Patent Publication Number: US-7591314-B2

Title: Measurement-while-fishing tool devices and methods

Description:
This application claims the priority of U.S. Provisional patent application Ser. No. 60/447,771 filed Feb. 14, 2003. 

   BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   The invention relates generally to methods and devices for detecting wellbore and tool operating conditions while engaged in fishing or other downhole manipulation operations to remove a wellbore obstruction or in other non-drilling applications, especially in very deep and/or deviated wellbores. 
   2. Description of the Related Art 
   Devices are known for measurement-while-drilling (MWD) and logging-while-drilling (LWD) wherein certain borehole conditions are measured and either recorded within storage media within the wellbore or transmitted to the surface using encoded transmission techniques, such a frequency shift keying (FSK). Transmission may be accomplished via radio waves or fluid pulsing within drilling mud. The conditions measured typically include temperature, annulus pressure, drilling parameters, such as weight-on-bit (WOB), rotational speed of the drill bit and/or the drill string (RPMs), and the drilling fluid flow rate. An MWD or LWD sub is incorporated into the drill string above the bottom hole assembly and then operated during drilling operations. Examples of drilling systems that utilize MWD/LWD technology are described in U.S. Pat. Nos. 6,233,524 and 6,021,377, both of which are owned by the assignee of the present invention and are incorporated herein by reference. 
   Aside from typical drilling operations, there are other situations where it is helpful to have certain information relating to operation of the tool that is operating downhole and its environment. In very deep and/or high angle wellbores, it is difficult to verify details concerning the operation of the downhole tools through surface indications alone. For example, if one were attempting to remove a stuck section of casing in a deep and/or deviated wellbore using a rotary milling device, it would be very helpful to be able to measure the amount of torque induced proximate the milling device. Without an indication of the amount of torque induced proximate the milling device, the milling string can be overtorqued at the surface and the string between the milling tool and the surface will absorb the torque forces without effectively transmitting them to the milling tool. Overtorquing the tool string in this situation may lead to a shearing of the tool string below the surface, thereby creating an obstruction that is even more difficult to remove. 
   To the inventors&#39; knowledge, there are no known, acceptable devices for providing useful downhole operating condition information, including torque, weight, compression, tension, speed of rotation, and direction of rotation, in non-drilling situations. Further, the use of standard MWD tools for such non-drilling applications is quite expensive. Current MWD tools are designed to obtain significant amounts of borehole information, much of which is not relevant outside of a drilling scenario. The devices for collecting this drilling specific information includes nuclear sensors, such as gamma ray tools for determining formation density, nuclear porosity and certain rock characteristics; resistivity sensors for determining formation resistivity, dielectric constant and the presence or absence of hydrocarbons; acoustic sensors for determining the acoustic porosity of the formation and the bed boundary in formation; and nuclear magnetic resonance sensors for determining the porosity and other petrophysical characteristics of the formation. To the inventors&#39; knowledge, there is no known and acceptable “fit-for-purpose” tool wherein the sensor portion of the tool may be customized to detect those data that are important to the job at hand while not detecting irrelevant or less relevant information. 
   There is a need for improved devices and methods that are capable of providing operating condition information to the surface in non-drilling situations. There is also a need for improved methods and devices for accomplishing fishing and retrieval-type operations. Additionally, there is a need for improved methods and devices for accomplishing other non-drilling applications, such as underreaming, in-hole casing cutting and the like. The present invention addresses the problems of the prior art. 
   SUMMARY OF THE INVENTION 
   The invention provides methods and devices for sensing operating conditions associated with downhole, non-drilling operations, including, fishing, but also with retrieval operations as well as underreaming or casing cutting operations and the like. In currently preferred embodiments, a condition sensing device is used to measure downhole operating parameters, including, for example, torque, tension, compression, direction of rotation and rate of rotation. The operating parameter information is then used to perform the downhole operation more effectively. 
   In one embodiment, a memory storage medium is contained within the tool proximate the sensors. The detected information is recorded and then downloaded after the tool has been removed from the borehole. In a further embodiment, the detected information is encoded and transmitted to the surface in the form of a coded signal. A receiver, or data acquisition system, at the surface receives the encoded signal and decodes it for use. Means for transmitting the information to the surface-based receiver include mud-pulse telemetry and other techniques that are useful for transmitting MWD/LWD information to the surface. In a further aspect of the invention, a controller is provided for adjusting the downhole operation in response to one or more detected operating conditions. 
   The invention provides for an inexpensive condition sensing tool that is useful in a wide variety of situations. The invention also provides a “fit-for-purpose” tool that may be easily customized to collect and provide desired operating condition information without collecting undesired information. In related aspects, the invention also provides for improved method of conducting non-drilling operations within a borehole, including fishing operations, wherein measured downhole operating condition information is used to improve the non-drilling operation and make it more effective. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The advantages and further aspects of the invention will be readily appreciated by those of ordinary skill in the art as the same becomes better understood by reference to the following detailed description when considered in conjunction with the accompanying drawings in which like reference characters designate like or similar elements throughout the several figures of the drawing and wherein: 
