Rockbit with attachable device for improved cone cleaning

#Roller cone bits, variously referred to as rock bits or drill bits, are used in earth drilling applications. Typically, these are used in petroleum or mining operations where the cost of drilling is significantly affected by the rate that the drill bits penetrate the various types of subterranean formations. There is a continual effort to optimize the design of drill bits to more rapidly drill specific formations so as to reduce these drilling costs.

#One design element that significantly affects the drilling rate of the rock bit is the hydraulics. As they drill, the rock bits generate rock fragments known as drill cuttings. These rock fragments are carried uphole to the surface by a moving column of drilling fluid that travels to the interior of the drill bit through the center of an attached drill string, is ejected from the face of the drill bit through a series of jet nozzles, and is carried uphole through an annulus formed by the outside of the drill string and the borehole wall.

#Bit hydraulics can be used to accomplish many different purposes on the hole bottom. Generally, a drill bit is configured with three cones at its bottom that are equidistantly spaced around the circumference of the bit. These cones are imbedded with inserts (otherwise known as teeth) that penetrate the formation as the drill bit rotates in the hole. Generally, between each pair of cones is a jet bore with an installed erosion resistant nozzle that directs the fluid from the face of the bit to the hole bottom to move the cuttings from the proximity of the bit and up the annulus to the surface. The placement and directionality of the nozzles as well as the nozzle sizing and nozzle extension significantly affect the ability of the fluid to remove cuttings from the bore hole.

#For a detailed description of a preferred embodiment of the invention, reference will now be made to the accompanying drawings wherein:

#FIG. 1 is a perspective view of a rock bit with an angled nozzle retention body;

#FIG. 2A is a perspective view of a rock bit with an angled nozzle retention body and a mini-extended nozzle;

#Referring to FIG. 1, a roller-cone bit in accordance with a preferred embodiment of the invention is shown. Roller cone bit 100 includes a body 102 and an upper end 104 that includes a threaded pin connection 106 for attachment of a drill string used to raise, lower, and rotate bit 100 during drilling. Drill bit body 102 forms an interior fluid chamber or plenum 13 (as shown in FIG. 2B) that acts as a conduit for drilling fluid that is pumped from the surface through an attached drill string. Body 102 includes a number of legs 108, preferably three with attached cutters 110. Each cutter 110 comprises a cone shell 111 and rows of cutting elements 112, or teeth. The teeth may be tungsten carbide inserts (TCI) or milled teeth, as is generally known in the art.

#Bit body 102 and cutters 110 rotating on bearing shafts (not shown) define a longitudinal axis 200 about which bit 100 rotates during drilling. Rotational or longitudinal axis 200 is the geometric center or centerline of the bit about which it is designed or intended to rotate and is collinear with the centerline of the threaded pin connection 106. A shorthand for describing the direction of this longitudinal axis is as being vertical, although such nomenclature is actually misdescriptive in applications such as directional drilling.

#Bit 100 includes directional nozzle retention bodies 130, also called directional Q-tubes, about its periphery preferably in locations defined between adjacent pairs of legs 108. Nozzle retention body 130 of bit 100 includes an inlet 230 (shown in FIG. 2B), an outlet nozzle receptacle 202 appropriate for insertion of a fluid nozzle, a lower load face 134, and an upper sloped portion 139. Load face 134 includes a plurality of apertures where hardened elements 136 are preferably installed. Other hardened elements 135 are located on the upper sloped portion 139 of nozzle retention body 130. Hardened elements can be made of natural diamond, polycrystalline diamond, tungsten carbide, or any other suitable hard material. They may also be of any suitable shape. The profile or load face 134 of the nozzle retention body 130 need not be straight, but may be tapered, curved, concave, convex, blended, rounded, sculptured, contoured, oval, conical or other. The hardened elements could also be replaced with a wear-resistant material that is weldably bonded to load face 134. The outer surface may also be off-gage (i.e. its outermost portion extends short of substantially the full diameter of the drill bit) or on-gage (i.e. its outermost portion extends to substantially the full diameter of the drill bit) in whole or in part, according to the downhole application.