Wells – Valves – closures or changeable restrictors – Fluid operated
Patent
1982-02-11
1984-09-11
Purser, Ernest R.
Wells
Valves, closures or changeable restrictors
Fluid operated
137117, E21B 3408
Patent
active
044704640
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
The present invention relates to the art of earth drilling and, more particularly, to valve means.
PRIOR ART
There is known a valve means that can be disposed inside a drilling string above a bottom hole positive displacement motor and serving for filling up and draining off the drill pipes during the round trips, as well as for separating the interior of the drill string from the annular space of the well bore.
The valve means comprises a hollow casing or housing having coaxially arranged inlet and outlet for the passage of a drilling fluid therethrough and through bores or holes provided in the wall of the housing to communicate the interior thereof with the annular space of the well bore. The inlet of the housing is connected to the interior of the drilling string, while the outlet thereof is connected to the interior of the bottom hole motor. A sealing couple is provided to prevent the interior of the housing from communicating with the annular space of the well bore in the course of drilling, the couple having a valve seat secured to the housing below the through holes and a spring-loaded valve element in the form of a plunger. Arranged inside the plunger to extend axially therethrough is a calibrated hole or bore serving to produce a pressure drop under the action of which the plunger is caused to move axially until it fits the valve seat to thereby close the through holes of the housing during the drilling operation; otherwise stated, to prevent the annular space of the well bore from communicating with the interior of the housing; the calibrated bore being actually a means for letting the drilling fluid out of the housing. The plunger is further provided with rubber sealing rings arranged on the outer surface thereof (cf. e.g., U.S. Pat. No. 3,661,218, published 1972, Cl. 175-107).
One disadvantageous feature of the above valve means construction resides in that the use of a drilling mud containing considerable amount of mechanical impurities as the drilling fluid is liable to cause malfunctioning of the valve means. Stoppages of the drilling operation, such as during pipe connection and the like, result in that the plunger tends to assume the initial (transport) upmost position thereby communicating the annular space of the well bore with the interior of the drilling string. Excessive sludge or drill cuttings in the critical zone may lead to the sludge tending to penetrate the space between the housing of the valve means and the outer surface of the plunger adjacent to the spring thereof. Repeated actuation of the surface pumps cause the drill cuttings to hamper the free downward movement of the plunger, which results in a partial overflow of the drilling mud into the annular space of the well bore via the open through holes of the housing.
The sealing rings arranged in the upper and lower exterior surface of the plunger may be damaged when the pressure drop causes the plunger to move downwards to assume the working position with some skewness or misalignment, after which subsequent functioning of the valve means may become impossible due to rapid deterioration of the sealing rings and the valve means becoming inoperable.
SUMMARY OF THE INVENTION
The present invention is directed toward the provision of a valve means wherein calibrated holes or orifices and a sealing couple would be of such a construction which, along with relative simplicity thereof, could enable to improve the reliability and extend the service life (durability) of the valve means in the course of operation in a drilling fluid containing mechanical impurities.
This is attained by that in a valve means installed in a drill string above a positive displacement motor comprising a hollow housing having an inlet for a drilling fluid and an outlet for the drilling fluid to pass through a plurality of calibrated openings to produce a pressure drop, the wall of the housing having through holes intended to communicate the interior of the housing with the annular space of the well bore and a sealing couple fo
REFERENCES:
patent: 2919709 (1960-01-01), Schwegman
patent: 3385370 (1968-05-01), Knox et al.
patent: 3661218 (1972-05-01), Brown
patent: 4300636 (1981-11-01), Lawrence
Baldenko Dmitry F.
Bezlepkin Nikolai P.
Semenets Valery I.
Bui Thuy M.
Purser Ernest R.
Schaffer Murray
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