Patent Publication Number: US-11396782-B2

Title: Mill to whipstock connector for a window cutting system

Description:
BACKGROUND 
     In the drilling and completion industry, boreholes are formed in a formation for the purpose of locating, identifying, and withdrawing formation fluids. Once formed, a casing may be installed in the borehole to support the formation. Often times, it is desirable to create a branch from the borehole. A whipstock is used to guide a window mill supported on a drillstring through the casing into the formation at an angle relative to the borehole. The whipstock directs the window mill to form a window or opening in the casing. 
     Generally, the window mill/whipstock is made up on a rig floor. The window mill includes a threaded hole and the whipstock includes a lug hole. Typically, the whipstock is mounted in a rotary table and the window mill is brought into position such that the threaded hole and lug hole are aligned. A shear bolt is passed through the lug hole and connected with the window mill. When the whipstock is in place and oriented, an anchor is activated. Orienting the whipstock and activating the anchor may cause the shear bolt to fracture pre-maturely resulting in an improper whipstock placement. Replacing the shear bolt and re-orienting the whipstock can be a difficult and time-consuming process. Given the need to increase efficiency, the art would be open to new systems for joining a window mill to a whipstock. 
     SUMMARY 
     Disclosed is a window cutting system including a whipstock having an outer surface, an inner surface, a recess, and a passage extending through the outer surface and the inner surface in the recess. A window mill is connected to the whipstock. The window mill includes a body having a tip portion, a pressure compartment formed in the tip portion, and an axial passage extending though the tip portion from the pressure compartment. A pin connects the window mill and the whipstock. The pin is arranged in the pressure compartment and extends through the axial passage and the passage into the recess. The pin is axially shiftable relative to the window mill and the whipstock when exposed to pressure in the pressure compartment. 
     Also disclosed is a resource exploration and recovery system including a surface system and a subsurface system including a tubular string extending from the surface system into an earth formation. The tubular string includes window cutting system including a whipstock having an outer surface, an inner surface having a recess, and a passage extending through the outer surface and the inner surface in the recess. A window mill connects to the whipstock. The window mill includes a body having a tip portion, a pressure compartment formed in the tip portion, and an axial passage extending though the tip portion from the pressure compartment. A pin connects the window mill and the whipstock. The pin is arranged in the pressure compartment and extending through the axial passage and the passage into the recess, the pin being axially shiftable relative to the window mill and the whipstock when exposed to pressure in the pressure compartment. 
     Still further disclosed is a method of disconnecting a window mill from a whipstock including running a tubular string including a window cutting system into a wellbore, introducing fluid into a pressure chamber in the window mill, shifting a pin in the window mill axially toward the whipstock, applying a torsional force to the window mill to break the pin, and shifting the window mill relative to the whipstock. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The following descriptions should not be considered limiting in any way. With reference to the accompanying drawings, like elements are numbered alike: 
         FIG. 1  depicts a resources exploration and recovery system including a window cutting system, in accordance with an exemplary embodiment; 
         FIG. 2  depicts a window cutting system including a window mill and whipstock, in accordance with an exemplary embodiment; 
         FIG. 3  depicts a glass view of the window mill joined to the whipstock through the connection system, in accordance with an exemplary aspect; 
         FIG. 4  depicts a cross-sectional side view of the window mill and whipstock in a run-in configuration, in accordance with an exemplary embodiment; 
         FIG. 5  depicts the window mill and whipstock of  FIG. 4  in a ready to disconnect configuration, in accordance with an exemplary embodiment; and 
         FIG. 6  depicts the window mill separated from the whipstock of  FIG. 4  in a ready to disconnect configuration, in accordance with an exemplary embodiment 
     
    
    
     DETAILED DESCRIPTION 
     A detailed description of one or more embodiments of the disclosed apparatus and method are presented herein by way of exemplification and not limitation with reference to the Figures. 
     A resource exploration and recovery system, in accordance with an exemplary embodiment, is indicated generally at  10 , in  FIG. 1 . Resource exploration and recovery system  10  should be understood to include well drilling operations, resource extraction and recovery, CO 2  sequestration, and the like. Resource exploration and recovery system  10  may include a first system  12  which, in some environments, may take the form of a surface system  14  operatively and fluidically connected to a second system  16  which, in some environments, may take the form of a subsurface system. 
