Patent Application
20220065080
Not applicable.
Not applicable.
Not applicable.
Not applicable.
Reserved for a later date, if necessary.
The disclosed subject matter is in the field of unconventional multistage well completions and perforating systems in conjunction with fracking operations.
Petroleum or crude oil and Natural Gas are keystone natural resources. Petroleum may be used to make gasoline which is an important resource of the transportation industry. Petroleum may also be used to make other items such as tires, refrigerators, life jackets, and anesthetics. Natural gas may be used for heating, cooking, electricity generation, or as fuel for vehicles. Beyond its utility as an energy resource, natural gas may also be used as a chemical feedstock for plastics or organic chemicals. In view of the foregoing, anyone can appreciate the need for technologies and related new methods of producing petroleum and natural gas.
One issue with producing crude oil and natural gas is that these products are generally found deep underground in rock formations. The underground location of these resources makes both oil and gas difficult to find and extract. But, because oil and gas are incredibly valuable, an entire industry has been built around the exploration, extraction, and processing of oil and gas.
Oil or natural gas extraction from an underground rock formation requires the drilling of a hole or wellbore into the formation. Many different methods exist by which the oil or natural gas can be brought to the surface via the wellbore. In one method, oil may be recovered with artificial lifting mechanisms such as beam pumps, electrical submersible pumps, or by injecting fluids such as water, steam, or carbon dioxide into a reservoir to increase reservoir pressure and enable the oil or natural gas to flow to surface. Using this method, the amount of oil and gas recovered relative to the amount of oil and gas in the reservoir or recovery rate is determined in part by the geology of the well formation. Particularly important to recovery rates are the permeability and the porosity of the rock formation. For instance, Shale rock formations tends to be more impermeable, inhibiting fluid flows while more permeable Sandstone rock formation allows fluids to flow more freely yielding higher recovery rates.
When attempting to recover oil or gas from a more impermeable rock formation (unconventional formation), it may be necessary to perform extra steps to increase formation permeability and recovery rates by stimulating the well. There are few stimulation methods that are useful such as explosives, acid injection and hydraulic fracking. The most common, safe, and beneficial stimulation method in these troublesome rock formations is hydraulic fracking.
Hydraulic fracturing or fracking is a well stimulation technique that involves injecting fracking fluids consisting of water, chemicals and proppants under high pressure into well formations to crack reservoir rock thus allowing for petroleum, or natural gas to flow substantially uninhibited. After the complete fracking is done, the injected fluids are flowed back from the well back to surface but leaving the hydraulic proppants within formation rock cracks to enable oil and gas continuous flow. Recently, hydraulic fracking has become a widespread stimulation method because of increased recovery rates and new accessibility to unconventional reservoirs such as shale formations, tight sands and coals beds brought about by advances in drilling technology. Hydraulic fracking in conjunction with new drilling techniques like directional drilling, multi-well pads, seismic monitoring, and the like, has changed the economics and the landscape of shale gas production leading to a fracking boom in the United States.
Before fracking, the United States' oil production had been steadily declining for decades and had become highly susceptible to changes in supply from foreign exporters. However, fracking and its related advances in shale production technology and methods has led the United States to become a net oil exporter and energy independent. In the United States, Shale oil production increased eight-fold after fracking was commonplace.
Unconventional reservoirs within Oil and Gas industry are tight formation rocks and in general cannot be produced unless they are fractured, and therefore the completions and processes for producing unconventional wells are unique and different than any other sector. It starts with drilling wells that penetrate the target formation covering 5,000 to 10,000 ft of horizontal reservoir section. Casing is run right after drilling the open hole section followed by cement operation to secure the casing and establish well integrity. Hydraulic fracturing is the chosen stimulation for developing nearly all unconventional reservoirs economically using fracturing fluid, propping material, and pressure to create or restore small fractures in a geological formation and thereby to stimulate hydrocarbon production from oil or gas wells. In this process, hydraulic fracturing fluid is pumped from surface into the wellbore traveling downhole till it reaches some perforated holes at a predetermined depth. The fluid travels through these holes across the casing and surrounding cement into the reservoir to break the rocks and creates conductive flow paths between the target reservoir and the wellbore. The high volume and high-pressured fluids create or restore fractures in the rocks so that hydrocarbon can move from geologic formations to fractures then to wellbores. The unconventional wells are completed in stages, usually ranges from 20 to 60 stages per well across the lateral section. Each stage consists of one isolation plug and multiple clusters (5 to 20 clusters) that are usually distributed across the stage with specific hole (shot) size, number of holes per foot, and with specific orientation across the casing depending on the frac design.
