"FLOW DIVERTER ASSEMBLY"

Field of the Invention

The present invention relates to a flow diverter assembly to be used in a core barrel assembly for diverting the flow of drilling fluid.

Background to the Invention

During certain drilling operations, such as coring, it is necessary to divert the flow of drilling fluid. In a core barrel assembly, there is generally provided an inner barrel for capturing a core sample and an outer barrel. During coring, drilling fluid is pumped through the space between the inner and outer barrels. However, drilling fluid is also generally pumped through the inner barrel prior to commencement of coring to clear the inner barrel and then the flow to the inner barrel must be prevented prior to coring. The present invention relates to a flow diverter assembly to be used as part of the core barrel assembly for diverting fluid flow into or away from the inner barrel prior to coring.

In one known arrangement, a steel ball is dropped to seal across the entry to the inner barrel to divert the flow of drilling fluid such that it only flows between the inner and outer barrels. Such an operation may be performed by dropping the ball from the surface. This requires though that there is a clear passage through the drill string for the ball to travel. Allowing such a clear passage can prevent difficulties when it is required to use other pieces of equipment such as hydraulic motors or mud pulse telemetry systems.

One solution for this problem is to provide a ball drop sub assembly to divert the fluid flow. The ball drop sub assembly is located below this other equipment and houses the ball. The ball drop sub includes a means to release the ball based on the flow rate of the drilling fluid. In one such system, a thin aluminium disc is provided which collapses under a pressure spike to release the ball. Some systems also employ a further thin sleeve which collapses to enclose the entire inner core barrel after coring to stop the core from dropping out. One disadvantage of such a system employing both of these features is

that, as a certain flow rate is required to release the ball, when the ball lands in its seat a pressure spike results that can cause the further thin sleeve around the inner core barrel to collapse, thereby rendering the entire process inoperative.

The present invention attempts to overcome, at least in part, the abovementioned problems.

Summary of the Invention According to one aspect of the present invention there is provided a flow diverter assembly comprising a sealing member moveable relative to an aperture in communication with an inner barrel of a core barrel assembly, the sealing member being moveable between a first position in which the aperture is open and a second position in which the sealing member seals across the aperture to divert the flow of drilling fluid such that drilling fluid is prevented from entering the inner barrel, wherein centrifugal force imparted by rotation of the core barrel assembly causes the sealing member to move from the first position to the second position and the sealing member remains in the second position on cessation of said rotation.

In one embodiment, the sealing member comprises a ball wherein in the first position the ball is retained and in the second position the ball is released to fall across the aperture. Preferably there is provided a pair of ball release members comprising arms pivotable between the first and the second positions.

Preferably the arms are pivotally mounted adjacent upper ends thereof and extend downwardly either side of the ball to lower ends that include inwardly turned ends such that the inwardly turned ends prevent release of the ball in the first position and the arms pivot away from each other to release the ball under the centrifugal force.

The arms are preferably spring biased such that the spring bias acts to move the arms towards the first position. The arms may be provided with lugs adjacent first ends thereof and springs connected between each of the lugs and an adjacent support pin.

In a preferred embodiment, there is provided a tubular ball support having open upper and lower ends located such that the inwardly turned ends of the arms extend across the open lower end of the tubular ball support when in the first position to prevent the ball from falling through the open lower end.

In a further embodiment, the ball is retained by a rod extending outwardly from a solenoid and the pivotally mounted arms are arranged such that the arms pivot outwardly under centrifugal force to make an electrical circuit which powers the solenoid and retracts the rod, thereby releasing the ball.

The ball is preferably located in a tubular ball support and the rod extends in the first position across the open lower end of the tubular ball support to retain the ball.

Preferably the arms are each connected to a centrally mounted member by a respective spring such that the arms move outwardly under centrifugal force when the assembly rotates faster than a predetermined speed such that lower ends of the arms touch contacts provided on an inner surface of a housing.

In a further embodiment, the flow diverter assembly comprises: a main body having an inlet port and an outlet port, the outlet port being in communication with the inner barrel and said aperture being provided between the inlet port and the outlet port; a cylindrical valve body rotatable between the first position in which a hole in the cylindrical valve body is aligned with the aperture and the second position in which the hole is not aligned with the aperture; a motor provided for rotating the cylindrical valve body between the first and second positions; and a centrifugal force sensor;

wherein when the centrifugal force sensor senses a predetermined level of centrifugal force caused by rotation of the core barrel assembly, a signal is sent to the motor to rotate the cylindrical valve body from the first position to the second position such that the aperture is sealed and drilling fluid prevented from entering the inner barrel.

