Dump valve arrangement for fracturing tool set
A dump valve arrangement for a fracking tool coupled to a length of coil tubing includes an axially displaceable inner mandrel which cooperates with a valve arrangement to allow for releasing fracturing fluid through the central bore of a fracturing tool to an outlet port positioned at the bottom of the tool string. Displacement of the inner mandrel is effected as a result of the normal sequence of operation of the fracturing tool set. The valve arrangement is in a closed position during both the insertion and positioning of the tool string.
1. Field of the Invention
The present invention concerns methods of extracting petroleum. In particular, the invention concerns an improved method of stimulating fluid flow in a well bore using a fracturing tool assembly.
2. Description of the Prior Art
Petroleum production from a well bore is often enhanced by a process that is characterized as fracturing or fracking According to the general principles of fracking, the fracturing process induces increased fluid flow from the well bore production face by generating additional cracks and fissures into the zone radiating from the well bore wall. The objective of creating cracks and fissures in the fracking zone is an increase in the production face area. This increased production area facilitates flow of a greater volume of petroleum fluid into the well production flow stream than would otherwise occur from the penetration area provided by the original borehole.
Among the known methods of creating or enlarging such cracks and fissures into a fluid production zone is that of forcing liquid into the formation under extremely high pressure. Mixed with the high pressure fracturing liquid are particulates such as coarse sand or fine gravel known as proppants. These proppants have the function of holding open and maintaining the permeability of zone fractures. A zone is fluidly isolated from other zones in the well bore by a suitable sealing means such as inflatable packers so that the fluid, including the proppant, is forced into the well bore thereby creating fissures which stimulate the flow of oil.
A problem occurs when fracking multiple zones within the same well bore. Unloading or releasing the fracking liquid when moving from one zone to the next is harmful to the tool set. The fracking liquid is highly abrasive and since prior art tools generally release the liquid from openings positioned on the side of the tool set the tools are damaged over time from the effects of the abrasive fluid contacting the portions of the tool below the release point.
SUMMARY OF THE INVENTIONA dump valve arrangement for a fracking tool coupled to a length of coil tubing includes an axially displaceable inner mandrel which cooperates with a valve arrangement to allow for releasing fracturing fluid through the central bore of a fracturing tool to an outlet port positioned at the bottom of the tool string. Displacement of the inner mandrel is effected as a result of the normal sequence of operation of the fracturing tool set. The valve arrangement is in a closed position during both the insertion and positioning of the tool string. Fluid pressure from the injection of fracturing fluid into the formation maintains the inner mandrel and valve arrangement in the closed position. When fluid injection ceases, withdrawal of the coil tubing unit causes axial displacement of the inner mandrel thereby opening the valve arrangement, allowing fluid to drain through the center of the tool string and out into the well bore through the outlet port.
It is a major object of the invention to provide a release valve arrangement for releasing fluid trapped in a fracturing tool set.
It is another object of the invention to provide a release valve arrangement for a fracturing tool set which can be integrated into a standard fracturing tool set.
It is another object of the invention to provide a release valve arrangement for a fracturing tool set which release fluid evenly into the annulus of the tool set.
It is another object of the invention to provide a release valve arrangement for a fracturing tool set which does not require electrical activation.
It is another object of the invention to provide a release valve arrangement for a fracturing tool set which is actuated by the normal operation of a coil tubing unit.
Finally, it is a general goal of the invention to provide improved elements and arrangements thereof in an apparatus for the purposes described which is dependable and fully effective in accomplishing its intended purposes.
These and other objects of the present invention will become readily apparent upon further review of the following specification and drawings.
The present invention meets or exceeds all the above objects and goals. Upon further study of the specification and appended claims, further objects and advantages of this invention will become apparent to those skilled in the art.
Various other objects, features, and attendant advantages of the present invention will become more fully appreciated as the same becomes better understood when considered with the accompanying drawings, in which like reference characters designate the same or similar parts throughout the several views, and wherein:
Referring now to
The bottom assembly 20 includes frusto conical end portion 30 which includes the centrally positioned outlet port 22. The end portion 30 also includes a plurality of radially spaced slips 32 which are spring loaded, biased in the non-extended position as shown. End cap 35 is slidably disposed about inner mandrel 37 with cone 36 threadably secured to end cap 35. Downward movement of end cap 35 (due to lowering of tool string) causes engagement of the cone 36 with the angled inner surface of the slips 32 causing them to move radially outward into engagement with the well bore W casing in a manner well known in the art. The exact configuration of the bottom hole assembly 20 is not described in detail as it is well known in the art and does not form a part of the invention.
Referring now to
Bottom gland 56 is threadedly secured to the plug end of valve main body 42 and serves to secure valve assembly 10 to the tool set 11 via threaded opening 57, the bottom gland also serving to prevent axial movement of plug 44. The interior surface 58 of bottom gland 56 tapers outwardly to form a conical passage 60 having its large diameter opening positioned securely against collar 50, the opening having a sufficiently large diameter to allow unobstructed fluid flow through ports 52 unless blocked by valve seat 54 as explained above. Mandrel 34 is secured within main body 42 at its top end by top gland 64 which provides a seal against contaminants (i.e. particulate matter) which could otherwise enter main body 42 and interfere with smooth axial transitioning of mandrel 34 between the open and closed positions.
From the foregoing description, one skilled in the art can easily ascertain the essential characteristics of this invention and, without departing from the spirit and scope thereof, can make various changes and modifications of the invention to adapt it to various usages and conditions.
It is 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 valve assembly for a fracturing tool set comprising:
- an elongated generally cylindrical valve main body having a central bore sized for slidably receiving an inner mandrel positioned therein, said inner mandrel connected to a length of coil tubing, said inner mandrel adapted for axial movement within said valve main body in response to axial movement of said coil tubing;
- a plug member positioned on an annular seat formed in an end portion of said valve main body, said plug member having a collar and a downwardly depending plug, said collar having a plurality of ports formed therein, said plug sized for frictional sliding engagement within said inner mandrel;
- whereby axial movement of said inner mandrel effects positioning of said valve assembly between open and closed positions.
Type: Application
Filed: Sep 23, 2011
Publication Date: Mar 28, 2013
Inventor: Michael Joseph Felthager, SR. (Trinidad, CO)
Application Number: 13/200,317
International Classification: E21B 34/00 (20060101);