Wireline (or Electric Line) is the most common method for perforating (creating holes) and isolating each stage (via plugs). This is achieved by pumping the perforating guns and plug downhole utilizing water pumps to the desired depth and then setting the plug before initiating the perforating guns via Electric Wireline cable. This provides simple, quick depth control and gun selectivity along with reduced safety risks of personnel and equipment. Pump Down Perforating (PDP) or Plug and Perf (PNP) means Wireline conveyed perforating services where fluid flow is used to transfer a plug and perforation assembly into a horizontal unconventional completion including associated depth control logging services. The detonating objective of a perforating gun is to provide holes within casing and achieve effective flow communication of frac fluid between the cased wellbore and productive reservoir. To achieve this, the perforating gun “penetrates” a pattern of perforations through the casing and cement sheath and into the productive formation. The gun usually contains several shaped explosive charges and available in different ranges of sizes and configurations.
The unconventional fracking operation is carried out by fracking one stage at a time till all stages are completed. The overall steps of multistage fracking operation now days are as follow:
Wireline Pump Down Perforating (PDP) always strive to avoid being on any critical path during frac operation, this is due to the high cost associated with Frac fleet. PDP operation can fall within below two operational scenarios:
The following is a listing of related art.
U.S. Pat. No. 9,085,969 to Clay, shown above, which discloses, “Bi-directional shaped charges for perforating a wellbore.”
US20110017453A1 to Mytopher discloses a, “Wellbore subassembly with a perforating gun.”
US20050178554A1 to Hromas discloses a, “Technique and Apparatus for Multiple Zone Perforating.”
U.S. Pat. No. 6,009,947 to Wilson discloses a, “Casing conveyed perforator.”
U.S. Pat. No. 4,154,303 to Fournier discloses a, “Valve assembly for controlling liquid flow in a wellbore.”
US20180051532A1 to Smith discloses a, “Frac Plug with Integrated Flapper Valve.”
US20130008671A1 to Booth discloses a, “Wellbore plug and method.”
U.S. Pat. No. 10,502,026 to Saraya discloses, “Methods and systems for fracing.”
U.S. Ser. No. 10/563,476 to Smith discloses a, “Frac plug with integrated flapper valve.”
US20050115708A1 to Jabusch discloses a, “Method and system for transmitting signals through a metal tubular.”
U.S. Pat. No. 6,536,524 to Snider discloses a, “Method and system for performing a casing conveyed perforating process and other operations in wells.”
WO2000065195A1 to Snider discloses a, “Casing conveyed perforating process and apparatus.”
U.S. Pat. No. 5,660,232 to Reinhardt discloses a, “Liner valve with externally mounted perforation charges.”
U.S. Pat. No. 8,127,832 to Bond discloses, “Well stimulation using reaction agents outside the casing.”
U.S. Pat. No. 9,664,013 to Coffey discloses, “Wellbore subassemblies and methods for creating a flowpath.”
U.S. Pat. No. 4,832,134 to Gill discloses a, “Shaped charge assembly with retaining clip.”
U.S. Ser. No. 10/246,974 to Greenway discloses a, “Punch and cut system for tubing.”
CA2953571C to Tolman discloses, “Methods for multi-zone fracture stimulation of a well.”
CN101148982A to Huisheng discloses a, “Side direction detonation symmetrical dual action perforator.”
U.S. Pat. No. 6,684,954 to George discloses a, “Bi-directional explosive transfer subassembly and method for use of same.”
U.S. Pat. No. 5,603,379 to Henke discloses a, “Bi-directional explosive transfer apparatus and method.”
The main objective of this invention is to eliminate the Wireline Pump Down Perforating (PDP) process and replace it with an innovative electric behind casing perforating and isolation system. It is mainly applicable to the unconventional well completion applications. However, this invention can be also utilized in many different completion applications which involve perforating operations, for example it can replace the Tubing Conveyed Perforating system (TCP) within normal well completions.
The invention approach is to install the perforating guns/charges and the isolation valves control mechanisms on the outside (behind) casing. The isolation valve itself is to be installed inside casing to enable the stage isolation. The casing assembly is then lowered into the open hole drilled section as per normal methods. The cementing operation to be done after casing is in place as per current existing procedures. This novel system will enable direct communication from surface with the perforating guns and isolation valves via one or combination of an electrical cable behind casing, series of acoustic repeaters/receivers behind casing, electromagnetic repeaters/receivers behind casing or fluid pressure pulses within casing.
