GB2275706A - Wireline valves - Google Patents

Abstract

The wireline valve includes an equalizing valve assembly which will allow the upstream and downstream well pressures to be equalised by a simple arrangement including lust a single equalising valve 82 and a bore 84 drilled through a hollow arm 20 from laterally behind the ram in a direction generally perpendicular to a wireline. <IMAGE>

Description

WIRELINE VALVES The present invention relates to wireline valves, sometimes referred to as wireline blowout preventers, which are designed to give positive protection from blowouts when operating with wirelines during well surface operations.

A wireline valve thus contrasts with a gate valve which could not be closed without severing the wireline.

A typical wireline valve is in practice capable of sealing with different wirelines such as a single or multistrand wire or other small tubing. This is achieved by selecting and dressing the wireline valve with appropriate rams and seals prior to commencing well surface operations.

During normal use, the rams and.seals are brought into abutment with the wireline by operation of ram control means, usually a pair of double-acting hydraulic jacks whose pistons are secured to parts of the rams remote from the seals.

Hitherto, to allow the ram control means to be repaired or replaced, an upstream gate valve must first be closed, which in turn means that the wireline extending through both the wireline valve and the gate valve must first be removed.

A wireline valve which overcomes that problem is the subject of our co-pending application 9102820.9 (GB-A2240800) from which the present application has been divided.

Hitherto, to allow the ram control means to be opened, the well pressure upstream of the wireline valve must first be equalised with the well pressure downstream of the wireline valve, by opening a series of equalising valves in passageways extending parallel to the wireline.

According to the present invention, however, a wireline valve comprises at least one ram assembly and an equalising valve assembly having at least one passageway extending from laterally behind the ram assembly in a direction generally perpendicular to a wireline which in use extends through the wireline valve.

Three embodiments of a compact wireline valve will now be described, in greater detail, by way of example only, with reference to the accompanying drawings, in which: Figure 1 is a front view of the right hand half of a compact wireline valve embodying the present invention; Figure 2 is a partial vertical section through the entire wireline valve of Figure 1, particularly illustrating its ram assemblies; Figure 3 is a partial vertical section through the right hand half of a modified compact wireline valve, particularly illustrating its equalising valve assembly; Figure 4 is a cross-sectional view taken along the line IV-IV of Figure 3; and Figure 5 is a partial vertical section through another modified compact wireline valve embodying the present invention.

A compact wireline valve 10, as shown in Figures 1 and 2, includes a main body 12 of hollow cruciform shape with vertically separated upper and lower connectors 14, 16 to which respective wireline components are to be secured, as well as horizontally separated left and right hand arms 18, 20 within which respective rams 22 are to be mounted.

The rams 22 are of conventional and complementary construction, each including a V-shaped wire guide 24, an inner seal 26 and an outer seal 28 all secured to a ram body 30 having a T-shaped slot 32 at the end opposite to the inner seal 26. Each of the rams 22 is slidable within its respective hollow arm 18, 20 under the control of an operating rod 34, with each of the operating rods 34 having an enlarged head 36 which is a sliding fit within a respective. one of the T-shaped slots 32. The operating rods 34 are reciprocable, either towards one another to bring the rams 22 into abutment around a wireline, or alternatively away from one another to open the wireline valve 10. Dowel pin located shims 38 are provided in known manner to resist rotation of the rams 22.

Hitherto, members equivalent to the operating rods 34 have formed the pistons of a pair of double-acting hydraulic jacks operable as ram control means. This has meant that the hydraulic jacks have needed to be of cylinder wall thicknesses sufficient to withstand any leakage of well pressure. The hydraulic jacks have therefore been of undesirable weight and expense, and their assembly, repair and replacement has been time-consuming and difficult.

As illustrated, however, each of the operating rods 34 is split into two sections, namely an inner section forming a ram rod 34' provided with the head 36 and an outer section forming a piston rod 34" of a hydraulic jack 40.

