Patent Abstract:
An automated flowback system allows control and operation of the system from a remote location away from the dangers of high-pressure gases or abrasives traveling at high velocities that cause damage or failure to equipment piping valves. The system provides techniques and mechanical components installed in flowlines in any position without having to cut and thread, weld or fabricate pipe to fit. This system includes an expansion coupling with axial adjusting lengths adequate to compensate for variations between two points. The expansion coupling is secured and installed into position eliminating field cut and threading, welding or fabrication. The system also includes a blast barrel with an installed choke nipple, choke bean or choke insert with a chosen orifice size for multiple chambered ports. The blast barrel retracts between two fixed points without having to dismantle any connections or be removed from the fluid flow.

Full Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application is based on U.S. Provisional Application Ser. No. 60/787,456, entitled “Automated Flowback and Information System” filed on Mar. 30, 2006, and is a Divisional Application of U.S. patent application Ser. No. 11/731,382, entitled “Automated Flowback and Information System” filed Mar. 29, 2007, now allowed, and owned by the Applicant hereof, and hereby expressly incorporated by reference herein. 
     
    
     BACKGROUND OF THE INVENTION 
       [0002]    1. Field of the Invention (Technical Field) 
         [0003]    The present invention relates to oil and gas wells, and more particularly to a system for providing a controlled flowback from the wellbore after a treatment procedure. 
         [0004]    2. Background Art 
         [0005]    Most oil and gas wells require some form of stimulation to enhance hydrocarbon flow to make or keep them economically viable. The servicing of oil and gas wells to stimulate production requires the pumping of fluids under high-pressure. The fluids are generally corrosive and abrasive because they are frequently laden with corrosive acids and abrasive propellants such as sharp sand, shale, coal or the like. 
         [0006]    The components which makeup the wellhead, typically, valves, a tubing hanger, a casing hanger, a casing head, and a blowout preventer (BOP) system, are generally selected for the characteristics of the well and not the flowback process and procedures. The abrasive propellants and or corrosive fluids required for well fracturing and stimulation procedures are required to fracture the formation to allow oil or gas to flow into the wellbore. After the well fracturing process has been completed, a procedure called flowback is conducted. This procedure is a controlled process of allowing fluids to flow from the wellbore following treatment either in preparation for a subsequent phase of treatment or preparation for cleanup and returning the well to production. 
         [0007]    The clean up period or flowback, generally follows a stimulation (called a frac job) treatment during which time treatment fluids return from the reservoir formation and wellbore. Depending on the treatment, the cleanup period can be short and uncomplicated. However, in more complicated and complex larger fracturing jobs the flowback process can become much more complex and hazardous. The controlled flowback process should be conducted carefully to avoid jeopardizing safety, equipment, environment or the long-term efficiency of the well stimulation. 
         [0008]    There are many different methods, techniques, processes and types of flowback practiced in the oil and gas industry used to clean up a wellbore and formation after the fracturing process has been completed. The prior art flowback procedures all generally utilized the same or similar types of components, parts, apparatuses, and methods, that are standards and known by those experienced in the art in the oil and gas industry. Most known flowback methods use some sort of part, apparatus or technique of controlling the pressures and rate of velocity of the fluids and propellants returning from the formation during clean out. 
         [0009]    These parts are commonly know as wellhead Christmas trees, casing valves, frac valves, flowback trees, frac stacks, casing isolation tools, tubing isolation tools, frac Y&#39;s, blowout preventer (BOP), chokes, choke manifolds, adjustable chokes, positive chokes, ceramic chokes, inline chokes, choke inserts, choke beans, choke nipples, cage nipples, and many various other apparatuses that attach, screw on, bolt on, hammer on, and clamp on to the flowback lines, equipment and parts. These parts and apparatuses or combination thereof, are used to perform a flowback and cleanup of wellbore and well formations. 
