US2713914A - Subsurface apparatus for controllably filling well casing - Google Patents

Description

July 26, 1955 B. KRIEGEL SUBSURFACE APPARATUS FOR CONTROLLABLY FILLING WELL CASING Filed Jan. 5, 1953 g i i i: 1

2 Sheets-Sheet l Baa/A20 KQ/EGEL INVENTOR.

ATTaQA/EYS July 26, 1955 B.

SUBSURFACE APPARATUS FOR Filed Jan. 5, 1953 KRIEGEL 2,713,914

CONTROLLABLY FILLING WELL CASING 2 Sheets-Sheet 2 EQ/VAED KQ/EGEL,

INVENTOR.

BY W W ATTOQNEYS United States Patent Oflfice 2,7l3,9 l4 Patented July 26, 1955 SUBSURFACE APPARATUS FOR CONTROLLABLY FILLING WELL CASING Bernard Kriegel, Los Angeles, Calif., assignor to Baker Oil Tools, Inc., Los Angeles, Calif., a corporation of California Application January 5, 1953, Serial No. 329,502

Claims. (Cl. 166225) The present invention relates to subsurface well apparatus, and more particularly to apparatus for automatically filling a string of well casing, or the like, with fluid in a well bore as it is lowered therewithin.

An object of the present invention is to incorporate a back pressure valve in well casing, and prevent such valve from engaging its companion seat during lowering of the casing in the well bore, in order that the casing will fill automatically with the well bore fluid, and in which improved means are provided for releasing the back pressure valve whenever desired, in order to allow it to engage its companion seat.

Another object of the invention is to provide apparatus embodying a back pressure valve which is initially prevented from closing, to enable the well casing to fill automatically with the well bore fluid during its lowering therein, and in which a simplified device is employed for maintaining the fluid level internally of the casing string at a predetermined lower level than that externally of the casing string.

A further object of the invention is to provide apparatus of the character above indicated which avoids the use of seal rings in the device for maintaining the internal fluid level lower than the external fluid level, thereby simplifying the device and enabling it to be made more economically.

This invention possesses many other advantages, and has other objects which may be made more clearly apparent from a consideration of a form in which it may be embodied. This form is shown in the drawings accompanying and forming part of the present specification. It will now be described in detail, for the purpose of illustrating the general principles of the invention; but it is to be understood that such detailed description is not to be taken in a limiting sense, since the scope of the invention is best defined by the appended claims.

Referring to the drawings:

Figure l is a longitudinal section through an apparatus embodying the invention, disclosed as attached to a casing section being lowered in a well bore, the parts being arranged to allow the well bore fluid to flow into the casing;

Fig. 2 is a view similar to Fig. l, with the lower valve mechanism closed;

Fig. 3 is a view similar to Figs. 1 and 2, disclosing the automatic filling portion of the apparatus being rendered ineffective and the back pressure valve thereabove freed for engagement with its companion seat;

Fig. 4 is a cross-section taken along the line 4--4 on Fig. 2;

Fig. 5 is a cross-section taken along the line 5-5 on Fig. 2.

The apparatus disclosed in the drawings actually forms part of a casing string to be lowered in a well bore to a desired depth. The apparatus is shown in the form of a casing shoe A secured to the lower end of an adjacent casing section B, but it is to be understood that the apparatus could also be constituted as a casing collar disposed at an upper or intermediate point in the casing string.

The apparatus includes an outer tubular member 10 having an upper threaded box 11 for threaded attachment to the lower end of the adjacent casing section B, forming part of the casing string extending to the top of the well bore. This outer tubular member 10 is provided with a plurality of longitudinally spaced internal grooves 12 to receive companion ribs 13 formed when a cementitious plug 14 is cast within the tubular member, in order to anchor the plug to the latter. The lower end 15 of the plug 14 is usually rounded, to provide a guiding nose, for the purpose of guiding or steering the casing string B past obstructions or restrictions that might be encountered in the well bore C.