Each ram rod 34' extends through a valve sealing wall or plate 42 which seals the well pressure within the otherwise open ends of the arms 18, 20. The valve sealing plates 42 are secured in position by collars 44 which make threaded engagement with the arms 18, 20 and also retain cylindrical carriers 46. More particularly, the collars 44 have inwardly extending flanges 48 which are sandwiched between outwardly extending flanges 50 and circlips 52 on the carriers 46. Conventional high-pressure seals 54 are located around the ram rods 34' where they pass through the valve sealing plates 42. The outer ends of the ram rods 34' are in threaded engagement with plates 56, which are reciprocable within the cylindrical walls of the carriers 46.The free ends of the ram rods 34' are formed with T-shaped heads 58 which are received in complementary Tshaped slots 60 formed in the piston rods 34".

The other ends of the piston rods 34" have piston heads 62 reciprocable within cylindrical housings 64 under the control of conventional hydraulic ports 66, 68. The cylindrical housings 64 are closed by end walls 70 to which can be secured, by bolts 72; end walls 74 of the cylindrical carriers 46. The hydraulic ports 66, 68 are accessible through a slot 76 formed in the lower surface of each of the carriers 46 opposite a larger window 78 milled in its upper surface.

It will be appreciated that, because the hydraulics of the hydraulic jacks 40 are entirely separate from the oil, gas or other fluid being controlled by the wireline valve 10, there is no danger whatsoever of the well pressure leaking into and through the hydraulic ports 66, 68. Any leakage of the well pressure past the valve sealing plates 42 escapes harmlessly into the atmosphere where it is readily apparent as a visible warning. It will further be appreciated that, again because of the isolation of the hydraulic jacks 40 from the well pressure, the cylindrical housings 64 can be of relatively thin, inexpensive and lightweight material and the carriers 46 need be no more than supporting brackets.

With the rams 22 in their open, separated position (pressure applied only to hydraulic ports 66) the hydraulic jacks 40 can be simply removed for replacement or repair.

This is achieved by disconnecting hoses from the hydraulic ports 66, 68, removing the bolts 72 and lifting such that the piston rods 34" are removed from the T-shaped heads 58 on the ram rods 34', and then removing the hydraulic jacks 40 through the windows 78 in the carriers 46. This operation can be performed on the right hand, left hand or both ram assemblies as required without necessitating removal of the wireline from the well head. Removal of the hydraulic jacks 40 with the rams 22 in their closed, abutted position (pressure applied only to hydraulic ports 68) is achieved in exactly the same manner. In other words, the hydraulic jacks 40 act as ram control means which are repairable or replacable in use without needing to shut off the well pressure upstream of the wireline valve 10.

It will also be noted that, in general terms, the Tshaped heads 58 presented by the ram rods 34' can be regarded as ram assembly connectors, and the complementary slots 60 presented by the piston rods 34" can be regarded as ram control connectors, with each pair of the ram assembly connectors and ram control connectors together presenting a head-and-slot type of releasable interengagement.

The cylindrical housings 64 and end walls 70 together form cylinders which are supported by the carriers 46 which are themselves supported by the hollow arms 18,20. Each of the carriers 46 is formed with at least one opening 76,78 for enabling removable hydraulic connection to be made with the cylinders 64,70, although in practice the hydraulic hoses would extend through the slots 76 and the hydraulic jacks 40 would be removable through the windows 78. The plates 56 secured to the ram rods 34' can act as guides during their reciprocation within the carriers 46. The plates 56 can also act as indicators, visible through the windows 78, to indicate at a glance the relative position of either ram 22, therefore eliminating potential damage resulting from partially closed rams 22.

