T-Frac Zone Test Tool and System

Abstract

The present invention is to a tool for testing various zones in a well without having to remove the drill string containing the tool(s) from the well. Each of the individual fracture test tool has an internal passage that can be blocked by a ball bearing to close off the passage. Increased fluid pressure on the internal passage causes a valve body defining the passage to move to open windows in the tool. A collet reset tool is insertable through the passage to pull the valve body back into the run in position to close the windows without requiring the tools be raised to the surface to reset the fracture test tools.

Description

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of U.S. Provisional Application 61/257,878, filed Nov. 4, 2009, entitled T-Frac Zone Test Tool and System, which is incorporated herein by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present application relates to a method of testing zones in a well and a system therefor.

2. Description of the Prior Art

Oil and natural gas wells are drilled deep into the earth. A central bore (“main drill hole”) is made with into the earth and stabilized with a steel pipe (“casing”) inserted into the hole to maintain the integrity of the bored hole and to separate various zones of the well found at different depths in the well. Different production zones may be operated on by drilling out sideways through openings (“windows”) created in or existing in the casing is at various depths to communicate with these zones. Over time, these zones may be tapped out, may collapse or may continue to be productive. Because of the depths involved and the inaccessibility of these production zones to workers, it may be difficult to ascertain the condition of various zones. Additionally, it may be very expensive to lower hundreds or thousands of feet of a drill string (i.e., down hole work tools) into a well to check on a particular zone, remove all of the tools and reinsert to check a different zone. Therefore, there exists a need to be able to test various fracture zones in a downhole bore without having to raise and lower the drill string out of the hole.

None of the prior inventions and patents to date, taken either singly or in combination, is seen to describe the instant invention as claimed.

SUMMARY OF THE INVENTION

Accordingly, it is a principal object of a preferred embodiment of the invention to provide a fracture test tool having individually addressable tools connected in a drill string.

It is another object of the invention to provide a fracture test tool that can be activated by dropping a ball bearing of a known size to activate a particular tool.

It is a further object of the invention to provide a fracture test tool that can have each of the test tools in a drill string activated in sequence.

Still another object of the invention is to provide a fracture test tool reset tool that can be reset test tools downhole without having to remove the tools to the surface.

It is an object of the invention to provide improved elements and arrangements thereof in an apparatus for the purposes described which is inexpensive, dependable and fully effective in accomplishing its intended purposes.

These and other objects of the present invention will be readily apparent upon review of the following detailed description of the invention and the accompanying drawings. These objects of the present invention are not exhaustive and are not to be construed as limiting the scope of the claimed invention. Further, it must be understood that no one embodiment of the present invention need include all of the aforementioned objects of the present invention. Rather, a given embodiment may include one or none of the aforementioned objects. Accordingly, these objects are not to be used to limit the scope of the claims of the present invention.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is diagrammatic cross-sectional view of a test fracture tool according to the present invention in a run in position

FIG. 2 is diagrammatic cross-sectional view of a test fracture tool according to the present invention in an operating position.

FIG. 3 is a diagrammatic view of a test fracture tool in a drill string.

FIG. 4 is a diagrammatic cross-sectional view of a reset tool for resetting the test fracture tool when the tool is in the operating position.

FIG. 5 is a diagrammatic view of a reset tool for resetting the test fracture tool with the reset tool inserted part way into the fracture tool.

FIG. 6 is a diagrammatic view of a reset tool for resetting the test fracture tool with the reset tool inserted fully into the fracture tool.

FIG. 7 is a diagrammatic view of a reset tool for resetting the test fracture tool with is the fracture tool reset to the run in position.

FIG. 8 is a diagrammatic view of a reset tool for resetting the test fracture tool with the reset tool inserted part way removed from the fracture tool.

FIG. 9 is a diagrammatic view of a reset tool for resetting the test fracture tool with the fracture tool reset to the run in position and the reset tool fully removed.

FIG. 10 is a front plan view of the reset tool.

FIG. 11 is an expanded, diagrammatic view of the collet tool of the reset tool in the test fracture tool.

Similar reference characters denote corresponding features consistently throughout the attached drawings.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT(S)

The present invention is to a tool for testing various zones in a well without having to remove the drill string containing the tool(s) from the well.

FIGS. 1-3 show one such tool embodying aspects of the invention. FIGS. 1 and 2 show a diagrammatic cross-sectional view of the invention. FIG. 3 shows one or more tools on a drill string separated by packers for running into a well.

