1989-09-15
1990-10-23
Novosad, Stephen J.
Wells
Combined
166142, 166240, 166373, 166385, 166386, E21B 3414, E21B 4706, E21B 4900, E21B 2300
Patent
active
049644602
DESCRIPTION:
BRIEF SUMMARY
The present invention relates to shut-in tools for use downhole in oil and gas wells in order to isolate or shut-in the reservoir from the surface to which it is connected via a tubing string. The use of such a tool to shut-in the reservoir allows reservoir pressure or other parameters to be measured as a function of time. The manner in which the pressure builds up when the oil or gas cannot escape provides useful information about the nature and capacity of the oil-bearing formation.
The value of such pressure measurements is well-known in the art and, therefore, various methods have been proposed for lowering the necessary pressure gauges downhole together with the necessary valve assembly to enable the reservoir to be shut-in. At least part of the required assembly is normally lowered into the tubing string via a wireline, which can provide electrical connections to the surface for the pressure gauges connected to the assembly. Since memory and mechanical gauges are also available for recording pressure variation with time, such an assembly may also be used with a slick wireline. Such an assembly is known as a shut-in tool. In order that repeated measurements may be made, without the need to raise the tool to the surface in between each measurement, it is desirable for the tool to provide not only for a shut-in position, but also for a flow position. Repeated measurements require that it should be possible to cycle the tool between its flow position and its shut-in position from the surface.
One existing proposal described in US-A- 4 678 035 (Schlumberger Technology Corporation) requires that a full-bore valve assembly be inserted into the tubing string. The actuator together with the pressure gauge is then lowered into the valve assembly on a wireline. This arrangement is known as the MUST (Trade Mark) configuration. The disadvantage of such an arrangement is that it is necessary to have a relatively complex valve assembly inserted permanently in the tubing string. This valve assembly incorporates moving parts, which may be subject to failure due to contamination by sand in the oil or gas being produced so that failure will inevitably occur. A primary technical problem is, therefore, the provision of a shut-in tool which allows any movable parts necessary for cycling between the shut-in and flow positions to be provided in a wireline retrievable tool, rather than in the tubing string.
A tubing string component known as a "landing nipple" has been proposed for incorporation into production tubing strings. Such nipples are used for landing safety valves or other wireline equipment. These landing nipples are designed to receive locking mandrels, which incorporate locking dogs mounted by means of double acting springs. These dogs are movable radially between retracted and expanded positions by means of an actuator sleeve, which is part of the locking mandrel. The sleeve moves axially downwardly when the locking mandrel engages against a no-go shoulder profile in the nipple, thereby causing the dogs to expand outwardly into a corresponding circumferential recess defined in the nipple wall. Such locking mandrels and their associated landing nipples are manufactured, for example, by Otis Engineering Corporation. The shut-in tool of the invention will be described for use with a no-go nipple. Alternative actuating techniques would be required for landing the tool in selective nipples above the no-go nipple. The skilled man will readily appreciate what necessary modifications may be made for using a selective nipple instead of a no-go nipple.
Landing nipples may also be manufactured with ports provided in an axially extending portion of the tubing string above the dog-receiving recess. Such a ported landing nipple is manufactured by AVA International as a standard component. This type of landing nipple is designed for incorporation permanently in the tubing string and is therefore resistant to damage by sand in the oil or gas. All moving parts to co-operate with such a landing nipple are provided on the locking
REFERENCES:
patent: 2752861 (1956-07-01), Hill
patent: 4108243 (1978-08-01), King et al.
patent: 4583592 (1986-04-01), Gazda et al.
patent: 4678035 (1987-07-01), Goldschild
patent: 4790378 (1988-12-01), Montgomery et al.
Armell Richard A.
Coull David
Eljay Well Services Limited
Novosad Stephen J.
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