United States Patent [72] Inventors Vladimir Riziuc;

Silvestru Huelscher, Pitesti, Romania [21] Appl. No. 796,829 [22] Filed Feb. 5, 1969 [45] Patented Mar. 16, 1971 [73] Assignee Trustul deForaj Pitesti Pitesti, Romania [32] Priority Feb. 9, 1968 33] Romania [31] 55,824

[54] DEVICE FOR FREEIN G SEIZED DRILL STRINGS 1 Claim, -1 Drawing Fig.

[52] US. Cl 175/296 [51} Int. Cl E2lb l/00, E2 lb 7/00 [50] Field ofSearch 175/296,

[56] References Cited UNITED STATES PATENTS 1,861,042 5/1932 Zublin 175/296x 3,038,548 6/1962 Brown 175/296x 3,180,433 4/1965 Mason... 175/296x 3,185,227 5/1965 Nelson l75/296x 3,213,941 10/1965 Nelson 175/296x Primary Examiner-David H. Brown Att0rneyl(arl F. Ross ABSTRACT: A device for freeing seized drill strings in which a longitudinally reciprocable valve controls up and down movement of a vibrating member imparting longitudinal shock to the drill string as controlled by the drilling fluid pressure. In addition, the longitudinally reciprocal member forms a valve in its casing to alternately block flow of drilling fluid and admit such flow to the lower part of the drill string whereby the pressure in the bore is alternately increased and decreased in the cadence of the longitudinal shock.

PATENTED HARISlHYI 3570.611

Vladimir Riziuc Silvesfru Huelscher INVENTORS'.

' Attorney The invention relates to a device for freeing a drill string seized in the bore hole by repeated hydraulical impacts at high frequency, applied to the drill string by a vibrating device acmated by the circulation of the drilling fluid.

The literature describes several devices to free a drill string seized by the walls of the bore hole, using a hydraulic vibrator introduced through the interior of the drill string. Such devices produce a series of vibrations or mechanical oscillations in the lower part of the seized drill string. The devices consist of a piston valve assembly with unidirectional impact action, descent of the piston being damped by a cushion system and the closing of the drilling fluid circuit being realized by a valve and a helicoidal return spring.

These devices have the drawback that, due to time-delaying elements in the system, hydraulic impacts of high frequency cannot be obtained. The system according to the invention does away with this drawback by using simultaneously the mechanical action of hydraulic high frequency impacts with longitudinal and transverse vibration of the entire drill string, and the creation at the same frequency of pressure differences between the fluid inside the drill string and the fluid in the annular space in the bore surrounding the string; the device consists of a cylindrical body, provided at the top part with an external thickened portion forming a valve. This cylindrical body is extended at the bottom by screwing it into a second cylindrical part with a larger outside diameter than the outside diameter of the valve formed by the upper cylindrical body and having thicker walls at the upper part, its thickness being smaller at the lower part, where it contains a fixed piston. The effective surface of this piston (corresponding to the inner diameter at the lower end of the cylindrical part) is larger than the diameter of the valve formed by the body of the upper cylinder. The end of the fixed piston has a valve seat upon which, under the action of the drilling fluid, a kicking valve, elastically suspended by an helicoidal spring in the interior of the cylindrical part is supported by a perforated disc and guided by a jig bushing, so that simultaneously with fluid circulation along the lower part of the first cylindrical body resting with the respective valve upon the seat of the valve (and through the inside of the second cylindrical body pressing upon the kicking valve against the action of the sustaining spring), the valve is urged toward its seat producing inside the cylindrical body and in the drilling fluid column, a greater pressure than the pressure of the fluid below the valve produced by the upper cylindrical body and the kicking valve. Due to the diameter difference between the lower body of the second cylindrical body, movable upon the fixed piston, and the outside diameter of the upper cylindrical valve, the valve system is thrown upwards, till the upper cylindrical body rests upon a limiting part; this movement allows the drilling fluid to have access through the outside part of the mobile valve assembly towards the bore hole. The downward return back of the valve assembly results from the reaction received from the limiting part, provided with an elastic element, and also due to the impingement force of the drilling fluid and to the weight of the entire valve assembly.

The invention is further described with reference to the accompanying drawing, the sole FIGURE of which is a sectional view through the device.

The vibrating outfit consists of a cylindrical body 1 so dimensioned that it can be inserted through the interior of the drill pipe, being provided inside with a threshold or step a and at the ends with two threaded bushings b and 0.

Inside the body l a movable double valve system (assembly) is mounted consisting of an upper cylindrical body 2, provided at its upper part with a thickened portion d and with a valve seat e. The upper cylindrical body 2, at its lower part, has a tenon f for joining with a second cylindrical part 3, consisting of an upper cylindrical part or apron with thick walls 3 and a lower part h, with thin walls. Below the cylindrical zone with thick walls g a kicking valve 4 is mounted in a supporting and guiding part 5 in the form of a perforated disc with an helicoidal spring 6 and a fixing part 7, the supporting and guiding part 5 being provided with circulating orifices i and the helicoidal spring 6 having the task to maintain the valve 4 in its opened position.

