The present invention relates to a combined crushing super-variable-diameter drill bit for natural gas hydrate exploitation, including a joint, an outer cylinder connected to the joint by thread, a nozzle I mounted in the outer cylinder, a mechanical locking mechanism, a blade telescoping mechanism, an end cap connected to the outer cylinder by thread, a seal ring IV mounted to the end cap, and a nozzle II mounted in the end cap by threaded connection. The present invention achieves integrated operation of conventional drilling and draw-back expanding, which can effectively solve the problems that the existing hydrate drill bit cannot drill a large borehole, cannot mechanically lock an extending position of the blade to stabilize the size of the borehole, and a single crushing method is inefficient.

The present invention relates to a combined crushing super-variable-diameter drill bit for natural gas hydrate exploitation, including a joint, an outer cylinder connected to the joint by thread, a nozzle I mounted in the outer cylinder, a mechanical locking mechanism, a blade telescoping mechanism, an end cap connected to the outer cylinder by thread, a seal ring IV mounted to the end cap, and a nozzle II mounted in the end cap by threaded connection. The present invention achieves integrated operation of conventional drilling and draw-back expanding, which can effectively solve the problems that the existing hydrate drill bit cannot drill a large borehole, cannot mechanically lock an extending position of the blade to stabilize the size of the borehole, and a single crushing method is inefficient.

A hybrid bit with roller cones having inserts is disclosed, includes a bit body, blades and roller cones. All the fixed cutting elements at the inner cone section, nose section and shoulder section of blades herein constitutes two sets of corresponding fixed cutting elements respectively, forming two profile envelopes of fixed cutting elements at least in the interval at the nose section and shoulder section, the two profile envelopes of fixed cutting elements are spaced at high and low intervals at the nose section and shoulder section, forming two stages of cutting by fixed cutting elements; and the cutting position of the cone insert mainly corresponds to the nose section and shoulder section of blades, the outermost cutting profile envelope of cone inserts formed by all or part of cutting elements on cones herein is higher than the outermost cutting profile envelope of fixed cutting elements, forming the third stage of cutting. The invention can effectively develop rate of penetration in hard and plastic formation, maintain and prolong the service life of the hybrid bit, and broaden the formation suitability of the hybrid bit.

A hybrid bit with roller cones having inserts is disclosed, includes a bit body, blades and roller cones. All the fixed cutting elements at the inner cone section, nose section and shoulder section of blades herein constitutes two sets of corresponding fixed cutting elements respectively, forming two profile envelopes of fixed cutting elements at least in the interval at the nose section and shoulder section, the two profile envelopes of fixed cutting elements are spaced at high and low intervals at the nose section and shoulder section, forming two stages of cutting by fixed cutting elements; and the cutting position of the cone insert mainly corresponds to the nose section and shoulder section of blades, the outermost cutting profile envelope of cone inserts formed by all or part of cutting elements on cones herein is higher than the outermost cutting profile envelope of fixed cutting elements, forming the third stage of cutting. The invention can effectively develop rate of penetration in hard and plastic formation, maintain and prolong the service life of the hybrid bit, and broaden the formation suitability of the hybrid bit.

An earth-boring tool may include at least one blade including a shoulder region and a face. A plurality of cutting elements may be arranged on the face of the blade and at least one cutting element may be positioned in the shoulder region such that a cutting face of the at least one cutting element is spaced a distance behind the face of the blade. A recessed portion of the blade may extend under at least one of the plurality of cutting elements arranged on the face of the blade and extending to the at least one cutting element positioned in the shoulder region.

A method includes receiving a drill bit design. The design specifies a design parameter for a plurality of cutter elements of a drill bit. The method also includes estimating a temperature value for the cutter elements based on the design parameter and a drilling parameter; estimating a wear value for the cutter elements based on the design parameter and the temperature value; updating a value of the design parameter for at least one of the cutter elements based on the wear value and a time period; and using the updated design parameter value, repeating the steps of estimating the temperature value, estimating the wear value, and updating the design parameter value until the design parameter value for the at least one of the cutter elements reaches a threshold value.

A method includes receiving a drill bit design. The design specifies a design parameter for a plurality of cutter elements of a drill bit. The method also includes estimating a temperature value for the cutter elements based on the design parameter and a drilling parameter; estimating a wear value for the cutter elements based on the design parameter and the temperature value; updating a value of the design parameter for at least one of the cutter elements based on the wear value and a time period; and using the updated design parameter value, repeating the steps of estimating the temperature value, estimating the wear value, and updating the design parameter value until the design parameter value for the at least one of the cutter elements reaches a threshold value.

An apparatus to increase a diameter of a well bore includes a drill pipe that includes a first end, a second end spaced apart from the first end, and a longitudinal axis. A first reamer is coupled to the drill pipe, the first reamer including a first plurality of teeth and a first reamer axis spaced radially apart from the longitudinal axis of the drill pipe. At least a second reamer is coupled to the drill pipe and spaced longitudinally apart from the first reamer. The at least a second reamer includes a second plurality of teeth and a second reamer axis spaced radially apart from the longitudinal axis of the drill pipe, the second reamer axis being angularly offset from the first reamer axis such that a drift diameter of the apparatus is smaller than a drill diameter of the apparatus.

An apparatus to increase a diameter of a well bore includes a drill pipe and a first reamer and at least a second reamer. The second reamer is positioned diametrically opposed to the first reamer. A first plurality of cutting teeth are positioned about each of the first reamer and the at least a second reamer. A top of each successive tooth in a direction counter to a rotation of the apparatus in the well bore extends a radial distance from the longitudinal axis. Each tooth of the first plurality of cutting teeth is positioned at a different circumferential location about each reamer from any adjacent teeth of the first plurality of teeth. At least a second plurality of cutting teeth are positioned about each of the first reamer and the at least a second reamer, the at least a second plurality of cutting teeth being spaced longitudinally apart from the first plurality of cutting teeth.

An apparatus to increase a diameter of a well bore includes a drill pipe and a first reamer and at least a second reamer. The second reamer is positioned diametrically opposed to the first reamer. A first plurality of cutting teeth are positioned about each of the first reamer and the at least a second reamer. A top of each successive tooth in a direction counter to a rotation of the apparatus in the well bore extends a radial distance from the longitudinal axis. Each tooth of the first plurality of cutting teeth is positioned at a different circumferential location about each reamer from any adjacent teeth of the first plurality of teeth. At least a second plurality of cutting teeth are positioned about each of the first reamer and the at least a second reamer, the at least a second plurality of cutting teeth being spaced longitudinally apart from the first plurality of cutting teeth.