         [0010]    There are many problems associated with the conventional methods and practices used to flowback a well using current industry standards, equipment or methods. One such problem is the installation of flowlines that connect or mate from a horizontal position to a targeted tee then to a vertical targeted tee, then back to the line lying in the horizontal position on the ground. The problem occurs because the distance and heights vary from location to location for various reasons, terrain, equipment configuration, styles, and placement of the wellhead and the surface casing. For these reasons, flowline connections to flowback tree or horizontal valves, used to connect, vary and require pipe to be cut, welded or fabricated to mate connections. Because of weather elements such as rain, wind, mud, snow, and cold, this function cannot be performed in an optimum environment so the quality and safety of the work performed could be compromised. Pipe threading and welding or fabricating are best preformed in a controlled environment. Other common problems that occur during installation are that many variables exist, such as lines that attach to choke manifolds or flowback tanks and earthed pits, all require variable lengths to mate connections. There are other problems, such as current flowbacks do not have a way to contain the pressures or corrosive acids and abrasive propellants such as sharp sand. The problem arises because the propellant fluids, acids, chemicals, and fracture products pumped into the wellbore formation during (flowback) clean up, travel at high velocity causing washing out of the lines and equipment from the inside out. The current flowback practices have no method or system to contain, control or monitor a washout. In addition, there is not a system that detects a washout or a warning system to notify when a potential washout might occur. When this event occurs, gases, propellants, fluids, acids, and chemicals could vent to the atmosphere causing unsafe conditions, injury and environmental contamination. 
       SUMMARY OF THE INVENTION 
     Disclosure Of The Invention 
       [0011]    The embodiments disclosed herein address the above stated needs by providing a flowback system for oil and gas wells. The new automated flowback system provides protection from all the hazards mentioned above. This flowback is a system that incorporates proven standard oilfield practices with new technology and mechanisms to solve flowback safety, mechanical, operational and environmental issues. The new system provides new techniques and mechanical devices that may be installed in flowlines, in the vertical or the horizontal position, without having to cut and thread, weld or fabricate pipe to fit. This new system provides an expansion sub, which is a mechanism with axial adjusting lengths adequate to compensate for variations in a distance between two points. This allows the expansion sub to be secured and installed precisely and quickly into position, eliminating field cut and threading, welding or fabrication. The expansion sub also provides multiple wash barriers for safety and prevention of washouts. The expansion sub can be manufactured in various lengths and sizes to adapt to any vertical or horizontal application, making it very desirable from a time, cost, safety, and environmental standpoint. 
         [0012]    In addition, this system advantageously provides a blast barrel that permits the ability to install a choke nipple, choke bean or choke insert with an orifice size chosen by a user into a multiple chambered apparatus. This apparatus, once in place, provides a service technician an in-line method to rotate the outer chamber counter clockwise so the outer chamber of the blast barrel slides away from the primary barrel head. Once this process is completed the inner flowtube, blast nipple and the cage nipple are visible. Next, the inner flowtube is rotated counter clockwise and it will retract within the expansion chamber, away from the barrelhead, releasing the blast nipple that can be removed or installed. The cage nipple can also be removed, and the choke insert can be installed or removed. Reassembly is performed in reverse order and the apparatus is ready for operation. These unique functions give the blast barrel assembly the ability to retract between two fixed points without having to disassemble or dismantle any connections or be removed from the secured flowlines for installation of a choke insert, blast nipple or to replace damaged or used internal parts. This apparatus also provides pressure ports that allow for monitoring of the upstream wellhead pressure by attaching an electronic pressure sensor module or high-pressure line to the primary barrelhead high-pressure chamber port. The actual pressure can safely be monitored and reported from a remote location. Additionally, a system for creating an electronic or manual chart, that records and documents history of the process, can be used. This information can be used to document the efficiency, and also help design procedure for future flowback operations. 
         [0013]    Another important embodiment is the provision of a monitoring port located in the center of the outer barrel known as the breach chamber. This chamber is equipped with internal high-pressure seals for containment. The monitoring port embodiment provides a safe method to monitor flowback operations away from a potential hazard or danger. The monitoring module attached to this chamber monitors whether a washout or breach of the choke insert, blast nipple or inner flowtube occurs. Thus, the system is able to alert a technician by sending an alarm signal to a command center automatically, shutting the system down or transmitting signals to close or open an alternate line. This alert or signal provides notice that the inner parts have been compromised and need to be replaced. The unique design and features of the blast barrel provide notice, even though the internal parts have been compromised, worn or washed out. The preferred design of the monitoring port is fabricated from hardened materials, which give it the ability to withstand the corrosive demand made on equipment during the flowback process for long periods of time. If a breach occurs, the system is still safe and secure, because the inner tubes and parts are encased within the outer barrel or breach chamber. The outer barrel is able to contain the pressures and abrasives internally for an indefinite amount of time. This allows the operator adequate time to alleviate the problem by shutting down and transferring the flow to another flowline equipped with the same system. 
