The present invention relates to a seat assembly for use with an isolation member, such as a ball, to fluidically isolate a well casing first portion from a well casing second portion and to thereby expose a geologic formation in fluid communication with the well casing first portion to, while isolating geologic formations in fluid communication with the well casing second portion from, fluid pressure applied for hydraulically fracturing the geologic formation in fluid communication with the well casing first portion. Hydraulic fracturing operations performed using the seat assembly can enhance recovery and rates of production of hydrocarbons from a well that penetrates the fractured geologic formation.
Hydraulic fracturing is the fracturing of oil-bearing rock using a pressurized liquid. Some hydraulic fractures form naturally. Induced hydraulic fracturing or hydro-fracturing, commonly known as “fracking,” is a technique in which a fluid, typically water, is mixed with a proppant and chemicals to form a mixture that is injected at high pressure into a well to create small fractures in a hydrocarbon-bearing geologic formation along which the hydrocarbon fluids such as gas, oil or condensate may migrate to the well for production to the surface. Hydraulic pressure is removed from the well, then small grains of the proppant, for example, sand or aluminum oxide, hold the fractures open once the formation pressure achieves an equilibrium. The technique is commonly used in wells for shale gas, tight gas, tight oil, coal seam gas and hard rock wells. This well stimulation technique is generally only conducted once in the life of the well and greatly enhances fluid removal rates and well productivity.
A hydraulic fracture is formed by pumping fracturing fluid into a perforated section of the well at a rate sufficient to increase pressure downhole at the target zone (determined by the location of the well casing perforations) to exceed that of the fracture gradient (pressure gradient) of the rock. The fracture gradient is defined as the pressure increase per unit of the depth due to its density and it is usually measured in pounds per square inch per foot or bars per meter. The rock cracks and the fracture fluid continues further into the rock, extending the crack still further, and so on. Fractures are localized because pressure drop off with frictional loss attributed to the distance from the well. Operators typically try to maintain “fracture width,” or slow its decline, following treatment by introducing into the injected fluid a proppant—a material such as grains of sand, ceramic beads or other particulates that prevent the fractures from closing when the injection is stopped and the pressure of the fluid is removed. The propped fracture is permeable enough to allow the flow of formation fluids to the well. Formation fluids include gas, oil, salt water and fluids introduced to the formation during completion of the well during fracturing.
The location of one or more fractures along the length of the borehole is strictly controlled by various methods that create or seal off holes in the side of the well. A well may be fracked in stages by setting an isolation member seat, such as a bridge seat, below the geologic formation to be fracked to isolate one or more lower geologic zones open to the well from the anticipated pressure to be later applied to a zone closer to the surface. An isolation member, such as a ball of a predetermined diameter and/or profile, is introduced into the well to engage the corresponding isolation member seat. When the isolation member engages the isolation member seat installed in the bore of the well casing, the isolation member seats in the isolation member seat to form a seal that isolates the well casing second portion below the seat from the hydraulic fracturing pressure to be imposed on a geologic formation in fluid communication with the well casing first portion of the casing having perforations above the seat. The hydraulic fracturing pressure is applied at the wellhead and fluidically communicated down the well casing.
Hydraulic-fracturing equipment used in oil and natural gas fields usually consists of a slurry blender, one or more high-pressure, high-volume fracturing pumps (typically powerful triplex or quintuplex pumps) and a monitoring unit. Associated equipment includes fracturing tanks, one or more units for storage and handling of proppant, high-pressure treating iron, a chemical additive unit (used to accurately monitor chemical addition), low-pressure flexible hoses, and many gauges and meters for flow rate, fluid density, and treating pressure. Chemical additives are typically 0.5% percent of the total fluid volume. Fracturing equipment operates over a range of pressures and injection rates, and can reach up to 100 megapascals (15,000 psi) and 265 litres per second (9.4 cu. ft./sec or 100 barrels per min.).
A problem that can be encountered in a fracking operation involves the impairment to subsequent operations that can result from the presence of the isolation member engaged with the isolation member seat. After the fracking operation is concluded, the surface pressure is restored to a pressure at which the well will flow and formation fluids flow to the wellhead at the surface for recovery. Conventional isolation member seats typically remain in the well casing. Conventional isolation member seats can restricts oil flow and/or obstruct subsequent well operations.