The cementitious plug 14 has a central passage 16 that may be considered as extending throughout its length. The upper portion of this passage is encompassed by a valve seat 17 cast into the plug 14 and adapted to be engaged by a back pressure valve element 18, preferably in the form of a ball buoyant in cement slurry, to prevent an upward flow of fluid into the casing string B. For the purpose of insuring against leakage between the ball 18 and its companion seat 17, a suitable seal ring or annular seal element 19 is clamped between the seat and a retainer ring 20, the retainer ring being urged against the seat 17 by a tubular stop member 21 disposed within the cementitious plug 14. This stop member is provided with a plurality of circumferentially spaced lugs or fingers 22, against which the ball valve member 18 may. rest when allowed to assume a lower position completely disengaged from its companion seat 17.

The mechanism so far described is known per se, and will function to allow downward passage of fluid through the casing string B that will prevent return flow of fluid into the casing string Whenever the ball valve member 18 is allowed to engage its valve seat 17. Initially, it is desired to preclude such engagement, for the purpose of allowing the fluid in the well bore to automatically fill the well casing B during lowering of the latter within the bore hole C to the desired landing depth.

The back pressure valve element 18 is prevented from engaging its seat 17 by a mechanism that allows the fluid to enter the casing string B through the shoe A, and this mechanism may be hydraulically actuated to release the ball valve element when desired. Moreover, the mecha nism for allowing the well casing to fill with fluid may be so designed and arranged to only allow the fluid to fill the well casing B to an elevation that is less than the fluid level externally of the well casing. It may be desirable to maintain the internal fluid level substantially less than the external fluid level, to provide a buoyancy in the well casing while it is being lowered through the fluid in the well bore. In addition, the maintenance of the fluid level internally of the well casing lower than that externally thereof is of advantage in preventing the fluid from flowing over the upper end of the casing string B, which oftentimes occurs during running of casing in a well bore. This flowing over drenches the equipment at the top of the hole, as well as the personnel, rendering the working conditions unsafe and uncomfortable. By maintaining the fluid level at a sufiicient distance below the top of the well casing, overflowing is prevented, as

well as the disadvantageous and unsafe conditions just noted.

The mechanism for controllably filling the well casing is disposed in the lower portion of the outer tubular member 10 and the cementitious plug 14. Thus, a valve housing member 23 has its upper end encompassing the lower portion of the stop member 21, an internal shoulder 24 on the housing engaging the lower end of the stop member 21. This valve housing has peripheral 3 grooves 25 formed therein for cooperation with companion ribs 26 in the cementitious plug 14, for the purpose of securing the valve housing member 23 to the plug against niovemeut in any direction. The valve housing member 23 is arranged coaxially of the apparatus.

Disposed within the valve housing 23 is a valve body 27 whose upper end is located in a predetern'iined position within the housing by engaging a downwardly facing stop shoulder 28 in the latter member. This valve body is secured initially in this upward position by one or more, shear screws 29 attaching it to the housing. For convenience of assembly, radial holes 39 may be provided in the outer tubular member 10 and the cementitious plug 14 through which the screws 29 may be threaded into their appropriate assembled positions. The lower portion of the valve body 27 is constituted as a spider 31 having a central hub. 32 carried by the outer portions of the valve body through generally radial ribs 33. The arcuate spaces 34 between the ribs constitute ports or passages through which fluid. may flow in an upward direction into the valve body 27, for passage through the upper end of the valve body, which is formed as a seat 35 that may have a frusto conical'or tapered shape. When permitted to do so, the fluid flows on upwardly through the valve housing 23 and stop member 21, around the back pressure ball valve member 18 and on up intov the casing string B above the casing shoe A. a

The, ability of the fluid to flow upwardly in the manner just referred to is determined by engagement or disengagement of a valve head 36. with its companion seat 35 at the, upper end of the valve body 27. This valve head is slidable along a valve stem 37 disposed coaxially of the valve body and the apparatus, the valve stem 37 being firmly secured to the valve body by threading its lower portion in the hub 32, a suitable lock nut 38 preventing inadvertent loosening of the valve stem. The head 36 is urged downwardly into engagement with its companion seat 35 by a helical compression spring 39 encircling the upper portion of the valve stem 37 and bearing upon the upper surface of the valve head 36, the upper end of the spring bearing upon a suitable spring seat 40 formed integrally with, or otherwise secured to, the valve stem 37.