         [0014]    The blast barrel assembly is preferably equipped with an expansion chamber in the lower assembly which provides the inner flowtube the ability to rotate counter clockwise and travel away from the blast nipple and barrelhead, releasing it from the inner lock position and unlocking the internal seals, allowing the internal parts to be removed and replaced as required. The expansion chamber is also equipped with the third port for allowing a pressure module to be installed to monitor the low-pressure chamber. By monitoring this chamber, a technician is able to calculate wear by comparing the upstream high-pressure and downstream low-pressure differentials and the orifice size installed in the blast barrel. For example, if there is 1000 pound per square inch (PSI) measured at the high-pressure barrelhead monitor, and a one quarter inch (¼″) orifice with one hundred twenty-five (125) PSI on the low-pressure monitor there is a pressure differential of eight hundred seventy-five (875) PSI. As the orifice begins to wear, the pressure differential becomes less, by using the charts and calculations an operator is able to avert wash or damage, and at the same time maintain total control of the flowback process by comparing and analyzing the data and readings coming from the blast barrel ports. These readings and information can be automatically recorded and documented on charts or graphs in real time, and transferred via satellite or cell phone to any office or location of choice for real time evaluation. This information permits the site technician or central engineering office to view real time information and interpret it into useful data and can be used in making crucial decisions and operational functions, safely away from the wellhead. 
         [0015]    It is the object of the present invention to provide a flowback system that improves operational job standards and job site quality assurance, as well as safety, health, environmental, and economic efficiencies. 
         [0016]    Another object of the present invention is to provide a quick and efficient mechanical apparatus to be able to adjust quickly to variable lengths and fit between two fixed connecting points, without requiring cutting, threading, welding or fabrication. 
         [0017]    It is another object of the present invention to provide a blast barrel that is able to withstand high pressures, corrosive fluids, and abrasive propellants traveling at high velocities for long periods and to be able to incorporate washout containment safety features. 
         [0018]    Yet another object of the present invention is to provide the ability to transmit data to a mobile command receiving center or central office for real time data interpretation, and the ability to remotely control or operate the system. 
         [0019]    It is also the object of the present invention to provide a system that notifies a user that a breach of the interior parts have been compromised or damaged and still be able to safely continue operations, allowing the user the flexibility and time required to safely make alternate decisions and adjustments to the system. 
         [0020]    An advantage of the present invention is that it is a quick, economical, and efficient system; yet still able to contain extreme pressures and abrasives traveling at high velocities. 
         [0021]    Another advantage of the present invention is the ability of the blast barrel to retract between two fixed points for disassembly giving the user access to internal parts for replacement or inspection without having to dismantle the high-pressure fixed lines. 
         [0022]    Yet another advantage of the present invention is that the system can be programmed to operate and function automatically from a control office or command center. 
         [0023]    Other objects, advantages and novel features, and further scope of applicability of the present invention will be set forth in part in the detailed description to follow, taken in conjunction with the accompanying drawings, and in part will become apparent to those skilled in the art upon examination of the following, or may be learned by practice of the invention. The objects and advantages of the invention may be realized and attained by means of the instrumentalities and combinations particularly pointed out in the appended claims. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0024]    The accompanying drawings, which are incorporated into and form a part of the specification, illustrate several embodiments of the present invention and, together with the description, serve to explain the principles of the invention. The drawings are only for the purpose of illustrating a preferred embodiment of the invention and are not to be construed as limiting the invention. In the drawings: 
           [0025]      FIG. 1  depicts an embodiment of the invention showing the overall system with the preferred components. 
           [0026]      FIG. 2  is a cross sectional view of the expansion sub embodiment. 
           [0027]      FIG. 3  is a cross sectional view of the preferred blast barrel. 
