Patent Application
20130161006
The subject disclosure relates to the field of oilfield well services and completion services. More specifically, the subject disclosure relates to techniques for sealing applications using an expandable settable material within an elastic membrane.
In forming downhole seals, such as between a casing wall and the borehole wall, typically cement is used. However there are situations when other types of seals may be more desirable. Examples of such situations are in open hole completions where mechanical packers or external casing packers may be used to provide zonal separation or isolation.
This summary is provided to introduce a selection of concepts that are further described below in the detailed description. This summary is not intended to identify key or essential features of the claimed subject matter, nor is it intended to be used as an aid in limiting the scope of the claimed subject matter.
In accordance with some embodiments a sealing system is provided for use in downhole sealing applications. The system includes an elastic membrane adapted to be deployed downhole; and a settable material housed within the elastic membrane prior to deployment of the membrane downhole, wherein the settable material is adapted to, when positioned downhole, set into an expanded solid form within the elastic membrane so as to form a sealing function when the system is positioned downhole.
According to some embodiments the settable material includes a granular material such as cement particles. According to other embodiments, the settable material is a pliable solid, or a fluid. A fluid may be introduced to facilitate or trigger the expansion and/or setting of the settable material. The introduced fluid may be diffused through the membrane or injected through orifices. According to some embodiments the settable material is expanded and/or set upon exposure to temperature change and/or a magnetic field. According to some embodiments a reactant material is used to aid in triggering the expanding and/or setting of the settable material.
According to some embodiments, a method is provided for downhole sealing. The method includes deploying an elastic membrane downhole, the membrane containing a settable material prior to deployment; expanding the settable material within the membrane while downhole; and setting the expanded settable material within the membrane so as to form a solid mass within the elastic membrane thereby forming a downhole seal.
Further features and advantages will become more readily apparent from the following detailed description when taken in conjunction with the accompanying Drawings.
Specific details are given in the following description to provide a thorough understanding of the embodiments. However, it will be understood by one of ordinary skill in the art that the embodiments may be practiced without these specific details. For example, systems, processes, and other elements in the invention may be shown as components in block diagram form in order not to obscure the embodiments in unnecessary detail. In other instances, well-known processes, structures, and techniques may be shown without unnecessary detail in order to avoid obscuring the embodiments. Further, like reference numbers and designations in the various drawings indicate like elements.
Also, it is noted that individual embodiments may be described as a process which is depicted as a flowchart, a flow diagram, a data flow diagram, a structure diagram, or a block diagram. Although a flowchart may describe the operations as a sequential process, many of the operations can be performed in parallel or concurrently. In addition, the order of the operations may be re-arranged. A process may be terminated when its operations are completed, but could have additional processes not discussed or included in a figure. Furthermore, not all operations in any particularly described process may occur in each embodiment. A process may correspond to a method, a function, a procedure, a subroutine, a subprogram, etc. When a process corresponds to a function, its termination corresponds to a return of the function to the calling function or the main function.
Furthermore, embodiments of the invention may be implemented, at least in part, either manually or automatically. Manual or automatic implementations may be executed, or at least assisted, through the use of machines, hardware, software, firmware, middleware, microcode, hardware description languages or any combination thereof. When implemented in software, firmware, middleware or microcode, the program code or code segments to perform the required tasks may be stored in a machine readable medium. A processor(s) may perform the required tasks.
According to some embodiments, a rubber pocket is provided that is suitable for use on tubing (packer type seal), casing (cement type seal), or liners. In non limitng examples, the rubber pocket may contain cement particles, rubber particles, swellable particles, cement filled rubber particles, cement filled swellable particles, calcium oxide, magnesium oxide, magnesium sulfate, iron (III) oxide, calcium sulfoaluminate, clay, magnetic particles, and/or reactants such as crosslinkers, retardants, or epoxy. The particles may be bulk spheres, bulk fibers, hollow spheres, hollow fibers, etc. The rubber pocket or bladder may also be fully or partially filled with fluids such as polymer reactants. The pocket may also be empty or contain a small volume of reactants. The slurry or epoxy or any other type of fluid and granular solid or injectable matter may be injected after the completion placement.
The rubber pocket may be initially compliant and/or small, because it is a compliant rubber bag or bladder filled with a granular material, unreacted and/or unswollen. After particle reaction, the pocket becomes either swollen or stiff, or both. In non-limiting examples, the activation may be related to water diffusion, temperature change, magnetic field, etc.
