RESTRICTION PLUG ELEMENT AND METHOD
A restriction plug element and method for positioning plugs to isolate fracture zones in a horizontal, vertical, or deviated wellbore is disclosed. The restriction plug element includes a partial hollow passage with an interior end. The partial passage enables the plug element to seat in a restriction sleeve member during treatment and subsequently degrade to form a complete hollow passage. The complete flow channel dissolves or degrades not only the outside but also the inside of the wall of the restriction plug element. Initially the flow is restricted by the closed end in the partial hollow passage and over time the flow channel opens up by degradation and allows fluid to pass through in either direction. During back flow in the well new fluid is circulated into the well and the restriction plug element continues to degrade.
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This application is a continuation-in-part of U.S. application Ser. No. 14/721,784, filed May 26, 2015, which claims the benefit of U.S. Provisional No. 62/081,399, filed Nov. 18, 2014, which is also a continuation-in-part of U.S. application Ser. No. 14/459,042, filed Aug. 13, 2014, now U.S. Pat. No. 9,062,543, the disclosures of which are fully incorporated herein by reference.
FIELD OF THE INVENTIONThe present invention generally relates to oil and gas extraction. Specifically, the invention attempts to isolate fracture zones through selectively positioning restriction elements within a wellbore casing.
PRIOR ART AND BACKGROUND OF THE INVENTION
Prior Art BackgroundThe process of extracting oil and gas typically consists of operations that include preparation, drilling, completion, production and abandonment.
Preparing a drilling site involves ensuring that it can be properly accessed and that the area where the rig and other equipment will be placed has been properly graded. Drilling pads and roads must be built and maintained which includes the spreading of stone on an impermeable liner to prevent impacts from any spills but also to allow any rain to drain properly.
In the drilling of oil and gas wells, a wellbore is formed using a drill bit that is urged downwardly at a lower end of a drill string. After drilling the wellbore is lined with a string of casing. An annular area is thus formed between the string of casing and the wellbore. A cementing operation is then conducted in order to fill the annular area with cement. The combination of cement and casing strengthens the wellbore and facilitates the isolation of certain areas of the formation behind the casing for the production of hydrocarbons.
The first step in completing a well is to create a connection between the final casing and the rock which is holding the oil and gas. There are various operations in which it may become necessary to isolate particular zones within the well. This is typically accomplished by temporarily plugging off the well casing at a given point or points with a plug.
A special tool, called a perforating gun, is lowered to the rock layer. This perforating gun is then fired, creating holes through the casing and the cement and into the targeted rock. These perforating holes connect the rock holding the oil and gas and the well bore.
Since these perforations are only a few inches long and are performed more than a mile underground, no activity is detectable on the surface. The perforation gun is then removed before the next step, hydraulic fracturing. Stimulation fluid, which is a mixture of over 90% water and sand, plus a few chemical additives, is pumped under controlled conditions into deep, underground reservoir formations. The chemicals are used for lubrication and to keep bacteria from forming and to carry the sand. These chemicals are typically non-hazardous and range in concentrations from 0.1% to 0.5% by volume and are needed to help improve the performance and efficiency of the hydraulic fracturing. This stimulation fluid is pumped at high pressure out through the perforations made by the perforating gun. This process creates fractures in the shale rock which contains the oil and natural gas.
In many instances a single wellbore may traverse multiple hydrocarbon formations that are otherwise isolated from one another within the Earth. It is also frequently desired to treat such hydrocarbon bearing formations with pressurized treatment fluids prior to producing from those formations. In order to ensure that a proper treatment is performed on a desired formation, that formation is typically isolated during treatment from other formations traversed by the wellbore. To achieve sequential treatment of multiple formations, the casing adjacent to the toe of a horizontal, vertical, or deviated wellbore is first perforated while the other portions of the casing are left unperforated. The perforated zone is then treated by pumping fluid under pressure into that zone through perforations. Following treatment a plug is placed adjacent to the perforated zone. The process is repeated until all the zones are perforated. The plugs are particularly useful in accomplishing operations such as isolating perforations in one portion of a well from perforations in another portion or for isolating the bottom of a well from a wellhead. The purpose of the plug is to isolate some portion of the well from another portion of the well.
Subsequently, production of hydrocarbons from these zones requires that the sequentially set plugs be removed from the well. In order to reestablish flow past the existing plugs an operator must remove and/or destroy the plugs by milling, drilling, or dissolving the plugs.
Restriction plug elements such as balls/plugs with large aspect ratio approaching 1 and seated in a large inner diameter restriction sleeve member do not degrade in wellbore fluids. The plug elements change shape from a circular to flying saucer shape because water is restricted on the edges and a sand pack that holds the ball on the seat prevents the plug element from interacting with the water and wellbore fluids. Therefore there is a need to add a mechanism to provide more surface area in the restriction plug element to provide contact with the restriction plug element after seating in a restriction sleeve member.
Prior Art System Overview (0100)As generally seen in the system diagram of
Furthermore, after well completion, sleeves used to set frac plugs may have a smaller inner diameter constricting fluid flow when well production is initiated. Therefore, there is a need for relatively large inner diameter sleeves after well completion that allow for unrestricted well production fluid flow.
