FIELD OF THE INVENTION The present invention generally relates to core barrels. More specifically, it relates to a core barrel head assembly.

BACKGROUND OF THE INVENTION In core drilling operations, it is often desired to obtain a core sample to obtain geological information on a particular site. This operation is to be ideally accomplished without removing the drill string from the borehole. For this purpose, hollow drill strings have been developed and include a bit end at the end of the drill string and a core barrel unit positioned proximate the coring bit end. The inner tube assembly unit can be transported through the drill string and thus ideally avoid having to remove the complete drill string to obtain a core sample.

The core barrel head assembly is the main component in wireline core drilling. It is a means for holding the inner tube in place during drilling. The core barrel head assembly may provide signals to drillers when the inner tube has landed in the correct position, through a landing indicator device. The core barrel head assembly is also used as a connection point for the wireline overshot to retrieve the core sample from the drill string.

In known prior art core barrel head assemblies, different landing indicator devices either produce a sustained signal or an instantaneous signal for the operator. These different landing indicator devices are typically not interchangeable, which implies that different back end components need to be used when there is a need to switch between devices. Currently, drillers need to use different head assemblies to utilize their specific features or advantages for a given drilling condition and/or equipment, often having to change outer tube components as well. When components within the head assembly wear out and are no longer operational, replacing the parts requires complete disassembly to replace a single or few parts.

For example, US 5,934,393 discloses a drilling apparatus and a valving mechanism for controlling fluid flow from one axial side of a latch body landing shoulder to the other. The drilling apparatus includes replaceable components, including the valving mechanism, that can be accessed by unthreading the latch body main body portion from the inner body portion, thus completely disassembling components within the latch body itself.

Moreover, the core barrel head assemblies known to the Applicant typically have two series of ports. The first series, located above the landing shoulder, acts also as pressure port when a landing indicator valve is present, while the second series located under the landing shoulder act as flow ports. When the landing indicator valve is activated, fluid flows through this landing indicator valve located between the two series of ports, thus creating a flow restriction. Since current assemblies also utilize the same fluid ports for landing indication valves and fluid flow for drilling, this restricts the amount of flow available for drilling and limits design possibilities. Consequently, there is still presently a need for a head assembly that is quickly reconfigurable in order to interchange different components thereof when switching between different drilling conditions or for maintenance purposes.

Consequently, there is also presently a need for a head assembly that improves the amount of fluid flow available for drilling while continuing to provide a landing indication mechanism. SUMMARY OF THE INVENTION

It is an object of the present invention to provide a head assembly that addresses at least one of the above-mentioned needs.

Accordingly, the present invention provides a core barrel head assembly positionable within a drill string of a drilling apparatus, the core barrel head assembly comprising:

-an upper latch body;

-a lower latch body;

-a mid latch body separating the upper latch body from the lower latch body and removably coupling the upper latch body to the lower latch body, the mid latch body being removably coupled to the upper latch body and the lower latch body, the mid latch body comprising a landing indicator device; and -a common central bore formed by the upper latch body, the lower latch body and the mid latch body.

The head assembly thus consists of common latch bodies with an interchangeable mid body component that may house different types of valves or devices for different drilling conditions and equipment and/or operator preference.

According to the present invention, there is also provided a core barrel head assembly positionable within a drill string of a drilling apparatus, the core barrel head assembly comprising:

-a landing shoulder;

-at least one upstream fluid flow port positionable within a fluid line of the drilling apparatus upstream of the landing shoulder;

- at least one downstream fluid flow port positionable within the fluid line of the drilling apparatus downstream of the landing shoulder; -a common central bore linking the at least one upstream fluid flow port and the at least one downstream fluid flow port;

-at least one fluid pressure communication port positionable within the fluid line of the drilling apparatus;

-a fluid pressure communication port control assembly for variably blocking the at least one fluid pressure communication port and variably restricting fluid flow therethrough; and

-a valving mechanism actuatable by fluid pressure through the at least one fluid pressure communication port and for variably blocking at least one of the at least one upstream fluid flow port, the at least one downstream fluid flow port and the common central bore, thereby variably restricting fluid flow therethrough and towards the at least one downstream fluid flow port.