The thickened portion d of the upper cylindrical body 2 rests upon the seat 8, fixed on the threshold a of the body I. I

The seat 8 is provided with three elastic sealing rings 9.

The lower part of the cylindrical part 3, represented as the zone h fits tightly around a fixed piston 10 with a hydraulic labyrinth seal. The piston 10 has at its top end a seat j upon which sits the valve 4 and is provided further with a thickening in which four circulation windows k have been cut, a threaded zone c for assembling the bushing, a threshold I for attachment to the upper part of the drill stem and a cylindrical part m provided with sealing rings 11, which enter in the central canal of the drill stern and form a sealing and guiding part for the device. 7

The cylindrical parts 2 and 3 define the mobile assembly of the device which slides axially in the body l, the stroke being adjustable and limited by a limiting part 12.

The limiting part 12 consists of a metallic core provided with three ribs n a central canal o and a cylindrical portion p. The limiting part 12 is supported by the lower part of the cylindrical portion p on a spacer ring 13, which has windows r for the circulation of the drilling fluid.

In the bushing b of the body 1 an extractor 14, provided with inner grooves r is screwed in. The extractor l4 finishes with a threaded tenon which is assembled in the bushing b and has at its lower part a seat into which an elastic damping gasket 15 is introduced. The seat 8, the spacer ring 13 and the elastic gasket 15 are fixed inside the body 1 by tightening the extractor 14.

On the outside surface of the extractor 14 an elastic guiding is constituted by four elastic lamellae 16, a fastening collar 17, fixed upon the extractor 14 by screwing and an upper part 18, screwed in at the upper part of the extractor 14, provided with a inner development t to allow the fastening of the elastic lamellae 16. The elastic guide serves to moderate the ball of the device, when introduced into the string, and the extractor 14 for allowing extraction of the device with a slip socket, introduced with a cable through the drilling string. 1

If the drill string is seized. in the bore hole, the vibrator is thrown through the drill pipe, the free-fall velocity being controlled by the lamellae 16 of the elastic guide. Arriving above the drill collar, the cylindrical portion m of the fixed piston 10 enters into the central canal of the drill collar and the threshold 1, which has a larger diameter, rests upon the upper part of the central canal, preventing the drilling fluid from passing through the annular space between drill pipe and the device. When circulation begins, the drilling fluid passes through: the inside of extractor M, the outside of the limiting part 12, the inside of upper cylindrical body 2, the orifices i of guiding part 5, and presses the kicking valve 4 onto the seat j. The drilling fluid circuit is thus interrupted. The resulting hydraulical impact is transmitted through the body 0 and the piston 10 to the drill collars. The increase of pressure is transmitted also to the inside surfaces of the zone h of the cylindrical part 3. The surface of this zone h, being larger than the surface of the thickened portion d of the upper cylindrical body 2 and the pressure of the drilling fluid being equal to the hydrostatic pressure in the annular space under the seat 8 between the outside of the movable valve assembly and the body 1, the movable double valve will be raised from the seat 8, raising the thickened portion d from seat 8;. The outside circulation circuit is opened letting the drilling fluid pass through the annular space between the cylindrical bodies 2 and 3 and the body 1 and enter through the windows It into the central canal of the fixed piston, the circuit being continued through the drillbit and the annular space in the borehole to the soil.

The upwards movement of the mobile double valve assembly is stopped at the moment at which the seat e of the upper cylindrical body 2 meets the lower part of the limiting part 12. The impact received by the limiting part 12 is taken over by the elastic string and by the effect of reaction, of its own weight and of the carrying away by the circulating drilling fluid, the mobile double valve assembly is projected downwards coming into its initial position, movement in which the operation cycle starts again; the number of cycles being proportional to the drilling fluid discharge, the frequency being about 1200 vibrations per minute.

At the moment the kicking valve 4 is shut stopping the drilling fluid circuit, a wave of low pressure appears in the fluid mass under the outfit, which is transmitted into the annular space in the borehole.

The method and the outfit, according to the invention, has the advantage that they assure a rapid and immediate overhauling of wells by simply throwing the outfit through the drill pipes frecing thus rapidly the seized drilling string, by an intricate mechanical and hydraulical action with high frequency.

We claim: 1. A device for facilitating the extraction of a drill string from a bore, comprising:

a tubular casing slidable in said drill string and formed at a lower end with a movable tubular member for passage of a drilling fluid below said device through the interior of said casing, said casing being formed with an annular valve seat at an intermediate location along its length and said member being provided with a tubular massive valve body engageable with said seat in a lower extreme position of said member for blocking the flow of drilling fluid through said casing except for the flow through said tubular member;

an abutment fixed to said casing above said valve body and engageable thereby upon elevation of said member to produce upward longitudinal shock; and

a spring-biased normally open kicker valve at the lower end of said member, said casing being provided with a further valve seat cooperating with said kicker valve for obstructing the flow of fluid from said member through said casing, said member and said casing defining a throttle passage for bleeding drilling fluid past said kicker valve in a closed position thereof under the pressure of drilling fluid in said member, said member forming a differential piston in a closed condition of said kicker valve tending to drive the member upwardly under the pressure of said fluid.