Additionally, frac plugs can be inadvertently set at undesired locations in the wellbore casing creating unwanted constrictions. The constrictions may latch wellbore tools that are run for future operations and cause unwanted removal process. Therefore, there is a need to prevent premature set conditions caused by conventional frac plugs.
Prior Art Method Overview (0200)As generally seen in the method of
The step (0206) requires that removal/milling equipment be run into the well on a conveyance string which may typically be wire line, coiled tubing or jointed pipe. The process of perforating and plug setting steps represent separate “trip” into and out of the wellbore with the required equipment. Each trip is time consuming and expensive. In addition, the process of drilling and milling the plugs creates debris that needs to be removed in another operation. Therefore, there is a need for isolating multiple hydraulic fracturing zones without the need for a milling operation. Furthermore, there is a need for positioning restrictive plug elements that could be removed in a feasible, economic, and timely manner before producing gas.
Deficiencies in the Prior ArtThe prior art as detailed above suffers from the following deficiencies:
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- Prior art systems do not provide for positioning a ball seat at a desired location after a wellbore casing has been installed, without depending on a predefined sleeve location integral to the wellbore casing to position the plug.
- Prior art systems do not provide for isolating multiple hydraulic fracturing zones without the need for a milling operation.
- Prior art systems do not provide for positioning restrictive elements that could be removed in a feasible, economic, and timely manner.
- Prior art systems do not provide for setting larger inner diameter sleeves to allow unrestricted well production fluid flow.
- Prior art systems cause undesired premature preset conditions preventing further wellbore operations.
While some of the prior art may teach some solutions to several of these problems, the core issue of isolating hydraulic fracturing zones without the need for a milling operation has not been addressed by prior art.
OBJECTIVES OF THE INVENTIONAccordingly, the objectives of the present invention are (among others) to circumvent the deficiencies in the prior art and affect the following objectives:
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- Provide for positioning a ball seat at a desired location after a wellbore casing has been installed, without depending on a predefined sleeve location integral to the wellbore casing to position the plug.
- Provide for isolating multiple hydraulic fracturing zones without the need for a milling operation.
- Provide for positioning restrictive elements that could be removed in a feasible, economic, and timely manner.
- Provide for setting larger inner diameter sleeves to allow unrestricted well production fluid flow.
- Provide for eliminating undesired premature preset conditions that prevent further wellbore operations.
While these objectives should not be understood to limit the teachings of the present invention, in general these objectives are achieved in part or in whole by the disclosed invention that is discussed in the following sections. One skilled in the art will no doubt be able to select aspects of the present invention as disclosed to affect any combination of the objectives described above.
BRIEF SUMMARY OF THE INVENTION System OverviewThe present invention in various embodiments addresses one or more of the above objectives in the following manner. The present invention provides a system to isolate fracture zones in a horizontal, vertical, or deviated wellbore without the need for a milling operation. The system includes a restriction plug element for use in a wellbore casing comprising a degradable material. The restriction plug element configured with a partial hollow passage extending from at least one interior end configured to block fluid communication from upstream to downstream during fluid treatment. The partial hollow passage degrades and forms a complete hollow passage to enable the fluid communication subsequent to the fluid treatment.
Method OverviewThe present invention system may be utilized in the context of an overall gas extraction method, wherein the restriction plug element described previously is controlled by a method having the following steps:
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- (1) deploying the restriction plug element into the wellbore casing and blocking fluid communication;
- (2) orienting the restriction plug element with the interior end to seat in a restriction sleeve member and isolating a stage;
- (3) treating the isolated stage with fracturing fluids;
- (4) degrading from the interior end in the partial hollow passage through contact with wellbore fluids;
- (5) creating a complete hollow passage from the partial hollow passage; and
- (6) unblocking the fluid communication.
Integration of this and other preferred exemplary embodiment methods in conjunction with a variety of preferred exemplary embodiment systems described herein in anticipation by the overall scope of the present invention.
For a fuller understanding of the advantages provided by the invention, reference should be made to the following detailed description together with the accompanying drawings wherein:
While this invention is susceptible of embodiment in many different forms, there is shown in the drawings and will herein be described in detailed preferred embodiment of the invention with the understanding that the present disclosure is to be considered as an exemplification of the principles of the invention and is not intended to limit the broad aspect of the invention to the embodiment illustrated.
The numerous innovative teachings of the present application will be described with particular reference to the presently preferred embodiment, wherein these innovative teachings are advantageously applied to the particular problems of a wellbore plug isolation system and method. However, it should be understood that this embodiment is only one example of the many advantageous uses of the innovative teachings herein. In general, statements made in the specification of the present application do not necessarily limit any of the various claimed inventions. Moreover, some statements may apply to some inventive features but not to others.
GLOSSARY OF TERMS
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- RSM: Restriction Sleeve Member, a cylindrical member positioned at a selected wellbore location.
- RPE: Restriction Plug Element, an element configured to isolate and block fluid communication.
- CSS: Conforming Seating Surface, a seat formed within RSM.
