US2163932A - Casing protector - Google Patents

Description

W. l, BETTIS CASING PROTECTOR Filed Dec. 6, 1957 M ttorfzey.

June 27, 1939.

m Y l `V/EEEE m Patented June 27, 1939v OASING PBOTEUIOR William l. Bettis, Los Angeles, Calif., assigner to Estelle B. Kleaver, Burbank, Calif.

Application December 6, 1937, Serial No. 178,297

3 Claims.

My invention relates to casing protectors for use in deep well drilling, and among its principal objects' are; rst, to yprovide means for drilling straighter well holes than have been attainable hitherto; second, to afford facilities for preventing, or greatly reducing, vibration ln suspended drill pipes, and damage that lis likely to result therefrom; third, to supply a method for accelerating the flow of circulating fluid in deep well drilling; and, fourth, to accomplish the stated objects simultaneously, by an improved type of casing protector.

My objects are attained in the manner illustrated in the accompanying drawing, in which:

Figure 1 is a plan view of a deep well in horlzontal cross-section, with an embodiment of my inventiontherein;

Figure 2 is an elevational cross-section of the construction shown in Fig. 1 taken on the stepped planes indicated by the broken line 2 2;

Figure 3 is a plan view of a deep Vwell in horizontal cross-section, wherein there is a second embodiment of my invention;

Figure 4 is. an elevational cross-section oi the constructionshown in Fig. 3, taken on the plane indicated by the broken line 44; and A Figure 5 is a plan view of a deep well in horizontal cross-section, wherein there is a third embodiment of my invention. l

Similar reference numerals refer to similar things throughout the several views.

In modern rotary drilling operations, relatively high `speeds of rotation are employed, such as 120 R.. P. M. or more; and aA great part of the weight of the drilling bit and drill pipe, is carried by a swivel bearing at the top. Suspending the drill pipe in this way. helps to secure straighter well holes; but it also puts the drilling string under heavy tension. Transverse vibration of the drill pipe is easily set up in consequence, and the vibrations are very likely to iniiict damaging blows upon the walls of the well casing.

Mere suspension of the drill pipe can exert but a slight effect toward securing `a, straight drill hole; vbecause of the considerable lateral play of the drill pipe within the casing; and by reason of the enormous relative length of the drill pipe, which permits easy bending thereof.

I have found it `possible tof secure straighter drill holes, by utilizing the cased bore of the well as a guide for the 4drill pipe, and thus keep-f ing the latter closely centered `within the casing. Maintaining the drill pipe in the center of the casing also eliminates all objectionable vibration of the pipe, and ailords better protection to the casing. Hitherto it has been practically impossible to fully accomplish these things, on account of the necessity for maintaining an adequate ow of circulating fluid betwern the drill 5 pipe and the wall of the casing. Allpreviously yused centering means, of which there necessarily has to be a, large number of units associated with each drill string, introduce great flow resistance in the circulating system, and require 1.0'

the maintenance 'of correspondingly high pressure at the pumps.

'I'he present invention solves the problem of maintaining accurately centered drill pipe without necessarily increasing flow resistance of the 15 circulating iluid. Use of the invention, in fact, may result in .decreasing the flow resistance under certain conditions, particularly in Very deep Wells where it is 4an important factor. t

In` the several gures of the accompanying drawing it is assumed that the drilling rotation is clockwise when looking downwardly, as indicated by arrows 1. Sections of well casing are shown at 8, and of the drill pipe within the casing at 9.

The embodimentexhibited in Figs. 1 and 2, before it is applied to a drill pipe, comprises two concentric hollow cylinders of similarly and suitably compounded vulcanized rubber. l Both of these cylinders are capable of being greatly stretched, and they are uniformly spaced from each other by radial quasi-helical vanes of the same material. The normal inside diameter of the inner cylinder is considerably smaller than the outside diameter of thedrill pipewith which it is to be used; and the normal outside diameter of the outer cylinder is smaller than the inside diameter of the well casing, in approximately the same proportion. y

The inner cylinder of thel device, when in service, is stretched around drill pipe9, as by forcing the latter through its bore. `It will then grip the pipe very tightly, and be practicallyimmovable, in its stretched state, as shown at II. Such expansion of the inner cylinder will cause the helical varies to move radiallyoutwardly, and thus vstretch, the outer `cylinder of the device. This last said stretching will not be circular however, because of the localized spaced pressures exerted by the vanes. The outer cylinder therefore will assume a polygonal form at the top. bottom, and every intermediate cross section o.

the device.

In Fig. 1,' the forward surfaces of six uniformly spaced helical vanes are shown at I2, I3, I4, 55

I5, I6 and I1; and the upper extremities of these vanes at I8, I9, 20, 2|, 22 and 23 respectively. In Fig. 2, the forward surfaces of vanes I4, i5 and I5 are shown; and the rear surfaces of vanes I2 and I3 are shown at 24 and 25 respectively.

It will be noted that, with respect to every plane which is perpendicular to the axis of the device just described, the stretched outer portion will be hexagonal, as shown at 26 in Fig. 1. On each such cross-section there are only six points, such as at 21, which are adapted for contacting the well casing. By reason of the quasi-helical shape of the vanes, however, the contact points in successive planes are angularly displaced in continuous progression, so that all contact points caused by each vane form a helical contact ridge. In plan view these ridges appear to be circular, as shown at 2B (Fig. l); and in elevation the expanded device will appear as a twisted hexagonal prism. When the axial length of the device is such that the helical outer edge of each vane subtends an angle of sixty degrees in plan, the device, in any angular position, is capable of contacting the Well casing around its entire inside circumference.

