US1981525A - Method of and apparatus for drilling oil wells - Google Patents

Description

B. E. PRICE Nov. 20; 1934.

METHOD OF AND APPARATUS FOR DRILLING OIL WELLS Filed Dec. 5, 1953 0) 9% g ATTORNEY 5 w 3 y w w Patented Nov. 20, 1934 UNETED STATES PATET METHOD OF AND APPARATUS FOR DRILLING OIL WELLS 11 Claims.

The invention relates to a method of, and apparatus for, drilling oil wells, and more particularly to a method and apparatus particularly adapted for use in drilling wells in localities where heaving shale is encountered.

One of the problems in the development of new oil fields arises from the likelihood of encountering a shale stratum before striking oil, which usually occurs after the boring has attained great depth. It is a generally accepted theory that the visible supply of oil would be enormously increased were it possible to drill through such a stratum of heaving shale. To the present time, no practical method or apparatus has been suggested which enables the continuation of the drilling operation when heaving shale is once encountered. This has resulted in the uniform practice under such conditions of abandoning all drilling operations, irrespective of the cost of the work prior to that time.

While it is a common practice when drilling for oil, to provide the bore with a lining casing for various purposes, the usual methods of applying such casings have been found not to be adaptable for use with conditions resulting from the presence of heaving shale, since when it is necessary to pull the drill and its rod from the bore for the purpose of inserting the casing, the portion of the bore passing through the shale stratum will be closed by the movement or expansion of the shale beforethe casing can be set.

With the above conditions in mind, I have provided a method and an apparatus for the practice of the method, by which a section of casing may be set without pulling back the drill and without allowing sufficient time for the shifting or swelling of the shale to an extent to require re-drilling or to interfere with the setting of the casing.

To secure the desired results, it is essential that a casing length be advanced with the drill head during the drilling operation, and that the circulation of the water for removing the cuttings continue during the advancement of the drill and its associated casing length. When the drill has penetrated the shale stratum for a distance determined by the length of the casing section, the drilling operation is interrupted and the power of the pumps is utilized to set the casing, the circulation of water during this interval being interrupted.

It is essential that the casing length carried by the drill head be of less diameter than the standard casing used in lining the bore, and that it be capable of being expanded to a diameter substantially co-extensive with that of the regular casing to permit the pulling back of the drill for the purpose of mounting another length of expansible casing in relation to the drill head, and the incidental. sharpening of the bit, preparatory to the resumption of the drilling operation. Underreaming of the bore may be resorted to if desired or if found necessary.

While the drill may be some feet in advance of the lower edge of the expansible casing, this is immaterial, since even if the heaving shale fills the bore below the expansible casing, it may be readily removed upon the succeeding drilling operation.

The action of heaving shale does not proceed sufficiently rapidly to interfere with the movements of the casing section carried by the drill head, so that after the initial penetration of thelower edge of the expansible casing section, this section serves to effectively prevent such movement of the shale about the casing as would obstruct the boring.

By utilizing hydraulic power for setting the casing, which setting involves its expansion to its maximum diameter and its attachment to the casing section next above it in the bore, the casing may be readily expanded by a progressive action which will overcome any pressure from the shale.

By the method of the invention, a shale stratum, irrespective of its thickness, may be pierced by a series of repeat operations by drilling methods ordinarily used, excepting as to the effecting of a temporarycasing off of the bore simultaneously with the penetration of the drill into the shale and a subsequent enlargement of the casing section used for this temporary casing off of the bore, to permit the pulling out of the drill and the re-introduction of the drill and another expansible casing length to permit the continuation of the drillingoperation.

In the practice of the method of the invention, I employ, in connection with'the drill and the drill rod, a supporting structure for a length of expansible casing adjacent the drill head which is so constructed as not to interfere with the turning of the drill or the maintenance of a circulation of water for removing the cuttings as they are made by the drill. This apparatus embodies therein an hydraulic cylinder, the piston of which supports a wedge acting upon gitudinal convolutions of an expansible casing section, such convolutions being utilized to re duce the diameter of the casing section to permit its passage through the upper ordinary or expanded casing sections while affording adequate space exteriorly of the corrugated section for the upflow of the circulating water and the cuttings in suspension therein.