- ICD: Inner Casing Diameter, inner diameter of a wellbore casing.
- ICS: Inner Casing Surface, inner surface of a wellbore casing.
- ISD: Inner Sleeve Diameter, inner diameter of a RSM.
- ISS: Inner Sleeve Surface, inner surface of a RSM.
- WST: Wellbore Setting Tool, a tool that functions to set and seal RSMs.
- GSA: Gun String Assembly, a cascaded string of perforating guns coupled to each other.
The present invention may be seen in more detail as generally illustrated in
In a preferred exemplary embodiment, the WST may set RSM (0303) to the ICS in compression mode to form an inner profile on the RSM (0303). The inner profile could form a tight or leaky seal preventing substantial axial movement of the RSM (0303). In another preferred exemplary embodiment, the WST may set RSM (0303) to the ICS in expansion mode providing more contact surface for sealing RSM (0303) against ICS. Further details of setting RSM (0303) through compression and expansion modes are further described below in
In another preferred exemplary embodiment, the WST may set RSM (0303) using a gripping/sealing element disposed of therein with RSM (0303) to grip the outside surface of RSM (0303) to ICS. Further details of setting RSM (0303) through compression and expansion modes are described below in
In another preferred exemplary embodiment, the WST may set RSM (0303) at any desired location within wellbore casing (0304). The desired location may be selected based on information such as the preferred hydrocarbon formation area, fraction stage, and wellbore conditions. The desired location may be chosen to create uneven hydraulic fracturing stages. For example, a shorter hydraulic fracturing stage may comprise a single perforating position so that the RSM locations are selected close to each other to accommodate the perforating position. Similarly, a longer hydraulic fracturing stage may comprise multiple perforating positions so that the RSM locations are selected as far to each other to accommodate the multiple perforating positions. Shorter and longer hydraulic fracturing positions may be determined based on the specific information of hydrocarbon formation (0302). A mudlog analyzes the mud during drilling operations for hydrocarbon information at locations in the wellbore. Prevailing mudlog conditions may be monitored to dynamically change the desired location of RSM (0303).
The WST may create a conforming seating surface (CSS) (0306) within RSM (0303). The WST may form a beveled edge on the production end (heel end) of the RSM (0303) by constricting the inner diameter region of RSM (0303) to create the CSS (0306). The inner surface of the CSS (0306) could be formed such that it seats and retains a restriction plug element (RPE) (0305). The diameter of the RPE (0305) is chosen such that it is less than the outer diameter and greater than the inner diameter of RSM (0303). The CSS (0306) and RPE (0305) may be complementary shaped such that RPE (0305) seats against CSS (0306). For example, RPE (0306) may be spherically shaped and the CSS (0306) may be beveled shaped to enable RPE (0305) to seat in CSS (0306) when a differential pressure is applied. The RPE (0305) may pressure lock against CSS (0306) when differential pressure is applied i.e., when the pressure upstream (production or heel end) of the RSM (0303) location is greater than the pressure downstream (injection or toe end) of the RSM (0303). The differential pressure established across the RSM (0303) locks RPE (0305) in place isolating downstream (injection or toe end) fluid communication. According to one preferred exemplary embodiment, RPE (0305) seated in CSS (0306) isolates a zone to enable hydraulic fracturing operations to be performed in the zone without affecting downstream (injection or toe end) hydraulic fracturing stages. The RPE (0305) may also be configured in other shapes such as a plug, dart or a cylinder. It should be noted that one skilled in the art would appreciate that any other shapes conforming to the seating surface may be used for RPEs to achieve similar isolation affect as described above.
According to another preferred exemplary embodiment, RPE (0305) may seat directly in RSM (0303) without the need for a CSS (0306). In this context, RPE (0305) may lock against the vertical edges of the RSM (0303) which may necessitate a larger diameter RPE (0305).
According to yet another preferred exemplary embodiment, RPE (0305) may degrade over time in the well fluids eliminating the need to be removed before production. The RPE (0305) degradation may also be accelerated by acidic components of hydraulic fracturing fluids or wellbore fluids, thereby reducing the diameter of RPE (0305) enabling it to flow out (pump out) of the wellbore casing or flow back (pump back) to the surface before production phase commences.
In another preferred exemplary embodiment, RPE (0305) may be made of a metallic material, non-metallic material, a carbide material, or any other commercially available material.
Preferred Embodiment Multistage System Diagram (0500)The present invention may be seen in more detail as generally illustrated in
According to one aspect of a preferred exemplary embodiment, RSMs may be set by WST at desired locations to enable RPEs to create multiple hydraulic fracturing zones in the wellbore casing. The hydraulic fracturing zones may be equally spaced or unevenly spaced depending on wellbore conditions or hydrocarbon formation locations.
According to another preferred exemplary embodiment, RPEs are locked in place due to pressure differential established across RSMs. For example, RPE (0502) is locked in the seat of RSM (0512) due to a positive pressure differential established across RSM (0512) i.e., pressure upstream (hydraulic fracturing stages 0520, 0521 and stages towards heel of the wellbore casing) is greater than pressure downstream (hydraulic fracturing stages 0522, 0523 and stages towards toe of the wellbore casing).
