Modular window mill assembly and method

Abstract

A modular window mill assembly includes a mill body having a first connection feature and a second connection feature; a mill head having a cutting structure and an engagement feature, the engagement feature configured to matingly engage with the first connection feature of the mill body to replaceably secure the mill head to the mill body; and, a blade having a cutting structure and a coupling feature, the coupling feature of each blade respectively matingly coupled to the second connection feature to replaceably secure the blade to the mill body. The mill body, mill head, and the blade are formed separately from each other prior to assemblage together to form the window mill assembly.

What is claimed is: 
     
         1 . A modular window mill assembly comprising:
 a mill body having a first connection feature and a second connection feature;   a mill head having a cutting structure and an engagement feature, the engagement feature configured to matingly engage with the first connection feature of the mill body to replaceably secure the mill head to the mill body; and   a blade having a cutting structure and a coupling feature, the coupling feature of each blade respectively matingly coupled to the second connection feature to replaceably secure the blade to the mill body;   wherein the mill body, mill head, and the blade are formed separately from each other prior to assemblage together to form the window mill assembly.   
     
     
         2 . The modular window mill assembly of  claim 1 , wherein the mill body includes a longitudinal axis, a first end and a longitudinally spaced second end, the mill head disposed at the first end of the mill body, and the blade longitudinally trapped by the mill head and a shoulder between the first and second ends of the mill body. 
     
     
         3 . The modular window mill assembly of  claim 1 , wherein the first connection feature is threadably engaged with the engagement feature. 
     
     
         4 . The modular window mill assembly of  claim 1 , wherein the engagement feature includes a male portion receivable within a female portion of the first connection feature. 
     
     
         5 . The modular window mill assembly of  claim 1 , wherein the second connection feature includes circumferentially spaced slots extending from a first longitudinal end of the mill body. 
     
     
         6 . The modular window mill assembly of  claim 5 , wherein a radial outermost end of the slots are narrower than a radial interior portion of the slots. 
     
     
         7 . The modular window mill assembly of  claim 5 , wherein the slots are dove-tail shaped or T-shaped. 
     
     
         8 . The modular window mill assembly of  claim 5 , wherein the mill body has a shoulder wall disposed between the first end of the mill body and a second end of the mill body, the slots extending from the first end of the mill body to the shoulder wall. 
     
     
         9 . The modular window mill assembly of  claim 1 , wherein the mill head is secured to the first end of the mill body through weldless engagement between the engagement feature and the first connection feature, and the blade is secured to the mill body through weldless coupling between the coupling feature of the blade and the second connection feature. 
     
     
         10 . The modular window mill assembly of  claim 1 , wherein the cutting structure of the mill head and the blade includes carbide and/or polycrystalline diamond compact inserts. 
     
     
         11 . The modular window mill assembly of  claim 1 , wherein the mill head includes a plurality of rows of cutting structures, each row aligned with cutting structures on a plurality of the blades when the blades and the mill head are secured to the mill body. 
     
     
         12 . The modular window mill assembly of  claim 1 , further comprising a fluid flow path extending along a longitudinal axis of the mill body. 
     
     
         13 . A system comprising:
 the modular window mill assembly of  claim 1 ;   a string, the window mill assembly attached to an end of the string; and, a tubular structure, the string and window mill assembly passable through an interior of the tubular structure and the window mill assembly rotatable by the string within the tubular structure.   
     
     
         14 . The system of  claim 13 , further comprising a whipstock within the tubular structure, the whipstock having a guide surface, and the window mill assembly configured to slide along the guide surface to cut an opening in the tubular structure. 
     
     
         15 . A method of assembling a modular window mill assembly, the method comprising:
 utilizing a mill body having a first connection feature and a second connection feature;   matingly coupling the blade having a cutting structure with the second connection feature of the mill body; and   matingly engaging a mill head having a cutting structure with the first connection feature.   
     
     
         16 . The method of  claim 15 , wherein coupling the blade with the second connection feature of the mill body includes sliding the blade within a slot in the mill body. 
     
     
         17 . The method of  claim 16 , wherein engaging the mill head with the first connection feature occurs subsequent to sliding the blade within the respective slot in the mill body, and longitudinally trapping the blade between the mill head and a shoulder wall of the mill body. 
     
     
         18 . The method of  claim 15 , wherein the mill body includes a first end, the first connection feature includes a female portion indented from the first end, and the mill head includes a male portion received within the female portion. 
     
     
         19 . The method of  claim 15 , wherein the mill head is threadably engaged to the first connection feature. 
     
     
         20 . The method of  claim 15 , further comprising attaching the window mill head assembly to a string, the string configured to rotate the window mill assembly.