Valves

Details Valves Valves

1991-10-08

1993-06-29

Neuder, William P.

Wells

Valves, closures or changeable restrictors

Fluid operated

251 62, E21B 4312

Patent

active

052225593

DESCRIPTION:

BRIEF SUMMARY
BACKGROUND OF THE INVENTION

1. Field of the Invention
This invention relates to valves, and concerns in particular the mechanism by which ball valves--especially those employed in tools used for the testing of subterranean wells, particularly oil wells--are operated against severe resistive forces.
2. Description of the Prior Art
Whether at sea or on land, the first steps in the production of a new hydrocarbon well--an oil well--are the drilling of the well bore itself through the various formations within the earth's crust beneath the drilling rig, followed by "casing" (the introduction and cementing into position of piping which will serve to support and line the bore) and the placing in the bore, at the depth of a formation of interest, of a device known as a packer, into which inner tubing (of smaller diameter than the casing) can subsequently be lodged.
The next work carried out is normally some programme of testing, for the purpose of evaluating the production potential of the chosen formation. The testing procedure usually involves the measurement of downhole temperatures and pressures, in both static and flow conditions (the latter being when fluid from the relevant formation is allowed to flow into and up the well), and the subsequent calculation of various well parameters. To collect the necessary data there is lowered into the well a test string--a length of tubing containing the tools required for testing. The flow of fluid from the formation of interest into the well bore and thus to the test tools is controlled by a valve known as a sub-surface control valve, and it is with valves suitable for this purpose, and their operating mechanisms, that the invention is concerned.
The operation of the various tools included in the downhole test string can be effected using one of three main types of mechanism. These types are those actuated by reciprocal motion of the pipe string (the inner tube, of which the test string constitutes a part), by rotational motion of the pipe string, or by changes in the pressure differential between the tubing and the annular space which surrounds it in the well--hereinafter referred to simply as "the annulus". Test strings wherein the tools thereof are actuated by changes in annulus pressure are at present much in vogue, and it is this type of actuation mechanism that is to be employed with the valves of the invention.
A mechanism of the annulus pressure-responsive type requires the provision and maintenance of a fixed "reference" pressure within the tool. This, used in conjunction with an adjustable (and higher) annulus pressure, allows the establishment of the chosen pressure differential necessary to control the operation of the appropriate component of the test string. The achievement of such a fixed reference pressure is the subject of our co-pending British Patent Application No. 89/07,098.1.
An essential component of the test string is a valve known as the sub-surface control valve. This governs the overall control of the testing procedure by permitting the flow of fluid out of the formation and into and up the well tubing to the various test tools. The density of drilling fluid in the tubing above this valve is adjusted such that its hydrostatic pressure at the depth of the formation is lower than the formation fluid pressure. Thus, when the valve is opened, formation fluid is permitted to enter the well bore through perforations in the casing and flow into the tubing string (and possibly to the surface therethrough). This contrasts with the situation during drilling, when the drilling fluid must exert a hydrostatic pressure greater than the formation fluid pressure in order to prevent the fluid's escape to the surface.
The sub-surface control valve is conveniently an example of a type of valve known as a ball valve. In principle, a ball valve is a variety of valve in which the valve member--the part physically preventing or allowing the passage of some fluid material along a passageway (a pipe, say)--is shaped like a ball with a hole extending therethrough, a

REFERENCES:
patent: 3685790 (1972-08-01), Crowe
patent: 4071088 (1978-01-01), Mott
patent: 4113012 (1978-09-01), Evans et al.
patent: 4265141 (1981-05-01), Bowman
patent: 4986357 (1991-01-01), Pringle

Affiliated with

Also associated with

Rating

Valves does not yet have a rating. At this time, there are no reviews or comments for this patent.

If you have personal experience with Valves, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Valves will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFUS-PAI-O-1748911