Below are the three major system components (surface, communication and downhole) of the behind casing perforating and isolation system along with all its sub-components from top of well head all the way to the lateral casing downhole:
Surface System:
This is the surface electronic system which will communicate with all downhole electronic components including addressable switches, perforating guns, detonators, and isolation valve control assemblies. The system has the telemetry software which enable shooting guns/stages selectively by communicating with a specific downhole electric addressable switch to initiate the perforating detonator. As well the system communicates with the isolation valve control assembly to initiate the closure of the downhole isolation valve inside the casing.
Communication System:
The communication system is the means of sending the command from surface to shoot a detonator downhole, activate an isolation valve downhole or get confirmation of downhole event back to surface. It can also be the means of communication between different downhole stage assemblies. The communication is achieved by using one or combination of below four options:
1. Electric Cable: The electric cable enables continuous communication between surface system and downhole components. It is run behind casing utilizing cable clamps to secure around the casing. The cable is typically connected to the ballistic electric interface assembly. An example of this cable can be the one that is currently used with the submersible pump systems.
2. Acoustic Repeaters: An acoustic communication system which enable sending and receiving acoustic signals through casing. This can be achieved via acoustic repeaters or similar telemetry component installed behind casing.
3. Electromagnetic waves: An electromagnetic waves communication system which enable sending and receiving electromagnetic signals through casing and rock formation. This can be achieved via electromagnetic repeaters/receivers or similar telemetry component installed behind casing.
4. Fluid Pressure Pulse: A fluid pressure pulse system that utilizes pressure pulses created at surface by a telemetry pump or variable pressure source. These pulses travel within the fluid system inside casing in which the commands are usually converted into an amplitude- or frequency-modulated pattern of fluid pulses that is received downhole by a specific downhole pressure receiver.
Downhole System:
The downhole system consists of multiple stages which can reach up to 60 stages depending on the well completion design. Each stage assembly consists of several gun assemblies and one ballistic isolation valve assembly connected to each other in series via downhole communication components explained in this document.
Below is full explanation of downhole stage assembly three sub-components:
1. Gun Assembly: Each stage has multiple gun assemblies depending on the stage design. The gun assembly itself consists of the following components:
a. Gun Housing: This is the housing that is attached to casing and surrounding it at the same time. It can be installed in a spiral way outside of casing body and contains all gun assembly components inside to protect it from damage during running casing in hole and cement operation later. The gun housing can be made of metal, composite, or any other material.
b. Addressable Switch: This is an electronic device that has a specific electronic unique address which is read by the surface acquisition system. The addressable switch can be combined with the explosive detonator in one assembly as well. The AS allows shooting all guns within same stage which are connected via ballistic electric line. It eliminates the need to have it installed in each gun assembly within the stage but needs to be installed within the first gun assembly of each full stage to allow shooting the whole stage guns with one addressable switch.
c. Explosive Detonator: This is the detonator that comes after the addressable switch and connects to the explosive detonating cord which goes through the explosive perforating charges. The explosive detonator and addressable switch can be combined in one assembly.
d. Explosive Detonating Cord: This is the cord that contains the explosives inside to transfer the ballistic force from the detonator to explosive charges.
e. Explosive Dual Action Perforating Charges: These charges can be distributed with any specific shot density and phasing. The charges will either face borehole to make a hole in casing or formation to penetrate the reservoir rock. The objective of these charges is to establish connectivity between borehole and formation which enable Frac fluid to reach the formation during frac operation. There two options for configuring these charges; either two separate charges opposite in direction with one separate detonating cord for each charge (total two detonating cords) or one combined charge with two opposite jet directions (one detonating cord).
2. Downhole Communication Components: The main purpose of these components is to accomplish communication between the gun assemblies and ballistic valve isolation assembly within each stage. It consists of the below optional items depending on the desired to communication method:
a. Ballistic Electric Line: The function of this line is to establish electric and ballistic communication within each stage which consists of several gun assemblies and one ballistic isolation valve assembly. It consists of a steel pipe that has a detonating cord inside with an electric line which can be coax (surrounding the detonating cord) or solid (adjacent to detonating cord).
b. Ballistic Electric Interface: This interface instrument objective is to enable the transition from electric cable to the ballistic electric control line or the other way around.