A workover operation can be implemented in which a drilling instrument is introduced into the well casing to drill out and to mechanically destroy the isolation member seat, but a workover operation requires that a workover rig be brought to the surface location of the well for downhole operations. The need for the rental, transportation, rigging up and use of a rig imposes substantial delays and substantial costs.
Seat assemblies for sealably receiving isolation members such as, for example, but not by way of limitation, balls pumped downhole from the surface into a well casing, can be secured in well casing at a predetermined position to cooperate with the isolation member received therein to isolate a well casing first portion from a well casing second portion. One type of seat assembly is secured in the well casing by radially outward expansion of one or more components of the seat assembly to engage the well casing in an interference fit. The expanded component of the seat assembly engages and grips the well casing to secure the seat assembly in position. Another type of seat assembly relies on one or more deployable gripping members such as, for example, but not by way of limitation, one or more deployable slips that can be moved from a run-in or retracted position to a deployed position to engage and grip the well casing.
An embodiment of the present invention provides a fracking isolation member seat assembly having one or more gripping components such as, for example, one or more deployable slips and one or more displacement members for engaging and deploying the one or more deployable slips, for securing the seat assembly in position in the well casing. The term “gripping components,” as that term is used herein, may include not just the one or more components of the seat assembly that are deployable to engage and bite into the well casing, but also the one or more components that engage and deploy or displace the one or more components that engage and bite into the well casing, components that provide support to the one or more components that engage and deploy or displace the one or more components that engage and bite into the well casing, and components that provide support to the one or more components that engage and bite into the well casing. It will be understood that the isolation member seat assembly can be released from its secured position within the well casing by disabling the one or more components that engage and deploy or displace the one or more components to engage and bite into the well casing. It will be further understood that the isolation member seat assembly can be released from its secured position that explosively compromising the body of the isolation member seat assembly into which the recesses are formed because, without the body having structural integrity, the components that engage and bite into the well casing (such as slips) and the components that engaging and displace the components that engage and bite into the well casing (such as the displacement members), have nothing to provide for reaction forces against the well casing. The one or more gripping components may be, but are not limited to, the body of the isolation member seat assembly, one or more slips of the isolation member seat assembly, and/or one or more slip displacement members that engage and then deploy one or more slips. The one or more gripping components can be disabled by detonation of a strategically placed explosive charge provided within the seat assembly such as, for example, within a chamber or a recess within a body of the seat assembly, or around the exterior of the body of the isolation member seat assembly, to produce, upon detonation of the explosive charge, displacement of or destruction of the one or more gripping components that secure the seat assembly in the well casing. The one or more gripping components of an embodiment of the seat assembly of the present invention may comprise a material that provides favorable hardness and favorable compressive strength for gripping a well casing or for engaging and displacing another component that grips the well casing, but one that subsequently shatters or fragments when exposed to the shock caused by detonation of an explosive charge disposed in close proximity thereto to disable the gripping component that grips the well casing. In one embodiment, the material is one that dissolves after exposure to well fluids due to the dramatically and substantially increased surface area resulting from the shattering or fragmentation caused by the explosive charge. In another embodiment, the body of the seat assembly may comprise a material that can be fragmented by detonation of an explosive charge and the fragments resulting therefrom may be of a material that is dissolvable in well fluids as a result of the dramatically increased surface area of the fragments as opposed to the limited surface area exposed prior to fragmentation. In this embodiment, as with other embodiments, the components of the seat assembly that are deployed to engage and bite into the well casing are not likely to comprise a dissolvable material since dissolvable materials are not optimal for forming teeth that effectively bite into steel well casing with the grip needed to withstand the large forces that will be imparted to the seat assembly and the isolation member received thereon during a fracturing operation.