As best shown in FIG. 1, a zone test tool 10 has a main body 12 sized to attach to a drill string 20 (FIG. 3) through threads 14 or appropriate connector such as shear pins, welds, etc. The body 12 is also sized to fit within the main well casing 16. The tool body may have a number of ports (“windows”) to selectively communicate between the interior of the tool 10 and the interior of the casing 16. FIG. 1 shows the ports 22 closed by an interposing test valve body 30. FIG. 2 shows the ports 22 uncovered (“open”) with valve body 30, the importance of which will be explained further hereunder. The valve body 30 has a central bore 32 through the body to allow fluid flow therethrough.

FIG. 1 also shows a check valve (“shut off valve”) 40 attached at a lower end of the zone test tool. This is a separate tool from the zone test tool and is typically provided attached to the lowermost zone test tool to aid in inserting and in commencing the sequencing of the zone test tools' operation. The shut off valve has a threaded body 42 (FIG. 3) sized to connect with the drill string such as at the bottom end of the zone test tool. The shut off valve has a number of ports 44 that allow flow through the tool when the tool is being inserted into the well bore to lower the resistance of the fluids in the well bore to the lowering of the tool by allowing flow therethrough. Flow from outside the tool displaced by the tool may flow into the ports through the interior of the shut off valve body and up through the tool as the tool is lowered.

As shown in FIG. 3, the composite tool may include a length of drill string 20 connected to a number of zone test tools 10 separated by a number of packer tools 50. The tools may be run in about 100 feet apart to operate on separate zones of the well. A number of centralizing tools 52 may also be included. Preferably these are in close proximity to the packer tools and have a diameter slightly larger than the retracted packer tools. The purpose of the centralizing tools is to protect the packers. The packers may be formed of rubber or similar material and “inflate” to mate closely with the interior surface of the casing to isolate the casing into several zones. As the tool is lowered, the centralizing tools will rub against the interior wall of the casing before the packer tools to space the packers apart from the casing and thus ensure the integrity of the packers. The centralizing tools are shown above the packers, but may be above, below or surround the packer tools as necessary.

In practice, a drill string 20 is run in to a well to be tested with a number of packers, centralizing tools, zone test tools and terminating in a shut off valve. Fluid displaced by the tool enters the shut-off valve ports 44 and flows up the tool through the interior of the drill string. The composite tool is lowered to a desire depth. At this point, the tool is ready to be used to test one or more of the various zones.

A ball 60 (FIG. 2) is dropped into the drill string to begin the process of opening one or port sets of port windows located at a zone of interest. The various tools 10 each have a valve body 30 having a central bore 32 of a predetermined size. Each tool 10 has a bore 32 of a certain size so that it may be individually identified. The higher tools have larger bores 32 than lower tools. A ball dropped from the top will “fall” through tools having a bore 32 larger than the diameter of the ball until it reaches a first tool valve bore 32 small than the ball. The use of the term “first” here and in the claims does not necessarily mean the highest tool or the lowest tool, but merely the tool that the first ball acts upon. Pressurized fluid piped down the drill string will cause the ball to continue to flow towards the outlet in the shut-off valve until it falls into a valve bore smaller than the ball, at which point the ball seats in the valve and pressure in the drill string and tools will continue to rise under the force of the pressurized fluid. In this way, the diameter of the ball inserted into the drill string can be selected to decide where the pressurize fluid will act first.

In most circumstances, the lower most zone to be acted on will be addressed first. This allows for larger balls to be dropped later sequentially acting on higher and higher zones. To act later on a lower zone, one or more balls would have to be removed as will be explained later to allow for smaller balls to fall through to the lower zones.

If a ball falls all the way to the lowest zone test tool as shown in FIG. 1, flow will no longer be able to continue to through the bore 32 to the shut off valve 40 since the bore is blocked by the ball 60. Once the operator senses that the pressure has begun to rise in the drill string, the pressure can be increased to a second level such as 2000 psi to activate the packers. The use of packers is well known to those skilled in the art. Their deployment under fluid pressure is also well known. The packers may expand to a certain level to mate securely against the inside of the casing to isolate the various zone test tools from each other. The packers may stay inflated only while under continued pressure or may have fill valves that capture the pressure until release by other action such as lifting up on the drill string, rotation of the drill string or by mechanical set/mechanical release systems known to those skilled in the art. Preferably the packers stay inflated after release of fluid pressure to maintain the isolation zones.

