Differential Fill Collar

Abstract

This invention relates to a well casing collar into which is built a sliding collar type valve which is opened by fluid pressure on the exterior when such pressure exceeds that on the interior by a predetermined amount. The valve, which is spring loaded, closes when the exterior pressure no longer exceeds the interior pressure.

Description

BACKGROUND OF THE INVENTION

This invention relates to casing collars for use in bore holes, and particularly to differential pressure actuated filled collars for such use.

A well casing that is to be lowered into a well bore and cemented therein is ordinarily equipped with a float shoe or collar at its lower end. An upwardly closing check valve, as usually provided in such floating equipment, prevents fluid passage into the well casing. Advantages found in these devices are prevention of blow outs, provision for buoyancy of the casing string, and retention of the placed cement until setting occurs.

When a well casing has been lowered to its final position, cement is pumped down through the casing, out through the check valve and thence into the well bore about the casing. The subsequent setting of this cement bonds the casing to the surrounding formation.

As is well known, the casing may be and usually is overly buoyant when lowered entirely empty. In response to such an undesirable condition a common practice is to partially fill the casing with fluids as said casing is being assembled and lowered into a well bore. Such filling is usually performed manually by the drilling crew and requires considerable extra time and effort. Various well casing attachments have been devised to have this filling operation performed as needed and without effort on the part of the crew. The most common of such attachments are devices incorporated into the previously mentioned float shoes. Problems confronting such devices have been only partially solved. For example, cuttings and other detritus suspended in the drilling fluids sometimes wedge or block such devices.

Fluid loss additive materials present in the drilling mud often for example, tend to clog the entry ports in fill collars and to collect inside such collars where later it is difficult to displace them as cement is pumped down the casing.

Accordingly, a principal object of this invention is to provide an improved fill collar for use in well casing and/or cementing operations.

Another object of this invention is to provide an improved, positive acting casing collar.

A further object of this invention is to provide an improved differential fill type casing collar which is relatively non-clogging during operation.

In accordance with this invention there is provided a differential pressure actuated valve fill collar having a body which encloses a spring loaded sleeve valve mechanism which opens to admit fluid to the interior of the casing through a port on the application of pressure exceeding a predetermined valve.

Pressure moves the sleeve valve upwardly to open the port, and the port remains open until pressure within the casing, plus the loading of the spring on the sleeve, forces the sleeve valve closed again.

The invention, as well as additional objects and advantages thereof, will best be understood when the following detailed description is read in connection with the accompanying drawing, in which:

FIG. 1 is a side elevational view, partly broken away and in section, of a differential fill collar assembly in accordance with this invention;

FIG. 2 is a fragmentary sectional view taken along the line 2-2 of FIG. 1;

FIG. 3 is a fragmentary sectional view taken along the line 3-3 of FIG. 1;

FIG. 4 is a fragmentary side elevational view, partly in section, of apparatus in accordance with this invention in which a spring loaded float valve is incorporated into the apparatus;

FIG. 5 is a fragmentary side elevational view, partly in section, of apparatus in accordance with this invention and which includes a flapper type float valve; and

FIG. 6 is a side elevational view of a cementing plug of a type suitable for use in the embodiment of the invention shown in FIG. 1.

Referring to the drawings, and particularly to FIG. 1, 2, and 3, there is shown differential pressure valve fill collar apparatus including a body 1 which is generally of cylindrical outer configuration and a hollow interior part.

The upper end of the apparatus has internal threads 21 and an upper inwardly extending shoulder 32 adjacent to the inner end of the threads 32.

The inner wall 34 part of the apparatus lying below the shoulder 33 is of uniform diameter with threads 35 at the lower and thereof.

A first hollow cylindrical sleeve 14 is disposed within the body 1 in slidable fit with the inner wall of the body part. O-ring seals 11 and 19 are disposed in spaced apart slots around the outer periphery of the sleeve 14, the seal 11 being near the lower end and the seal 19 being near the upper end. O-rings seals 9 and 10 are disposed on the outer periphery of sleeve 14 just above the port 2, which lies just above the seal 11.

An expandable piston ring type element 18 is disposed in a slot adjacent to the upper end of the sleeve 14 and is adapted to expand into a slot 20 on the inner wall 34 of the body 1 when the sleeve 14 is moved downwardly so the element 18 is aligned with the slot 20.

The sleeve 14 contains a longitudinally extending slot 17 into which guide pine 16 extends, limiting lateral movement of the sleeve 14.