     First system  12  may include pumps  18  that aid in completion and/or extraction processes as well as fluid storage  20 . Fluid storage  20  may contain a stimulation fluid which may be introduced into second system  16 . First system  12  may also include a control system  23  that may monitor and/or activate one or more downhole operations. Second system  16  may include a tubular string  30  formed from one or more tubulars (not separately labeled) that is extended into a wellbore  34  formed in an earth formation  36 . Wellbore  34  includes an annular wall  38  that may be defined by a casing tubular  40  that extends from first system  12  towards a toe  42  of wellbore  34 . 
     In accordance with an exemplary aspect, a window cutting system  50  is connected to tubular string  30  as is introduced into wellbore  34 . Window cutting system  50  is lowered to a selected depth, affixed to casing tubular  40 , and activated to form a window. The window represents an opening in casing tubular  40  that allows a branch to be formed from wellbore  34 . In the embodiment shown, window cutting system  50  is formed from a number of tubular segments  62   a .  62   b , and  62   c  as shown in  FIG. 2 . Each segment  62   a .  62   b , and  62   c  may be made up off-site and delivered to first system  12  for introduction into wellbore  34 . 
     In an embodiment, first segment  62   a  may support a measurement while drilling (MWD) system  65  that includes various instrumentation systems that monitor window cutting operations. Second segment  62   b  may include a whipstock valve  68 , a first flex joint  70 , an upper watermelon mill  72 , and a second flex joint  74 . Third segment  62   c  may include a lower watermelon mill  78 , a window mill  80 , a whipstock  82 , and a tubular  84  that support an anchor  88  which may take the form of a selectively expandable packer  89 . Third segment  62   c  may also support a brush or scraper  90  arranged adjacent to anchor  88 . 
     Referring to  FIGS. 3-5 , window mill  80  is secured to whipstock  82  through a connection system  100  as will be detailed herein. In an embodiment, window mill  80  includes a body  104  having a tip portion  108 . A plurality of blades (not shown) extend along body  104  and support a number of cutting elements (also not shown). In accordance with an exemplary aspect, a pressure compartment  112  is disposed within body  104 . A fluid port  115  extends through body  104  and is fluidically connected to pressure compartment  112 . Fluid port  115  also connects with a hydraulic line  118  that extends from surface system  14  to packer  89 . As will be detailed herein, in addition to providing an activating force to packer  89 , hydraulic line  118  delivers an actuation force to pressure compartment  112  which separates window mill  80  from whipstock  82 . Window mill  80  is also shown to include an axial passage  123  that extends from pressure compartment  112  through tip portion  108 . Pressure chamber  112  includes an angled or tapered wall  128  that leads into axial passage  123 . 
     Whipstock  82  includes a first surface  136  and a second surface  138 . Second surface  136  may be recessed relative to an annular lip (not separately labeled) that receives tip portion  108 . Second surface  136  is spaced from window mill  80  by a gap  141 . Gap  141  may define a space between Second surface  136  and window mill  80  or merely represent a separable interface between components. Whipstock  82  includes a recess  144  that extends through first surface  138  toward second surface  136 . A passage  148  extends from recess  144  through second surface  136  and aligns with axial passage  123 . Recess  144  includes a tapered surface section  152  that leads into passage  148 . 
     In accordance with an exemplary embodiment illustrated in  FIG. 4 , a pin  164  extends between and connects window mill  80  and whipstock  82 . Pin  164  is slidable within pressure compartment  112  and recess  144  as will be discussed herein. Pin  164  may be rotationally fixed relative to window mill  80 . Pin  164  includes a first end  166  disposed in pressure compartment  112  and a second end  168  that is disposed in recess  144 . First end  166  defines a piston portion  172  having a tapered surface portion  174  that may nest within angled wall  128 . Pin  164  also includes a shaft portion  178  that defines, at least in part, second end  168 . Shaft portion  178  extends through axial passage  123  and passage  148 . In an embodiment, shaft portion  178  has a diameter that forms a clearance fit relative to axial passage  123  and passage  148 . The clearance fit may define a seal e.g., a tight or interference fit relative to passage  148  so as to prevent axial movement in the absence of a motivating force. 
