Patent Application
20200362638
The present disclosure relates to a hybrid bit with roller cone having inserts in petroleum, natural gas and geological drilling, which is suitable for the penetration in stringer and hard formation.
In present technologies, a conventional polycrystalline diamond cutter (PDC) bit drills at bottom-hole through scraping when encountering hard formation during drilling, the main cutting elements are difficult to penetrate into rocks at bottom hole, so the rate-of-penetration (ROP) of a diamond bit becomes very slow, while a roller cone bit fractures rock through crushing, deeper broken pits are easy to be produced. Due to hard formation, volumetric fracture in rock cannot be produced, and hence the ROP of a roller cone bit is very slow. On the other hand, when encountering formation with staggered stringers from soft to hard, the cutting elements of a PDC bit tend to be broken by impact. In order to cope with the condition, a roller cone and PDC hybrid bit with relatively high comprehensive property is put forward to improve its ROP by making preliminary breakage to formation through cone cutters to release formation stress, and then scraping the formation through cutters in fixed blades, and meanwhile, the cutters in the fixed blades are protected well to prolong its service life, but the structure of available roller cone and diamond bit is not reasonable enough. On one hand, each row of cone inserts with the same cutting trajectory among the rows of available hybrid bit is located at the same cone, and the structure of cutter placement in each cone of available hybrid bit is different, as a result, each cone of a hybrid bit is unevenly stressed, a single cone gets failed due to premature failure of its bearing, which leads to the failure of a hybrid bit; on the other hand, when penetrating into hard formation, the wear resistance property of cone inserts is far lower than that of PDC cutters in a PDC bit. In general, the wear of cone inserts leads to the failure of hybrid bit, while in available hybrid bit, each row of cone inserts with the same cutting trajectory is located at the same cone, as a result, the space of a cone is partly wasted, and insert numbers are reduced.
The present disclosure provides a hybrid bit with roller cone having inserts, the hybrid bit with roller cone having inserts includes a bit body, a plurality of blades disposed on the bit body and a plurality of nozzles disposed on the bit body, the blade includes an inner cone, a nose, a shoulder and gage sections from inside to outside, a plurality of fixed cutting elements are mounted along the inner cone, the nose, the shoulder and the gage sections; a head is disposed between two adjacent blades with its upper end integrated with the bit body, and a roller cone disposed at its lower end, the roller cone is roller cone having inserts, and the cutting position of which corresponds to the nose and the shoulder sections of blades, several rows of cone inserts are arranged herein, with each row of cone inserts disposed at intervals along a round of cone weft, and closely arranged from inside to outside along the cutting profile envelope, with each adjacent row of cone inserts disposed at alternate intervals along cone meridian and the insert placement structure of each cone is the same.
In some embodiments, a plurality of fixed cutting elements are laid out from inside to outside at the said blades, covering the whole bottom-hole, and forming profile envelopes of fixed cutting elements, and gyration radiuses of all the fixed cutting elements at each blade are different, that is, the structure of cutter placement at each blade is different.
In some embodiments, an outermost profile envelope of the cone inserts and the profile envelope of the fixed cutting elements are in parallel and spaced at some intervals. The interval between the outermost profile envelope of cone inserts herein and the outermost profile envelope of fixed cutting elements is from −2.0 mm to 2.0 mm.
In some embodiments, a center line of inserts overlaps with or approximates to a center line of each corresponding cutting elements of blades when each row of cone inserts is at the lowest point of cutting trajectory.
In some embodiments, there are two to six blades, and there are two to six roller cones herein, and the roller cones are equal to or less than blade numbers.
In some embodiments, the cone inserts comprise 6-20 rows of cone inserts; each row of cone inserts comprises 6-20 cone inserts.
In some embodiments, the said cone inserts are cemented carbide inserts or mixed cutting elements with cemented carbide and polycrystalline diamond.
In some embodiments, the said fixed cutting elements are diamond cutters.