According to a further preferred exemplary embodiment, RPEs (0501, 0502, 0503) may degrade over time, flowed back by pumping, or flowed into the wellbore, after completion of all stages in the wellbore, eliminating the need for additional milling operations.
According to a further preferred exemplary embodiment the RPE's may change shape or strength such that they may pass through a RSM in either the production (heel end) or injection direction (toe end). For example RPE (0512) may degrade and change shape such that it may pass through RSM (0511) in the production direction or RSM (0513) in the injection direction. The RPEs may also be degraded such that they are in between the RSMs of current stage and a previous stage restricting fluid communication towards the injection end (toe end) but enabling fluid flow in the production direction (heel end). For example, RPE (0502) may degrade such that it is seated against the injection end (toe end) of RSM (0511) that may have flow channels. Flow channels in the RSM are further described below in
According to yet another preferred exemplary embodiment, inner diameters of RSMs (0511, 0512, 0513) may be the same and large enough to allow unrestricted fluid flow during well production operations. The RSMs (0511, 0512, 0513) may further degrade in well fluids to provide an even larger diameter comparable to the inner diameter of the well casing (0504) allowing enhanced fluid flow during well production. The degradation could be accelerated by acids in the hydraulic fracturing fluids.
Preferred Exemplary Restriction Plug Elements (RPE)It should be noted that some of the material and designs of the RPE described below may not be limited and should not be construed as a limitation. This basic RPE design and materials may be augmented with a variety of ancillary embodiments, including but not limited to:
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- Made of multi layered materials, where at least one layer of the material melts or deforms at temperature allowing the size or shape to change.
- May be a solid core with an outer layer of meltable material.
- May or may not have another outer layer, such as a rubber coating.
- May be a single material, non-degradable.
- Outer layer may or may not have holes in it, such that an inner layer could melt and liquid may escape.
- Passage ways through them which are filled with meltable, degradable, or dissolving materials.
- Use of downhole temperature and pressure, which change during the stimulation and subsequent well warm up to change the shape of barriers with laminated multilayered materials.
- Use of a solid core that is degradable or erodible.
- Use of acid soluble alloy balls.
- Use of water dissolvable polymer frac balls.
- Use of poly glycolic acid balls.
As generally seen in the flow chart of
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- (1) installing the wellbore casing (0601);
- (2) deploying the WST along with the RSM to a desired wellbore location in the wellbore casing along with a perforating gun string assembly (GSA); the WST could be deployed by wireline, coil tube, or tubing-conveyed perforating (TCP) (0602); the perforating GSA may comprise plural perforating guns;
- (3) setting the RSM at the desired wellbore location with the WST; the WST could set RSM with a power charge or pressure (0603); The power charge generates pressure inside the setting tool that sets the RSM; the RSM may or may not have a conforming seating surface (CSS); the CSS may be machined or formed by the WST at the desired wellbore location;
- (4) perforating hydrocarbon formation with the perforating GSA; the perforating GSA may perforate one interval at a time followed by pulling the GSA and perforating the next interval in the stage; the perforation operation is continued until all the intervals in the stage are completed;
- (5) removing the WST and the perforating GSA from the wellbore casing; the WST could be removed by wireline, coil tube, or TCP (0605);
- (6) deploying the RPE to seat in the RSM isolating fluid communication between upstream (heel or production end) of the RSM and downstream (toe or injection end) of the RSM and creating a hydraulic fracturing stage; RPE may be pumped from the surface, deployed by gravity, or set by a tool; If a CSS is present in the RSM, the RPE may be seated in the CSS; RPE and CSS complementary shapes enable RPE to seat into the CSS; positive differential pressure may enable RPE to be driven and locked into the CSS (0606);
- (7) fracturing the hydraulic fracturing stage; by pumping hydraulic fracturing fluid at high pressure to create pathways in hydrocarbon formations (0607);
- (8) checking if all hydraulic fracturing stages in the wellbore casing have been completed, if not so, proceeding to step (0602); prepare to deploy the WST to a different wellbore location towards the heel end of the already fractured stage; hydraulic fracturing stages may be determined by the length of the casing installed in the hydrocarbon formation; if all stages have been fractured proceed to step (0609), (0608);
- (9) enabling fluid flow in the production (heel end) direction; fluid flow may been enabled through flow channels designed in the RSM while the RPEs are positioned in between the RSMs; fluid flow may also be been enabled through flow channels designed in the RPEs and RSMs; alternatively RPEs may also be removed from the wellbore casing or the RPEs could be flowed back to surface, pumped into the wellbore, or degraded in the presence of wellbore fluids or acid (0609); and
- (10) commencing oil and gas production from all the hydraulically fractured stages (0610).
One preferred embodiment may be seen in more detail as generally illustrated in
The diameter of the RPE (0702) is chosen such that it is less than the outer diameter and greater than the inner diameter of RSM (0703). The CSS (0704) and RPE (0702) may be complementary shaped such that RPE (0702) seats against CSS (0704). For example, RPE (0702) may be cylindrically shaped and CSS (0704) may be beveled shaped to enable RPE (0702) to seat in CSS (0704) when a differential pressure is applied. The RPE (0702) may pressure lock against CSS (0704) when differential pressure is applied.