The construction of the arms and the wedge acting thereon are such as to ensure a progressive expansion of the corrugations of the casing section, thus permitting the application of the maximum power applied through the wedge to small areas of the casing and avoiding any material variation in its diameter throughout the length of the expanded casing, although the form of the arms is such that the lower portion of the casing will be expanded to a slightly greater extent than toward the top thereof.

The arms above referred to are also utilized in transmitting power for turning the drill.

The cylinder, the piston rod and wedge are also so constructed as to form a part of the circulating water channel and to permit the diversion of the circulating water from the portion of the drill rod, adjacent the bit, to the hydraulic cylinder following the stoppage of the drilling operation and during the setting of the expansible casing.

Each expansible casing section, at its opposite ends, is provided with exterior and interior means to permit the attachment of adjoining sections together to ensure the desired continuity as well as the support of these sections of the boring casing.

The expanding means, including the wedge, the cylinder and the piston and its rod, are, during the drilling operation, maintained in a position to permit the actuation of the wedge when desired, by the resistance to downward movement of the wedge by the expanding spring arms.

The invention consists in the novel steps and practices, and in the novel features of construction and combination of parts in the apparatus used, all as hereinafter set forth and described and more particularly pointed out in the claims hereto appended.

Referring to the drawing,

Fig. 1 is a vertical section upon a greatly reduced scale illustrating the method of the invention and an embodiment of the apparatus used;

Fig. 2 is a section on the line 2-2 of Fig. 1;

Fig. 3 is a section on the line 33 of Fig. 1; and

Fig. i is a longitudinally condensed view upon a reduced scale, andpartly in vertical section, of a length of collapsible casing.

Like numerals refer to like-parts throughout the several views.

In drilling oil wells,-a drill head is used which is advanced and turned by means of a hollow drill rod through which water is constantly delivered through openings in the drill head adjacent the bit, this water passing upwardly through the bore and carrying with it, in suspension, the cuttings from the drill. A common practice is to drive a casing, in suitable lengths, through the top of the bore, this casing being of a diameter to provide space about the drill rod for the flow of the circulating water. This practice forms a part of the method of my present invention, which departs from the usual practice in the respects that when encountering shale, the drill is pulled back in the usual manner and the drill rod is provided, intermediate itslowermost end and the drill head, with means by which a casing, of smaller diameter than that ordinarily used in a bore of the diameter of the ordinary casing, but capable of being expanded to a diameter approximately that of said other casing, is mounted just above the drill head. The mechanisms supporting this expansible casing length are provided with means by which said casing length may be expanded to its maximum diame ter when required.

The drill, rod, and other equipment, is then lowered in the bore until the drill contacts with the shale stratum, whereupon the drilling operation proceeds in the usual manner accompanied by the usual circulation of water for removing the cuttings. With this condition, as the drill penetrates the body of shale and before the shale 'has had an opportunity to move or swell, the

contracted casing length is carried by the drill into the bore, thus preventing any material dislodging, shifting or swelling of the shale as a result of the action of the water thereon or from any other cause. This operation continues until the drill has advanced to a point where the top of the expansible casing length is closely adjacent the bottom of the regular casing, whereupon drilling is stopped and the mechanism used for expanding the casing is actuated by the application of the pressure for circulating water, to this mechanism.

When the casing has been expanded to its maximum diameter, the dril and the expansion mechanism are pulled out of the bore, the expanded casing remaining in position to prevent the clogging or blocking of the bore throughout its length until a new casing length is mounted in relation to the drill head and the above practices are repeated. In this manner, it is possible, during the sequence of operations of. each repeat, by a series of repeats, to pierce the shale stratum and to provide, first, a temporary, and then, a permanent, casing.

If desired, immediately following the expansion of the casing length adjacent the drill. head, the circulation of water may be resumed to facilitate the pulling back of the drill.

While, in the practice of the method, the bit may be several feet in advance of expansible casing, this is immaterial since it merely involves a ice-drilling of this portion of the bore upon the succeeding drilling operation, which may be quickly done.

By using the above methods, which are ordinarily only required when the drilling has proceeded to a great depth, possibly ten thousand feet, it is obvious that the immediate casing of the bore in the shale stratum permits the completion of the drilling operation through the shale in succeeding stages by reason of the fact that each portion otthe bore is cased imme- Were diately following the drilling operation. it not for this, experience has shown that the time required to pull back a drill and prepare it for the resumption of drilling operations,

would result in the closing of the bore by the i shale so as to make it impossible to proceed with the drilling operation.