An embodiment of the seat assembly of the present invention provides a fracking isolation member seat assembly having one or more gripping components such as, for example, one or more deployable slips and one or more displacement members for engaging and deploying the one or more deployable slips, for securing the seat assembly in position in the well casing. The term “gripping components,” as that term is used herein, may include not just the one or more components of the seat assembly that are deployable to engage and bite into the well casing, but may also be the one or more components that engage and deploy or displace the one or more components that engage and bite into the well casing. It will be understood that the seat assembly can be released from its secured position within the well casing by disabling the one or more components that engage and deploy or displace the one or more components to engage and bite into the well casing. The one or more gripping components may be, but are not limited to, one or more slips, and/or the one or more slip displacement members that engage and then deploy the one or more slips. The one or more gripping components can be disabled by detonation of a strategically placed explosive charge provided within the seat assembly such as, for example, within a chamber or a recess within a body of the seat assembly, or around the exterior of the body of the isolation member seat assembly, to produce, upon detonation of the explosive charge, displacement of or destruction of the one or more gripping components that secure the seat assembly in the well casing. The one or more gripping components of an embodiment of the seat assembly of the present invention may comprise a material that provides favorable hardness and favorable compressive strength for gripping a well casing or for engaging and displacing another component that grips the well casing, but one that subsequently shatters or fragments when exposed to the shock caused by detonation of an explosive charge disposed in close proximity thereto to disable the gripping component. In one embodiment, the material is one that dissolves after exposure to well fluids due to the dramatically and substantially increased surface area resulting from the shattering or fragmentation caused by the explosive charge. In another embodiment, the body of the seat assembly may comprise a material that can be fragmented by detonation of an explosive charge and the fragments resulting therefrom may be of a material that is dissolvable in well fluids as a result of the dramatically increased surface area of the fragments as opposed to the limited surface area exposed prior to fragmentation. In this embodiment, as with other embodiments, the components of the seat assembly that are deployed to engage and bite into the well casing are not likely to comprise a dissolvable material since dissolvable materials are not optimal for forming teeth that effectively bite into steel well casing with the grip needed to withstand the large forces that will be imparted to the seat assembly and the isolation member received thereon during a fracturing operation.
In one embodiment of the isolation member seat assembly of the present invention, one or more gripping components of the seat assembly such as, for example, one or more slips, can be movably disposed on a body of the seat assembly, the one or more gripping components movable from a run-in or retracted position proximal to, or within a recess or a chamber in, a body of the seat assembly to a deployed position distal to, or deployed from a recess or a chamber in, the body of the seat assembly. An explosive charge strategically positioned proximal to the one or more gripping components can be detonated after the geologic formation fracturing operation to disable the one or more gripping components so that the isolation member seat assembly can be removed from its position within the well casing and retrieved to the surface using a tool run on a wireline or a coiled tubing string. “Disabling,” as that term is used herein, includes destroying, shattering, damaging, displacing, dislodging, compromising and/or fragmenting the one or more gripping components.
In one embodiment of the isolation member seat assembly, one or more gripping components of the seat assembly such as, for example, one or more slips, can be movably disposed on, or within a recess or chamber of, the body of the seat assembly, the one or more slips movable from a run-in position to a deployed position, and a displacement member can be disposed adjacent to the one or more slips, the displacement member movable from a retracted position to an engaged position to engage and displace the one or more gripping components from the run-in position to the deployed position to engage and grip the well casing and to thereby secure the seat assembly in a position within the well casing. An explosive charge is strategically positioned on, or within a chamber or recess of, the body of the seat assembly and proximal to one of the one or more gripping components. For example, but not by way of limitation, the explosive charge may be positioned on, or within a chamber or recess of, the body of the seat assembly and proximal to at least one of a displacement member and a slip that can be engaged by and deployed to a gripping position by movement of the displacement member. The explosive charge can be detonated after the fracturing operation to disable at least one of the displacement member and the one or more slips so that the isolation member seat assembly can be subsequently removed from its position within the well casing using, for example, a tool run on a wireline or a coiled tubing string. In one embodiment, the explosive charge can be disposed within a chamber of the body of the seating assembly that is sealed to prevent unwanted contamination by or exposure to well fluids wherein the chamber of the body is proximal to at least one of the displacement member in the engaged position and the one or more slips in the deployed position so that upon detonation of the explosive charge at least one of the displacement member and the one or more slips are disabled and the seat assembly is thereby released from its secured position within the well casing.
In one embodiment of the isolation member seat assembly of the present invention, a battery, a pressure sensor and a circuit are included on, or within a chamber or a recess of, the body of the seat assembly along with the explosive charge. The pressure sensor is disposed in fluid communication with fluid in the well casing and detects a predetermined pressure threshold or, alternately, a pressure drop, or both in sequence. The pressure sensor may optionally, upon sensing the pressure threshold, pressure drop or sequence of both, initiate a predetermined timer delay period prior to sending a detonation signal or charge from the battery to the explosive charge to detonate the explosive charge, or it may generate and send the detonation signal or charge upon detecting the pressure threshold, pressure drop or sequence of both. For the embodiment of the seat assembly wherein the pressure sensor initiates a predetermined time delay after detecting the pressure threshold or pressure drop, upon elapse of the predetermined timer delay period, a circuit is completed that delivers an electrical current from the battery to the explosive charge to detonate the explosive charge and to thereby disable one or more of the gripping components of the isolation member seat assembly that secure the seat assembly in a position within the well casing. For the pressure subsidence-triggered embodiment, upon subsidence of the pressure in the well casing at the seat assembly to a predetermined pressure that is less than the higher threshold pressure that initiates the detonation process by arming the circuit, a circuit is completed that delivers an electrical current from the battery to the one or more explosive charges to detonate the one or more explosive charges and to thereby disable the one or more gripping components of the seat assembly that secure the seat assembly in the well casing.
