Wells – Processes – Perforating – weakening – bending or separating pipe at an...
Reexamination Certificate
2000-03-10
2001-09-11
Suchfield, George (Department: 3672)
Wells
Processes
Perforating, weakening, bending or separating pipe at an...
C166S055100, C166S240000, C175S061000
Reexamination Certificate
active
06286599
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to the drilling of side tracks from a main wellbore, and more particularly, to the use of hydrajetting to cut a window in the well casing prior to drilling, thereby facilitating the drilling operation and providing a desired window shape and size. This allows a fit for subsequent tools or casing strings to be inserted through this window.
2. Description of the Prior Art
Many wells today have a deviated bore or side track drilled extending away at an angle from a generally vertical main wellbore. The drilling of such a side track is accomplished by several steps. After casing the main wellbore, a multi-stage milling process is utilized to laterally cut a window through the casing at the general location where it is desired to start the side track. Once the window is milled open, the drilling process may begin. The problem is that casing is made of hard steel, and it is very common for the drill bit to chatter on the steel. This can cause drill breakage and/or produce erratic cutting of the window. Typically, the window is a relatively long, elongated opening, preferably somewhat teardrop shaped, and cutting the window is very time consuming and correspondingly expensive.
There is a need, therefore, for apparatus and methods of cutting windows which can be accomplished more quickly and less expensively and also in a manner assuring a more precise cut of the casing.
The present invention solves this problem by providing for the use of hydrajetting to cut, or at least partially cut, the window in the casing. After the window is more precisely cut using this method, drilling of the actual side track is carried out more quickly and with fewer problems.
SUMMARY OF THE INVENTION
The present invention relates to methods of drilling a side track in a well and apparatus therefor. The method generally comprises the steps of positioning a hydrajetting tool or tools adjacent to a preselected portion of a length of casing in the well, pumping fluid preferably containing abrasives through the tool such that the fluid is jetted therefrom, moving the tool or tools in a predetermined pattern while jetting fluid therefrom such that the pattern is at least partially cut into an inner surface of the well casing to form a window therein, and drilling through the window to form the side track extending from the casing. The preferred predetermined pattern is generally teardrop shaped.
In this method, the tool comprises a guidance or cam means such as a J-sub and a hydrajetting sub with a jetting head and nozzle thereon. The J-sub comprises a collar defining a collar J-slot therein which is generally shaped in the predetermined pattern, and a mandrel having a mandrel pin extending into the collar such that relative movement between the mandrel and collar is guided by the engagement of the mandrel pin in the collar J-slot. The guidance means can comprise substantially any known cam and follower apparatus known by those skilled in the art which would provide the desired shape through travel of the follower, in guiding the jetting head, about the cam. The jetting head is connected to the mandrel and movable therewith. The step of moving the tool comprises moving the mandrel longitudinally and rotationally with respect to the collar.
In an alternate embodiment, the tool comprises an actuator sub connected to at least one mandrel. The step of moving the mandrel comprises activating the actuator sub. Preferably, the actuator sub is hydraulically activated and the step of activating comprises alternately pressurizing and depressurizing the hydrajetting tool.
The actuator sub comprises a housing and a plunger defining a central opening therethrough and movably disposed in the housing. The housing and plunger define a hydraulic chamber therebetween in communication with the central opening of the plunger. Pressurizing the hydraulic chamber relatively moves the housing with respect to the plunger. Relative rotational and longitudinal movement is possible between the plunger and housing.
The method preferably further comprises holding the collar substantially stationary during the step of moving the mandrel. This may comprise hydraulically actuating hydraulic slips on the collar into engagement with the casing.
Stated in another way, the present invention includes a method of forming a side track in a well comprising the steps of (a) positioning a tool string in the casing adjacent to a desired casing portion wherein the tool string comprises a cam and follower such as a J-sub having a J-slot therein and a hydrajetting sub connected to the J-sub and having at least one jetting nozzle thereon directed toward the casing portion, (b) actuating the J-sub such that the hydrajetting sub is substantially moved and guided by the J-slot, (c) substantially simultaneously with step (b), pumping fluid through the tool string and jetting the fluid from the hydrajetting sub such that a window is at least partially cut into the well casing generally in the shape of the J-slot, (d) positioning a drill bit adjacent to the window, and (e) drilling through the window to form the side track extending from the window.
The present invention also includes an apparatus for cutting a window in a portion of well casing. This apparatus generally comprises a J-sub connectable to a tool string, and the hydrajetting sub connected to the J-sub and movable with a portion thereof. The hydrajetting sub comprises a jetting nozzle thereon which may be directed toward the casing.
More specifically, the J-sub comprises a collar defining a collar J-slot therein, the collar J-slot being generally shaped in a predetermined pattern for the window, a mandrel movably disposed in the collar, and a mandrel pin extending from the mandrel into the collar J-slot. As the mandrel pin is moved through the collar J-slot, the mandrel and hydrajetting sub are moved in a path following the predetermined pattern such that fluid jetted from the jetting nozzle will generally cut the window in this pattern.
The apparatus may further comprise an actuator sub connected to the mandrel for providing rotational and longitudinal movement thereof. In the preferred embodiment, this actuator sub is pressure activated and comprises a housing and a plunger defining a central opening therethrough and movably disposed in the housing. Alternately pressurizing and depressurizing the hydraulic chamber results in relative movement between the housing and the plunger. There may be relative longitudinal and rotational movement between the plunger and housing. This results in the mandrel and hydrajetting sub being guided by the engagement of the mandrel pin with the collar J-slot such that the jetted fluid may be directed toward the casing in the pattern of the collar J-slot.
Numerous objects and advantages of the invention will become apparent as the following detailed description of the preferred embodiments of the apparatus and methods is shown in conjunction with the drawings which illustrate such embodiments.
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Grundmann Steven R.
Keene Gary T.
Surjaatmadja Jim B.
Halliburton Energy Service,s Inc.
Kennedy Neal R.
Kent Robert A.
Suchfield George
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