It should be noted that, if a CSS is not present in the RSM (0703) or not formed by the WST, the cylindrical RPE (0702) may directly seat against the edges of the RSM (0703).
Preferred Embodiment Side View Dart Restriction Plug System Block Diagram (0900-1020)Yet another preferred embodiment may be seen in more detail as generally illustrated in
One preferred embodiment may be seen in more detail as generally illustrated in
Yet another preferred embodiment may be seen in more detail as generally illustrated in
Similarly,
As generally seen in the aforementioned flow chart of
As described above in steps (0601), (0602), and (0603)
A further preferred embodiment may be seen in more detail as generally illustrated in
According to yet another preferred embodiment, the RSMs may be designed with fingers on either end to facilitate milling operation, if needed. Toe end fingers (3302) and heel end fingers (3304) may be designed on the toe end and heel end the RSM (3306) respectively. In the context of a milling operation, the toe end fingers may be pushed towards the heel end fingers of the next RSM (toeward) such that the fingers are intertwined and interlocked. Subsequently, all the RSMs may be interlocked with each other finally eventually mill out in one operation as compared to the current method of milling each RSM separately.
Preferred Embodiment Wellbore Setting Tool (WST) System Double Set Block Diagram (3500-3700)As generally illustrated in
According to a preferred exemplary embodiment, a double set option is provided with a WST to seal one end of the RSM directly to the inner surface of the wellbore casing while the other end is sealed with a gripping element to prevent substantial axial and longitudinal movement.
Preferred Embodiment Wellbore Setting Tool (WST) System Multiple Set Block Diagram (3800-4100)As generally illustrated in
According to a preferred exemplary embodiment, the restricted sleeve member could still be configured with or without a CSS. The inner sleeve surface (ISS) of the RSM may be made of a polished bore receptacle (PBR). Instead of an independently pumped down RPE, however, a sealing device could be deployed on a wireline or as part of a tubular string. The sealing device could then seal with sealing elements within the restricted diameter of the internal sleeve surface (ISS), but not in the ICS surface. PBR surface within the ISS provides a distinct advantage of selectively sealing RSM at desired wellbore locations to perform treatment or re-treatment operations between the sealed locations, well production test, or test for casing integrity.
Preferred Embodiment Restriction Plug ElementRestriction plug element such as balls with large aspect ratio approaching 1 and seated in a large inner diameter restriction sleeve member do not degrade in wellbore fluids. The plug elements change shape from a circular to flying saucer shape because water is restricted on the edge and a sand pack that holds the ball on the seat prevents the plug element from interacting with the water and wellbore fluids. Therefore there is a need to add a mechanism to provide more surface area in the restriction plug element to contact with the restriction plug element after seating in a restriction sleeve member. According to a preferred exemplary embodiment, a partially hollow passage, (herein also referenced as a partial Flow channel) in the restriction plug element enables the plug element to seat in a restriction sleeve member during treatment and subsequently degrade to form a complete hollow passage so that there is a higher probability for water and wellbore liquids to back flow and degrade the restriction plug element. The complete flow channel dissolves or degrades not only the outside but also the inside of the wall of the restriction plug element. Initially the flow is restricted by the closed end in the partial hollow passage and over time the flow channel opens up by degradation and allows fluid to pass through in either direction. During back flow in the well new fluid is circulated into the well and the restriction plug element continues to degrade. It should be noted that the terms “flow channel” and “hollow passage” may hereinafter be interchangeably used referencing a hollow cavity within a restriction plug element.
According to a preferred exemplary embodiment, a restriction plug element for use in a wellbore casing may comprise a degradable material and be configured with a partial hollow passage extending from at least one interior end. The interior end configured to block fluid communication from upstream to downstream during fluid treatment and the partial hollow passage configured to degrade and form a complete hollow passage to enable said fluid communication subsequent to the fluid treatment.
According to another preferred exemplary embodiment the interior end is further configured with an terminus; the terminus configured to orient such that the restriction plug element seats in a restriction sleeve member and restricts substantial fluid bypass during a fluid treatment. The terminus may include any shape such as a nose, a conical shape, or a tail (arrow terminus). The orientation feature may enable changing the center of rotation so that there is a preferred rotation axis while the restriction plug element is being pumped down. For instance, a ball with a single hollow passage will preferentially rotate around the axis of that hollow passage, and therefore orient itself. It should be noted that ball may orient and may not orient but produce the same effect seating in a restriction sleeve member.
