Not applicable.
The present invention pertains to a method and apparatus for measuring formation fracture width under static and dynamic conditions.
Fractures have been created in underground geologic formations for many years and many purposes. The initiation, propagation, and propping of these fractures has been widely studied and modeled in both the industry and academia. Largely, however, these fractures propagate vertically throughout the formations, and the vast majority of the literature and measurement techniques are devoted to vertical fractures. Horizontally initiated fractures are used in mining and for the storage of energy. The performance of these fractures is largely dependent on the fracture “width”. The width of a horizontal fracture can vary widely, and measuring this width under dynamic conditions is essential for understanding the static and dynamic performance of the fracture.
Present technologies available for measuring fracture width include an SIMFIP probe, which was developed to measure very small changes in fracture width for largely vertical fractures of well bores. The SIMFIP probe functions as a system of strain gauges to measure relative motion in all directions within a downhole environment. As it is composed of strain gauges, it can only measure relatively small displacements, where it has been successful at capturing those small displacements in a downhole environment. Unfortunately, this device has a very limited range of motion, and cannot be applied to a dynamically responding horizontal fracture. Freepoint measuring tools are designed to measure strain in tubing, casing, and drilling strings. These strain gauge-based measurement devices cannot respond to the large changes in width of a horizontal fracture. Downhole cameras have also been attempted to be used to view and measure fracture width. Unfortunately, image quality and optical clarity of flowing fluids are not of sufficient quality to quantitatively measure dynamic fracture motions.
Consequently, there is a need for an apparatus and method capable of measuring fracture width under static and dynamic conditions commonly encountered in fractures utilized for the storage of energy, water injection, and hydrocarbon production.
These and other needs in the art are addressed in one embodiment by a wireline width measuring apparatus and associated method which may be used to gauge static and dynamic fracture width in hydraulic fractures with a horizontal component. The wireline width measuring apparatus provides the ability to monitor the real time fracture width while injecting and flowing from the horizontal fracture. This device consists of a wireline caliper tool resting on a plug positioned below the fracture, while the caliper arms are engaged with the borehole just above the fracture opening. As the fracture moves, it is recorded as an apparent change in hole diameter that can then be mapped to vertical motion. The apparatus and method serve to measure the width of any fracture that intersects a wellbore over a reasonable length of wellbore. The apparatus measures width in real time, and functions while fluid is flowing to/from the fracture opening. Additionally, the method provides an inexpensive and robust methodology to measure fracture width in real time using commercial off-the-shelf wireline equipment, and does not need any special electronics or hardware. Instead, the method leverages the capabilities of existing technologies used in a unique configuration and process.
The foregoing has outlined rather broadly the features and technical advantages of the present invention in order that the detailed description of the invention that follows may be better understood. Additional features and advantages of the invention will be described hereinafter that form the subject of the claims of the invention. It should be appreciated by those skilled in the art that the conception and the specific embodiments disclosed may be readily utilized as a basis for modifying or designing other embodiments for carrying out the same purposes of the present invention. It should also be realized by those skilled in the art that such equivalent embodiments do not depart from the spirit and scope of the invention as set forth in the appended claims. Additionally, in the following disclosure of the representative embodiments of the invention, including the claims, directional terms, such as “above,” “upper,” “upward” and similar terms refer to a direction towards the earth's surface along a wellbore, and “below,” “lower,” “downward” and similar terms refer to a direction away from the earth's surface along the wellbore.
For a detailed description of the preferred embodiments of the invention, reference will now be made to the accompanying drawings in which:
Referring to
Wireline connection component 110 may comprise any wireline connection device known in the art which may be suitable for connecting caliper tool string 100 to a wireline. Similarly, centralizers 120, 130 may comprise any centralizer device known in the art which may be suitable for use in caliper tool string 100. In embodiments, centralizers 120, 130 may be adjustable bow spring centralizers, which may be configurable to individually adjust relative friction between a wellbore casing 10 and centralizer 120, and between the wellbore casing 10 and centralizer 130.
Caliper electronics module 140 and caliper apparatus 150 may act in unison to provide surface measurements of diameter M as illustrated in
Spacer 160 allows caliper apparatus 150 to be positioned at a fracture window when caliper tool string 100 is disposed in an operational position at the bottom of a wellbore. Spacer 160 may be any suitable length allowing caliper apparatus 150 to be positioned at the fracture window. For example, spacer 160 may be a length wherein a caliper tool string 100 comprising spacer 160 may be 8 feet in length to greater than 60 feet in length. In embodiments, caliper tool string comprising spacer 160 may be between 8 and 30 feet in length, between 20 and 40 feet in length, between 30 and 50 feet in length, or between 40 and 60 feet in length.