       
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Best Modes For Carrying Out The Invention 
       [0028]      FIG. 1  shows an overall view of the equipment and component parts as assembled in a complete field installation hereinafter referred to as a flowback system  10 . Flowback system  10  includes a frac tree or flowback tree  62  which include a series of valves that can be of various sizes and pressure ratings used in opening and closing the well  64  before and after fracturing stimulation and flowback clean up of a well. A high-pressure flowline, pup joint or sub  12  of various sizes and pressure ratings are installed in a horizontal position, and vary in length based on the application. High-pressure flowlines  12  are typically attached or installed by a connection, known in the oil and gas industry, as a hammer union (not shown). These connections are made by rotating the wingnut portion of the union onto the threaded portion of the union, and connected to integral union cushion elbow or targeted tee  14 . The integral union cushion elbow  14  is designed to absorb and deflect the products being carried by the internal flow of the wellbore during clean out. Integral union cushion elbow  14  is connected to a first end of expansion sub  16 , a mechanism with axial adjusting lengths adequate to compensate for variations in a distance between two fixed points. Expansion subs  16  and  16 ′ are designed to be secured and installed precisely and quickly into a vertical position eliminating the need of having to cut, fit, thread, weld, or field fabricate. Expansion subs  16  and  16 ′ are shown in detail in  FIG. 2  and defined later on in this application. 
         [0029]    A second end of expansion sub  16  is connected to another integral union cushion elbow or targeted tee  14 , as shown. Connected to the second integral union cushion elbow  14 ′ are high-pressure flowlines  18 , known as pup joint or sub, which can be of various sizes and pressure ratings. High-pressure flowlines  18  are installed and secured by adjustable cement blocks  56 , which are designed to restrain movement of the high-pressure flowlines  18  in a horizontal position. High-pressure flowlines or the pup joints  18  vary in length and quantity requirements, and are based on distance and application. High-pressure flowlines  18  are also attached or installed by hammer unions (not shown). A second end of high-pressure flowlines  18  is connected to a second expansion sub  16 ′, as shown. Second expansion sub  16 ′ is connected to a choke and kill manifold assembly  44 . An integrated one-piece flange  20  with a hammer union thread half connection is mated to choke and kill manifold  44  and is attached to manually operated gate valves  22 , which are of various sizes or pressures ratings depending on the well. Manually operated gate valves  22  are used to close, block or divert flow to alternate sides or ports on choke manifold  20 . A user is then able to apply flow, to chosen outlets on the manifold system. 
         [0030]    Studded or threaded cross  24  is used to integrate the manifold into one unit from manually operated gate valves  22 , and  26 , for closing, blocking or diverting flow to alternate sides or ports on choke manifold  44 . Air or hydraulic remotely operated valves  26 , both preferably placed in a ninety degrees (90°) position from studded cross  24 , are used to operate the system from a remote location by sending power from power supply  40  through valve operating cables  54 , to activate remotely operated valves  26 . A variable operated, adjustable choke valve  28  is installed on a port side of remotely operated valve  26 , and one installed on the starboard side of remotely operated valve  26 ′. Variable adjustable chokes  28  are designed to control the rate of flow passing through lines, by blocking a seat opening with a cone shaped steel rod know as choke stem. In this flowback system, adjustable choke valves  28  are used only to pressure up the system when bringing a flowback online. An integrated one-piece adapter flange  30  preferred for its consistent smooth wear resistant bore qualities with a hammer union wing half connection, is mated to adjustable choke valves  28  manually operated gate valves  22 , and attached to high-pressure flowlines  18 . 
         [0031]    A blast barrel  32  is installed and mated to one or more outlet pup joints  18 , with matching connection types with a choke nipple, choke bean or choke insert with orifice size of choice into multiple chambers. As previously described, outlet pup joints  18  can be secured by additional adjustable cement clocks  56 . The preferred blast barrel  32  is explained in more detail below and in  FIG. 3 . Blast barrel  32 , once placed in line provides for an outer chamber of the blast barrel to slide away from the primary barrelhead to expose the inner flowtube, blast nipple and the cage nipple when rotated. 
         [0032]    This apparatus also provides pressure ports that allow the monitoring of the upstream wellhead pressure by attaching electronic pressure sensor modules for monitoring by command center  34 . The pressure sensor module signals are transmitted through sensor cables  48  to command center  34 . Command center  34  can also provide an electronic or manual chart  38 , that records and documents history of the process. This information can be used to document the efficiency and also help design procedure for future flowback. 