It is evident that when the pressure below the valve, head 36 is suflicient to overcome the force of the spring 39 and the hydrostatic head of fluid internally of the casing string B, the valve head 36 is shifted upwardly from its seat 35, allowing the fluid to flow around the head '36 in an upward direction through they apparatus. Normally, the back pressure ball valve member 13. will tend, to engage its seat 17, but. such engagement is preeluded during the; lowering of the casing string B to its desired landing depth by a retainer member, disclosed in the form of an arm 41 suitably secured to the spring seat 49, as by a welding operation. This arm engages the ball valve element 18 and holds it, to one side within the stop member 21, in a position in which it cannot move upwardly into engagement with its companion valve seat 17 and seal ring 19. When the retainer arm 41 is ejected, in the manner described below, then the ball valve element 18 is free to move upwardly into engagement with its companion seat 17, in order to preclude upward passage of fluid in the casing string B.

During the lowering of the casing string B, with the apparatus A attached to its lower end, through the fluid in the well bore C, the hydrostatic head of fluid externally of the well casingis acting on the underside of the valve head 36 and tends to shift it upwardly to open position, so that the fluid can flow throughthe apparatus into the casing string B. This action of the external well fluid is resisted by the force of the spring 39,. When this forceis overcome, the valve head 36 is opened and the well fluid will flow into the casing string. However,

as the fluid level in the casing string B rises, then pressure corresponding to the fluid level within the casing string is acting in a downward direction on the valve head 36, tending to shift it downwardly into a closed position engaging its seat 35. Since the force tending to shift the valve head downwardly is a combination of the spring force and that attributable to the hydro-' static head of fluid within the casing string, the valve head will be shifted upwardly to open position when the hydrostatic head of fluid externally of the casing string exceeds this combined force. In other words, the valve head will just be in a force balanced condition when the following equation is satisfied:

P1=P2+F in which P1=the unit pressure corresponding to the hydrostatic head of fluid externally of the casing string,

P2=the unit pressure corresponding to the hydrostatic head of fluid internally of the casing string, and

F :the force exerted by the spring per unit of crosssectional' area of the valve head.

From the above equation, it is evident that during lowering oi the casing string, the pressure P1 corresponding to the external hydrostatic head will increase, and

when this pressure exceeds, the sum of the, other. two pressures noted in the equation, the valve head 36 will. be shifted upwardly to open position. This allows the fluid level in the casing B to rise, so that the value of P2 becomes greater, until a condition exists in whichthe sum oi P2 plus F just exceeds the value of P1, Which then shifts the valve head 36 downwardly to closed posi tion against its seat 35. It is evident that the unit pressure corresponding to the hydrostatic head of fluid internally of the casing string will be less than the pressure corresponding to the hydrostatic head of fluid externally. of the casing string by an amount or value that is equal to the unit spring force F.

If the spring is assumed to exert a, total force of 600 lbs, and if the cross-sectional, area of the valve head is assumed to be. about three square inches, then it is evident that the spring 3? exerts a force tending to keep the valve head downwardly in its closed position corresponding to a pressure of about 200 p. s. i. Assuming that thev well bore C is filled with drilling, mud, 1 p. s. i. will be equivalent to about 2 ft. of hydrostatic head. In other words, the spring 39 is exerting a closing force on the valve head 3.6, in the, example given above, corresponding to about 400 ft. of the well. bore fluid. As a result, the fluid level internally of thecasing string B will be maintained about 400, ft. below the fluid, externally of the well easing. Of course, it is to. be understood that the total force ofthe spring 39 can, be varied, as well as the cross-sectional area of the valve head 36,

in order to maintain the fluid level internally of. the cas-,

ing string at any predetermined level lower than that externally of the casing string;

The apparatus is run in the well bore with theparts in the position disclosed in Fig. 1, in which, the shear screws 29 are. intact, the retainer arm 41 holding the back'pressure ball valve or element 18 from its seat 17. During the lowering action, the hydrostatic head of fluid externally of the well casing B will shift the valve. head. 36 upwardly against the force of. the spring 39, to allow the casing string to fill with the well bore fluid to. a predetermined level that is lower than that of the external hydrostatic head by an amount corresponding to the closing force exerted bythe spring on the, head; By maintaining I the fluid level at a lower point, the danger of the drilling I mud, or other fluid, overflowing atthe topzof thewell bore,

and, drenching the equipment and personnel iszprecluded. In-addition, if the spring 39 is made sufliciently strong in relation to the cross-sectional area'ofithe valve. head 36;, the fluid levelmay be maintained at asubstantially lower level than the hydrostatiohead. of fluidexternally. oiathe well casing, which will enable the casing string B to be floated in the well bore while precluding the imposition of very great hydrostatic head differentials on the lower portions of the casing string during its running to comparatively great depths in the well bore, such as to depths of 10,000 to 15,000 ft.