     In an embodiment, second end  168  of pin  164  includes an opening  180  which may take the form of a threaded cylindrical bore (not separately labeled) that receives a mechanical fastener  189 . Mechanical fastener  189  includes a tapered surface  192  that may nest against tapered surface section  152 . Tapered surface  192  prevents mechanical fastener  189  from coming out of recess  144 . As will be detailed herein, pin  164  selectively secures window mill  80  to whipstock  82 . That is, in addition to maintaining the connection, pin  164  also facilitates a separation of window mill  80  from whipstock  82  prior to a window milling operation as will be detailed herein. 
     In an embodiment, pin  164  includes an area of weakness  200  defined in shaft portion  178 . Area of weakness  200  may take the form of a localized reduction in diameter  202 . In operation, window cutting system  50  is run in to wellbore  34  with pin  164  securing window mill  80  to whipstock  82 . Area of weakness  200  is located within pressure compartment  112  as shown in  FIG. 4 . Once in position and oriented, surface system  14  introduces a hydraulic fluid into hydraulic line  118 . The hydraulic fluid flows to packer  89  locking window cutting system  50  to casing tubular  40 . 
     At the same time, the hydraulic fluid passes from hydraulic line  118 , through fluid port  115  and into pressure compartment  112 . The hydraulic fluid acts upon piston portion  172  forcing pin  164  toward whipstock  82  onto causing tapered surface portion  174  to rest against angled wall  128 . In this position, area of weakness  200  is positioned at gap  141  as shown in  FIG. 5 . Once area of weakness  200  is positioned at gap  141 , a torsional force may be applied to window cutting system  50  causing pin  164  to fail at area of weakness  200  separating window mill  80  from whipstock  82  as shown in  FIG. 6 . Once separated, a window cutting operation may commence. 
     Set forth below are some embodiments of the foregoing disclosure: 
     Embodiment 1 
     A window cutting system comprising: a whipstock including an outer surface, an inner surface, a recess, and a passage extending through the outer surface and the inner surface in the recess; a window mill connected to the whipstock, the window mill including a body having a tip portion, a pressure compartment formed in the tip portion, and an axial passage extending though the tip portion from the pressure compartment; and a pin connecting the window mill and the whipstock, the pin being arranged in the pressure compartment and extending through the axial passage and the passage into the recess, the pin being axially shiftable relative to the window mill and the whipstock when exposed to pressure in the pressure compartment. 
     Embodiment 2 
     The window cutting system according to any prior embodiment, further comprising: a fluid port extending through the window mill into the pressure compartment. 
     Embodiment 3 
     The window cutting system according to any prior embodiment, comprising: a hydraulic line connected to the fluid port. 
     Embodiment 4 
     The window cutting system according to any prior embodiment, further comprising: a gap extending between the whipstock and the window mill. 
     Embodiment 5 
     The window cutting system according to any prior embodiment, wherein the pin includes an area of weakness, the pin being selectively separable at the area of weakness to disengage the window mill from the whipstock. 
     Embodiment 6 
     The window cutting system according to any prior embodiment, wherein the pin is selectively shiftable between a first position, wherein the area of weakness is disposed in the pressure chamber, and a second position, wherein the area of weakness is disposed at the gap. 
     Embodiment 7 
     The window cutting system according to any prior embodiment, further comprising: a mechanical fastener extending into the pin in the recess. 
     Embodiment 8 
     The window cutting system according to any prior embodiment, wherein the mechanical fastener includes a tapered surface that selectively engages with a tapered surface section of the passage. 
     Embodiment 9 
     A resource exploration and recovery system comprising: a surface system; a subsurface system including a tubular string extending from the surface system into an earth formation, the tubular string including window cutting system comprising: a whipstock including an outer surface, an inner surface having a recess, and a passage extending through the outer surface and the inner surface in the recess; a window mill connected to the whipstock, the window mill including a body having a tip portion, a pressure compartment formed in the tip portion, and an axial passage extending though the tip portion from the pressure compartment; and a pin connecting the window mill and the whipstock, the pin being arranged in the pressure compartment and extending through the axial passage and the passage into the recess, the pin being axially shiftable relative to the window mill and the whipstock when exposed to pressure in the pressure compartment. 