A port 36 extends through the wall of the sleeve 14 and is aligned with the port 2 when the sleeve 14 is held in its upper position by the shear pin 13 which extends through the wall of the body 1 and into sleeve 14.

A sleeve 15, spaced from the sleeve 14, is secured to the threads 35 at the lower part of the body 1.

A sleeve retaining and positioning member 37 is threadedly coupled at 38 intermediate the ends of the sleeve 14 substantially above the port 36. The member 37 is generally tubular in configuration, and has a thicker wall at the end where it is coupled to the sleeve 14, the remainder 39 of the side wall being parallel to and spaced from the inner side wall of the sleeve 14.

A small port 7 extends through the side wall of the member 37 just below the thicker part of the side wall.

A tapered seating surface 12 is provided on the upper end part of the member 37,

A tubular sleeve valve element 3 having a tapered surface at its lower end which faces the ports 2, 36 is positioned between the inner wall of the sleeve 14 and side wall part 39 of the member 37.

An array of coil springs 4 are disposed between the upper end of the valve element 3 and the shoulder of the thicker walled part of the member 37. The ends of the springs are set in shallow bores in the top of elements 3 and shoulder of the member 37.

O-ring seals 8, 40, set in circumferential grooves in the inner and outer wall, respectively, of the valve element 3 bear against the inner wall of sleeve 14 and outer wall part 39 of the member 37, preventing the upward passage of fluid along the valve element 3.

A retainer ring 41 is threaded onto the lower inner surface of the sleeve 14 and has a ring type seal 6 set in its upper surface which contacts the lower end of the valve element 3.

In operation, as the casing to which the apparatus is attached is lowered through the fluids in the well bore, fluid pressure on the slanted surface 5 of the valve element 3 forces the valve element 3 upwardly whenever the internal pressure plus the pressure of the springs 4 is exceeded, thus admitting fluid into the interior of the apparatus and casing (not shown). When the pressure of the interior of the apparatus is almost as great as the pressure on the exterior of the apparatus, the spring loaded valve element 3 closes.

The opening and closing of the valve element 3 continues as pressure differential demands as the casing is lowered into the bore hole.

After the casing is lowered into position in the well bore, cement is pumped down the casing and into the well bore through the apparatus of the invention. The cement is followed by a plug 48 of the type shown in FIG. 6, for example, which seats against the surface 12. Further application of pressure then shears the pin 13 and drives the sleeve 14 downwardly until its lower end seats against the top of the fixed sleeve 15. In this position the port 2 is covered and the seal elements between the sleeve 14 and body 1 prevent the passage of fluids.

The pin 16, riding in the slot 17, prevents rotation of the sleeve 14 as the plug 48 is later drilled out of the apparatus.

When the sleeve 14 is seated in its lower position, the piston ringlike elements 18 expands into the slot 20 and prevents further up or down movement of the sleeve 14.

The flow of material through the ports 2 and 36 is from the side of the casing rather than from the bottom of the casing, resulting in less intake of material which tends to plug the apparatus. The valve element 3 is positive acting and reliable in operation.

FIG. 4 shows a modified apparatus similar to that shown in FIG. 1, except that a spring loaded valve is used to control the flow of cement and/or other fluid through the interior of the apparatus.

A diaphragm 22 having an axial bore 23 therethrough is bonded to the valve element 3 and acts as a partition across the apparatus with the bore 23 being the only means for fluid passage through the apparatus.

A spider assembly 26 extends across and is coupled to the body 1 of the apparatus below the lower end of the fixed sleeve 41.

The diaphragm or partition 22 has a valve seat surface on the wall of the bore 23. A valve 24 extends from the valve seat surface on the wall of the bore 23 to below the spider 26, having a retained retainer sleeve 42 coupled to its lower end below the spider 26. A spring 25, under compression, extends between the spider 26 and the upper shoulder of the valve 24, holding the valve 24 seated against the seating surface on the wall of the bore 23.

The positioning of the retainer sleeve 42 is such that the valve 24 may close against the seating surface on the wall of the bore 23 when the sleeve valve element 3 is closed.

However, when the sleeve element 3 moves upwardly in response to external pressure as previously described, the simultaneous raising of the diaphragm provides a passageway through the opening between the valve seating surface on the wall of bore 23 and the upper end of the valve.

It should be noted that fluid may thus pass into the casing from the ports 2, 36 and also through the spider 26. The differential in pressure between inside and outside the apparatus continues to control fluid intake.

Referring now to FIG. 5, there is shown apparatus similar to that illustrated in FIG. 1, but using a flapper type valve to prevent backward flow up the apparatus.

