Mud by-pass regulator apparatus for measurement while drilling system

Claim 2

A by-pass device for use in controlling the pressure differential across a drilling fluid operated power generator located in a drill string, characterised in that the device comprises a valve (94) in the drill string (30) mounted up stream of the power generator (88,42) and operable to control fluid flow past the generator; a valve actuator (50) operable to displace the valve (94) in variable relation between first (Fig. 2) and second (Fig. 4) positions; and a valve acutator control (60,64,72) operable to control the valve actuator in order to move the valve and thereby maintain a fluid pressure differential across the generator (88,42) within a predetermined range.

Claim 3

A by-pass device according to claim 1 characterised in that the valve actuator control (60,64, 72) has a plurality of fluid pressure sensing portions operable to sense the differential pressure across the valve (94), and the valve actuator (50) has an area exposed to relatively high fluid pressure from the drilling fluid, and another area on an opposing portion thereof exposed to relatively low fluid pressure from the drilling fluid, and a spring (58) urging the valve actuator in a sense to move the valve member (94) toward the first position (Fig. 2).

Claim 4

A by-pass device accordingly to claim 1 or claim 2 characterised in that the valve (94), valve actuator (50), and generator (88,42) are contained within a housing (34,38,40); the generator (88,42) comprises a turbine (88) mounted to receive drilling fluid flowing through the drill string; and the valve (94) comprises a sleeve (94) longitudinally slidably mounted within the housing (34,38:40) and having an end portion which, when the valve (94) is in the first position (Fig. 2), is adjacent the turbine (88) to provide a relatively high fluid flow into the turbine (88) and which, when the valve (94) is in the second position (Fig. 4), is spaced from the turbine (88) to decrease the fluid flow into the turbine (88).

Claim 5

A by-pass device according to claim 3 characterised in that the valve actuator (50) has a plurality of seals (52,62,74) around the exterior portions thereof residing in sealing contact with an interior surface of the housing (34,38,40) thereby forming a high pressure fluid chamber (72) and a low pressure fluid chamber (64), the high pressure fluid chamber (72) being in fluid communication (78) with drilling fluid in the drill string at a location upstream of said turbine (88), and the low pressure fluid chamber (64) being in fluid communication by an aperture (66) through the housing (38) with a relatively low pressure drilling fluid present around the exterior of the housing (34,38,40) within said drill string; and the low pressure fluid chamber (64) has opposed internal abutments with a spring (58) mounted therebetween to urge the valve (94) toward the first position, the valve (94) being urged toward the first position by the spring (58) and low fluid pressure acting in the low pressure fluid chamber (64) in opposition to force due to high pressure fluid in the high pressure fluid chamber (72), the valve actuator (50) being adapted in operation to maintain a pressure differential across said turbine (88) within a predetermined range of values.

Claim 6

A by-pass device according to claim 4 characterised in that the range of values of pressure differential across said turbine (88) is between about 344 k Pa and about 3440 kPa and said valve (94) is moved toward said turbine (88) by said spring (58) alone when drilling fluid pressure is equalized between inner and outer portions of said housing (34,38,40) including said low (64) and said high (72) pressure fluid chambers, the arrangement being such that when drilling fluid pressure in said drill string is increased during operation of said system, said pressure drop increases the fluid pressure in said high pressure fluid chamber (72) which displaces said valve (94) from said first position toward said second position in opposition to said spring (58) and the force of said low pressure fluid acting on said valve actuator in said low pressure fluid chamber (64) in order to increase the quantity of drilling fluid by-passing said turbine (88), and when drilling fluid pressure in said drill string is decreased during operation of said system, thisdecreases the fluid pressure in said high pressure fluid chamber (72) which displaces said valve (94) toward said first position in order to decrease the quantity of drilling fluid by-passing said turbine (88) and increases the quantity of drilling fluid directed into said turbine (88).

Claim 7

A by-pass device according to any preceding claim characterised in that the range of values of pressure differential across said generator is between about 1033 kPaand about 137u kPa.

Claim 8

A by-pass device according to any preceding claim characterised in that the position of said valve (94) is adjustable to correspondingly preset the proportional drilling fluid flow rate past the generator (88,42).

Claim 9

A by-pass device according to claim 7 characterised in that the position of the valve (94) is manually adjustable from the exterior of said valve (94), said valve actuator (50) and said valve actuator control (60,64,72).

Claim 10

A by-pass device according to any preceding claim characterised in that said generator (88,42) is an electrical power generator.

Claim 11

A measurement while drilling system comprising a sensor in a drill string to sense a parameter; a transmitter to transmit sensed data to the earth's surface; a drilling fluid operated power generator to provide operating power for the sensor and or the transmitter; and a by-pass device according to any preceding claim for controlling the pressure differential across the power generator.