The hollow passage may be machined by drilling a cavity into a body of a degradable material restriction plug element (“ball”), such that there is a thinner web section that would degrade more quickly, creating a flow channel through the ball which further enhances degradation, and more surface area with which to speed the degradation rate of the composite ball. The pattern and the size of the holes will have design considerations so that they create a sufficient flow path or increase in surface area, while not compromising the seating of the ball. The holes could be drilled from one side leaving a web, or drilled from the outside to the center, leaving a small core which would need to degrade. The holes may be subsequently capped with degradable or non-degradable material. Small amounts of eutectic metal, or non-degradable metal, composite, or injection molded structures with flow channels could be used to support the inner structure of the ball. The altered center of mass could determine the likelihood that the ball would seat on any particular orientation. This could be manipulated advantageously in order to position the ball on the seat as desired. According to a preferred exemplary embodiment the ball seals when seated on restriction sleeve member during a fracture treatment while the holes in the partial hollow passage are not blocked to prevent the seating. An arrow tail or terminus on the interior end of the ball may force the ball to land in a sealing position (holes not on the seat). For example the ball may orient such that the hollow passage (flow channel) is substantially parallel to the wellbore casing in a horizontal well.
As generally illustrated in
According to a preferred exemplary embodiment the complete hollow passage enables the restriction plug element to deform such that the restriction plug element passes through a restriction sleeve member in the wellbore casing. According to another preferred exemplary embodiment a shape of the restriction plug element is selected from a group comprised of: circular, cylinder, sphere, oval or elongated. According to yet another preferred exemplary embodiment a shape of cross section of said hollow passage is selected from a group comprised of: circle, square, oval or elongated.
According to a preferred exemplary embodiment the partial hollow passage is capped at an open end with a degradable material. The open end and the interior end forming two ends of said hollow passage. For example, interior end (4203) and open end or surface end (4204) may form two ends of hollow passage (4201). The open end (4204) may be capped with a degradable material that degrades in the presence of wellbore fluids expected in the wellbore casing. According to another preferred exemplary embodiment the partial hollow passage extends to a surface of the restriction plug element.
According to another preferred exemplary embodiment the partial hollow passage may extend from one interior end to another interior end. For example interior end (4201) may not extend all the way to the surface but terminate interior to the core leaving a thin web section similar to section (4206). Therefore, the two ends of the hollow passage may be interior to the core. The thin sections of on either ends may degrade and form a complete open flow channel or passage. According to yet another preferred exemplary embodiment the partial hollow passage passes through a center of the restriction plug element. According to a further preferred exemplary embodiment the partial hollow passage does not pass through a center of the restriction plug element. For example passage (4201) may be slightly offset from the center and achieve a similar result as a passage that passes through the center of the plug element.
For example, flow channel (4301) and flow channel (4304) are aligned to each other and an axis through the channel may pass through the center of the restriction plug element (4300). Similarly flow channel (4302) and flow channel (4305), flow channel (4303) and flow channel (4306) may be aligned to each other. The partial flow channels may further degrade and form complete flow channels extending diametrically or cordially from a surface end/hole to another surface hole/end. The increased surface area in the completed flow channels may further enhance the degradation of the restriction plug element (4300). A perspective view (4310) of the restriction plug element is generally illustrated in
According to a preferred exemplary embodiment at least one of the partial hollow passage intersects with at least one other partial hollow passage. For example, partial flow channel (4302) may be drilled with an angle such that it intersects channel (4301) or channel (4303) depending on the angle of drilling.
According to a preferred exemplary embodiment at least one of the partial hollow passages does not intersect with any other partial hollow passage. For example, all the partial hollow passages in
According to another preferred exemplary embodiment at least one of the partial hollow passages comprises a plurality of interior ends. The plurality of interior ends may be spread out or fanned out. For example, one partial hollow passage may form plural passage ways with a plurality of interior ends that degrade and complete the channels. An end view (4310) of restriction plug element (4300) is generally illustrated in
According to another preferred exemplary embodiment, the restriction plug element may comprise at least one partial hollow passage extending to a surface of the restriction plug element on both ends of said flow channel creating a complete passage. For example, as illustrated in an end view of
As generally seen in the flow chart of
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- (1) deploying the restriction plug element into the wellbore casing and blocking fluid communication (4601);
- The restriction plug element may be pumped down or dropped down to seat in a restriction sleeve member at a desired location.
- (2) orienting the restriction plug element with the interior end to seat in a restriction sleeve member and isolating a stage (4602);
- An arrow tail or terminus on the interior end of the ball may force the ball to land in a sealing position (holes not on the seat). For example the ball may orient such that the hollow passage (flow channel) is substantially parallel to the wellbore casing in a horizontal well. According to a preferred exemplary embodiment, the orienting step (4602) further seals the restriction plug element to restrict substantial fluid bypass in the treating step (4603). According to another preferred exemplary embodiment the orienting step (4602) orients the restriction plug element such that the hollow passage is unblocked by the restriction sleeve member. The terminus may include any shape such as a nose, a conical shape, or a tail (arrow terminus). The orientation feature may enable changing the center of rotation so that there is a preferred rotation axis while the restriction plug element is being pumped down. For instance, a ball with a single hollow passage will preferentially rotate around the axis of that hollow passage, and therefore orient itself. It should be noted that ball may orient and may not orient but produce the same effect seating in a restriction sleeve member. Therefore, orienting step (4602) may be skipped during the degradation method. A complete passage or partial passage may be designed such that orienting is important, where it will always orient, or where orienting is unimportant. The passage may be partial or complete. The complete hollow passage may provide some of the same benefits as a partial passage if the ball is configured to seat in such a way as the passage does not communicate across a restriction sleeve member. If the complete passage does communicate across the restriction sleeve, but is small enough, the same effect of increased surface area and dissolve rate may be achieved.