According to the present invention, there is also provided a core barrel head assembly positionable within a drill string of a drilling apparatus, the core barrel head assembly comprising:

-a landing shoulder;

-at least one upstream fluid flow port positionable within a drilling fluid line of the drilling apparatus upstream of the landing shoulder;

- at least one downstream fluid flow port positionable within the fluid line of the drilling apparatus downstream of the landing shoulder;

-at least one fluid pressure communication port positionable within the fluid line of the drilling apparatus;

-a fluid pressure communication port control assembly for variably blocking the at least one fluid pressure communication port and variably restricting fluid flow therethrough;

-an upper latch body;

-a lower latch body;

-a mid latch body separating the upper latch body from the lower latch body and removably coupling the upper latch body to the lower latch body, the mid latch body being removably coupled to the upper latch body and the lower latch body, the mid latch body housing at least part of the valving mechanism; -a common central bore formed by the upper latch body, the lower latch body and the mid latch body, the common central bore linking the at least one upstream fluid flow port and the at least one downstream fluid flow port; and

-a valving mechanism actuatable by fluid pressure through the at least one fluid pressure communication port and for variably blocking at least one of the at least one upstream fluid flow port, the at least one downstream fluid flow port and the common central bore, thereby variably restricting fluid flow therethrough and towards the at least one downstream fluid flow port.

The head assembly according to the present invention thus also consists of separate fluid flow ports and fluid pressure communication ports upstream, of the landing shoulder. Such an assembly has the advantages of increased fluid flow during drilling which means it is less likely to collect debris and pack with mud and provide also a more efficient pumping system, since fluid flow is not constrained to pass through a single port system upstream of the landing shoulder.

BRIEF DESCRIPTION OF THE DRAWINGS

The foregoing summary, as well as the detailed description of the preferred embodiments of the present invention, will be better understood when read in conjunction with the appended drawings. For the purpose of illustrating the invention, there is shown in the drawings, which are diagrammatic, embodiments that are presently preferred. It should be understood, however, that the present invention is not limited to the precise arrangements and instrumentalities shown. In the drawings: Figure 1 is an exploded view of a head assembly according to a preferred embodiment of the present invention, with interchangeable mid latch bodies.

Figures 2A to 2C are cross-sectional side views of a head assembly according to another preferred embodiment of the present invention.

Figures 3A to 3C are detailed cross-sectional side views of the head assembly corresponding to the views shown in Figures 2A to 2C, illustrating flow streamlines through the valve assembly.

Figures 4A to 4C are cross-sectional side views of a head assembly according to another preferred embodiment of the present invention.

Figures 5A and 5B are detailed cross-sectional side views of the head assembly corresponding to the views shown in Figures 4A and 4B, illustrating flow streamlines through the valve assembly.

Figures 6A to 6C are cross-sectional side views of a head assembly according to another preferred embodiment of the present invention.

Figures 7A to 7C are detailed cross-sectional side views of the head assembly corresponding to the views shown in Figures 6A to 6C, illustrating flow streamlines through the valve assembly. Figures 8A to 8D are partial detailed cross-sectional side views of the head assembly with a valve assembly according to another preferred embodiment of the present invention, illustrating a preferred sequential use of the valve assembly.

Figures 9A and 9B are partial side views of an upper latch body and latch retracting case of the head assembly shown in Figures 6A to 6C. Figures 10A and 10B are a partial cross-sectional view of a valve assembly and partial side view of a joined upper latch body and latch retracting case, respectively, of the head assembly shown in Figures 6A to 6C, during a descent phase of a preferred sequential use of the valve assembly.

Figures 1 1 A and 1 1 B are a partial cross-sectional view of a valve assembly and partial side view of a joined upper latch body and latch retracting case, respectively, of the head assembly shown in Figures 6A to 6C, during a signal phase of a preferred sequential use of the valve assembly.

Figures 12A and 12B are a partial cross-sectional view of a valve assembly and partial side view of a joined upper latch body and latch retracting case, respectively, of the head assembly shown in Figures 6A to 6C, during a working phase of a preferred sequential use of the valve assembly.

Figures 13A and 13B are a partial cross-sectional view of a valve assembly and partial side view of a joined upper latch body and latch retracting case, respectively, of the head assembly shown in Figures 6A to 6C, during a transition to the retracting/retrieval phase of a preferred sequential use of the valve assembly.

Figures 14A and 14B are a partial cross-sectional view of a valve assembly and partial side view of a joined upper latch body and latch retracting case, respectively, of the head assembly shown in Figures 6A to 6C, during a retracting/retrieval phase of a preferred sequential use of the valve assembly.

Figure 15 is a detailed cross-sectional side view of an inner tube member of another preferred embodiment of the present invention. PREFERRED EMBODIMENTS OF THE PRESENT INVENTION

Before any embodiments of the invention are explained in detail, it is to be understood that the invention is not limited in its application to the details of construction and the arrangement of components set forth in the following description or illustrated in the following drawings. The invention is capable of other embodiments and of being practiced or of being carried out in various ways. Also, it is to be understood that the phraseology and terminology used herein is for the purpose of description and should not be regarded as limiting. The use of "including," "comprising," or "having" and variations thereof herein is meant to encompass the items listed thereafter and equivalents thereof as well as additional items. Unless specified or limited otherwise, the terms "mounted," "connected," "supported," and "coupled" and variations thereof are used broadly and encompass both direct and indirect mountings, connections, supports, and couplings and are thus intended to include direct connections between two members without any other members interposed therebetween and indirect connections between members in which one or more other members are interposed therebetween. Further, "connected" and "coupled" are not restricted to physical or mechanical connections or couplings. Additionally, the words "lower", "upper", "upward", "down" and "downward" designate directions in the drawings to which reference is made. The terminology includes the words specifically mentioned above, derivatives thereof, and words or similar import.