After the casing string B has been run in the well bore to the desired depth, the automatic filling portion of the apparatus is no longer necessary. At the same time, it is desired to release the back pressure valve member 18. Accordingly, the casing string can be filled to the top of the well bore from its upper portion, and the fluid in the casing string then subjected to pressure. This pressure action will insure that the valve head 36 is in engagement with its seat 35, and the pressure will then act over the entire cross-sectional area of the valve body 27. When the pressure exerted has increased to an extent suficient to overcome the shear value of the screws 29, they are disrupted, and the entire valve body 27, valve stem 37, valve head 36, spring 39, and retainer arm 41 are ejected hydraulically from the casing shoe (as shown in Fig. 3), the arm 41 being freed from the back pressure ball valve member 18, which is limited in its downward movement by engaging the stop lugs 22. Thereafter, fluid can be pumped down the well casing for ejection from the lower end of the casing shoe A, if desired. When the casing string is to be cemented in place, cement slurry is pumped down through its interior, passing around the ball valve element 18 and out through its lower end, for upward movement through the annulus between the casing B and wall of the well bore C. When the cementing operation has been completed, the pressure in the casing string can be relieved, any tendency for the cement slurry to flow back into the casing string being precluded by upward movement of the ball valve member 18 into engagement with its companion valve seat 17 and seal ring 19.

It is, accordingly, apparent that a comparatively simple, yet strong and sturdy, apparatus has been provided for obtaining the automatic filling of a well casing string to a predetermined level that is lower than the fluid level externally of the casing string, the apparatus maintaining the back pressure valve member in ineflfective position until it is desired to release the latter. Such release occurs simply by applying pressure to the fluid internally of the casing string, whereupon the ball valve member is allowed to operate in its normal manner.

The inventor claims:

1. In well apparatus: a tubular member having means thereon for securing said member in a casing string, said member having a fluid passage; back pressure valve means in said tubular member adapted to close said passage against upward flow of fluid through said passage; a valve device in said tubular member below said back pressure valve means movable downwardly in said tubular member and including a valve element movable upwardly to open position to allow upward flow of fluid in said passage, said valve element being movable downwardly to closed position to prevent upward flow of fluid in said passage, spring means engaging said valve element to urge said valve element downwardly to closed position; and releasable retaining means engaging said back pressure valve means and valve device to prevent said back pressure valve means from closing said passage, release of said retaining means allowing said valve device to move downwardly in said tubular member.

2. In well apparatus: a tubular member having means thereon for securing said member in a casing string, said member having a fluid passage; back pressure valve means in said tubular member adapted to close said passage against upward flow or" fluid through said passage; a valve device movable longitudinally in said tubular member and including valve body means having a valve seat, a valve head movable downwardly into engagement with said seat to close said passage, spring means engaging said valve head to urge said head downwardly into engagement with said seat; and releasable retaining means secured to said valve device and engaging said back pressure valve means to prevent said back pressure valve means from closing said passage; said valve device being movable longitudinally in said tubular means to release said retaining means from said back pressure valve means.

3. In well apparatus: a tubular member having means thereon for securing said member in a casing string, said member having a fluid passage; back pressure valve means in said tubular member adapted to close said passage against upward flow of fluid through said passage; a valve device movable longitudinally in said tubular member and including valve body means having a valve seat, a valve head movable downwardly into engagement with said seat to close said passage, spring means engaging said valve head to urge said head downwardly into engagement with said seat; and retaining means secured to said valve device and engaging said back pressure valve means to prevent said back pressure valve means from closing said passage; and means releasably securing said valve device in said tubular member to hold said retaining means engaged with said back pressure valve means, release of said releasable means enabling said valve device to move longitudinally in said tubular member to a position disengaging said retaining means from said back pressure valve means.