- (3) treating the isolated stage with fracturing fluids (4603);
- The restriction plug elements seats and seals in a restriction sleeve member during the treatment stage.
- (4) degrading from the interior end in the partial hollow passage through contact with wellbore fluids (4604);
- The interior end starts degrading a thin section and allowing contact of well fluids with the restriction plug element. According to another preferred exemplary embodiment the degrading step (4604) occurs immediately after the treating step (4603).
- (5) creating a complete hollow passage from the partial hollow passage (4605); and The partial hollow passage or flow channel may be transformed into a complete flow channel when the thin section completely degrades. According to another preferred exemplary embodiment the creating step (4605) accelerates rate of degradation of the restriction plug element.
- (6) unblocking the fluid communication (4606).
- (1) deploying the restriction plug element into the wellbore casing and blocking fluid communication (4601);
According to a further preferred exemplary embodiment the step of degrading the restriction plug element to deform.
According to a most preferred exemplary embodiment a ratio of diameter of the restriction plug element to an inner diameter of the restriction sleeve member ranges from 0.5 to 0.99.
Mass Vs Time and Diameter Vs Time of a Solid Ball and a Preferred Exemplary Hollow Passage Restriction Plug Element (4700-4800)The present invention system anticipates a wide variety of variations in the basic theme of extracting gas utilizing wellbore casings, but can be generalized as a restriction plug element for use in a wellbore casing, the restriction plug element comprising a degradable material; the restriction plug element configured with a partial hollow passage extending from at least one interior end; the interior end configured to block fluid communication from upstream to downstream during fluid treatment; and the partial hollow passage configured to degrade and form a complete hollow passage to enable the fluid communication subsequent to the fluid treatment.
This general system summary may be augmented by the various elements described herein to produce a wide variety of invention embodiments consistent with this overall design description.
Method SummaryThe present invention method anticipates a wide variety of variations in the basic theme of implementation, but can be generalized as a restriction plug element degradation method, the method operating in conjunction with a restriction plug element (RPE) for use in a wellbore casing, the restriction plug element comprising a degradable material; the restriction plug element configured with at least one partial hollow passage that extends from an interior end;
-
- wherein the method comprises the steps of:
- (1) deploying the restriction plug element into the wellbore casing and blocking fluid communication;
- (2) orienting the restriction plug element with the interior end to seat in a restriction sleeve member and isolating a stage;
- (3) treating the isolated stage with fracturing fluids;
- (4) degrading from the interior end in the partial hollow passage through contact with wellbore fluids;
- (5) creating a complete hollow passage from the partial hollow passage; and
- (6) unblocking the fluid communication.
This general method summary may be augmented by the various elements described herein to produce a wide variety of invention embodiments consistent with this overall design description.
System/Method VariationsThe present invention anticipates a wide variety of variations in the basic theme of oil and gas extraction. The examples presented previously do not represent the entire scope of possible usages. They are meant to cite a few of the almost limitless possibilities.
This basic system and method may be augmented with a variety of ancillary embodiments, including but not limited to:
-
- An embodiment wherein the interior end is further configured with an arrow terminus; the arrow terminus configured to orient such that the restriction plug element seats in a restriction sleeve member and restricts substantial fluid bypass during the fluid treatment.
- An embodiment wherein the partial hollow passage substantially increases a surface area of contact of the restriction plug element with fluids expected in the wellbore casing.
- An embodiment wherein the partial hollow passage is capped at an open end with a degradable material; the open end and the interior end forming two ends of the hollow passage.
- An embodiment wherein the partial hollow passage extends from the interior end to another interior end.
- An embodiment wherein the partial hollow passage extends to a surface of the restriction plug element.
- An embodiment further comprises at least one partial hollow passage extending to a surface of the restriction plug element on both ends of the flow channel.
- An embodiment wherein the partial hollow passage passes through a center of the restriction plug element.
- An embodiment wherein at least one of the partial hollow passages intersects with at least one other partial hollow passage.
- An embodiment wherein at least one of the partial hollow passages does not intersect with any other partial hollow passage.
- An embodiment wherein at least one of the partial hollow passages comprises a plurality of interior ends; the plurality of interior ends are configured to be spread out.
- An embodiment whereby the complete hollow passage enables the restriction plug element to deform such that the restriction plug element passes through a restriction sleeve member in the wellbore casing.
- An embodiment wherein at least one of the partial hollow passages is aligned to another partial hollow passage.
- An embodiment wherein a shape of the restriction plug element is selected from a group comprised of: circular, cylinder, sphere, oval or elongated.
- An embodiment wherein a shape of cross section of the hollow passage is selected from a group comprised of: circle, square, oval or elongated.
One skilled in the art will recognize that other embodiments are possible based on combinations of elements taught within the above invention description.
