WO2008153406A1

WO2008153406A1 - Liquid pressure driven sequential valve for axially operative jar

Info

Publication number: WO2008153406A1
Application number: PCT/NO2008/000203
Authority: WO
Inventors: Per Olav Haughom
Original assignee: Petro Tools As
Priority date: 2007-06-13
Filing date: 2008-06-05
Publication date: 2008-12-18
Also published as: NO20073009L

Abstract

The present invention concerns a liquid pressure activated sequence valve for use in generating oscillating hammering movements, in which the sequence valve comprises a valve design comprising an outer housing (1) connected to adapters (3) and (5) in each end, an inner elongated concentrically supported cylindrical pipe part comprising a valve face (18), a ring element (7) comprising a valve face (8) and a ring valve (17) comprising a valve face (22). The invention is distinguished in that the liquid pressure activated sequence valve's pressure affected annular areas and pressure differences satisfies the following relation: A3 /A4 • (1 - Fs/A2 • P) ≥ 1 where A2, A3 and A4 are annular areas defined by reference to fig 3, P is a liquid pressure entering through holes (9, 20) from a longitudinally hollow string part (12) generating axial force Fh by working on the annular area A2, FS is the force generated by a spring (14).

Description

Liquid pressure activated sequence valve for axially operating jars

The present invention regards a sequence valve of the kind activated by the differential pressure in a liquid flow. More specifically, it regards a valve construction wherein the pressure difference in a liquid is utilized to provide an oscillating axial movement in that the valve construction by means of liquid pressure alternately opens and closes for liquid flow in two end positions. These oscillating movements may be utilized in different hammering or jarring, tools wherein a weight is put in oscillating axial movement.

Today, liquid driven jars are used in several contexts within the oil industry, in land based drilling in hard rock formations and in other drilling applications. In land based drilling, liquid driven hammers are used for drilling where the hammer is located at the end of a hollow drilling string through which liquid is pumped to the hammer. In the oil industry, liquid driven hammers are especially used for drilling and removal of deposits in pipelines, but also as jars for opening and closing valve functions.

Today, there are liquid driven hammering solutions operable with hollow drill strings, but common for these are that they require absolutely clean liquid in order to function. In addition, they are very sensitive to pressure differences and may only be operated within narrow pressure limits.

NO 2004 2727 discloses a liquid driven hammer with accompanying valve systems. However, experience and tests have shown that a valve design of this kind poses clearly defined requirements to mutual relationships between the pressure faces acted upon by liquid pressure. If these conditions are not met, the valve will not function. As NO 2004 2727 is shown and disclosed, the valve will not function. The description only generally indicates that the valve parts shall open or close by pressure equalization and impact against valve seats, without explaining which particular mutual physical conditions must be fulfilled in order for the valve system to work. The present invention provides a robust valve embodiment, which makes it possible to provide an oscillating axial movement by utilizing the pressure difference between the pressure in the drill string and the ambient pressure in the well bore. Based on a long time of testing and development, one has arrived 5 at a robust valve function tolerating contamination in the liquid, and additionally is operable with large variations in the pressure difference.

The present invention is based upon physical tests and experience from real tests in working operations within a wellbore. 0

In the following a non-limiting detailed description of a preferred exemplary embodiment is provided with reference to the accompanying drawings, in which:

Fig 1 shows a valve with associated hammer function;

Fig 2 shows a cross section through a valve design in start position; 5 Fig 3 shows a detail of a valve construction;

Fig 4 shows a cross section through a valve in its end position; and

Fig 5 shows a cross section through a valve in its return position.

Fig 1 shows a sequence valve according to the present invention with o associated hammer function built into a pipe housing 1 having adapters 5 and 3 for connection to a drill string and a tool, respectively.

