Oil well scraping device

Claim 2

A scraping device for passing along a borehole to clear the borehole of scale and the like, comprising, in combination: a. a central mandrel having a plurality of grooves tapering in depth in its exterior side walls running parallel to the axis of the mandrel and spaced circumferentially from each other about the periphery of the mandrel; b. scraper means slidable in an axial direction in said grooves, the floor of the grooves sloping radially inwardly to define the taper of the grooves so that the axial position of the scraper means in the grooves determines their minimum radial extent beyond the periphery of said mandrel; and c. an adjustable collar threaded exteriorly onto said mandrel and axially adjustable along the mandrel to function as a stop against axial movement of the scraper means after an adjusted axial position of the adjustable collar relative to the groove has been made, whereby the minimum radial extent of the scraper means is adjustable by adjusting the threaded position of the adjustable collar; each of the scraper means being spring-loaded in a radial outward direction so that a continuous engagement of the borehole side wall by the scraper means will take place and yet positive seating of the scraper means on the floor of the grooves determines a minimum diameter for the borehole which is cleared.

Claim 3

A scraping device according to claim 1, in which said mandrel has a central passage and is threaded at its ends for insertion in an oil pipe string whereby circulation can be maintained while scraping an oil well borehole.

Claim 4

A scraping device according to claim 2, in which the sloping floor of each of the grooves is shallow at its upper end and deepest at its lower end, said adjustable collar being disposed above the scraper means to act as a check against upward movement of the scraper means during a scraping operation when lowering the pipe string in the borehole, upward movement of the pipe string loosening any sticking of the scraper means to the borehole side walls as a consequence of the deeper portions of the grooves being positioned to accommodate radial inward movement of the scraper means.

Claim 5

A scraping device according to claim 3, in which each of the scraper means is keyed into its associated groove against completely outward radial movement of the scraper means to a point where it is free of the grooves along a major portion of the grooves, an end portion of the grooves being free of the keying of the scraper means so that they may be slid free of the grooves by backing off the adjustable collar.

Claim 6

A scraping device for passing along a borehole to clear the borehole of scale and the like and to define a given inside minimum diameter for the borehole, comprising, in combination: a. a central mandrel having an upper set of tapered grooves on its exterior wall running in the axial direction of the mandrel and circumferentially spaced and a lower set of tapered grooves on its exterior wall running in the axial direction of the mandrel and axially spaced below said upper set and circumferentially spaced with respect to said upper set, each of the tapered grooves having a sloping floor defining a shallow upper end and a deeper lower end, the edges of the side walls of the grooves being undercut along a major portion of their lengths; b. an adjustable collar surrounding said mandrel above the lower ends of said upper set of grooves and being threadedly engaged with said mandrel so that said collar is movable axially along said mandrel by rotating the collar; c. an upper set of scrapers slidable in said upper grooves along the sloping floors thereof respectively such that their minimum radial extent from said mandrel is determined by their axial positions in the upper grooves; d. a lower set of scrapers slidable in said lower grooves along the floors thereof respectively such that their minimum radial extent from said mandrel is determined by their axial positions in the lower grooves each of the upper and lower scrapers having a foot portion with laterally extending flanges receivable in the under-cut portions of the side walls of the groove to hold the scraper in the groove; e. a spacing collar surrounding said mandrel between the upper and lower sets of scrapers and axially movable along said mandrel; and f. means biasing the scrapers radially outwardly away from the floor of the groove so that the flanges engage under the under-cut portion to hold the scraper in a set axial position, whereby the threaded axial position of said adjustable collar determines the position of the scrapers along the grooves so that a positive setting of the adjustable collar defines a given minimum radial extent of the scrapers to define said given inside minimum diameter, readjustment of said adjustable collar changing the minimum radial extent of the scrapers so that a different inside diameter may be cleared in the borehole.

Claim 7

A scraping device for passing along a borehole to clear the borehole of scale and the like and to define a given inside minimum diameter for the borehole, comprising, in combination: a. a central mandrel having an upper set of tapered grooves on its exterior wall running in the axial direction of the mandrel and circumferentially spaced and a lower set of tapered grooves on its exterior wall running in the axial direction of the mandrel and axially spaced below said upper set and circumferentially spaced with respect to said upper set, each of the tapered grooves having a sloping floor defining a shallow upper end and a deeper lower end, the edges of the side walls of the grooves being undercut along a major portion of their lengths; b. an adjustable collar surrounding said mandrel above the lower ends of said upper set of grooves and being threadedly engaged with said mandrel so that said collar is movable axially along said mandrel by rotating the collar; c. an upper set of scrapers slidable in said upper grooves along the sloping floors thereof respectively such that their minimum radial extent from said mandrel is determined by their axial positions in the upper grooves; d. a lower set of scrapers slidable in said lower grooves along the floors thereof respectively such that their minimum radial extent from said mandrel is determined by their axial positions in the lower grooves each of the upper and lower scrapers having a foot portion with laterally extending flanges receivable in the under-cut portions of the side walls of the groove to hold the scraper in the groove; e. a spacing collar surrounding said mandrel between the upper and lower sets of scrapers and axially movable along said mandrel; and f. means biasing the scrapers radially outwardly away from the floor of the groove so that the flanges engage under the under-cut portion to hold the scraper in a set axial position, whereby the threaded axial position of said adjustable collar determines the position of the scrapers along the grooves so that a positive setting of the adjustable collar defines a given minimum radial extent of the scrapers to define said given inside minimum diameter, readjustment of said adjustable collar changing the minimum radial extent of the scrapers so that a different inside diameter may be cleared in the borehole.

Claim 8

A scraping device according to claim 5, in which said central mandrel includes a center passage and threaded upper and lower ends for insertion in an oil pipe strong so that said scraping device can be used to scrape an oil well borehole while maintaining circulation through the well pipe string.

Claim 9

A scraping device according to claim 5, in which said means biasing the scrapers radially outwardly inCludes spring means on the foot of each scraper engaging the floor of the groove to bias the scraper outwardly.

Claim 10

A scraping device according to claim 5, in which the under-cut portions of the groove walls terminate at the upper shallow end of the groove so that the scrapers may be slid out of their grooves by backing off the adjustable collar and spacing collar to facilitate the replacement of said scrapers.

Claim 11

A scraping device according to claim 5, in which there are provided four grooves in the upper set and four grooves in the lower set circumferentially spaced at ninety degrees to each other respectively, the staggering of the lower set being such that the lower set is circumferentially spaced 45* from the upper set, and in which each of said scrapers has a scraping surface extending over a given circumferential distance greater than 45* to that engagement of the borehole side walls by the scrapers total a complete 360*, the upper set of scrapers engaging portions of the borehole side wall missed by the lower set of scrapers.

Claim 12

A scraping device according to claim 5 including spring means on the mandrel bearing against the lower ends of the lower set of scrapers to exert an upward axial force thereon said force being transmitted through said spacing collar to the upper set of scrapers to sandwich the upper scrapers between said spacing collar and adjustable collar.

Claim 13

A scraping device according to claim 5, including a stop collar threaded onto the lower end of said mandrel below said lower set of scrapers so that lower exposed portions of said lower set of tapered grooves may be partially eclipsed by the upper portion of said stop collar.