CONCLUSIONA restriction plug element and method for positioning plugs to isolate fracture zones in a horizontal, vertical, or deviated wellbore has been disclosed. The restriction plug element includes a partial hollow passage with an interior end. The partial passage enables the plug element to seat in a restriction sleeve member during treatment and subsequently degrade to form a complete hollow passage. The complete flow channel dissolves or degrades not only the outside but also the inside of the wall of the restriction plug element. Initially the flow is restricted by the closed end in the partial hollow passage and over time the flow channel opens up by degradation and allows fluid to pass through in either direction. During back flow in the well, new fluid is circulated into the well and the restriction plug element continues to degrade.
CLAIMSAlthough a preferred embodiment of the present invention has been illustrated in the accompanying drawings and described in the foregoing Description, it will be understood that the invention is not limited to the embodiments disclosed, but is capable of numerous rearrangements, modifications, and substitutions without departing from the spirit of the invention as set forth and defined by the following claims.
Claims
1. A restriction plug element for use in a wellbore casing, said restriction plug element comprising a degradable material; said restriction plug element configured with a partial hollow passage extending from at least one interior end; said interior end configured to block fluid communication from upstream to downstream during fluid treatment; and said partial hollow passage configured to degrade and form a complete hollow passage to enable said fluid communication subsequent to said fluid treatment.
2. The restriction plug element of claim 1 wherein said interior end is further configured with a terminus; said terminus configured to orient such that said restriction plug element seats in a restriction sleeve member and restricts substantial fluid bypass during said fluid treatment.
3. The restriction plug element of claim 1 wherein said partial hollow passage substantially increases a surface area of contact of said restriction plug element with fluids expected in said wellbore casing.
4. The restriction plug element of claim 1 wherein said partial hollow passage is capped at an open end with a degradable material; said open end and said interior end forming two ends of said partial hollow passage.
5. The restriction plug element of claim 1 wherein said partial hollow passage extends from said interior end to another interior end.
6. The restriction plug element of claim 1 wherein said partial hollow passage extends to a surface of said restriction plug element.
7. The restriction plug element of claim 1 further comprises at least one of said partial hollow passages extending to said surface of said restriction plug element on both ends of a flow channel.
8. The restriction plug element of claim 1 wherein said partial hollow passage passes through a center of said restriction plug element.
9. The restriction plug element of claim 1 wherein at least one said partial hollow passage intersects with at least one other partial hollow passage.
10. The restriction plug element of claim 1 wherein at least one said partial hollow passage does not intersect with any other said partial hollow passage.
11. The restriction plug element of claim 1 wherein at least one said partial hollow passage comprises a plurality of interior ends; said plurality of interior ends are configured to be spread out.
12. The restriction plug element of claim 1 whereby said complete hollow passage enables said restriction plug element to deform such that said restriction plug element passes through a restriction sleeve member in said wellbore casing.
13. The restriction plug element of claim 1 wherein at least one of said partial hollow passage is aligned to another partial hollow passage.
14. The restriction plug element of claim 1 wherein a shape of said restriction plug element is selected from a group comprising: circular, cylinder, sphere, oval or elongated.
15. The restriction plug element of claim 1 wherein a shape of cross section of said hollow passage is selected from a group comprising: circle, square, oval or elongated.
16. A restriction plug element degradation method, said method operating in conjunction with a restriction plug element (RPE) for use in a wellbore casing, said restriction plug element comprising a degradable material; said restriction plug element configured with at least one partial hollow passage that extends from an interior end;
- wherein said method comprises the steps of:
- (1) deploying said restriction plug element into said wellbore casing and blocking fluid communication;
- (2) orienting said restriction plug element with said interior end to seat in a restriction sleeve member and isolating a stage;
- (3) treating said isolating stage with fracturing fluids;
- (4) degrading from said interior end in said partial hollow passage through contact with wellbore fluids;
- (5) creating a complete hollow passage from said partial hollow passage; and
- (6) unblocking said fluid communication.
17. The restriction plug element degradation method of claim 16 wherein said orienting step (2) further seals said restriction plug element to restrict substantial fluid bypass in said treating step (3).
18. The restriction plug element degradation method of claim 16 wherein said orienting step (2) orients said restriction plug element such that said hollow passage is unblocked by said restriction sleeve member.
19. The restriction plug element degradation method of claim 16 wherein said orienting step (2) seats said restriction plug element but not orientated.
20. The restriction plug element degradation method of claim 16 wherein said degrading step (4) occurs immediately after said treating step (3).
21. The restriction plug element degradation method of claim 16 wherein said creating step (5) accelerates rate of degradation of said restriction plug element.
22. The restriction plug element degradation method of claim 16 further comprises the step of degrading said restriction plug element to deform.
23. The restriction plug element degradation method of claim 16 wherein a ratio of diameter of said restriction plug element to an inner diameter of said restriction sleeve member ranges from 0.5 to 0.99.
Type: Application
Filed: Apr 5, 2016
Publication Date: Dec 8, 2016
Applicant: GEODynamics, Inc. (Millsap, TX)
Inventors: John T. Hardesty (Weatherford, TX), Michael D. Wroblicky (Weatherford, TX)
Application Number: 15/090,953