In fact, the common practice, as stated, has been to abandon drilling where shale is encountered, and salvage much oi the cas- 1.

ing as possible. This former practice resulted in large losses, and, as stated, prevented access to what is believed to be an almost inexhaustible supply of oil.

Incarrying on the method of the invention, 1'

preferably employ an apparatus which will now be described.

In the drawing, a fragmentary portion of an ordinary drill head is shown at 10 and a portion of the hollow drill rod at 11. Ordinarily, this drill rod is connected directly to the drill head by means of screw threads. In the apparatus of the invention, the drill rod is connected by means of screw threads to the head 12 of an hydraulic cylinder 13, within which is a piston 14 having a hollow piston rod 15 passing through the piston 14 and communicating through a tapered port 16 with the interior of the drill rod 11.

Secured to the end 1'? of the cylinder 13 are a plurality of spring arms 18, adapted to be flexed outwardly to increase the diameter of an expansible casing length, by a wedge 19 carried by the lower end of the piston rod 15.

Each of the spring arms 18 at one end thereof is outwardly formed to afford space for the reception of the wedge 19 during a normal drilling operation. The other end of each of the spring arms is similarly outwardly formed to permit the spring arms to resume their normal positions after the completion of the expansion of the casing length, so as to afford clearance for the passage of the arms, the drill head and the bit through the casing when pulling out the drill. The portion of the spring arms intermediate the bulged top and the bulged bottom portions thereof is operative upon the expansible tube. lhe upper bulged portion is shown at 20 and the lower bulged portion is shown at 21.

Adjacent and above the bulged portion 21 of the arms 18 a shoulder 22 is formed, the arms being screw threaded adjacent this shoulder for the purpose of permitting the attachment of an expansible casing length to these arms.

The arms 18 are attached to the drill head by means of a fitting 23 having screw threads thereon co-operating with the screw threads upon the drill head. One end of the arms 18 is connected with the end 17 of the cylinder, by means of interlocking tongues and grooves upon said arms and said cylinder end, as shown at 24, and these arms are held in relation to the cylinder by means of a metal band 25 en circling all of the arms and holding them against movement in relation to the cylinder. This band 25 may be held in position by a driving fit with the arms, or may be secured in any desired manner in relation to the cylinder to permit the disengagement of the band from the arms for permitting the collapsing of the mandrel structure provided by the arms, when mounting a casing length in position to be carried into the bore and set in a manner to be hereinafter described.

The opposite ends of the arms are connected to the fitting 23 by means of co-operating tongues and grooves 26 upon said arms and upon fitting, and are held in relation to said fitting by a band 27, corresponding with the band 25, operative upon the opposite ends of said arms.

The arms 18 preferably are of progressively increasing thickness from adjacent the bulged portion 20 at one end thereof to adjacent the bulged portion 21 at the other end thereof, so that with the flexure of these spring arms by the wedge member 19 there will be greater expansion of the casing length toward the bottom than'toward the top thereof to compensate for the thickness in the material of said casing and avoid a progressive reduction in the diameter of the casing as a result of the use of a number of connected expansible casing lengths. This construction permits the addition of any desired number of casing lengths without any substantial reduction in the diameter of the cased bore.

The arms 18 are made of readily deformable spring metal, one, or the inner face of which preferably presents a plane surface toward the wedge 19, as shown at 28. The outer surface 29 of each arm is curved upon a radius which will ensure a substantially circular form of the casing when expanded.

Th wedge member 19 may be made with flat wedging surfaces, there being one surface for each arm 18.

The arms 18 are preferably of the same width throughout the entire length thereof, the portions of the arms intermediate the bulged end portions being in abutting relation to each otherto avoid displacement of the arms and to develop the necessary torque during the opera tion of the drill.

The drill head 10 is provided with the usual water channel shown at 30, and carried by this head and projecting upwardly between the arms 18 through an opening in the wedge 19 and into the hollow piston rod 15, is a tube 31 of a length to engage a go devil 32 and unseat it at the end of the piston movement so as to relieve the pressure within the cylinder 13 upon the completion of the stroke of this cylinder during the operation of expanding the casing length.

Toward the end 17 of the hydraulic cylinder, is an inlet port 33 through which pressure may be applied to the under side of the piston 14: preparatory to the mounting of an expansible casing length upon the arms 18.