In another embodiment of the isolation member seat assembly of the present invention, the seat assembly includes the one or more explosive charges for disabling the gripping components that secure the seat assembly in a position in the well casing. For example, one embodiment includes gripping components comprising a displacement member that is movable on the body of the seat assembly from a run-in position to an engaged position. The run-in position of the displacement member is the position in which an adjacent one or more slips are left in a run-in or retracted position, and the engaged position of the displacement member is the position in which the displacement member engages and displaces the adjacent one or more slips from the run-in or retracted position to the deployed position. In one embodiment of the seat assembly, the seat assembly does not include a battery, a pressure sensor or a circuit. Instead, the electrical charge required for detonating the one or more explosive charges and thereby disabling the one or more gripping components of the seat assembly is provided by way of a wireline unit, a coiled tubing string or some other tool for being run into a well to the isolation seat assembly. The explosive charge is, in this embodiment, protected against inadvertent detonation due to, for example, a malfunction in or failure of the pressure sensor or the circuit. The isolation member seat assembly that includes the one or more explosive charges may also include electrical leads coupled at a first end to the one or more explosive charges and having a second end disposed in a position on the isolation member seat assembly to engage a tool that is lowered into the well casing from the surface to electrically detonate the one or more explosive charges and to thereby disable one or more gripping components of the isolation member seat assembly. For example, the electrical leads may terminate at one or more electrical contacts disposed in a position adjacent to a seat of the seat assembly that is sealably engaged by the isolation member during the fracking operation, the seat being disposed at a proximal end of the isolation member seat assembly. A tool having one or more electrical contacts may be disposed into engagement with the seat assembly after the fracking operation, and the one or more contacts on the tool that is run into the well to engage the seat assembly may be positioned on the tool at a predetermined position and/or spacing, and the contacts may be positioned, spaced and/or sized for engagement with corresponding electrical contacts on the seat assembly so that an electrical charge can be delivered from the tool that is run into the well casing through the engaged contacts and to the one or more explosive charges to thereby detonate the one or more explosive charges and thereby disable the one or more gripping components that secure the isolation member seat assembly in the well casing prior to detonation of the one or more explosive charges.
The unobstructed well casing obtainable by use of embodiments of the fracking isolation member seat assembly of the present invention, along with the lack of obstruction of subsequent well operations, increases the success and effectiveness of the fracking process, lowers or eliminates workover rig rental costs, prevents unwanted delays in subsequent well operations after the fracking process, and gets oil to market faster and with less expense.
The embodiment of the isolation member seat assembly contains one or more explosive charges that can be detonated to disable one or more gripping components of the isolation member seat assembly that are deployed to secure the seat assembly in the well casing. Once the isolation member seat assembly is movable within the well casing, it can be retrieved to the surface and removed from the well casing to prevent unwanted obstructions.
It will be understood that the seat of the isolation member seat assembly may have a variety of exterior shapes that can be adapted to engage and seal with a correspondingly shaped isolation member such as, for example, but not by way of limitation, a ball or a dart. Although, the appended drawings illustrate an apparatus of the present invention having a seat for engaging a spherical sector of a spherical isolation member, the appended drawings merely illustrate a function that can be provided by other isolation members with alternate exterior shapes and configurations for engaging a correspondingly shaped seat of an isolation member seat assembly. The appended drawings are merely for illustration and should not be considered as limiting of the invention and other shapes, such as, for example, wedges, cones or cylinders, can also be employed for establishing a seal.