A plate 30 having an axial bore 31 therein and a valve seating surface 29 adjacent to the bottom of the bore 29, is coupled across the lower end of the sleeve valve element 3.

A flapper valve supporting structure 43 in the shape of a tube having an outwardly extending flange at its lower end is coupled by piston ring-like element 47 to the inner surface of fixed sleeve 41, the flange bearing against the inner wall of the body 1.

A support element 44, coupled to the structure 43, carries a hinged flapper valve 28, with seating surface 45, and stop means 46 to prevent excessive upward movement of the flapper valve 28.

In operation, the flapper valve 28 has its surface 45 normally seated against the surface 29. However, external pressure may raise the sleeve valve element 3 as described above, raising the seat 29 away from valve seating surface 45, permitting fluid to enter the interior of the apparatus through the ports 2, 36 and from below the valve 28. After cementing operations begin, the flapper valve 28 functions in a conventional manner.

Thus, it may be seen that the instant invention provides simple, reliable means for maintaining a predetermined differential pressure between interior and exterior as casing is lowered into a bore hole containing fluid.

Claims

I claim:

1. Apparatus to be attached to the lower end part of well casing for maintaining a predetermined pressure differential between the exterior and interior of well casing lowered into a bore hole containing fluid, comprising an elongated tubular body section having attachment means at its upper end, a first tubular sleeve, said first sleeve fitting closely but slidably within said body section intermediate the ends of said body section, means for maintaining said first sleeve in fixed position during a first condition of operation of said apparatus, a pair of ports, one of said ports extending through said body section opposite to said first sleeve, the other port extending through said first sleeve and being axially aligned with said port in said body section during said first condition of operation. first and second valve sleeve positioning and retaining means fixedly coupled to the interior of said first sleeve, said first positioning and retaining means being one on one side of said port in said first sleeve and said second positioning and retaining means being on the other side of said port in said first sleeve, a valve sleeve element, said sleeve valve element being slidably disposed against the inner wall of said first sleeve and between said first and second valve sleeve positioning and retaining means to control flow through said ports, spring loading means, said spring loading means being coupled between said valve sleeve element and said first positioning and retaining means in longitudinal alignment with said valve sleeve elements, said valve sleeve element having a fluid pressure responsive slanted surface extending outwardly from the lower end part of said valve sleeve element to the outer surface of said valve sleeve element and exposed to the fluid pressure at said ports, a spring loaded float valve assembly having a seat structure rigidly coupled to said valve sleeve element and a spring loaded valve slidably coupled for limited movement with said body section whereby said seat structure is raised away from said valve when said seat structure is raised away from said valve when said valve sleeve element is raised, and means coupled to said first sleeve whereby on seating of a closure element, said first sleeve may be displaced downwardly in a second condition of operation to close said ports.

2. Apparatus to be attached to the lower end part of well casing for maintaining a predetermined pressure differential between the exterior and interior of well casing lowered into a bore hole containing fluid, comprising an elongated tubular body section having attachment means at its upper end, a first tubular sleeve, said first sleeve fitting closely but slidably within said body section intermediate the ends of said section, means for maintaining said first sleeve in fixed position during a first condition of operation of said apparatus, a pair of ports, one of said ports extending through said body section opposite to said first sleeve, the other port extending through said first sleeve and being axially aligned with said port in said body section during said first condition of operation, first and second valve sleeve positioning and retaining means fixedly coupled to the interior of said first sleeve, said first positioning and retaining means being on one side of said port in said first sleeve and said second positioning and retaining means being on the other side of said port in said first sleeve, a valve sleeve elements element, said sleeve valve element being slidably disposed against the inner wall of said first sleeve and between said first and second valve sleeve positioning and retaining means to control flow through said ports, spring loading means, said spring loading means being coupled between said valve sleeve element and said first positioning and retaining means in longitudinal alignment with said valve sleeve element, said valve sleeve element having a fluid pressure responsive slanted surface extending outwardly from the lower end part of said valve sleeve element to the outer surface of said valve sleeve element and exposed to the fluid pressure at said ports, a valve seat, said valve seat being rigidly coupled to said valve sleeve element below said slanted surface, a flapper valve structure hingedly coupled to said second valve sleeve positioning and retaining means, said flapper valve structure having stop means thereon to limit upward movement of said flapper valve, and means coupled to said first sleeve whereby on seating of a closure element, said first sleeve may be displaced downwardly in a second condition of operation to close said ports.