The form of easing length used is shown in Fig. 4 of the drawing. It consists of a fairly heavy gauge metal tubing 34, the diameter of which is reduced by the formation of longitudinal corrugations, shown at 35 in the drawing. The casing length may have a slight taper from top to bottom. About the outer surface of this casing length, at one end thereof, screw threads or circumferential tongues and grooves 36 are i formed. Upon the inner surface, at the opposite end thereof, similar screw threads or tongues and grooves 37 are formed. The sole function of the screw threads or tongues and grooves 36 and 37 is to provide interlocking means, exteriorly of each casing length, adapted to interlock with the co-operating tongues and grooves formed upon the inner wall of another casing length. I refer to the use of screw threads because of simplicity in the production of these as compared with other forms of interlocking means.

The screw threads or other locking means need not be continuous, although they are so shown in the drawing. The longitudinal cor- .ij.

rugations may be formed as a last step in the production of the casing lengths, and in so forming them, the entire tube will be drawn in sufficiently to reduce its diameter to a point where the tube may be readily passed through an expanded tube of the same type and still afford suincient clearance within and about the corrugated portions for the flow of the circulating water.

The casing lengths used must be made of Illa after the stoppage of the drill.

readily deformable metal, but the material of the tubing is no part of my invention and is capable of wide .variation. The cost of the material of such tubing is no factor. These tubes may range from six inches in diameter upwardly when fully expanded.

In view of. the small scale of the various views of the drawing, no attempt has been made to preserve the relative proportions of parts.

The procedure in drilling a well in accordance with my invention is substantially as follows:-

In Fig. 1 of the drawing, the cross. hatching at the opposite edges indicates a shale stratum S which has been partiallyv pierced and cased. It will be understood that the drilling operation, prior to encountering shale, involves standard practices. Upon encountering the shale, such drillin operations are stopped, and the drill rod and drill pulled back and the drill head detached from the drill rod.

The cylinder 13 is connected with the end of the drill rod, and a fitting 23 is connected to the end of the drill head. The spring arms are secured thereto by, means of the interlocking tongues and-grooves 26 and the band 27.

When positioning the expansible casing length upon the arms, its lower edge abuts the shoulder 22 and the screw threads 37 interlock with the screw threads upon the arms adjacent said shoulder.

Before connecting the spring arms with the fitting 23, the tube 31 is mounted upon the drill head and passed. through the axially extending opening inthe wedge 19 into the hollow piston 14. When the parts are thus assembled, it is possible to proceed with the drilling operation in accordance with the method of my invention. The drill is then lowered inthe bore, the casing length 35 passing freely through the casing already set in the bore until the drill strikes the shale. The drilling operation is then resumed, water being circulated through the drill rod, the piston rod, the tube 31 and the channel 30 and discharged through the bit openings into the bore in the usual manner.

It will be noted that as the drill penetrates the shale, a casing length 35 is advanced with the drill so that the continuous wall of this contracted casing length will present a barrier preventing the caving in of the walls of the bore as the drill progresses.

The time required in drilling through heaving shale is not great, and the action of the shale is slow compared with the time required for the drilling operation. Consequently, a casing length 35 will be positioned before there has been any substantial contraction of the bore about it by reason of the action of the shale. When the boring has proceeded to a depth which will bring the top of one casing length within a suitable distance from the bottom of the casing length through which it has just passed, which may result in the overlapping of the ca ing by approximately a foot, the drilling operation is interrupted, although the circulation or" water may be maintained for a short interval The go devil 32 is then dropped into the drill rod and ultimately seats upon the end of the piston rod 15 where it passes through the cylinder head so as to be exposed within the tapered port 16 of the cylinder head. This interrupts the how of water through the hollow piston rod 15 and stops the circulation of the water for carrying the mud from the bore. The water pump is kept in operation so that the pressure of the water acting upon the go devil will force it through the tapered port 16 by a slow movement of the piston until the water under pressure is admitted to the cylinder adjacent its head 12. Upon the seating of the go devil there will be a rise in the pressure of the water, but this pressure will be lowered immediately upon the opening of the port to admit the water to the cylinder. Q

The piston may have a diameter of five or six inches, more or less, according to'the size of the bore, so that considerable power is developed by the hydraulic cylinder. With the downward movement of the piston, the wedge 19 is forced downwardly between the spring arms 18, which, as shown in dotted lines Fig. 1, will bulge with the progress of the wedge so as to conform thereto and thus permit the full power developed by the piston movement and by the wedge to be progressively applied to the corrugated portions 36, thus ensuring the progressive expansion of the casing length with the movement oi the Wedge. Immediately following the passing of the wedge bycach point of the casing length, the spring arms will reflex.