Referring now to the drawings in detail, wherein like numbers are used to indicate like elements throughout, there is shown in FIG. 1 an exploded view of a presently preferred embodiment of an core barrel head assembly 10 for a drilling apparatus.

The core barrel head assembly 10 is positionable within a drill string of a drilling apparatus. The core barrel head assembly 10 comprises an upper latch body 12 and a lower latch body 14. The head assembly 10 further comprises a mid latch body 16 separating the upper latch body 12 from the lower latch body 14 and removably coupling the upper latch body 12 to the lower latch body 14. Figure 1 shows three different sample embodiments of the mid latch body 16A, 16B, 16C to illustrate the interchangeability of the mid latch body 16. In all cases, the mid latch body 16 is removably coupled to the upper latch body 12 and the lower latch body 14. The mid latch body 16 houses a landing indicator device 18. A common central bore 20 is formed by the upper latch body 12, the lower latch body 14 and the mid latch body 16. Preferably, as illustrated in Figure 1 , the head assembly includes an upper latch body 12 with a latching assembly 30 and fluid pressure communication ports 32. The lower latch body 14 holds a landing shoulder 34 by a removable sleeve 36 and includes fluid flow ports 38 downstream of the landing shoulder. The mid latch body component 16 also has fluid flow ports 40 upstream of the landing shoulder, and connects the upper and lower latch bodies, 12,14, with a central bore 20 connecting the fluid flow ports 38,40. The mid latch body 16 contains a valving mechanism 42 which can provide a landing indication signal. The common central bore 20 is present through all body components. The head assembly preferably includes two sets of ports: the first set for fluid pressure communication with the internal valving mechanism 42, the second set for fluid flow required for drilling in which the fluid flow is blocked or opened by the internal valving mechanism 42. This fluid port design offers the advantages of increased fluid flow during drilling which means it is less likely to collect debris and pack with mud and thus results also in a more efficient pumping system, compared to a head assembly where all the fluid circulates through a single port system upstream of the landing shoulder (thus more subject to blockage) from the upper latch body to the lower latch body, with no bypass port. Given the reconfigurable nature of the head assembly, different valving systems can be used depending on drilling conditions and also can be easily upgraded when a newer type of valve is developed. Figure 1 illustrates an example of three different head assemblies in which the upper 12 and lower 14 latch bodies are similar and could be shared, but where a changeout of the mid latch body 16 allows the use of different valving mechanism designs that can be tailored to a specific drilling condition.

The following sections will illustrate different valving mechanisms that can be changed out through different mid latch bodies 16 while also benefiting from the advantages of having the distinct fluid pressure communication ports 32 and fluid flow ports 40 upstream of the landing shoulder.

First Embodiment- Timed Signal Valve

Referring now to the drawings, there is shown in FIG. 2A to 3C a first preferred embodiment of a valve assembly 100 for use in an inner tube member 1 12 of a core barrel head assembly positionable within a drill string of a drilling apparatus. The valve assembly 100 comprises at least one pressure port 32 formed in a sidewall of the inner tube member 1 12. There is also at least one fluid flow port 40 formed in the sidewall of the inner tube member 1 12. Preferably, in a first descent configuration, a pressure piston member 1 18 is positioned on top of an annular element, preferably a bushing 120, wherein the piston member 1 18 and bushing 120 are in sealed engagement. The piston member 1 18 is preferably held in place by a compression spring 124 that is acting on a latch piston 126 that is connected to a retracting case 28 through a pin 127. The retracting case 28 serves as a linkage element between the latch piston 126 and the piston member 1 18, as it is connected to the piston member through another pin 129 that traverses the upper latch body 12 through a slot. A valve member 130 blocks the fluid flow ports 40 of the mid latch body 16. Preferably, seal members or 0-rings 134 on the valve member 130 ensure proper sealing of the flow ports 40. The valve member 130 is connected to the pressure piston member 1 18 by a connecting rod 136. The pressure piston member 1 18 is connected directly to the retracting case 28 or has a limited movement connection with the retracting case 28, holding it in a middle, latch-retracted position, allowing the inner tube member 12 to travel in the drill string at an increased rate due to a reduction in the drag of the latches on the inside wall of the drill string, thus also reducing wear of the latches. As described above, the interaction between the pins 127,129 and the slots in the upper latch body 12 and slots in the retracting case 28 can help provide the limited movement connection of the piston member 1 18 with respect to any movement of the retracting case.