In combination, caliper tool string 100, comprising caliper apparatus 150, and the computational procedures just described enable a method of measuring static and dynamic performance of a fracture used for energy storage.
The method begins by first running caliper tool string 100 into the wellbore to identify the depth of the bottom of the wellbore and the depths of a window cut into the casing 10 at the desired depth of a fracture. To measure these depths, caliper tool string 100 may be run into the wellbore through known wireline operations until caliper tool string 100 touches the bottom of the wellbore, which may include debris 18 remaining from cutting the window in the casing 10 at the surrounding formation. Caliper tool string 100 may then be raised until the one or more arms 12 of the caliper apparatus 150 register the bottom of the fracture window, which may be identified when the caliper apparatus 150 registers an increase in the diameter M measured by its one or more arms 12, wherein the arms 12 are freed to extend to an extended position due to the opening in the casing 10 wall. Caliper tool string 100 may then be raised further until the one or more arms 12 begin to register a decrease in the diameter M, which will correspond to the arms 12 engaging the casing 10 opening at the top of the fracture window, wherein the arms 12 come into contact with the casing 10 causing the arms 12 to return to a retracted position.
From these known measurements of the fracture window and the wellbore bottom, which may or may not comprise debris 18, a desired location for a plug 16 to be positioned below the fracture window may be determined. Once desired location is determined, the plug 16 may be set at the desired location using known plug setting techniques and any suitable plug known in the art capable of providing a firmly seated upper surface. For example, the plug 16 may be a bridge plug or a composite fracture plug.
After the plug 16 has been set, caliper tool string 100 may be run into the wellbore until it comes to rest on the upper surface of the seated plug 16. Caliper tool string 100 may then be pulled slowly up-hole until the one or more arms 12 begin to register a decrease in the measured diameter M, indicating that they may be in contact with the casing 10 at the top of the fracture window, and the depth at which the decrease in the measured diameter M is recorded. Based upon this measured depth, a desired length for spacer 160 may be determined, which may position the caliper apparatus 150 such that its one or more arms 12 may be positioned in slidable contact with the casing 10 edge at the top of the fracture window and also allow the arms 12 to remain in contact with the casing 10 edge while the fracture is inflated and uninflated during operational injection or production cycles.
Once the desired length of spacer 160 has been determined, caliper tool string 100 may be returned to the surface, spacer 160 may be sized to the desired length, and caliper tool string 100 assembled to include spacer 160 disposed between caliper apparatus 150 and centralizer 130. At this time weights may be added to caliper tool string 100, and centralizers 120, 130 may be adjusted such that when caliper tool string 100 is disposed at a position wherein it is in resting contact with the seated plug 16 at the wellbore bottom, the friction between the wellbore casing 10 and centralizer 120 may be decreased, and the friction between the wellbore casing 10 and centralizer 130 may be increased. These weights and/or adjustments in relative friction between the two centralizers may assist caliper tool string 100 to remain in resting contact with the seated plug 16 at the wellbore bottom, while the one or more arms 12 of caliper apparatus 150 remain in slidable contact with the casing 10 edge at the top of the fracture window as the fracture modulates between inflated and uninflated states.
Once assembled, caliper tool string 100 may be run down-hole until caliper tool string 100 is disposed at a depth wherein it is in resting contact with the set bridge plug 16 at the wellbore bottom. Once in position, the tension in the wireline is reduced, setting the slack tension to zero, such that caliper tool string 100 rests on the set plug 16's upper surface under the force of gravity acting on its own weight. In this operational position, any increases in the friction between the wellbore casing 10 and centralizer 130 may assist caliper tool string to remain in resting contact with the upper surface of the set plug 16 at the wellbore bottom. In this position, caliper tool string 100 is now readied for operation.
In operation, caliper tool string 100 remains in resting contact with the upper surface of the set plug 16 at the wellbore bottom, while the one or more arms 12 of caliper apparatus 150 register changes in apparent diameter M of the wellbore casing 10 as the fracture is inflated or uninflated as a result of fluid being injected into or produced from the fracture. These changes in apparent diameter M result from increases or decreases in the angle 9 between the one or more arms 12 and the centerline 14 of caliper apparatus 150 while the edge of the wellbore casing 10 at the top of the fracture window slides along and/or against the one or more arms 12 of caliper apparatus 150. As illustrated in
Although the present invention and its advantages have been described in detail, it should be understood that various changes, substitutions and alterations may be made herein without departing from the spirit and scope of the invention as defined by the appended claims.
This application is a non-provisional application that claims the benefit of U.S. Provisional Application No. 63/186,678 filed on May 10, 2021, the disclosure of which is incorporated by reference herein in its entirety.
Number | Date | Country | |
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63186678 | May 2021 | US |