Fig 2 shows a cross section through the sequence valve with associated hammer function. An inner elongated cylindrical pipe part 12 having a central5 bore 19 around its axis of rotation is concentrically supported by bearings 21 , 21 in both ends toward the adapters 3 and 5. In order to provide the hammering effect, the cylindrical pipe part 12 comprises a weight 13 with an impact face 15 against the adapter 3. Concentrically supported around the cylindrical pipe part 12 is displaced a ring element 7 having valve faces 18 forming a valve sealo when resting against an opposite valve seat 8 on the cylindrical pipe part 12. The ring element 7 is axially displaceable and has an annular sealing against the housing 1 and an adapter 2, and further comprises holes 9 and 10 for liquid flow from the central bore 19 via a radial hole 20. In the start phase of the sequence, pipe part 12 is forced to the left due to the spring force from the spring 14, so that the valve faces 8 and 18 rest against each other, the ring element 7 at the same time resting against the face 16 and the weight 13 resting against the face 15.

In this position liquid from the central bore 19 exits through the radial hole 20, via the hole 9 and into the annular space formed between a face 16 and the closed valve faces 8,18.

The pressure will in this position apply to an annular area A2 = A3 - A1 (ref fig3), in that the annular areas A1 and A3 are exposed to the low pressure side (i.e. the ambient pressure in the wellbore) through radial holes 6 and 4, as these holes in this state are aligned with each other. The axial force F_h working to the right (ref fig 3) correspond to a liquid pressure P times A2, i.e.:

F_h = P^*A2

This force is opposed by a spring force F₈ from the spring 11. Provided that F_h is greater than the spring force F₅, the pipe part 12 and ring element 7 move against the spring force Fs until the valve faces 22, 23 impact against each other, and encloses an annular volume V1 between the valve faces 8, 18 and 22, 23 (ref fig (3)).

The ring valve 17 is retained by the spring 11 , but is axially displaceable so that said enclosed annular volume V1 is compressed, whereby a pressure increase occurs. The axial force F_k compressing said annular volume V1 is P times A2 minus the spring force Fs (ref fig 4), i.e.

F_k = P^*A2 - F_s

The axial force F_k builds up pressure in said enclosed annular volume V1 until force balance between the axial force F_k and F_h is achieved. Force balance is achieved when the pressure within the annular volume V1 generates a force over the annular face A4 satisfying the following formula: A1 • P2 = P • A2 - F_s

In order for the valve faces 8, 18 to be opened, the force generated by pressure 5 P2 over the area A3 must be greater than P^*A2, thus:

P2 A3 > P - A2

Hence, A3 ^• (P ^• A2 - F_s)/A4 must be greater than or equal to P ^• A2, i.e. 0

A3 ^■ (P • A2 - F_s)/A4 > P • A2

This criterion must be fulfilled for the valve face 8, 18 to open and the sequence valve to work. 5

This means that the following formula must be satisfied:

1 o At the moment valve face 8, 18 opens, the axial force P ^• A2 on the ring element 7, which accelerates forcibly to the left and is displaced relative to the pipe part 12, so that the passage through the holes 20, 9 is closed. The pipe part 12 accelerates to the left by the spring force from spring 14 so that the valve faces 22, 23 opens and releases said enclosed liquid volume through hole 6 (ref fig5 5).

The pipe part 12 with the weight 13 and the ring element 7 is moved to the left until the ring element impacts against a face 16 and the weight impacts against a face 15. In this position holes 9, 20 opens in that the valve faces 8, 18 impactso again, and new sequence is repeated.

Claims

1. Liquid pressure activated sequence valve for use in generating oscillating hammering movements, in which the sequence valve comprises a valve design comprising an outer housing (1) connected to adapters (3) and (5) in each end, an inner elongated concentrically supported cylindrical pipe part comprising a valve face (18), a ring element (7) comprising a valve face (8) and a ring valve (17) comprising a valve face (22), characterized in that the liquid pressure activated sequence valve's pressure affected annular areas and pressure differences satisfies the following relation:

1

where A2, A3 and A4 are annular areas defined by reference to fig 3,

P is a liquid pressure entering through holes (9, 20) from a longitudinally hollow string part (12) generating axial force F_h by working on the annular area A2, F₅ is the force generated by a spring (14).