The beneficial effects of the disclosure lie in: 1. The cone insert arrangement of each roller cone is the same, the force distribution of the whole drill bit is balanced, which reduces premature failure of some bearings due to excessive force caused by uneven insert placement and improves the service life of the drilling bit. 2. Cone inserts are in alternate, weft and meridian arrangement, so that the inserts are not only distributed at cone surface evenly with rational insert placement, but also the cone space is saved more effectively, as a result, the density of insert placement is improved, ROP of the drilling bit is developed, rock fracture and wear resistance property of cones are improved, and hence the service life of the drilling bit is prolonged. 3. When each row of the cone inserts is at the lowest point of cutting trajectory, the center line of inserts overlaps with or approximates to the center line of each corresponding fixed cutting elements in the blades, which leads to the rational share of cutting and the service life of drilling bit is improved.
In order to explain the exemplary embodiments of the present invention or the technical proposal of present technologies clearly, description of the invention briefly summarized in the following may be had by reference to the embodiments thereof that are illustrated in the appended drawings which form a part of this specification. It's to be noted that, the drawings illustrated are only some embodiments of the disclosed invention, and for ordinary technicians of this field, other drawings can be attained without their creative labor.
In combination with the appended drawings in the exemplary embodiments of the disclosure, the technical proposal in the exemplary embodiments of the disclosure is described clearly and completely. It's to be noted, however, that the drawings illustrate only some embodiments of the disclosure and therefore are not to be considered limiting of its scope as the disclosure may admit to other equally effective disclosure; While the disclosure has been shown or described in only some of its forms, it should be apparent to those skilled in the art that it is not so limited, but is susceptible to various changes without departing from the scope of the disclosure. Based on the embodiments in the disclosure, all other embodiments obtained by ordinary technicians in this field without the premise of carrying out creative labor shall fall within the scope of this disclosure protection.
As shown in
A head 105 is disposed between each two adjacent blades, with its upper end welded to be integrated with the bit body, and a journal pin disposed at its lower end, a roller cone 106 mounted into the journal pin axially fixed with steel balls, roller cones and blades are in alternate arrangement. Alternatively, cones are roller cones having inserts.
There are three roller cones named as A, B and C, having cone inserts 107 mounted, the cutting position of cone inserts herein corresponds to the nose and shoulder sections of a blade. There are eight rows of cone inserts, with each row of cone inserts disposed at intervals along a round of cone weft, and closely arranged from inside to outside along the outermost profile envelope of cutting elements, each adjacent row of cone inserts are in alternate, weft and meridian arrangement along the cone cutters with the same insert placement structure at each cone.
The outermost profile envelope 111 formed by cone inserts covers the nose and shoulder sections of the drilling bit beyond the outside of the outermost profile envelope 110 formed by fixed cutting elements of the said blades. The distance H between the outermost profile envelope 111 of cone inserts and the outermost profile envelope 110 of fixed cutting elements is 1.0 mm. When each row of cone inserts is at the lowest point of cutting trajectory, the center line of inserts overlaps with or approximates to the center line of each corresponding cutting elements of blades, that is, the center line of each row of inserts at cones 11B˜18B overlaps with the center line of each fixed cutting elements 11˜18 at nose and shoulder of a blade. The outermost inserts at the said cones cut rocks at wall of a wellbore along with the fixed cutting elements at the gage section of blades, the cutting trajectory of the said cone inserts overlaps with that of the said fixed cutting elements. In addition, cutters for gage protection are disposed at the outer diameter of a head and blade flank.
While the disclosure has been described with respect to a limited number of embodiments, those skilled in the art, having benefit of this disclosure, will appreciate that other embodiments can be devised which do not depart from the scope of the invention as disclosed herein. Accordingly, the scope of the disclosure should be limited only by the attached claims.
| Number | Date | Country | Kind |
|---|---|---|---|
| 201711138078.X | Nov 2017 | CN | national |
The present application is a national stage of PCT/CN2018/112519, filed on Oct. 30, 2018, which claims priority to Chinese patent application number 201711138078.X and an application date of Nov. 16, 2017, and the disclosure contents of the PCT and Chinese patent applications are herein incorporated by reference.
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/CN2018/112519 | 10/30/2018 | WO | 00 |