Preferably, an internal chamber is provided in the main body, the internal chamber including a cylindrical upper end portion in which the cylindrical valve body is received and wherein the inlet port extends from an outer side wall of the main body to said aperture provided in an inner side wall of the upper end portion of the internal chamber such that drilling fluid can flow into the chamber through the inlet port when the cylindrical valve body is in the first position thereof.

The cylindrical valve body is preferably mounted to a central shaft extending through the main body and the motor is connected to the central shaft to rotate the cylindrical valve body between the first and second positions.

Advantageously, there may be provided a position sensor to sense whether the valve body is in the first or the second position. In one embodiment, there is provided a disc connected to a lower end of the shaft having a magnet thereon that aligns with the position sensor such that the position sensor detects the presence of the magnet, thereby providing an indication of the rotational position of the valve body.

There may be provided a housing adjacent a lower end of the main body containing control circuitry and a power supply and a channel provided in the main body extending from the housing to adjacent an upper end of the flow diverter assembly through which power and control cables are run to provide power and control signals to the motor.

In one embodiment, the predetermined centrifugal force must be exceeded for a predetermined time period in order for the valve body to move from the first position to the second position.

In a further embodiment, the valve body includes a vent hole that is aligned with the aperture in the second position such that, during coring, mud may exit the vent hole as the core sample is captured in the inner barrel.

The valve body may also be rotatable to a third position in which the aperture is fully closed. Preferably the valve body is rotatable from the second position to the third position when a second predetermined centrifugal force is exceeded for a second predetermined time period

Brief Description of the Drawings

The invention will now be described, by way of example, with reference to the following drawings in which:

Figure 1 is a side cross sectional view of a first embodiment of a flow diverter assembly in accordance with the present invention with the ball release members in the first position thereof such that the ball is retained;

Figure 2 is a side cross sectional view of the flow diverter assembly of Figure 1 with the ball release members in the second position thereof, allowing release of the ball;

Figure 3 is a side cross sectional view of a second embodiment of a release mechanism of a flow diverter assembly in accordance with the present invention with the ball release member in the first position thereof such that the ball is retained;

Figure 4 is a side cross sectional view of the ball release mechanism of Figure

3 with the ball release member in the second position thereof, allowing release of the ball;

Figure 5 is a side cross sectional view of a further embodiment of a flow diverter assembly in accordance with the present invention with the cylindrical valve in a first position; and

Figure 6 is a side cross sectional view of the flow diverter assembly of Figure

6 with the cylindrical valve in a second position.

Detailed Description of Preferred Embodiments

Referring to Figures 1 and 2, there is shown a first embodiment of a flow diverter assembly 10. The flow diverter assembly 10 is provided in a core barrel assembly located above an aperture (not shown) which is in communication with the inside of an inner barrel. The flow diverter assembly

10 includes a sealing 13 member moveable to seal the aperture such that the flow of drilling fluid through the aperture is prevented. The sealing member 13 in the embodiment shown comprises a ball 14 and there is provided a ball release mechanism 12 for releasing, at an appropriate point in the drilling operation, the ball 14. The ball 14 is sized to seal across the aperture.

The flow diverter assembly 10 comprises a hollow cylindrical body 16 having a first opening 18, positioned uppermost in use, and a second opening 20, positioned lowermost in use, such that drilling fluid passes into the first opening 18 and out of the second opening 20. Drilling fluid passes in use from the second opening 20 into the aperture in communication with the inner barrel.

Within the cylindrical body 16 is located the ball release mechanism 12. The ball release mechanism 12 includes two ball release members. The ball release members comprise pivotally mounted arms 22. Each of the arms 22 is pivotally secured adjacent an upper end 24 thereof.

Referring to the embodiment of Figures 1 and 2, the upper ends 24 of the arms 22 are secured to a common pivot pin 25. The upper ends 24 of the arms 22 extend away from the pivot pin 25 and downwardly, as can be seen in the Figures. The arms 22 extend from the upper ends 24 downwardly to second ends 26 thereof. The second ends 26 of the arms 22 each include an inwardly turned end 28. The inwardly turned ends 28 extend generally transversely to the arms 22 and towards each other.