As the piston approaches the limit of its downward movement, the wedge in its entirety passes into the bulged portion 21 of the arms and thus permits all of the spring arms to resume their normal position. The initial expansion of the arms engages the screw threads or other tongue and groove portions 36 thereof with the inner screw threads or tongues and grooves 37 of the casing length immediately above. The screw threaded portion of the arms 18, adjacent the shoulder 22, will prevent deformation of the innor screw threads 3'? of the casing length by the power applied to the arms 18 while the casing is being expanded.

As the piston 14 approaches the limit of its movement, the bottom of the go devil 32 engages the top of the tube 31 and is unseated so as to interrupt the application of power to the piston, water being permitted to flow through the go devil into the tube 31 so that, if desired, there may be a continued operation of the pump following the expansion of the casing length for the purpose of maintaining the circulation of water for a sufficient time to facilitate the pulling out of the drill. 1

When the casing length has been set, it is of a diameter to permit the withdrawal of the arms and the drill head through the casing, since notwithstanding the outward flare toward the bottom of the casing, the minimum diameter thereof will be sufiicient to permit the free passage of the drill head and the arms through the expanded casing.

The taper toward the bottom of each casing length results from the increased thickness of the spring arms 18 toward the bulge 21 thereof.

By providing this taper, the minimum diameter cased bore as would interfere with the drilling operation and the flow of the well.

The above operation may be carried on in successive repeats until the shale stratum has been completely pierced, and the presence or absence of oil has been determined.

After the piston 14 has been actuated in the manner described, it is necessary, before another casing length can be applied thereto, preparatory to a succeeding repeat of the drilling operation as described, that the wedge 19 should be restored to its position adjacent the end of the cylinder. The port 33 is provided to permit the application of fluid pressure to the under side of the piston 14 to impart a reverse movement thereto and to said wedge. Said port also permits the escape of any fluid from within the cylinder below the piston, this action being in the nature of a venting of the cylinder.

It will be noted that, in the manner above described, a casing length is advanced with the drill so as to ensure a progressive casing off of the bore while maintaining a continuous circulation of water about the casing length for removing the cuttings, and either keeping the space about the casing length clear of such cuttings or providing space between the lower edge of the casing length and the drill into which small particles of shale may fall.

Upon the completion of this stage of simulta neous drilling and temporarily casing the bore, the casing is expanded to form a permanent casing through which the drill head and the other parts of the drilling mechanism may be pulled back preparatory to a repetition of the steps of this method.

The actualdrilling and permanent setting of the casing length should require approximately a minute per foot of bore, so that the time interval during which the shale can be active toan extent to interfere with the drilling and casing 01f operation, is so limited as to preclude difficulty from this source. This will be readily appreciated when it is realized that after each drilling and casing operation is completed, it may require from four to five hours to pull out the drill, sharpen it and again run it into the bore preparatory to the next drilling operation. With this longer time interval, it is obvious that after each drilling operation involving the method of the invention the bore will be completely closed before the drilling operation could be resumed.

It is obvious that the details of construction of theapparatus used in the practice of this method, as shown in the accompanying drawing and herein described, may be varied without departing from the spirit and scope of the invention.

Having described the invention, what I claim as new and desire to have protected by Letters Patent, is:

l. The herein described method of drilling oil wells which consists in progressively advancing a collapsed casing length into the bore simulta neously with, and adjacent, the drill, whereby a temporary casing of a diameter less than, and for a progresisvely increasing length of, the bore, is provided adjacent the drill, maintaining a circulation of water into and from the bore and about said casing length, stopping the drilling operation, interrupting the circulation of water, and expanding the casing length to provide a permanent casing for a length of bore, immediately following the completion of the drilling operation.