In one embodiment, the gripping components of the isolation member seat assembly that are deployed to secure the isolation member seat assembly in the well casing. The gripping components can be made of a composite material whereby the gripping components, such as, for example, but not by way of limitation, slips or displacement members to engage and displace the slips, are dislodged and/or fragmented by an explosive charge directed at the slips and/or the displacement members. The isolation member seat assembly can then be retrieved to the surface of the well with a fishing tool thereby clearing the well of any unwanted obstruction. Gripping components, that that terms is used herein, may refer to slips, displacement members to engage and displace the slips, or both, or to other components that can be used to effect the securing of the isolation member seat assembly in the well casing.
One embodiment of the isolation member seat assembly comprises a body having one or more recesses, apertures or holes into or through which components, such as, for example, a safety fuse, a pressure sensor, an explosive charge, a battery, and a timer circuit may be inserted. It will be understood that an embodiment of an isolation member seat assembly may have other configurations and may also be assembled from mating components to form a closed chamber to contain the components.
Embodiments of an isolation member seat assembly of the present invention may further include a timer-controlled detonator. The pressure sensor may be provided to generate a signal that enables or initiates the electrical circuit that delivers a detonating current flow from a battery to the one or more explosive charges. The provision of the pressure sensor to complete and thereby enable the detonation circuit causes the pressure sensor to function as a safety fuse without which the explosive charge would not be detonated and the isolation member seat assembly would be unable to self-release.
In one embodiment, the dissolvable components of embodiments of the apparatus may comprise one of many magnesium and aluminum compositions. For example, but not by way of limitation, in embodiments of the isolation member seat assembly of the present invention in which the body of the isolation member seat assembly is explosively disabled to release the isolation member seat assembly from a fixed position within the well casing, the body may comprise one or both of magnesium and aluminum, or some other material that will dissolve in certain well fluids so that debris can be eliminated from the well and fragmented or shattered components of the isolation member seat assembly will not present unwanted obstructions for other tools and downhole devices.
Also shown in
It will be understood that the use of a detonation tool 181 to engage and deliver an electrical current to detonate the explosive charge 40 of an isolation member seat assembly 100 offers flexibility and cost savings by enabling an operator to run the detonation tool 181 into a well casing 88 and to detonate the explosive charge 40 after each stage of a fracturing operation. The isolation member seat assembly 100 released by the detonation can be left in the well casing 88 while subsequent stages of the fracturing operation commence uphole, resulting in additional isolation member seat assemblies 100 being secured in the well casing 88, used for the fracturing of a stage, then engaged by the detonation tool 181 to detonate the explosive charge(s) 40 to release the isolation member seat assembly 100 which is also left in the well casing 88. This approach allows multiple released isolation member seat assemblies 100 to be harvested from the well casing 88 in a single trip using a retrieval tool adapted for retrieving the released seat assemblies 100, as will be discussed in more detail below in relation to
It will be further understood that while the embodiment of the setting tool 70 with the threaded shaft and the sacrificial retainer arms used to set or deploy the gripping components of the isolation member seat assembly is illustrated herein at
It will be understood that other various tools can be used to deploy the gripping components of the seat assembly of the present invention and/or to retrieve the released isolation member seat assembly from the well casing without departure from the spirit and scope of the present invention, which is defined by the claims appended hereto. It will be understood that other various tools may be used to retrieve the released isolation member seat assembly from the well casing without departure from the spirit and scope of the present invention, which is defined by the claims appended hereto.
The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. As used herein, the singular forms “a”, “an” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms “comprises” and/or “comprising,” when used in this specification, specify the presence of stated features, integers, steps, operations, elements, components and/or groups, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof. The terms “preferably,” “preferred,” “prefer,” “optionally,” “may,” and similar terms are used to indicate that an item, condition or step being referred to is an optional (not required) feature of the invention.
The corresponding structures, materials, acts, and equivalents of all means or steps plus function elements in the claims below are intended to include any structure, material, or act for performing the function in combination with other claimed elements as specifically claimed. The description of the present invention has been presented for purposes of illustration and description, but it is not intended to be exhaustive or limited to the invention in the form disclosed.
Many modifications and variations will be apparent to those of ordinary skill in the art without departing from the scope and spirit of the invention. The embodiment was chosen and described in order to best explain the principles of the invention and the practical application, and to enable others of ordinary skill in the art to understand the invention for various embodiments with various modifications as are suited to the particular use contemplated.
This application depends from and claims priority to U.S. Provisional Application No. 62/556,922 filed on Sep. 11, 2017.
Number | Date | Country | |
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62556922 | Sep 2017 | US |