In its stretched position on a drill pipe, there should be Very little clearance between the contact ridges of this device and the inner wall of the casing as indicated at 29 (Fig. 1). The drill pipe is kept closely centered in the casing in this manner; and the casing is thus utilized to guide the drill pipe, and to very greatly assist in the desired attainment of straight drill holes. Moreover, the slight clearance does not allow objectionable vibration of the drill pipe, and thus eliminates all heavy pounding of the latter against the inner wall of the casing.

In order to permit the small clearances described, it is necessary to provide flow passages through the body of the protectoryfor carrying the upwar flow of circulating fluid. The spaces between the innerand outer walls of the device, afford such passages; and the helical shape of the spacing vanes therebetween, enables the vanes to act as impellers. 'I'his very greatly aids in maintaining fiow of the circulating fluid, and lessens the duty upon the fluid pumps. I prefer to shape the impelling surfaces of the vanes with an entrance angle of about 30 from horizontal, as shown at 3|; and to have the upper ends of the impeller surfaces practically perpendicular, as shown at 32 (see Fig. 2). Such vanes are not truly helical, of course; but I consider them somewhat more satisfactory for the present purpose.

In the embodiment of my invention which is illustrated in Figs. 3 and 4, I make use of a pair of metallic parts, of which each comprises anV inner semi-cylinder 33 and an outer semi-cylinder 34. These semi-cylinders are uniformly spaced by radial quasi-helical vanes, of which the forward surfaces are shown in Fig. 3 at 35, 35, 31, 39, 39 and 40. The upper extremities of these vanes are shown at 4I, 42, 43, 44, 45 and 49 respectively. The rear surface of vane 35 is shown in Fig. iat 41. These vanes are made integral with the respective semi-cylinders; andthe latter are assembled face to face for service, by means of the bolts 49, so as to grip drill pipe l9.

The outer cylindrical surface of the assembled semi-cylinders, carries either a continuous or 1ongitudinally split rubber cylinder 49,'as the case may be. If the device is to be applied to drill pipe without necessity for passing over tool Joints or couplings, a complete cylinder of rubber may be used; and the two halves of the Vdevice may be sufdciently separated for application, by loosening bolts 48 and driving wedges into spaces 5I (Fig. 3). If the device is to be applied to drill pipe carrying tool joints or couplings however,

rubber cylinder 49 must be longitudinally split at one or both sides, on the plane 4-4. In such cases, the rubber is permanently cemented or vulcanized to the outer cylindrical metallic surfaces of the device. A small clearance is provided at 52, as in the case of the previously described embodiment of Figs. 1 and 2.

A third specific form of my invention, which I have selected for illustration, is shown in plan in Fig; 5. This comprises an inner cylinder of relatively soft rubber, shown at 53 as stretched around the drill pipe 9. A concentric outer cyl- Inder 54 is made of much harder material, which ldoes not stretch appreciably, and which is adapted to maintain substantially its original shape against the outward forces exerted by six helical spacing vanes. The forward surfaces of these vanes are indicated at 55. 56, 51, 58, 59 and 60.

When inner cylinder 53 is stretched around the drill pipe, the inner edges of these vanes necessarily move outwardly; but, since their outer edges cannot move similarly by reason of the unyielding cylinder 54, the vanes assume the bent form shown in the plan view of their respective upper ends at 6I, 62, 63, 64, 65 and 66. To assure this result, the vanes are given a slight initial curvature,l A small clearance 61 is provided, as in the other two cases, and this species of the invention functions in service in the same manner as the others.

Because of the vast experience which has now been acquired, by manufacturers and users of rubber devices of a similar nature; the proper methods for compounding and heat-treating rubber, to meet all requirements of the devices herein disclosed, are well known to those familiar with the art involved.

in U. S. Patent No. 1,573,031, issued Feb. 16, 1926 to Leroy H. Perry and myself, a rubber well casing protector is shown. In that disclosure, provision was made for upward flow of circulating fluid within the space limits occupied by the device; but, at the date of that patent, neither Mr. Perry nor I had any conception of utilizing the invention to accelerate the flow of circulating uid. Consequently there is no suggestion or teaching of such functioning in the patent, and no provision was made for accomplishing it.

In U. S. Patent No. 1,863,740, issued June 21, 1932 to myself, another form of casing protector was shown and described. In that disclosure, no provision was made for the flow of circulating huid, except by means of very considerable clearance between the device and the well casing; and no means for accelerating the fluid were disclosed.

It will be obvious to those familiar with the art, that many detail changes may be made in the devices described, without departing from the essence of the invention. ThereforeI do not limit my inventionV to the forms herein shown, except as set forth in the following claims.

I claim as my invention:

1. A device of the character described, made of rubber-like'material and having continuous co-axial walls from end to end; the walls being spaced by a plurality of quasi-helical vanes; and the inner wall being adapted for frictionally gripping a drill-pipe.

2. A device of the character described, made of rubber-like material and having continuous co-axial walls from end to end;\the walls-being spaced by a plurality of quasi-helical vanes integral with the walls; the inner wall being adapted for irictionally gripping a drill-pipe; and Said vanes being adapted to function as impellers for circulating fluid when the device is rotated about its axis.

3. A device of the character described, formed ot resilient and stretchable material, and having continuous co-axial cylindrical walls from end 10 to end; the walls heinz spaced by a plurality of quasi-helical vanes; the vanes being adapted to function as impellers when the device is rotated about its axis; the inner wall being adapted for irictionally gripping a co-axial -drill pipe by stretching therearound: and the outer wall being adapted to expand by said stretching so as to iit within a co-operating well casing with small clearance therebetween.

WILLIAMLBEITIS.

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