With the packers set, the individual set of windows 22 within the particular zone may be opened by fluid pressure. The ports 22 may align with ports 64 in the casing or may both be contained in the 100 foot or so isolation zone created by the surrounding packers. The operator may increase the pressure to a third level such as 4000 psi to activate opening of the zone test tool port window if they are for example blocked by other means. Flow into the drill string flows through the valve bodies 30 that do not have their bores 32 blocked by a ball and thus do not have the same pressure acting on the face 34 of their valve body as the blocked valve body 30. The pressure building against the desired (“blocked”) valve body causes the valve body to slide down the zone test tool body 12 under the pressure of the fluid. The valve body may resist by friction, shear pins, other devices or a combination thereof. When the pressure on the face of the valve body exceeds the resistance of the valve body, the valve body moves to expose (“open”) the ports 22 as shown in FIG. 2. Since the check valve is no longer needed the a valve plate 46 or similar device may be used to close the pathway through the valve body by blocking the passage from the lower end to no longer allow fluid to flow through the valve plate 46 through holes 48. Preferably, once the valve moves to the location shown in FIG. 2, it will not spring back or move back to the position shown in FIG. 1 until removal from the well or acted upon by a reset tool

Once the valve body opens the ports 22, there should be a noticeable drop in the pressure in the system notifying the operator that the windows were successfully open. The particular zone can now be tested by flowing materials into the zone or by shutting off the flow and testing for flow to the surface, etc.

When testing has been completed, the process can be repeated by dropping a ball of slightly larger diameter to act upon the next higher zone test tool. Raising pressure once the next higher zone test tool valve body bore is blocked will cause flow to cease to the lower zone test tool. Instead, pressure will rise on the blocked zone valve body face 34 moving the valve body downward, opening (“uncovering”) ports 22 to expose the new zone. Since the ports in the newly unblocked zone test tool are separated from the lower zone test tool, a new zone area can be tested different from the earlier test zone. In this way, subsequent test zones can be tested.

If desired, the balls can be removed to aid in withdrawal of the tool or for other reasons. Once the packer tools are released, by releasing the flow through the tool, by lifting on the tool or by other mechanical releases or methods known to those skilled in the art, a reverse flow can be initiated. Pressurized water or other fluid can be initiated along the outside of the drill string but inside the casing. The flow will along the outside of the tool until it finds an open port (“window”) in the tool. The main portion of the flow will continue to flow outside the tool under the force of pressurized fluid and/or gravity and once enough flow has been pumped will enter all of the open windows, though not necessarily at the same rate through each open window. The flow will go through the port and upwards along the tool. The bottom shut off valve will help encourage flow to move only upwardly in the tool. The flow will dislodge any ball at or above the port and will cause the balls to flow upwardly where they can be trapped or caught at the surface. The flow may now be discontinued so that the tool may be raised, allowing displaced fluid to flow through the tool and out the windows including the bottom most window.

Alternatively, the windows may now be reset with the balls removed. FIG. 4 shows a tool for resetting the valve bodies to their original position (as shown in FIG. 1).

FIGS. 10 and 4-9 show a reset tool 70 for resetting the valve body 30 in situ. The reset tool 70 must be able to be inserted (“squeeze”) through a number of upper valve bodies 32 in upper zone test tools 10 before being able to act on a lower tool 10. This is accomplished by providing retractable elements of the tool 70, namely centering springs 72, guide 74 and collet tool 76. The centering springs retract (see FIG. 5) to fit through valve body bore 32 when passing through an upper tool or to attach to a desired is valve body. Collet tool 76 (FIG. 10) has a number of retractable fingers 78 which are sized to fold and fit through the valve bodies 30 in one direction and catch on the valve body when pulled in the opposite direction. Finger guides 74 help center the collet about the bore 32 to distribute the fingers about the valve body bore as it exits the valve body 30 and is pulled back in contact with the valve body. One or more centering guides 72 may be provided to help guide the collet tool into the valve bore as it is being pushed down into the tools. Providing multiple centering tools helps ensure that the main shaft 75 of the reset tool 70 stays centered in the tool thus easily guiding the collet tool into the bore of the valve body.

