30,000 psi. At this pressure, when the member passes a profile, there will be a indicative overpull or decrease in drill string weight.
The at least one member can be biased outwardly by any desired m
Castano Jaime A.
Griffin Jeffrey E.
Schlumberger Technology Corporation
Suchfield George
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