Preferably, as shown in FIG, 2A and 3A, when the inner tube member 1 12 reaches the end of the drill string, a landing shoulder 34 will create a seal with the landing ring 35. This seal will build up the water pressure in the drill string. The valve member 130 blocks flow through the flow port 40 and the common bore 20 towards the lower latch body 14. This built-up pressure is transferred to the pressure piston member 1 18 through the pressure communication port 32. At a predetermined pressure, the force acting on the pressure piston member 1 18 will be great enough to push the piston member 1 18 through the bushing 120 and moving the head assembly into its second, drilling position. The increased pressure acts as a signal to the driller that the assembly has reached the end of the drill string and the latches 142 have extended to lock the head assembly into place. The interaction and relative displacement between the piston member 1 18 and the annular element or bushing 120 can help provide to the operator a pressure signal for a significant length of time.

As shown in FIG. 2B and 3B, when the piston member 1 18 has moved below and further past the bushing 120, the valve member 130 is also moved down to open the fluid flow ports 40 for drilling. The retracting case 28 is also moved to a lower, latched-extended position. This position can only be achieved when the latches 142 are able to fully extend, in a latched configuration, as the latches will keep the latch piston 126 from moving to the proper locked position (through the interaction between the pin 127 and the corresponding slot in the retracting case 28) if the landing position is incorrect. Continuing the operation of the valve assembly, a retrieval device can be preferably latched onto a spearhead 50 when the inner tube member 1 12 is ready to be brought back to the surface. The spearhead 50 is connected to the retracting case 28. When pulled by the retrieval device, the spearhead 50 will unlock the latches 142 and the assembly will be in a third, retrieval, position as shown in FIG. 2C and 3C. This movement of the retracting case 28 also moves the pressure piston member 1 18 back on top of the bushing 120 and moves the valve member 130 back, past the drilling fluid flow ports 40, leaving the flow ports 40 open slightly to allow fluid flow during retrieval. The pulling of the retrieval device moves the assembly from the second position to the third position.

When the retrieval device is removed from the spearhead 50, the compression spring 124 will automatically reset the system and move the valve assembly components to their first, descent position. Ports in the assembly although shown as being radial in the figures an also be axial in direction. Alternatively, in another embodiment of the present invention, the valve member 130 used to open and close the flow ports 40 may be part of the retracting case 28.

Another aspect of the present invention is to provide a mechanism that can help absorb momentum of the head assembly upon landing thereof. Such a mechanism is illustrated in Figure 15. In this embodiment of the present invention, the piston member 1 18 comprises a slotted aperture 300, and a linking member, such as a pin 129, slideable within the slotted aperture 300 and connected to the retracting case 28. A biasing element 302, such as a spring or any other mechanical equivalent, urges the linking member 129 towards abutted engagement with an extremity of the slotted aperture 300 within the piston member 1 19 and for absorbing momentum of the core barrel head assembly upon landing of the landing shoulder with a corresponding structure of the inner tube assembly. As it can be seen from the figure, the biasing element 302 will more specifically absorb the momentum of the linking member or pin 129 that is linked to the retracting case 28, as the pin attempts to slide within the slotted aperture 300 upon landing, but is restrained by the biasing element.

Second Embodiment-Sustained Landing Indication Valve

Another embodiment based on the valve assembly shown in Figures 4A to 5B, can also be provided. As mentioned above, the valving assembly comprises a piston member 1 18 mounted for axial movement within the mid latch body 16. A valve member 130 is mounted for axial movement within a central bore 20 of the mid latch body 16. First biasing means can be provided to urge the valve member 130 towards a blocking position for blocking fluid flow between the fluid flow port 40 and the central bore 20. Second biasing means (not shown) urge the piston member 1 18 away from the flow port 40, the second biasing means having a biasing force greater than the first biasing means. Releasable locking means 125 are provided for releasably locking the piston member 1 18 to the valve member 130 when the piston member 1 18 is in proximate engagement with the valve member 130.

Upon alignment of the at least one pressure communication port 32 with at least one aperture or port of an external port blocking structure, fluid pressure of a predetermined value through the at least one pressure communication port 32 urges the piston member 1 18 towards lockable engagement with the valve member 130. Upon reduction of the fluid pressure below the predetermined value, the second biasing means overcomes the first biasing means and urges the valve member 130 away from the blocking position and allows circulation of fluid flow between the fluid flow port 40 and the central bore 20.