In operation as shown in FIGS. 4-9, the reset tool 70 is pushed downward through the drill string. While the reset tool shaft 75 is shown having a set length, one skilled in the art would appreciate that the overall length of the tool will be sufficient to reach the surface where the operator can manipulate the position of the tool by further lowering a known (or measured) length of the tool into the drill string or by equivalent means. The reset tool will strike the uppermost tool 10 at some point. With the collet tool 76 centered by the centering tool(s) 72, further downward motion of the reset tool will cause the collet tool to enter the bore hole. As shown in FIG. 5, the fingers 78 of the collet tool are designed to collapse under pressure to a diameter equal or smaller than the diameter of the valve body bore 32. Further downward travel will cause the collet tool to travel down the valve body 30 and the centering spring tool(s) to enter the valve body as shown in FIG. 5.

The collet tool will eventually exit the valve body as shown in FIG. 6. By keeping track of the length of travel of the reset tool, the operator will know which fracture test tool is being acted upon. The rest tool can be sent past the zone test tool 10 and then drawn back to catch the valve body 30 of the tool 10 with the collet tool 76. Preferably, the tool is sent all the way to the bottom of the tool, and acts on the lowermost tool first and then acts on the other tools on the way upward.

After passing through the valve body 30, the re-expanded fingers of the collet tool with catch on the valve body as shown in FIG. 6 as the reset tool is pulled back upwards. The reset tool is then used to pull the valve body back to its original position as illustrated in FIG. 7. The collet tool fingers 78 are designed to have a sloped upper face 80 (FIG. 11) that cause the collet tool to slightly reenter the bore 32 as the collet tool reengages the valve body. The collet tool is thus able to provide an upward force on the valve body 30, but be positioned to recollapse upon sufficient force. In this way, after the valve body is pulled in place, further upward force on the reset tool causes the fingers to be forced inwardly again to pull back through the valve body. By setting the spring resistance of the collet fingers at a sufficient level, the reset tool can provide sufficient force to pull the valve body into place before the collet fingers 78 collapse.

As shown in FIG. 7, when a sufficient force is applied to the reset tool, the collet tool will carry the valve body upward relative to tool 10 positioning the valve body back in position covering (“closing”) ports 22. When the valve body is no longer able to move to release pressure on the collet tool fingers, the force on the reset tool will cause the collet tool fingers 78 to collapse allowing the reset tool to pull through the valve body 30. FIG. 9 shows the collet tool and centering tools re-expanded after withdrawal from the tool 10.

The tool can be further lifted to engage the next higher tool and reset the valve body of the next higher tool 10 and so on until all of the zone test tools 10 are back in place. In this way, the zone test tools are completely reset so that further action on the zones can be implemented or the tool can be left in place for other operations or reasons or for subsequent testing.

As an alternative method of operation, after a particular zone has been tested, that window may be closed according to the above method prior to opening the next higher window. Among other things, this will make pressurizing the system easier and simplify the use of packers in the system.

While this invention has been described as having a preferred design, it is understood that it is capable of further modifications, uses and/or adaptations of the invention following in general the principle of the invention and including such departures from the present disclosure as come within the known or customary practice in the art to which the invention pertains and as maybe applied to the central features hereinbefore set forth, and fall within the scope of the invention and the limits of the appended claims. It is therefore to be understood that the present invention is not limited to the sole embodiment described above, but encompasses any and all embodiments within the scope of the following claims.

Claims

1. A method of testing fracture zones in a downhole well, comprising:

providing a zone test tool having an outer housing defining a number of windows;

providing a valve body within said outer housing, said valve body having an internal passage to allow fluid flow through the valve body and said valve body being selectively slidable from a first position to a second position, wherein when said valve body is in a first position the valve body blocks fluid flow from inside the outer housing to an area outside the outer housing, and when said valve body is in said second position, said valve body allows fluid flow from inside the outer housing to an area outside the outer housing;

lowering said a plurality of zone test tools on a drill string in a well bore;

lowering at least one ball bearing within the drill string to a seat on the valve body of a first of said plurality of zone test tools to seal the internal passage of the first zone test tool;

raising the fluid pressure above said first zone test tool whereby fluid pressure acts upon said first zone test tool valve body to cause the valve body to slide from the first valve body position to the second valve body position to open a window of the first zone test tool; using a zone test tool reset tool to reset the zone test tool without substantially raising said zone test tool toward the surface.