The ball release mechanism 12 of Figures 1 and 2 also includes a tubular ball support 30. The tubular ball support 30 includes open upper and lower ends and is sized to receive the ball 14.

When the arms 22 are subject to no force, the arms 22 are located in a first position thereof, as shown in Figure 1. In the first position, the arms 22 extend from the upper ends 24 generally parallel to each other and the inwardly turned ends 28 of the arms 22 extend across the open lower end of the tubular ball support 30. That is, in the first position thereof, the inwardly turned ends 28 prevent the ball 14 from falling from the open lower end of the tubular ball support 30.

Each of the arms 22 is also provided with a spring bias means which tends to move the arms 22 towards the first positions thereof. In the embodiment shown, there is provided lugs 32 on the upper ends 24 of the arms 22. Also provided are a pair of support pins 34, one located either side of the lugs 32 transversely to the longitudinal axis of the flow diverter assembly 10. A spring 36 is secured between each lug 32 and one of the support pins 34 such that the force of the spring 36 tends to pull the lug 32 so that the respective arm 22 moves towards the first position thereof.

In use, the flow diverter assembly 10 is rotated about its longitudinal axis. During rotation, centrifugal forces tend to cause the arms 22 to pivot away from each other from the first position to a second position thereof when this force is sufficient to overcome the force of the springs 36 (as shown in Figure 2). That is, at a certain rotational speed, each arm 22 will move from the first position thereof to the second position. In the second positions, the inwardly turned ends 28 of the arms 22 move away from the tubular ball support 30 and no longer obstruct the open lower end thereof. That is, the ball 14 is free to fall from the open lower end of the tubular ball support 30 and seal across the aperture (not shown) to divert the flow of drilling fluid as required.

Figures 3 and 4 show a second embodiment of a release mechanism 12 of a flow diverter assembly 10 in accordance with the present invention. In the

embodiment of Figures 3 and 4, the arms 22 are each separately mounted adjacent upper ends 24 thereof for pivotal movement. The arms 22 are mounted within a chamber of a sealed housing 40. Each of the arms 22 is connected to a centrally mounted member 42 by a respective spring 36. As in the first embodiment, the springs 36 are arranged such that the arms 22 will move outwardly under centrifugal force when the assembly rotates faster than a predetermined speed.

In the embodiment of Figures 3 and 4, the ball 14 is located in a tubular ball support 30 and retained from falling out of the tubular ball support 30 by a rod 44 of a solenoid 46. The rod 44 is arranged such that when the solenoid 46 is not connected to a power source, the rod 44 is extended to retain the ball 14. When the solenoid 46 is connected to a power source, the rod 44 is retracted into the solenoid 46 to release the ball 14.

The housing 40 is provided with a pair of contacts 48 each located such that when an associated one of the arms 22 moves outwardly under centrifugal force, the lower end of the arm 22 touches the contact 48. The arms 22 are electrically connected at the upper ends 24 thereof to the solenoid 46. Also, the contacts 48 are electrically connected across a power source, in this case being a battery 50. The electrical connections extend from the contacts 48 and arms 22 out of the housing 40 through an insulated carrier 41 around the chamber. Therefore, when the arms 22 move outwardly under centrifugal force caused by rotation of the flow diverter assembly 10, the arms 22 touch the contacts 48 and provide power to the solenoid 46 to retract the rod 44 and release the ball 14, as can be seen in Figure 4.

The use of a pair of arms 22 with associated contacts 48, rather than a single arm 22, is expected to reduce the likelihood of vibration of the flow diverter assembly 10 causing release of the ball 14. If a single arm were to be used, vibration may cause the arm to move sufficiently to make contact. It is less likely that vibration would cause both arms 22 to move and make contact at the same time.

Figures 4 and 5 shows a further embodiment of a flow diverter assembly 10. The flow diverter assembly 10 includes a main body 60, a lower end of which is received in an inner barrel 62 of a drilling assembly. The flow diverter assembly 10 is provided to allow drilling fluid to flow initially down the inner barrel 62 and then prevent further flow of drilling fluid into the inner barrel 62 at the appropriate point in the drilling operation.