3. Isolation Valve Assembly: This assembly has only the isolation valve itself inside casing while all other control and initiation mechanisms are placed behind casing. It consists of following components:
a. Isolation Valve Housing: This is the housing that is attached to casing and surrounding it at the same time. It is installed outside of the casing body and contains isolation explosive detonator and isolation release assembly components inside to protect it from damage during running casing in hole and cement operation later. The isolation valve housing can be made of metal, composite, or any other material.
b. Addressable Switch: This is an electronic device that has a specific electronic unique address which is read by the surface acquisition system. The addressable switch can be combined with the explosive detonator in one assembly as well. The addressable switch also allows activating the isolation valve inside casing after triggering the detonator which is connected to the isolation release assembly. Every ballistic isolation valve assembly has one addressable switch connected to it to allow triggering that specific isolation valve assembly.
c. Isolation Explosive Detonator: This detonator is connected to downhole communication system as well as the isolation release assembly.
d. Isolation Release Assembly: This is the assembly which activates the isolation valve to shut inside the casing. It has a release rod or another suitable mechanism that prevents the isolation valve from closing unless the isolation explosive detonator was shot.
e. Isolation Valve: This is the isolation valve itself which exist inside the casing and can be only shut in if the isolation release assembly was triggered by the Isolation explosive detonator or similar functional device. This can be a flapper valve, ball valve or any other suitable isolation valve.
Step by Step and Operational Procedure:
The electric behind casing perforating and isolation system can work as per the following generic steps:
1. The supervisor sends a signal from surface to the addressable switch of the deepest isolation valve to trigger shooting the detonator that initiates the isolation release assembly to close the isolation valve inside casing. The confirmation of valve closure can be checked by pumping in fluid right after or via a confirmation signal from a downhole sensor.
2. The supervisor then sends a command to the correct addressable switch to trigger the detonation of the 1st stage which is the deepest in depth and right above the isolation valve that was closed in previous step. The stage contains multiple gun assemblies depending on well completion design. Gun assemblies within same stage assembly can be all fired at once if utilizing electric cable communication. This is accomplished via the ballistic electric line which contains the detonating cord to transfer the ballistic energy. Another option would be to shoot each gun assembly separately if utilizing the acoustic repeaters, electromagnetic waves, or pressure pulse communication systems. In case the electric cable communication is used then the addressable switch can be mounted inside top gun of the stage (in case the configuration is top bottom shooting) or the deepest gun of the stage (in case the configuration is bottom up shooting).
3. Frac operation is then done across the perforated guns within the specific stage by pumping frac fluid at high pressure and volume as per the completion design.
4. Once Frac operation is completed, supervisor repeats previous three steps for the next stage moving up hole. This operation is repeated till all stages within the well are completed.
5. Coiled tubing or any other suitable intervention comes after all stages are completed to drill or reopen all isolation valves and put the completed (fracked) well on production. (note: some isolation valves are dissolvable and do not need drilling with coiled tubing).
Benefits of the Invention:
The behind casing well perforating and isolation system may be preferable to traditional perforation systems because the behind casing perforating and isolation system eliminates or substantially reduces the need for wireline operation, pumps, and water. The elimination of these components may create environmental, efficiency, and cost benefits. The elimination or reduction of the pumps has major potential environmental benefits. Pump elimination or reduction is estimated to save, on a yearly basis, billions of barrels of water, millions of gallons of diesel fuel, and decrease greenhouse gas emission (CO2, NOX, CO, unburned Hydrocarbons) by about 20 million metric tons. There may also be an anticipated 20% yearly cost reduction and an expected 30% gain in pumping hour efficiency due to elimination or reduction of pump down perforating methods, pumps, and water. The behind casing well perforating and isolation system may facilitate a 30% fracking fleet reduction yielding a significant reduction in total asset costs.
The behind casing well perforating and isolation system may also increase efficiency by eliminating standby time, well switching time, time lost during wireline operations, time spent opening and closing well heads, and time spent pressure testing between stages. The behind casing well perforating and isolation system is expected to increase fracking efficiency by roughly 40% to 60%, yielding more than 20 pumping hours daily. Further, the behind casing well perforating and isolation system may enable operators to frack each well completely before moving to the next well within same pad.
Other objectives of the disclosure will become apparent to those skilled in the art once the invention has been shown and described. The manner in which these objectives and other desirable characteristics can be obtained is explained in the following description and attached figures in which:
It is to be noted, however, that the appended figures illustrate only typical embodiments of this invention and are therefore not to be considered limiting of its scope, for the invention may admit to other equally effective embodiments that will be appreciated by those reasonably skilled in the relevant arts. Also, figures are not necessarily made to scale but are representative.
Disclosed may be a behind casing well perforating and isolation system and methods. The system and related devices may be generalized as a fracking, perforating and isolation system that places explosive charges and isolation valve control mechanism on the outside of the metal well casing while keeping the isolation valve itself inside casing. It utilizes a form of communication to surface that allows shooting these explosive charges and controlling the isolation valve. The more specific details of this system, devices, and related methods are disclosed in connection with the figures.