2. The herein described method of drilling oil wells consisting in piercing a stratum of heaving shale by a sequence of repeat operations, each of which consists in progressively advancing a collapsed casing length into the bore simultaneously with, and adjacent, the drill, whereby a tem-,

porary casing of a diameter less than, and for a progressively increasing length of, the bore, is provided adjacent the drill, maintaining a circulation of water into and from the bore and about said casing length, stopping the drilling operation, interrupting the circulation of water, expanding the casing length to provide a permanent casing for a length of bore, immediately following the completion of the drilling operation, and pulling out and running in the drill and its appurtenances between the succeeding repeat operations.

3. An apparatus for drilling oil wells embodying therein a cylinder having a port in the head thereof, means carried by said head whereby it may be connected with a hollow drill rod, a piston within said cylinder, a hollow piston rod, a fitting having meam whereby it may be attached to a drill head, a plurality of spring arms adapted to engagelongitudinal corrugations of a casing length, means connecting one end of each of said arms respectively with said cylinder, and the other end of each of said arms respectively with said fitting, a wedge, carried by said piston rod, having an axial opening therethrough, and positioned within and acting upon said spring arms, a pipe connection extending from said fitting through the opening in said wedge and having a telescopic connection with said piston rod, and means whereby the port in said cylinder head may be closed, said means being adapted to engage said tube and be unseated toward the conclusion of piston movement.

4. An apparatus for drilling oil wells embodying therein a cylinder having a port in the head thereof, means carried by said head whereby it may be connected with a hollow drill rod, a piston within said cylinder, a hollow piston rod, a fitting having means whereby it may be attached to a drill head, a plurality of spring arms adapted to engage longitudinal corrugations of a casing length, each of said arms having a bulged portion adjacent each of its ends, means connecting one end of each of said arms respectively with said cylinder, and the other end of each of said arms respectively with said fitting, a wedge, carried by said piston rod, having an axial opening therethrough, and positioned with.- in and acting upon said spring arms, the bulged portions of said arms affording space for the reception' of said wedge, a pipe connection extending from said fitting through the opening in said wedge and having a telescopic connection with said piston rod, and means whereby the port in said cylinder head may be closed, said means being adapted to engage said tube and be unseated toward the conclusion of piston movement.

5. An apparatus for drilling oil wells embodying therein a cylinder having a port in the head thereof, means carried by said head whereby it may be connected with a hollow drill rod, a piston within said cylinderpahollow piston rod, a fitting having means whereby it may be attached to a drill head, a plurality of spring arms of progressively increasing thickness from top liiC to bottom adapted to engage longitudinal corrugations of a casing length, means connecting one end of each of said arms respectively with said cylinder, and the other end of each of said arms respectively with said fitting, a wedge, carried by said piston rod, having an axial opening. therethrough, and positioned within and acting upon said spring arms, a pipe connection ex tending from said fitting through the opening in said wedge and having a telescopic connection with said piston rod, and means, whereby the port in said cylinder head may be closed, said means being adapted to engage said tube and be unseated toward the conclusion of piston movement.

6. An apparatus for drilling oil wells embodying therein a cylinder having a port in the head thereof, means carried by said head whereby it may be connected with a hollow drill rod, a piston within said cylinder, a hollow piston rod, a fitting having'means whereby it may be attached to a drill head, a plurality of spring arms of progressively increasing thickness from top to bottom adapted to engage longitudinal corruga- T tions of a casing length, each of said arms having a bulged portion adjacent each of its ends, means connecting one endof each of said arms respectively with said cylinder, and the other end of each of said arms respectively with said fitting, a wedge, carried by said piston rod, having an axial opening therethrough, and positioned within and acting upon said spring arms, the bulged portions of said arms affording space for the reception of said wedge, a pipe connection extending from said fitting through the opening in said Wedge and having a telescopic connection with said piston rod, and means whereby the port in said cylinder head may be closed, said means being adapted to engage said tube and be unseated toward the conclusion of piston movement.

7. An apparatus for drilling oil wells embodying therein a cylinder having a port in the head thereof, means carried by said head whereby it may be connected with a hollow drill rod, a piston within said cylinder, .a hollow piston rod, a fitting having means whereby it may be attached to a drill head, a plurality of spring arms adapted to engage longitudinal corrugations of a casing length, interlocking tongues and grooves upon said cylinder and upon one end of each of said arms respectively, a band engaging said arms and'preventing the disengagement of said tongues and grooves, co-operating tongues and grooves upon said fitting and the other end of each of said arms respectivelyya band engaging said arms and preventing the disengagement of said tongues and grooves, a wedge, carried by said piston rod, having an axial opening therethrough, and positioned within and acting upon said spring arms, a pipe connection extending from said fitting through the opening in said wedge and having a telescopic connection with .said piston rod, and means whereby the port in said cylinder headmay be closed, said means being adapted to engage said tube and be unseated toward the conclusion of piston move-- ment.