The valving assembly illustrated in the preferred embodiment shown in Fig. 4A to 5B consists of separate pressure communication ports 32 and fluid flow ports 40. Such a design eliminates fluid flow obstructions and limitations with using a single set of ports for both fluid pressure signals and fluid flow upstream of the landing shoulder, as is the case in current and past designs known in the art. Preferably, the fluid flow ports 40 are downstream from the pressure communication ports 32. The fluid flow ports 40, are blocked by the valve member 130, preferably a valve spool or similar valve element, in the initial first blocking position. The valve spool 130 is releasably connectable to the piston member 1 18, with the ability to lock to the piston member 1 18 at a predetermined position. Relative motion between the valve spool 130 and piston member 1 18 is biased to the closed position by the first and second biasing means, a weak spring and a strong spring respectively. This slideable connection is lockable at a certain position and is manually or automatically unlockable. Increased fluid pressure is communicated via the pressure communication ports 32 to the piston member 1 18 and acts to compress the strong spring. As pressure increases, the force on the piston member 1 18 increases, compressing the strong spring. At a predetermined pressure, the piston member 1 18 will have moved a predetermined distance depending on the spring force. At this distance, the piston member 1 18 will lock onto the valve spool 130. This can be achieved in any way, including a ball lock, lock finger, cam and pin, profiled slot and pin, the preferred method being a ball lock to lock pin. At this point, the driller or the computerized drill will notice the increased fluid pressure and will release the pumping pressure. When this is done, the strong spring will overcome the remaining hydrostatic pressure and move the piston member 1 18 to its original position. The valve spool 130 which is now locked onto the piston member 1 18 is also moved with the piston member 1 18, opening the fluid flow port 40, allowing drilling fluid, such as water, to flow for drilling.

When the head assembly 10 is brought back to the surface, the valve spool 130 may be automatically or manually unlocked from the piston member 1 18, closing the port 40 and ready to be dropped back down the hole. Resetting of the valve may occur during ascent and retrieval, at the surface, or during unlatching and landing. A separate port or the same port may be opened to allow fluid flow during retrieval to avoid lifting the water column.

Preferably, the valve spool 130 may also be unlocked manually using a button, a twist lock, a pin or any other device or mechanism to unlock the spool from the piston. The weak spring will move the valve spool 130 to the blocked position when the valving mechanism is reset.

Preferably, to provide a substantial seal and to block fluid flow when desired, the valve spool 130 may contain some sort of sealing member or device such as an o- ring or gasket 134.

Preferably, to make the system operational at different depths and water pressures, the springs may be changed with different spring rates (or adjusted through adjustment mechanisms to match the drilling condition.) The piston diameter and/ or surfaces areas may also be changed to the same effect.

Preferably, the valving assembly 100 may be an integral part of the mid latch body or constructed as a separate removable and/or replaceable assembly. Alternatively, the valve can block or open, to allow fluid flow, any of the following locations: below the fluid flow ports, at the central bore and above the fluid flow ports.

As described above, the head assembly allows for an interchangeable mid latch body 16 between an upper latch body 12 and a lower latch body 14. Also, the valving assembly in the mid latch body benefits from the use of separate pressure communication ports 32 and fluid flow ports 40. In a first position, during "descent" of the head assembly, the valve member 130, preferably a valve spool or other similar valve element, blocks the fluid flow ports 40. The valve member 130 has sealing members, such as o-rings or gaskets, to ensure a proper seal of the fluid flow ports 40, and a pin 146 extending from one end containing a ball lock mechanism 147 that is biased to the locked position and is unlocked by pressing a button 145. This valve position is maintained by a first biasing means such as a spring 1 1 1 or other equivalent resilient element, between the valve member 130 and spring seat 143. The pressure piston member 1 18 is in a top position and maintained there by a second biasing means such as a spring 1 13, or other equivalent resilient element, located between the spring seat 143 and a pressure piston seat 148. Spring 1 13 has a higher spring rate than spring 1 1 1 .

As shown in FIG. 4A, when the inner tube assembly has landed at the bottom of the drill string, a seal is created between the landing shoulder 34 and the landing ring 35, and this stops the drilling fluid from flowing, thus increasing the fluid pressure. This increase in fluid pressure applies a downward force to the pressure piston member 1 18 via the fluid pressure port 32, compressing spring 1 13 a certain distance. At a predetermined pressure, the pressure piston member 1 18 will travel a predetermined distance at which point the valve pin 146 ball lock will lock onto the valve spool 130: this is designated as the second position. The increased fluid pressure will remain in the drill string until the driller turns off the fluid pump and relieves the system pressure.