         [0033]    Another important feature of blast barrel  32  is that it provides a center monitoring port located in the center of the outer barrel known as the breach chamber this chamber is equipped with internal high-pressure seals for containment. The monitoring port provides the system with a safe method to remotely monitor flowback operations away from the hazard or danger. The system is able to alert a technician by sending an alarm through monitoring cables  50  to command center  34  or via wireless communication systems to a remote command center  60 . Command center  34  or remote command center  60  can automatically shut down the system or transmit a signal via valve operating cables  46  or  54 , to close or open alternate lines. This function can be preferably conducted automatically or alternatively, manually. 
         [0034]    Blast barrel assembly  32  is equipped with an expansion chamber in the lower assembly which provides the inner flowtube the ability to rotate counter clockwise, and travel away from the blast nipple and barrelhead, releasing it from the inner lock position, and unlocking the internal seals allowing the internal parts to be removed and replaced as required. The expansion chamber is also equipped with a third port for monitoring the low-pressure chamber. By monitoring this port via low-pressure monitoring cables  52  from a remote location, a technician is able to calculate wear by comparing the upstream high-pressure and downstream low-pressure differentials. For example, if there is 1000 PSI in the high-pressure barrelhead monitor, and a one-quarter inch (¼″) orifice with one hundred twenty-five (125) PSI on the low-pressure monitor there is a pressure differential of eight hundred seventy-five (875) PSI. As the orifice begins to wear, the hole in the orifice becomes larger, and as this happens, the pressure on low-pressure chamber begins to increase, and the pressure on the high-pressure chamber remains the same. By using the charts and calculation, an operator is aware and able to avert washout or damage, and at the same time, maintain total control of the flowback process. These readings and information can be automatically recorded and documented on charts or graphs  38  in real time and transferred via a communication system  36  via a satellite or cell phone to any office or location of choice for real time evaluation. This information permits the site technician or central engineering office to view real time information from command center  34 , and interpret it into useful data to be used in making crucial on-the-spot decisions, and execute operational functions safely away from hazards. 
         [0035]    Also affixed to blast barrel assembly  32  are high-pressure flowlines  18  secured by adjustable cement blocks  56 , and connected to one or more mufflers  58  for deflecting the water and sand into a pit during clean out. 
         [0036]    Command center  34  incorporates many special features all working in cooperation to perform multiple functions upon request. A communication system  36  consisting of a transmitter and receiver are used to send and receive signals and data commands sent by command center  34 . A data recording apparatus  38  is used to document data either electronically or mechanically. A series of electronic and mechanical valves in a manifold are able to execute receive commands sent by remote command center  60  or a mobile unit or vehicle via communications system  36  that transmits signals to activate electricity over hydraulic power packs  40  and electronic operated valve manifold  42 , which activate and engage hydraulic or air power through cables  46  or  54 . This opens or closes port  26  and  26 ′ to maintain a constant back-pressure on the well. 
         [0037]      FIG. 2  shows a cross-sectional view of the preferred expansion sub  210 . Expansion subs  210  are used for high-pressure lines. Expansion sub  210  has a primary inner master tube adapter chamber  232 , this chamber  232  is equipped with external adapter threads  212 , and these threads can be of various sizes and rating depending on application. In addition, the inner master tube adapter expansion sub  232  has a second set of threads  214  used to adapt and mate to master housing  216 . Second set of threads or retainer threads  214 , when rotated clockwise will engage and lock master housing  216 , inner master tube adapter to expansion hub  232 . Special external outer seals  222  and  230  located at both ends of master inner tube adapter capable of withstanding the rotation of expansion sub primary screw  220  and high internal flow pressures. 
         [0038]    Master outer housing  216 , houses and retains the assembly together when under pressure, and has a set of machined internal threads  218  located at end of master housing  216  for holding and retaining sub primary screw  220  in a fixed position. Machined internal threads  218  are designed for adequate strength to contain all forces equal to the rating of the assembly. 
         [0039]    Expansion sub primary screw  220  has threads  226  and are designed and machined to a length equal to the length of master housing  216 . Expansion sub primary screw  220  is configured to quickly expand or retract telescopically  227  to the desired length by rotation  229  of special double lead thread  226 . Expansion sub primary screw  220  is also attached or installed by a hammer union  224 , by rotating the wingnut potion of the union onto the threaded portion of the union. Expansion sub primary screw  220  is also able to contain the high internal pressure with special internal seals  228  located at the end of expansion sub primary screw  220 . 