No special means need be provided for preventing undesired opening of the rams 22, but for safety manually operated screw bolts 80 can be provided. A pair of the bolts 80 is shown in threaded engagement with one of the end walls 74 and in abutting engagement with one of the plates 56. The reason that the rams 22 remain shut is that, with no fluid communication from below to above the rams 22, the well pressure acts through gaps between for example the shims 38 and the respective arms 18,20 upon about half of the area of the rear or outer ends of the rams 22. Indeed, in the absence of an equalising valve for allowing the well pressure to bypass the rams 22, it would be impossible or at least extremely difficult to open the rams 22 without damaging the outer seals 28.

To achieve the present invention, an equalising valve 82 is provided in such a position that there is no need to thicken the walls of the main body 12 of the wireline valve 10 merely to provide an equalising pressure passageway.

Instead, advantage is taken of parts of the main body 12 whose walls are already sufficiently thick to allow an equalising pressure passageway to be drilled therethrough.

As shown in the modification of Figures 3 and 4, in which the attitude of the rams 22 has been reversed in comparison with Figures 1 and 2, a bore 84 extends from the rear of, i.e. laterally behind the ram body 30 through the arm 20.

The bore 84 extends in a direction generally perpendicular to the direction of the wireline with which the wireline valve 10 is to be used. The bore 84 intersects, at the equalising valve 82 of conventional construction, with another bore 86 which extends inwardly of the main body 12 to open above the rams 22.

More particularly, the well pressure upstream of the ram 22 is initially directed through at least one gap 88 between the ram 22 and an upstream portion of the hollow arm 20 to the rear of the ram 22 from where the well pressure is directed through the bore 84 formed in a downstream portion of the hollow arm 20 to act continuously upon the equalising valve 82 which is located at the junction of the bore 84 and the bore 86 opening downstream of the-ram 22, with the at least one gap 88 and the bore 84 constituting the at least one passageway.

The equalising valve 82 operates in a conventional manner such that a central element 90 thereof is movable inwardly or outwardly respectively to block or open the bores 84,86 to well pressure communication therethrough.

Another modified compact wireline valve is shown in Figure 5 which is similar to the previously described wireline valves but differs therefrom mainly in the construction of the carriers.

As shown in the left hand half of Figure 5, the cylinder 92 is formed with an integral end wall presenting a threadede stud 94. The carrier 96 is formed with a slot 98 in its integral end wall 100 for receiving the threaded stud 94 and a threaded flanged nut 102. Thus, the cylinder 92 and the end of the carrier 96 remote from the hollow arm 18 together present a head-and-slot type of releasable interengagement.

As shown in the right hand half of Figure 5, the end wall 100 of the carrier 96 is adapted to support at least one manually operable screw 104, preferably two of the screws 104 which are spaced apart horizontally rather than vertically so that only one is visible with the other being hidden behind the cylinder 92, the screws 104 being provided for preventing movement of the plate 56 and thus maintaining the ram 22 in a closed position thereof even when the cylinder 92 has been removed for replacement or repair.

As shown in Figure 5, the plates 56 are indicating open positions for the rams 22.

Claims (3)

1. A wireline valve comprising at least one ram assembly and an equalising valve assembly having at least one passageway extending from laterally behind the ram assembly in a direction generally perpendicular to a wireline which in use extends through the wireline valve.

2. A wireline valve according to claim 1, in which the ram assembly is reciprocable within a hollow arm, and the well pressure upstream of the ram assembly is initially directed through at least one gap between the ram assembly and an upstream portion of the hollow arm to the rear of the ram assembly from where the well pressure is directed through a bore formed in a downstream portion of the hollow arm to act continuously upon the equalising valve assembly which is located at the junction of the bore and another bore opening downstream of the ram assembly, with the at least one gap and the bore constituting the at least one passageway.

3. A wireline valve according to claim 1 or claim 2, in which the ram assembly is reciprocable by ram control means, which ram control means is repairable or replacable in use without needing to shut off the well pressure upstream of the wireline valve, which wireline valve has a body of hollow cruciform shape housing two of said ram assemblies, but only one said equalising valve assembly.