As shown in FIG. 4B and 5B, when the pressure drops, the second spring 1 13 will push the pressure piston member 1 18 upwards as well as the valve member 130 connected to the piston member 1 18, in turn compressing the first spring 1 1 1 and also opening the fluid flow ports 40: this is designated as the third - valve open position.

Preferably, at the surface, after the inner tube assembly has been retrieved, the driller presses the unlock button 145 to put the assembly back into the first position as shown in FIG. 4C with the valve assembly closed and ready for another run. Spring 1 13 can be easily changed to match specifically designed drilling depth and drill pump operating pressures. Alternatively, the operational surface area of the pressure piston member 1 18 can be altered to the same effect. The unlock button 145 can be replaced with any known equivalent resetting mechanism that can be operated manually or automatically.

In other embodiments of the invention, the valve member 130 can block the central bore 20 instead of the fluid flow ports 40. Alternatively, any of the ports can be in a radial or axial direction or any angle in between. The fluid pressure communication ports 32 can be opened or closed by ports on the retracting case in the different retracting case positions to indicate latch position. When the ports are in alignment, the valve will work normally, indicating a normal condition. When the ports are misaligned, the pressure piston member 1 18 is not exposed to the increased fluid pressure and the system fluid pressure will remain high, indicating that the latches have not fully extended.

Third Embodiment-Fluid Controlled Valve

FIG. 6A-14B show different embodiments of a head assembly in accordance with another preferred embodiment of the present invention. Once again, the head assembly allows for an interchangeable mid latch body 16 between an upper latch body 12 and a lower latch body 14. Also, the valving assembly in the mid latch body benefits from the use of separate pressure communication ports 32 and fluid flow ports 40. The head assembly includes a valve assembly 100 for use in a core barrel head assembly 10 positionable within a drill string of a drilling apparatus. The valve assembly 100 comprises at least one pressure port 32 formed in a sidewall of the core barrel head assembly 100 upstream of the landing shoulder. There is also at least one fluid flow port 40 formed in the sidewall of the core barrel head assembly 100 upstream of the landing shoulder. The valve assembly 100 also includes a movable valve element 218 having a first side 220 in fluid communication with pressurized fluid through the head assembly and having a first surface that is influenced in the supply direction by a force FA from said fluid. A second side 222 faces in the opposite direction, in fluid communication with the pressurized fluid through the head assembly and having a second surface that is influenced in the opposite direction by a force FB from the fluid. A biasing element, such as a spring 224 or any equivalent resilient element is provided for urging the valve assembly towards an opened configuration by displacing the valve element 218 from a closed position, blocking the at least one fluid flow port 40, to an open position.

The area of the second surface is greater than that of the first surface so that the force influencing the valve element 218 in a closing direction, in the form of the force F _B from the pressurized fluid acting on the second surface exceeds the force influencing the valve element in an opening direction, in the form of the combined force Fs from the spring and the force FA from the pressurized fluid acting on the first surface, whereby the valve element is retained in the closed position of the valve when pressurized fluid is supplied, as illustrated in FIG. 6A and 7A

Preferably, upon a reduction in the supply of pressurized fluid to the closed valve, the pressure force differential decreases between said first and second sides 220,222, and the spring 224 then urges the valve element 218 to be displaced from its closed position to its open position unblocking the at least one fluid flow port 40 as shown in FIG. 6B and 7B.

Preferably, the valve assembly further comprises a locking device for mechanically locking the valve element in its closed position. In one possible embodiment illustrated in FIG. 8A to 8D, the locking device comprises a pressure sleeve 226 mechanically connected through the retracting case 28 to a latch locking mechanism 232 of the inner tube member. Another possible embodiment of the locking device is illustrated in FIG. 6A to 7C and FIG. 9A-14B and will be described in further detail below. According to the present invention, there is also provided a method for operating the valve assembly for use in a core barrel head assembly positionable within a drill string of a drilling apparatus driven by pressurized fluid, the

the method comprising the steps of:

a) supplying the pressurized fluid to the valve element 218 in its closed position whereupon the valve assembly remains closed;

b) reducing the supply of pressurized fluid to the closed valve assembly; and c) allowing a pressure force differential to decrease between the first and second sides 220,222, thereby enabling the biasing means 224 to urge the valve element 18 towards the open position, and thereby allowing fluid flow through the at least one fluid flow port and remain open.