4. In well apparatus: a tubular member having means thereon for securing said member in a casing string, said member having a fluid passage; back pressure valve means in said tubular member adapted to close said passage against upward flow of fluid through said passage; valve body means having a valve seat and movable longitudinally in said tubular member; a valve head movable downwardly into engagement with said seat to close said passage; spring means engaging said valve head to urge said head downwardly into engagement with said seat; retaining means secured to said valve body means and engaging said back pressure valve means to prevent said back pressure valve means from closing said passage;

and means releasably securing said valve body means in.

said tubular member to hold said retaining means engaged with said back pressure valve means, release of said releasable means enabling said valve body to move longitudinally in said tubular member to a position disengaging said retaining means from said back pressure valve means.

5. In well apparatus: a tubular member having means thereon for securing said member in a casing string, said member having a fluid passage; back pressure valve means in said tubular member adapted to close said passage against upward flow of fluid through said passage; valve body means having a valve seat and movable longitudinally in said tubular member; a valve head movable downwardly into engagement with said seat to close said passage; spring means engaging said valve head to urge said head downwardly into engagement with said seat; retaining means secured to said valve body means and engaging said back pressure valve means to prevent said back pressure valve means from closing said passage; and frangible means releasably securing said valve body means in said tubular member to hold said retaining means engaged with said back pressure valve means, said frangible means being disruptable hydraulically by fluid in said passage above said valve head to shift said valve body means downwardly in said tubular member to a position disengaging said retaining means from said back pressure valve means.

6. In well apparatus: a tubular member having means thereon for securing said member in a casing string, said member having a fluid passage; back pressure valve means in said tubular member adapted to close said passage against upward flow of fluid through said passage; a valve housing fixed in said tubular member; valve body means slidable longitudinally in said housing; said valve body means including a valve seat; a valve head movable downwardly into engagement with said seat; spring means engaging said valve head to urge said valve head downwardly to closed position in engagement with said seat; retaining means secured to said valve body means and engaging said back pressure valve, means to prevent said back pressure valve means from closing said fluid passage; and frangible means securing said valve body means to said housing.

7. In well apparatus: a tubular member having means thereon for securing said member in a casing string, said member having a fluid passage; back pressure valve means in said tubular member adapted to close said passage against upward flow or" fluid through said passage; a valve housing fixed in said tubular member; valve body means slidably mounted in said housing and having a central stem portion surrounded by a valve seat; a valve head slidable longitudinally along said stem portion and movable downwardly into engagement with said seat; spring means surrounding and engaging said stern portion and bearing against said valve head to urge said valve head downwardly into engagement with said seat; a retaining member secured to said valve body means and engaging said back pressure valve means to prevent said back pressure valve means from closing said passage; and frangible means securing said valve body means to said housing.

8. t In well apparatus: a tubular member having means thereon for securing said member in a casing string, said member having a fluid passage; back pressure valve means in said tubular member adapted to close said passage against upward flow offluid through said passage; a valve device in said tubular member movable longitudinally in said tubular member and including a valve ele-.

ment movable upwardly to open position to allow upward flow offluid in said passage, said valve element being movable downwardly to closed position to prevent upi ward flow of fluid in said passage, spring means engaging said valve element to urge said valve element downwardly to closed position; and releasable retaining means engaging said back pressure valve means and valve device to prevent said back pressure valve means from closing said passage, release of said retaining means allowing said valve device to move longitudinally in said tubular member.

9. In well apparatus: a tubular member having means thereon for securing said member in a casing string, said member having a fluid passage; back. pressure valve means in said tubular member adapted to close said passage against upward flow of fluid through said passage; a valve device in said tubular member movable longitudinally in said tubular member and including a valve element movable upwardly to open position to allow upward flow of fluid in said passage, said valve element being movable downwardly to closed position to preventupward flow of fluid in said passage, means engaging said valve element to urge said valve element downwardly to closed position; and releasable retaining means engaging said back pressure valve means and valve device to prevent said back pressure valve means from closing .said

passage, release of said retaining means allowing said valve device to move longitudinally in said tubular member. a

10. In well apparatus: a'tubular member having mean thereon for securing said member in a casing string, said member having a fluid passage; back pressure valve means in said tubular member adapted to close said passage against upward flow of fluid through. said passage; a valve device movable longitudinally in said tubular memher and including valve body means having a valve seat,

References Cited in thegfile of thispatent UNETED STATES PATENTS Brown June 16, 1953 wulmsn

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