# US 11,111,748 B2 · Milling tools with a secondary attrition system > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 11,111,748 B2 - Document ID: US11111748B2 - Status: Granted - Kind: B2 - Application number: 16/747,510 - Filed: 2020-01-20 - Published: 2020-05-14 - Granted: 2021-09-07 - Earliest claimed: 2014-08-06 - Assignees: Wellbore Integrity Solutions LLC - Applicants: Wellbore Integrity Solutions LLC - Inventors: Manoj D. Mahajan; Charles H. Dewey; Shantanu N. Swadi; Walter E. Friedl; Christopher Kang Potter; Alan Fairweather; Kenneth Daniel Hora - Web page: https://patentgrep.com/patent/US11111748B2 ## CPC - E21B 29/002: {Cutting, e.g. milling, a pipe with a cutter rotating along the circumference of the pipe} - E21B 4/02: Fluid rotary type drives - E21B 10/42: Rotary drag type drill bits with teeth, blades or like cutting elements, e.g. fork-type bits, fish tail bits (characterised by wear resisting parts E21B10/46; by conduits or nozzles for drilling fluid E21B10/60; by detachable or adjustable parts E21B10/62) - E21B 10/60: characterised by conduits or nozzles for drilling fluids (for roller bits E21B10/18; for percussion drill bits E21B10/38) - E21B: EARTH OR ROCK DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS ## Abstract Milling systems, tools, and methods include using a mill with secondary attrition system to re-mill cuttings and other debris away from the face of the mill. The secondary attrition system may be located uphole of the mill may be used to stage conditioning and re-sizing of debris. After debris is generated by the mill, the secondary attrition system may re-mill the debris to a finer size before allowing the debris to pass out of the sleeve. The debris may be re-milled by secondary cutting elements while within an annular gap positioned radially between the sleeve and a drive shaft for the mill. The annular gap may have a variable width as a result of a tapered outer surface of the drive shaft and/or a tapered inner surface of the sleeve. The variable width may cause debris to be re-milled into increasingly finer sizes. ## Claims ### Claim 1 A secondary attrition system for a milling system, comprising: a sleeve having an inner surface and an outer surface; a tubular component within the sleeve and rotationally connected to the sleeve, the tubular component having an outer surface cooperating with the inner surface of the sleeve to define a gap having a variable width along at least a portion of a length of the tubular component; and at least one cutting element coupled to the inner surface of the sleeve or the outer surface of the tubular component and the at least one cutting element located within the gap. ### Claim 2 (depends on 1) The secondary attrition system of claim 1, the tubular component including a drive shaft. ### Claim 3 (depends on 2) The secondary attrition system of claim 2, the drive shaft being a drive shaft of a downhole motor. ### Claim 4 (depends on 2) The secondary attrition system of claim 2, the drive shaft including a drive shaft extension. ### Claim 5 (depends on 1) The secondary attrition system of claim 1, the tubular component including a drill string. ### Claim 6 (depends on 1) The secondary attrition system of claim 1, a tapered section of the outer surface of the tubular component defining at least a portion of the gap having the variable width. ### Claim 7 (depends on 1) The secondary attrition system of claim 1, a tapered section of the inner surface of the sleeve defining at least a portion of the gap having the variable width. ### Claim 8 (depends on 1) The secondary attrition system of claim 1, the tubular component being configured to rotate relative to the sleeve. ### Claim 9 A secondary attrition system for a milling system, comprising: a first tubular member having an inner surface and an outer surface, a second tubular member having an inner surface and an outer surface, the second tubular member being coupled to the first tubular member and at least partially disposed within the first tubular member to form an annulus between the outer surface of the second tubular member and the inner surface of the first tubular member; a first opening allowing for flow of drilling fluid and milling debris into the annulus; a second opening allowing for flow of drilling fluid and milling debris out of the annulus; at least one cutting element located within the annulus and coupled to the inner surface of the first tubular member or to the outer surface of the second tubular member; and wherein milling debris flowing into the annulus is reduce in size by the at least one cutting element prior to flowing out of the annulus through the second opening. ### Claim 10 (depends on 9) The secondary attrition system of claim 9, wherein the first tubular member has an outer diameter of 3 inches to 6 inches. ### Claim 11 (depends on 9) The secondary attrition system of claim 9, wherein the first tubular member has an inner diameter of 2 inches to 5.5 inches. ### Claim 12 (depends on 9) The secondary attrition system of claim 9, wherein the first opening is configured to allow milling debris of a first predetermined size to pass through the first opening; the second opening is configured to allow milling debris of a second predetermined size to pass through the second opening; and the second predetermined size is smaller than the first predetermined size. ### Claim 13 (depends on 9) The secondary attrition system of claim 9, wherein the second tubular member is configured to rotate relative to the first tubular member. ### Claim 14 (depends on 9) The secondary attrition system of claim 9, wherein the width of the annulus has a variable width. ### Claim 15 (depends on 14) The secondary attrition system of claim 14, wherein the width of the annulus is tapered. ### Claim 16 (depends on 15) The secondary attrition system of claim 15, wherein the taper of the annulus comprises a linear taper, a parabolic taper, or a stepped taper. ### Claim 17 (depends on 9) The secondary attrition system of claim 9, wherein the at least one cutting element comprises hardfacing, crushed carbide, or a cutting insert.