Preferably, when the valve assembly 100 further comprises a locking device for mechanically locking the valve element in its closed position, in step a), the valve element is in a mechanically locked closed position, and the method further comprises the step, between steps a) and b) of:

i) causing the locking device to cease locking the valve element 218 in the closed position. Preferably, the locking device comprises a pressure sleeve 226 mechanically connected to a latch locking mechanism 232 of the head assembly and step i) further comprises the step of allowing fluid pressure to displace the pressure sleeve 226 and engage a latch lock 228 of the latch locking mechanism 232. As mentioned above, another embodiment of the fluid controlled valve assembly, and in particular the locking device, illustrated in FIG. 6A-7C and 9A-14B, will now be presented. Preferably, the valve element is a two-piece valve comprising a valve body 250 and a valve piston 252. The valve body 250 is used to selectively block the fluid flow port 40 and includes a side 222 which applies a force to urge the valve assembly towards a closed configuration. The valve piston 252 includes a side 220 which applies a force to urge the valve assembly towards an open configuration, The valve piston 252 further comprises a slotted stem 254 to allow fluid flow to flush debris and a pin 256 to co-operate with the profiled slots in the upper latch body 12 and latch retracting case 28 to be able to selectively lock the valve assembly in a closed configuration.

Preferably, as better shown in FIG. 9A the upper latch body 12 comprises a profiled slot 258 to co-operate with the pin 256 of the valve piston 252 to lock the valve-in the closed position and allow the valve to move to the open position after a predetermined rise in fluid pressure. More specifically, the profiled slot 258 allows axial movement of the pin within the main slot portion 260. A top end 262 of the slot 258 extends at an angle transversely with respect to the main slot portion, at least partially radially and towards the opposite bottom end to prevent the pin 256 from moving downward. The pin 256 is held in the radially extended slot position by the spring 224 that biases the valve assembly towards the open position.

Preferably, as the fluid pressure rises and the force on the surface of side 220 overcomes the spring force, both valve body 250 and piston 252 will move up and the pin 256 on the valve piston 252 will be directed by the angled slot extension 262 to move the pin 256 radially (or rotate it) towards the main slot portion 260 to allow for axial movement of the pin and hence the valve member when the pressure is released.

Preferably, the latch retracting case 28 also has a profiled slot 270 to cooperate with the pin 256 on the valve piston 252. The latch retracting case 28 automatically moves the pin 256 to the locked position on the profiled slot 258 of the upper latch body 12 when the latches 142 are retracted. The profiled slot thus helps to hold the latch retracting case 28 and latch lock in an intermediate up position such that the latch lock is not engaged to the latches 142, greatly reducing the latch drag on the drill rod during descent. The profiled slot 270 allows for axial movement of the pin 256 within a main slot portion 272. A bottom end 274 of the slot extends at an angle with respect to the main slot portion 272, at least partially radially and axially lower than the main slot portion 272, thus rotating the pin 256 towards the locked position in the upper latch body 12 when the latch retracting case 28 is moved up to retract the latches 142. The pin 256 during the latch retraction can then extend back towards the bottom end 274 in a direction parallel to the main slot. Preferably, when released from the overshot and during descent, the biaising means 280, such as a spring or other equivalent resilient element, in the retracting case 28 will bias the retracting case 28 towards the down position. The bottom end portion 274 of the profiled slot 270 will prevent the retracting case 28 from moving to the fully down position, preventing the latch lock from engaging with the latches 142, once again greatly reducing the latch drag on the drill rod during descent.

An operational sequence of the valve assembly will now be described. Reference will be made to components illustrated in the two different groups of embodiments illustrated respectively in FIG. 6A to 7C/1 OA to 14B and FIG. 8A to 8D,. Descent

Before inserting the inner tube head assembly in the drill string, the latch retracting case 28 is pulled up (right side in FIGs. 6A, 8A or 10A) to its first position. This will disengage the latch lock 228 and allow the latches 142 to move freely from the engaged position to the retracted position and vice versa. The valve biasing means 224 and retracting case biasing means 236 are compressed. In the embodiment shown in FIG. 8A, the latch retracing case 28 is directly connected to the pressure sleeve 226. The pressure sleeve 226 and/or the latch retracting case 28 are held in this first position (with a mechanical lock) as it is travelling through the drill string, to reduce the latch drag on the drill rod during descent. In the embodiment shown in FIG. 6A or 10A-10B, the pin 256 attached to the valve piston 252 is constrained through interaction with profiled slots 258, 270 and thus prevented from moving down to lock the latches 142, thereby reducing latch drag on the drill rod. The valve body 250 blocks fluid flow through the fluid flow port 40.

