1. Field of Invention
The invention relates generally to a device for perforating a wellbore. More specifically, the present invention relates to a charge device having a perforating bullet equipped with energetic material.
2. Description of Prior Art
Perforating systems are used for the purpose, among others, of making hydraulic communication passages, called perforations, in wellbores drilled through earth formations so that predetermined zones of the earth formations can be hydraulically connected to the wellbore. Perforations are needed because wellbores are typically completed by coaxially inserting a pipe or casing into the wellbore. The casing is retained in the wellbore by pumping cement into the annular space between the wellbore and the casing. The cemented casing is provided in the wellbore for the specific purpose of hydraulically isolating from each other the various earth formations penetrated by the wellbore.
Perforating systems typically include one or more perforating guns connected together in series to form a perforating gun string, which can sometimes surpass a thousand feet of perforating length. The gun strings are usually lowered into a wellbore on a wireline, where the individual perforating guns are generally coupled together by connector subs. Often, a surface truck accompanies the perforating systems that connects to an upper end of the wireline. In addition to being used for raising and lowering the gun string, the wireline typically is used as a communication means and control signal path between the truck and the perforating string. The wireline is generally threaded through pulleys supported above the wellbore. Derricks, slips and other similar systems may sometimes be used in lieu of a surface truck for inserting and retrieving the perforating system into and from a wellbore. Also, tubing, drill pipe, slick line, and/or coiled tubing are alternatives to wireline for disposing perforating systems into a wellbore.
Disclosed herein is are examples of a device and method for fracturing a subterranean formation. A charge device for use in fracturing a formation adjacent a wellbore is described, that in one example embodiment includes a housing with an explosive. Also included is a bullet assembly provided in the housing made up of a jacket with forward and rearward ends. An energetic material is within the jacket along with a delay fuse in selective communication with the energetic material. A detonation wave is formed that directs the bullet assembly into the formation when the explosive in the housing is detonated. A reaction of the energetic material is initiated by the delay fuse when the bullet assembly is in the formation to form a fracture in the formation. In an example embodiment, the jacket is formed from an energetic material. Optionally, the delay fuse can be ignited by communication with the explosive. A seal ring may be included that circumscribes the jacket. In an alternate embodiment, a perforation forms in the formation when the bullet assembly is projected into the formation and the seal ring provides a pressure barrier between the bullet assembly and an inner surface of the perforation. The forward end of the bullet assembly can be frangible, so that when expanding gases are produced by initiating the energetic material, pressure from the expanding gases is directed into the formation through the forward end. In an example embodiment, the energetic material may be a substance such as an oxidizing agent, a propellant, explosive powder, or combinations thereof.
Also included herein is a method of fracturing a subterranean formation that in one example includes providing a bullet assembly having a jacket, an energetic material, and a delay fuse. The bullet assembly is disposed in a wellbore and then launched from the wellbore and a distance into the formation. This produces a perforation in the formation. The energetic material is reacted after the bullet assembly is launched a distance into the wellbore. Reacting the energetic material generates pressure within the formation to fracture the formation. In an example embodiment, the bullet assembly is part of a charge device that is set within a perforating gun. Optionally, an end of the delay fuse is exposed to a detonation wave so that the delay fuse transfers the detonation wave to the energetic material for reacting the energetic material. In an example embodiment, the energetic material is a substance such as an oxidizing agent, a propellant, high explosive, or combinations thereof. Alternatively, a force generated by the bullet assembly impacting the formation is transferred into the bullet assembly for reacting the energetic material. The method may optionally further include sealing between the bullet assembly and the perforation. Optionally, the energetic material is reacted when the bullet assembly reaches an end of the perforation.
Some of the features and benefits of the present invention having been stated, others will become apparent as the description proceeds when taken in conjunction with the accompanying drawings, in which:
While the invention will be described in connection with the preferred embodiments, it will be understood that it is not intended to limit the invention to that embodiment. On the contrary, it is intended to cover all alternatives, modifications, and equivalents, as may be included within the spirit and scope of the invention as defined by the appended claims.
The method and system of the present disclosure will now be described more fully hereinafter with reference to the accompanying drawings in which embodiments are shown. The method and system of the present disclosure may be in many different forms and should not be construed as limited to the illustrated embodiments set forth herein; rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey its scope to those skilled in the art. Like numbers refer to like elements throughout.
It is to be further understood that the scope of the present disclosure is not limited to the exact details of construction, operation, exact materials, or embodiments shown and described, as modifications and equivalents will be apparent to one skilled in the art. In the drawings and specification, there have been disclosed illustrative embodiments and, although specific terms are employed, they are used in a generic and descriptive sense only and not for the purpose of limitation. Accordingly, the improvements herein described are therefore to be limited only by the scope of the appended claims.
The bullet assembly 14 of
Referring now to
One example of a fracturing operation as shown in partial sectional view in
The present invention described herein, therefore, is well adapted to carry out the objects and attain the ends and advantages mentioned, as well as others inherent therein. While a presently preferred embodiment of the invention has been given for purposes of disclosure, numerous changes exist in the details of procedures for accomplishing the desired results. These and other similar modifications will readily suggest themselves to those skilled in the art, and are intended to be encompassed within the spirit of the present invention disclosed herein and the scope of the appended claims.