8. An apparatus for drilling oil wells embodying therein a cylinder having a port in the head thereof, means carried by said head whereby it may be connected with a hollow drill rod, a piston Within said cylinder, a hollow piston rod, a fitting having means whereby. it may be attached to adrill head, a shoulder adjacent said means, and screw threads adjacent said shoulder, a plurality of spring arms adapted to engage longitudinal corrugations of a casing length having interior screw threads adapted to inter lock with the screw threads adjacent said shoulder, means connecting one end of each of said arms respectively with said cylinder, and the other end of each of said arms respectively with said fitting, a wedge, carried by said piston rod, having an axial opening therethrough, and positioned within and acting upon said spring arms, a pipe connection extending from said fitting through the opening in said wedge and having a telescopic connection with said piston rod, and means whereby the port in said cylinder head may be closed, said means being adapted to engage said tube and be unseated toward the conclusion of piston movement.

9. An apparatus for drilling oil wells embodying therein a cylinder having a port in the head thereof, means carried by said head whereby .it may be connected with a hollow drill rod, .a piston within said cylinder, a hollow piston rod extending through said piston and the port in the head of said cylinder, a fitting :having means whereby it may be attached to a drill head, a plurality of spring arms adapted to engage longitudinal corrugations of a casing length, means connecting one end of each of said arms respectively with said cylinder, and the other end of each of said arms respectively with said fitting, a wedge, carried by said piston rod, having an axial opening therethrough, and positioned within and acting upon said spring arms,

a pipe connection extending from said fitting through the opening in said wedge and having a telescopic connection with said piston rod, and means whereby the port in said cylinder head may be closed, said'means being adapted to engage said tube and be unseated toward the conclusion of piston movement.

10. An apparatus for drilling oil wells em bodying therein a cylinder having a port in the head thereof, and a vent port adjacent the end of said cylinder opposite said head, whereby fluid pressure may be delivered to the cylinder for imparting movement to a piston toward said head, means carried by said head whereby it may be connectedwith a hollow drill rod, a piston within said cylinder, a hollow piston rod, a fitting having means whereby it may be attached to a drill head, a plurality of spring arms adapted to engage longitudinal corrugations of a casing length, means connecting one end of each of said arms respectively with said cylinder, and the other end of each of said arms respectively with said fitting, a wedge, carried by said piston rod, having an axial opening therethrough, and positioned within and acting upon said spring arms, a pipe connection extending from said fitting through the opening in said Wedge and having a telescopic connection with said piston rod, and means whereby the port in said cylinder head may be closed, said means being adapted to engage said tube and be unseated toward the conclusion of piston movement.

11. An apparatus for drilling oil wells embodying' therein a cylinder having a port in the head thereof, and a vent port adjacent the end of said cylinder opposite said head, whereby fluid pressure may be delivered to the cylinder for imparting movement to a piston toward said head, means carried by said head whereby it may be connected with a hollow drill rod, a piston Within said cylinder, a hollow piston rod extending through said piston and the port in the head of said cylinder, a fitting having means whereby it may be attached to a drill head, a shoulder adjacent said means and screw threads adjacent said shoulder, a plurality of spring arms of progressively increasing thickness from top to bottom adapted to engage longitudinal corrugations of a casing length, each of said arms having a bulged portion adjacent each of its ends, interlocking tongues and grooves upon said cylinder and upon one .end of each of said arms respectively, a band engaging said arms and preventing the disengagement of said tongues and grooves, co-operating tongues and grooves upon said fitting and the other end of each of said arms respectively, a band engaging said arms and preventing the disengagement of said tongues and grooves, a wedge, carried by said piston rod, having an axial opening therethrough, and positioned within and acting upon said spring arms, a pipe connection extending from said fitting through the opening in said wedge and having a telescopic action with said piston rod, and means whereby the port in said cylinder head may be closed, said means being adapted to engage said tube and be unseated toward the conclusion of piston movement.

BAILEY E. PRICE.

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