The main body 60 includes an internal chamber 64. An upper end portion 65 of the chamber 64 is generally cylindrical and includes an inlet port 66. The inlet port 66 extends from an outer side wall of the main body 60 to an inner side wall of the upper end portion 65 of the chamber 64 such that drilling fluid can flow into the chamber 64 through the inlet port 66. The end of the inlet port 66 at the inner side wall of the upper portion 65 of the chamber 64 comprises the aperture to be sealed by the sealing member 13. Within the upper end portion 65 of the chamber 64 is provided a cylindrical valve body 68 that comprises the sealing member 13. The cylindrical valve body 68 is mounted to a central shaft 70 extending through the main body 60. The valve body 68 includes a hole 69 in the wall thereof.

The shaft 70 is rotatable relative to the main body 60 such that the valve body 68 is rotated between a first position in which the hole 69 therein aligns with the inlet port 66 such that drilling fluid can flow into the internal chamber 64 and a second position in which the hole 69 is moved out of alignment with the inlet port 66, thereby preventing drilling fluid from flowing into the internal chamber 64.

An outlet port 67 is provided adjacent a lower end of the internal chamber 64 and opens into the inner barrel 62. Therefore, when the valve body 68 is in the first position thereof (as shown in Figure 5), drilling fluid can flow into the inner barrel 62 via the inlet port 66, the internal chamber 64 and the outlet port 67. When the valve body 68 has rotated to the second position thereof (as shown in Figure 6), drilling fluid is prevented from flowing into the chamber 64 and thereby prevented from entering the inner barrel 62.

Adjacent an upper end of the main body 60 is provided a motor 72. The motor 72 is provided connected to an upper end of the shaft 70 such that the motor 72 can drive the valve body 68 between the first and second positions by rotating the shaft 70. The motor 72 is controlled by a centrifugal force sensor (not shown) such that when the centrifugal force sensor senses a predetermined level of centrifugal force caused by rotation of the diverter assembly 10, a signal is sent to the motor 72 to rotate the valve body 68 from the first position to the second position. Control circuitry may be provided to sense also the time for which the predetermined centrifugal force has been exceeded such that the valve body 68 is only moved from the first position to the second position if the predetermined centrifugal force has been exceed for a predetermined time period. That is, the core barrel assembly will need to be driven for this time period at a certain rotational speed in order to cause the valve body to move to the second position. When the core barrel assembly is slowed, the valve body will then remain in the second position.

The diverter assembly 10 may also be provided with a position sensor 78 to sense the position of the valve body 68. In the embodiment shown, a disc 74 is provided connected to a lower end of the shaft 70. The disc 74 includes a magnet 76 thereon that aligns with the position sensor 78 such that the position sensor 78 detects the presence of the magnet 76, thereby providing an indication of the rotational position of the valve body 68. The magnet 76 may be provided on the disc 74, for example, such that it aligns with the position sensor 78 when the valve body 68 is in the second position.

The cylindrical valve body 68 is preferably provided with a relatively small vent hole (not shown) that aligns with the inlet port 66 when in the second position. The vent hole is provided to allow mud to pass outwardly from the inner barrel as the core sample enters the inner barrel.

The cylindrical valve body 68 may also be rotatable to a third position. In the third 68, the vent hole is moved out of alignment the inlet port 66 such that the inlet port 66 is completely closed. The third position may therefore be used

during moving the core barrel assembly into position prior to flushing and then coring.

The control circuitry may be provided such that the valve body 68 moves sequentially through each of the positions each time the centrifugal force sensor determines that the predetermined centrifugal force has been exceeded for the predetermined time period. That is, rotating the core barrel assembly at a first predetermined rotational speed for a first time period causes the valve body 68 to move from the first position to the second position and rotating the core barrel assembly at a second predetermined rotational speed for a second time period causes the valve body 68 to move from the second position to the third position. Rotating the core barrel assembly at a third predetermined rotational speed for a third time period will cause the valve body 68 to move from the third position back to the first position. The first, second and third centrifugal forces and first, second and third predetermined time periods may each be the same or different.

The diverter assembly 10 may include also a housing 80 adjacent the lower end thereof to contain control circuitry and a power supply. A channel 82 is provided in the main body 60 extending from the housing 80 to adjacent the upper end of the flow diverter assembly 10 through which power and control cables can be run to provide power and control signals to the motor 72.

It will be readily apparent to persons skilled in the relevant arts that various modifications and improvements may be made to the foregoing embodiments, in addition to those already described, without departing from the basic inventive concepts of the present invention.