     Embodiment 10 
     The resource exploration and recovery system according to any prior embodiment, further comprising: a fluid port extending through the window mill into the pressure compartment. 
     Embodiment 11 
     The resource exploration and recovery system according to any prior embodiment, further comprising: a hydraulic line connected to the fluid port. 
     Embodiment 12 
     The resource exploration and recovery system according to any prior embodiment, further comprising: a gap extending between the whipstock and the window mill. 
     Embodiment 13 
     The resource exploration and recovery system according to any prior embodiment, wherein the pin includes an area of weakness, the pin being selectively separable at the area of weakness to disengage the window mill from the whipstock. 
     Embodiment 14 
     The resource exploration and recovery system according to any prior embodiment, wherein the pin is selectively shiftable between a first position, wherein the area of weakness is disposed in the pressure chamber, and a second position, wherein the area of weakness is disposed at the gap. 
     Embodiment 15 
     The resource exploration and recovery system according to any prior embodiment, further comprising: a mechanical fastener extending into the pin in the recess. 
     Embodiment 16 
     The resource exploration and recovery system according to any prior embodiment, wherein the mechanical fastener includes a tapered surface that selectively engages with a tapered surface section of the passage. 
     Embodiment 17 
     A method of disconnecting a window mill from a whipstock comprising: running a tubular string including a window cutting system into a wellbore; introducing fluid into a pressure chamber in the window mill; shifting a pin in the window mill axially toward the whipstock; applying a torsional force to the window mill to break the pin; and shifting the window mill relative to the whipstock. 
     Embodiment 18 
     The method according to any prior embodiment, wherein shifting the pin includes positioning an area of weakness in the pin between the window mill and the whipstock. 
     Embodiment 19 
     The method according to any prior embodiment, wherein applying the torsional force includes shearing the area of weakness. 
     Embodiment 20 
     The method according to any prior embodiment, wherein introducing the fluid includes passing fluid from a surface system to a packer supported on the tubular string and into the pressure chamber. 
     The use of the terms “a” and “an” and “the” and similar referents in the context of describing the invention (especially in the context of the following claims) are to be construed to cover both the singular and the plural, unless otherwise indicated herein or clearly contradicted by context. Further, it should be noted that the terms “first,” “second,” and the like herein do not denote any order, quantity, or importance, but rather are used to distinguish one element from another. 
     The terms “about” and “substantially” are intended to include the degree of error associated with measurement of the particular quantity based upon the equipment available at the time of filing the application. For example, “about” and/or “substantially” can include a range of 8% or 5%, or 2% of a given value. 
     The teachings of the present disclosure may be used in a variety of well operations. These operations may involve using one or more treatment agents to treat a formation, the fluids resident in a formation, a wellbore, and/or equipment in the wellbore, such as production tubing. The treatment agents may be in the form of liquids, gases, solids, semi-solids, and mixtures thereof. Illustrative treatment agents include, but are not limited to, fracturing fluids, acids, steam, water, brine, anti-corrosion agents, cement, permeability modifiers, drilling muds, emulsifiers, demulsifiers, tracers, flow improvers etc. Illustrative well operations include, but are not limited to, hydraulic fracturing, stimulation, tracer injection, cleaning, acidizing, steam injection, water flooding, cementing, etc. 
     While the invention has been described with reference to an exemplary embodiment or embodiments, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted for elements thereof without departing from the scope of the invention. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the invention without departing from the essential scope thereof. Therefore, it is intended that the invention not be limited to the particular embodiment disclosed as the best mode contemplated for carrying out this invention, but that the invention will include all embodiments falling within the scope of the claims. Also, in the drawings and the description, there have been disclosed exemplary embodiments of the invention and, although specific terms may have been employed, they are unless otherwise stated used in a generic and descriptive sense only and not for purposes of limitation, the scope of the invention therefore not being so limited.