The membrane 120 may be initially compliant (easily deformable and stretchable). According to some embodiments, the elastic membrane 120 is made of rubber and the filler material 210 is a granular material. According to some other embodiments the material 210 is a fluid or a small amount of reactant. The granular material 210 according to some embodiments is cement particles. According to some embodiments other granular material could be used alone or in combination (a mixture) such as: oil swellable particles, water swellable particle, other swellable particles, grafted cement particles, cement filled rubber particles, cement filled swellable particles, epoxy particles, particles comprising calcium oxide, magnesium oxide magnesium sulfate, iron (III) oxide, calcium sulfoaluminate or combinations thereof, clay particles, magnetic particles, reactants such as cross-linkers, retardants. Examples of a fluid or viscous solid material 210 include: cement slurry, epoxy/organic blends, and epoxy reactants. According to some embodiments, the particles are of random shape, bulk spheres, hollow spheres, short or long fibers, and/or hollow fibers. According to some embodiments, the particles of material 210 are settable and become stiff, such as cement or epoxy. According to some embodiments the material 210 swells and sets, such as cement+CaO, cement+MgO, MgO, and clay. According to yet other embodiments, the material can reversibly stiffen under a field, such as by using magnetic particles.
When in contact with water, or oil, or temperature or a magnetic field, or with time alone, the granular material 210 will either swell, or percolate, or stiffen, or a combination of those. In other words, the material 210 reacts and changes the behavior of the material. According to some embodiments, the material 210 reversibly stiffen, through the use of magnetic particles within material 210. The encapsulant membrane or pocket may be permeable to water, or transparent to the magnetic field, according to the intended mechanism of operation, as well as compliant enough to expand according to the expansion properties of the filler material 210 and the application at hand. According to some embodiments membrane 120 is made of rubber. Rubber has been found to be a good option for many applications as it is permeable to oil and water, mostly transparent to fields, very compliant, and super-elastic (can stretch to several hundreds of percent without failing).
According to some embodiments the structure 200 is used as an external casing packer (ECP). ECPs are located in the completion string to provide formation zone isolation in an open hole wellbore. The ECP is thus designed to seal against the reservoir formation walls. Usual technologies for ECPs involve inflatable and swellable packers.
According to some other embodiments, the membrane 120 is nearly or completely empty upon initial deployment downhole. Then the material 210 is injected into the pocket while downhole.
As in the case of the embodiments of
In the case where the membrane 120 is initially almost or completely empty or the internal volume increases by a large ratio, material 210 (fluid, mixture of fluid and solid particles, etc.) can be injected in the bladder through orifices 330, 332 and 334 to cause expansion. In this case, a small amount of reactant (material that would trigger the swelling or setting reaction such as a hardener in an epoxy system) could be inserted in the bladder during manufacturing, such as a coating on the internal surface of the membrane 120 and/or on the outer surface of the casing wall 116 or external tubing. The small amount of material reacts with the injected material downhole to set, swell and/or harden. According to some embodiments, a granular material is present in the membrane prior to deployment to reduce the amount of epoxy to inject.
The small amount of reactants could be amine hardeners, including but not limited to secondary amines such as ethylenediamine, diethylenetriamine (DETA) and triethylenetetramine (TETA). Resin and initiators/hardeners could also be injected as a mixture through static or metered mixers into the bladder enclosure. The resins include but are not limited to classical epoxy resin, fatty acid oligomers, and polyols. The initiators or hardeners include but are not limited to urea, secondary amines, and isocyanate. The combination of various resins and hardeners produces polyamides, classical epoxy, linear epoxy-amines, supra plastic, self healing rubber, and hybrid networks, hybrid epoxy-amine supra-networks, hybrid amides, polyurethanes, etc., that can polymerize, expand, and fill the bladder enclosure.
Although the sealing applications shown in
Although only a few example embodiments have been described in detail above, those skilled in the art will readily appreciate that many modifications are possible in the example embodiments without materially departing from this invention. Accordingly, all such modifications are intended to be included within the scope of this disclosure as defined in the following claims. In the claims, means-plus-function clauses are intended to cover the structures described herein as performing the recited function and not only structural equivalents, but also equivalent structures. Thus, although a nail and a screw may not be structural equivalents in that a nail employs a cylindrical surface to secure wood parts together, whereas a screw employs a helical surface, in the environment of fastening wood parts, a nail and screw may be equivalent structures. It is the express intention of the applicant not to invoke 35 U.S.C. §112, paragraph 6 for any limitations of any of the claims herein, except for those in which the claim expressly uses the words “means for” together with an associated function.