         [0040]    Expansion sub assembly  210 , is a mechanism with axial adjusting lengths, for telescopic expansion or retraction  227 , adequate to compensate for variations in a distance between two fixed points, allowing expansion sub  210  to be secured and installed precisely and quickly into a vertical position, eliminating the need of having to cut, fit, thread, weld, or field fabricate. 
         [0041]      FIG. 3  is a cross sectional view of the preferred blast barrel  352 . This apparatus provides several unique functions. First, it attaches between two high-pressure lines, second, it provides a high-pressure port  312  where a pressure sending module or line  313  can be installed, and third, this apparatus has an internal preparation system that accepts a cage nipple  314  used to hold a choke insert  316 . Before outer barrel  320  is assembled to barrelhead  310 , choke insert  316  must be installed into cage nipple  314  by rotating cage nipple  314  clockwise until tight. 
         [0042]    Cage nipple assembly  314  can now be installed into barrelhead  310  by rotating cage nipple  314  clockwise until seal  340  engages and is tight. These unique functions give blast barrel assembly  352  the ability to telescopically retract  353  between two fixed points by rotating outer barrel  320  from second inner flowtube  330  without having to disassemble or dismantle any connections or be removed from the secured flowlines to install or replace damaged or used internal parts. 
         [0043]    Blast nipple  318  is installed by sliding over cage nipple  314  and locking into place. By rotating clockwise, inner flowtubes  324  and  330  will engage into blast nipple  318  and seals  344  and  346 . Outer barrel  320  is moved forward towards barrelhead  310  until threads from outer barrel  320  contact treads from barrelhead  310 . Once contact is made, outer barrel  320  can be rotated clockwise until barrelhead  310  and outer barrel  320  make contact and are tight. 
         [0044]    Outer barrel or breach chamber  320  is the master safety housing. It contains a pressure port  322  where a pressure sensor or line  323  can be installed. Outer barrel  320 , or the breach chamber, contains the pressure and abrasives, should a breach occur. Pressure port  322  is the second port in the center of outer barrel  320 ; it is designed to notify the user, via sensors, that a breach has taken place. The assembly contains a lockdown retainer cap  326  to secure the first inner flowtube  324  by abutting against a no go shoulder once it is assembled on outer barrel  320  and lockdown retainer cap  326 . Master chamber seals  348  in outer barrel  320 , barrel head seals  342  and retainer cap  328  prevent flow from outer barrel  320  or first inner flowtube  234 . Second inner flowtube  330  is installed before installing expansion chamber funnel head  336  through the rear of expansion chamber housing  332  and seal chamber. Once the treads on second inner flowtube  330  contact the inner drive head  350  thread, second inner flowtube  330  is rotated clockwise until drive head  338  meets and butts up against the body of chamber housing  332 . Expansion chamber funnel head  336  can now be installed by rotating clockwise until funnel head  336  butts up against expansion chamber housing  332 . First inner flowtube  324  is connected to second inner flowtube  330  and the expansion chamber inner drive head  338 . Expansion chamber housing  332  is designed with a low-pressure port  334  to monitor the downstream low-pressure, via low pressure sensor  335 . Expansion chamber housing assembly  332 , and connection to second inner flowtube  330  can be installed by rotating clockwise until tight to first inner flowtube  324 . The blast barrel assembly is now ready for installation. 
         [0045]    The blast barrel is unique because even if the inner parts have been compromised and need to be changed, it remains safe due to the inner choke insert and the inner blast nipple, both made from hardened tool material, giving it the ability to withstand the corrosive demand made upon equipment during the flowback process for long periods of time; unlike standard pipe or steel. If a breach occurs, the system is still safe and secure because the inner tubes and parts are encased with the outer barrel or breach chamber that is able to contain the pressures and abrasives internally for an indefinite amount of time allowing the operator/technician adequate time to shut down and transfer to another flowline equipped with the same equipment. 
         [0046]    Although the invention has been described in detail with particular reference to these preferred embodiments, other embodiments can achieve the same results. Variations and modifications of the present invention will be obvious to those skilled in the art and it is intended to cover in the appended claims all such modifications and equivalents. The entire disclosures of all references, applications, patents, and publications cited above, are hereby incorporated by reference.

Technology Classification (CPC): 4