Signal

When the head assembly 10 has landed in the correct position, for the embodiment shown in FIG. 4B, fluid pressure will increase and act on the surface 220 and push with a force at a first predetermined value less than a second predetermined value, such as for example, maximum pump pressure, to move the pressure sleeve 226 down and engage the latch lock 228 with which it is directly connected through the latch retracting case 28. In this configuration, the latches 142 are engaged and locked into the outer tube and the valve element 218, which is connected to the retracting case 28 by slot 242 is allowed to operate normally. If the latches 142 are not in the correct position, the latch lock 228 and its directly connected components will not be able to move down to the second position and allow the valve to operate normally. Fluid pressure will remain high even after it has been released to the atmosphere, indicating to the driller that the latches are not properly engaged and corrective action must be taken. In the second position, the fluid pressure continues to rise and acts on first surface 220 through pressure communication port 32 and second surface 222 through fluid flow port 38. The first surface area is smaller than the second surface area such that when fluid pressure is present, the force generated by the second surface area is greater than the combined force generated by the first surface area and the force of the spring 224. This will maintain the valve in the closed position while fluid pressure is acting on the valve.

For the embodiment shown in FIG. 1 1 A-1 1 B, under similar fluid pressure conditions, the increased pressure will displace the valve body 250 and valve piston 252 up, which through interaction with the profiled slots 258,260, induces rotation of the pin 256 out of its locked configuration. This permits the valve piston 252 to move and allows the retracting case 28 to descend while the latches 142 become engaged. However, if the latches 142 are jammed, the retracting case 28 will not move down, thus blocking movement of the valve 252 piston and valve assembly and preventing opening of the fluid flow port 40.

Working

For the embodiment shown in FIG. 8C, when the fluid pump is stopped and the pressure is relieved, a pressure force differential decreases between the first and second surfaces 220,222 so that the biasing means 224 or spring force will move the valve element 218 down to an open, third position. The pump will then be turned back on and drilling fluid will flow freely through fluid flow port 40 to the drill bit for drilling.

For the embodiment shown in FIGs. 6B and 12A,12B, once fluid pressure is relieved, the biasing means 224 or spring force also overcomes the pressure force differential between the first and second surfaces 220,222 to urge the valve element 218 towards an open position. In this configuration, fluid flows through the slots in the valve piston 254 and through the valve body 250 into the central bore 20.

Retracting/Retrieval When the inner tube is full of core, the retrieval device or overshot is sent down the drill string and connects to the spearhead 50. For the embodiment shown in FIG. 8D, the spearhead 50, which is connected to the retracting case 28 is pulled up for retrieval and moves the retracting case 28 up past the first position it had during descent to its fourth position. The valve element 218 and valve body 250, being slideably connected to the retracting case 28, is moved up past the first position as well to allow fluid to flow through the apertures 260. When the overshot is disconnected from the spearhead 50, the spring 236 will return the valve assembly to the first descent position and it will be ready for the next trip down the hole.

For the embodiment shown in FIG. 6C and 13A-13B, under similar conditions, retraction of the retracting case 28, induces rotation of the pin 256 towards a locked configuration thus keeping the latches 142 in an unlatched configuration and minimize drag of the latches on the drill rod during retrieval of the spearhead 50. This configuration also positions the valve body 250 in a configuration which keeps the fluid flow port 40 open during the retrieval operation.

Manual Reset For the embodiment shown in FIG. 14A-14B, once the valve assembly is returned to the surface, the valve body 150 must be displaced manually at the surface location in order to position the valve body 150 in a closed configuration that will be ready once again for the next descent down the hole.

The present invention also provides a wire line core drill system comprising a wire line core drill having an inner tube by means of which core samples are collected, an outer tube connected to a drill bit, and a valve assembly situated at the rear end of the inner tube, said valve assembly controlling the supply of a flushing medium in the form of a pressurized fluid, wherein the valve assembly is constructed as described in one of the embodiments provided above. In other embodiments of the present invention, the ports on the mid body and latch body may be aligned with ports on a movable outer component to allow fluid flow with the core barrel head assembly in a latched position and misaligned to block fluid flow when not in a properly latched position.

As shown in the several different examples illustrated above, the head assembly can contain a variety of internal components including, but not limited to: valves, electronics, measuring devices, and mechanical assemblies. Internal components and/or assemblies can be placed in any one or combination of the lower latch body, mid latch body, upper latch body, or other external body component. Internal components and/or assemblies may also be an integral part of any single or combination of the body components. The external body components and their corresponding assemblies and the internal components and/or assemblies may be interchangeable with different head assembly designs and/or configurations and still be compatible with all other body components and core barrel parts. The head assembly components may also be interchangeable with parts used with head assemblies for other hole dimensions and sizes. The upper latch body may utilize any type of latching mechanism or device to hold the inner tube assembly in place while drilling and to be disengagable for retrieval with a wireline device. The latching mechanism or device may also be part of the mid latch body or lower latch body or any combination of body components. The upper latch body may or may not contain any of the fluid and/or communication ports.

Although preferred embodiments of the present invention have been described in detail herein and illustrated in the accompanying drawings, it is to be understood that the invention is not limited to these precise embodiments and that various changes and modifications may be effected therein without departing from the scope of the present invention.