The behind casing well perforating and isolation system 1 is a departure in some ways from traditional fracking systems. Like traditional systems, the behind casing well perforating system 1 penetrates the casing 11, cement liner 12, and a formation rock 13. However, the behind casing well perforating system 1 differs from traditional systems in that the behind casing well perforating system 1 (a) places a plurality of dual action perforation gun assemblies 8 outside the casing 11 instead of inside the casing 11, (b) features isolation valve release mechanisms outside casing 11 combined with isolation valves 9 (flapper valve in this example) inside casing 11 instead of traditional plugs which is run with wireline 9, and, (c) allows for direct continuous communication between the surface system 2 and perforating gun assemblies 8 via an electrical cable 3, series of acoustic repeaters 4, electromagnetic communication or pressure pulse sensor 19, or a combination of all.
As mentioned, frac operations uses multiple stage assemblies 6 to perforate a wellbore 14. Using multiple stage assemblies 6 allows wellbore 14 to be thoroughly perforated and completed at the lateral reservoir section. As shown an electric cable 3 is connected to a ballistic interface box 5 which uses a ballistic electric control line 7 to connect a plurality of stage assemblies 6. A typical stage operation starts with sending an electric signal to activate the closure of isolation valve 9 which is part of the isolation valve assembly 15. After confirming the isolation valve 9 closure (flapper valve in this example), an electric signal is sent to shoot all charges 8a which are arranged inside multiple gun assemblies 8 within the stage assembly 6 right above the closed isolation valve 9. Once all gun assemblies 8 within the stage assembly 6 are shot then the fracking pumps can start the fracking operation within the same stage. This typical stage operation is repeated till all stages within the wellbore 14 lateral reservoir section are completed.
Since there are no plugs, the behind casing perforating and isolation system 1 employs an isolation valve assembly 15. As shown by
The addressable switch 8b has a unique electronic address which is read by the surface acquisition system 2. The addressable switch 8b allows the isolation valve 9 (flapper, ball or similar) to be activated inside casing after triggering the detonator 15c which is connected to the release mechanism 15a. Every valve assembly 15 has one addressable switch 8b to allow specific activation of the valve assembly 15. Activating the detonator 15c may release the rod 15a which closes the isolation valve 9 (flapper, ball or similar) inside the casing 11. This isolation valve 9 closure is followed by shooting gun assemblies 8 within that specific stage assembly 6 which enables fracking operation to start right after.
A critical element of perforation operations is a gun assembly 8 explained in
Although the method and apparatus is described above in terms of various exemplary embodiments and implementations, it should be understood that the various features, aspects and functionality described in one or more of the individual embodiments are not limited in their applicability to the particular embodiment with which they are described, but instead might be applied, alone or in various combinations, to one or more of the other embodiments of the disclosed method and apparatus, whether or not such embodiments are described and whether or not such features are presented as being a part of a described embodiment. Thus, the breadth and scope of the claimed invention should not be limited by any of the above-described embodiments.
Terms and phrases used in this document, and variations thereof, unless otherwise expressly stated, should be construed as open-ended as opposed to limiting. As examples of the foregoing: the term “including” should be read as meaning “including, without limitation” or the like, the term “example” is used to provide exemplary instances of the item in discussion, not an exhaustive or limiting list thereof, the terms “a” or “an” should be read as meaning “at least one,” “one or more,” or the like, and adjectives such as “conventional,” “traditional,” “normal,” “standard,” “known” and terms of similar meaning should not be construed as limiting the item described to a given time period or to an item available as of a given time, but instead should be read to encompass conventional, traditional, normal, or standard technologies that might be available or known now or at any time in the future. Likewise, where this document refers to technologies that would be apparent or known to one of ordinary skill in the art, such technologies encompass those apparent or known to the skilled artisan now or at any time in the future.
The presence of broadening words and phrases such as “one or more,” “at least,” “but not limited to” or other like phrases in some instances shall not be read to mean that the narrower case is intended or required in instances where such broadening phrases might be absent. The use of the term “assembly” does not imply that the components or functionality described or claimed as part of the module are all configured in a common package. Indeed, any or all the various components of a module, whether control logic or other components, might be combined in a single package or separately maintained and might further be distributed across multiple locations.
Additionally, the various embodiments set forth herein are described in terms of exemplary block diagrams, flow charts and other illustrations. As will become apparent to one of ordinary skill in the art after reading this document, the illustrated embodiments and their various alternatives might be implemented without confinement to the illustrated examples. For example, block diagrams and their accompanying description should not be construed as mandating a particular architecture or configuration.
All original claims submitted with this specification are incorporated by reference in their entirety as if fully set forth herein.