       FIG. 1  is a schematic, cross-sectional view of an exemplary wellbore employing a tool and tool assembly constructed in accordance with the present invention. 
       FIG. 2  is an isometric view, partially in cross-section, of an exemplary condition-sensing tool constructed in accordance with the present invention. 
       FIG. 3  is a side cross-sectional, schematic depiction of an illustrative fishing application wherein a section of production tubing and packer are being removed from a borehole, in accordance with the present invention. 
       FIG. 4  is a side cross-sectional, schematic depiction of an illustrative backoff operation conducted in accordance with the present invention. 
       FIG. 5  is a schematic side, cross-sectional view of an illustrative casing cutting arrangement conducted in accordance with the present invention. 
       FIG. 6  is a schematic side, cross-sectional view of an illustrative underreaming arrangement conducted in accordance with the present invention. 
       FIG. 7  is a schematic side, cross-sectional view of an illustrative fishing application for removal of a packer from within a borehole, conducted in accordance with the present invention. 
       FIG. 8  is a schematic side, cross-sectional view of an illustrative pilot milling application conducted in accordance with the present invention. 
       FIG. 9  is a schematic side, cross-sectional view of an illustrative washover retrieval operation for retrieval of a stuck bottom hole assembly, conducted in accordance with the present invention. 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     FIG. 1  is a schematic drawing depicting, in general terms, the structure and operation of a tool and tool assembly constructed in accordance with the present invention as well as methods and systems in accordance with the present invention. These tools, tool assemblies, systems and methods may be referred to herein for shorthand convenience as “measurement-while-fishing” systems, although this term is not intended to limit the invention to “fishing” applications. Those of skill in the art will understand that there are, in fact, numerous non-drilling applications for the systems, methods and devices of the present invention. 
     FIG. 1  shows a rig  10  for a hydrocarbon well  12 . It will be understood that, while a land-based rig  10  is shown, the systems and methods of the present invention are also applicable to offshore rigs, platforms and floating vessels. From the rig  10 , a borehole  12  extends downwardly from the surface  14 . A tool string  16  is shown disposed within the borehole  12 . The tool string  16  may comprise a string of drill pipe sections, production tubing sections or coiled tubing. The tool string  16  is tubular and defines a bore therein through which drilling mud or other fluid may be pumped. Although not depicted in  FIG. 1 , the rig  10  includes means for pumping drilling fluid or other fluid into the tool string  16  as well as means for rotating the tool string  16  within the borehole  12 . At the lower end of the tool string  16  there is secured a condition sensing tool  18 , the lower end of which is, in turn, affixed to a workpiece  20 . The workpiece  20  refers generally to a tool or device that is performing a function within the borehole  12  and for which certain operational data is desired at the surface  14 . As will be understood by reference to the exemplary embodiments described shortly, the workpiece  20  may comprise a fishing device, such as a jarring tool or latching mechanism, or a cutting tool, such as an underreamer or casing cutter, or other device. 
   It is noted that the borehole  12  may extend rather deeply below the surface (i.e., 30,000 feet or more) and, while shown in  FIG. 1  to be substantially vertically oriented, may actually be deviated or even horizontal along some of its length. At the surface  14  is a data acquisition system  22  and a controller  24 . An operator at the surface typically controls operation of the workpiece  20  by adjusting such parameters as weight on the workpiece, fluid flow through the tool string  16 , rate and direction of rotation of the tool string  16  (if any) and so forth. 
   Referring now to  FIG. 2 , there is shown in cross-section details for the construction and operation of an exemplary condition-sensing tool  18  constructed in accordance with the present invention. The tool  18  includes a generally cylindrical outer housing  26  having axial ends  28 ,  30  that are configured for threaded engagement to adjoining portions of the tool string  16  and the workpiece  20 . The housing  26  defines a flowbore  32  therethrough to permit the passage of drilling fluid or other fluid. One or more wear pads  34  may be circumferentially secured about the tool  18  to assist in protection of the tool  18  from damage caused by borehole friction and engagement. The tool  18  includes a sensor section  36  having a plurality of condition sensors mounted thereupon. In the exemplary tool  18  shown, the sensor section  36  includes a weight sensor  38  that is capable of determining the amount of weight exerted by the tool string  16  upon the workpiece  20  and a torque gauge  40  that is capable of measuring torque exerted upon the workpiece  20  by rotation of the tool string  16 . Additionally, the sensor section  36  includes an angular bending gauge  42 , which is capable of measuring angular deflection or bending forces within the tool string  16 . Additionally, the sensor section  36  includes an annulus pressure gauge  44 , which measures the fluid pressure within the annulus created between the housing  26  and the borehole  12 . A bore pressure gauge  46  measures the fluid pressure within the bore  32  of the tool  18 . While the operable electrical interconnections for each of these sensors is not illustrated in  FIG. 2 , such are well known to those of skill in the art and, thus, will not be described in detail herein. An accelerometer  48  is illustrated as well that is operable to determine acceleration of the tool  18  in an axial, lateral or angular direction. Through each of the above described sensors, the sensor section  36  obtains and generates data relating to the operating parameters of the workpiece  20 . 
   In a currently preferred embodiment, the condition sensing tool  18  may comprise portions of a CoPilot® MWD tool, which is available commercially from the INTEQ division of Baker Hughes, Incorporated, Houston, Tex., the assignee of the present application. It is noted that the condition sensing tool  18  does not require, and typically will not include, those components and assemblies that are useful primarily or only in a drilling situation. These would include, for example, gamma count devices and directional sensors used to orient the tool with respect to the surrounding formation. This greatly reduces the cost and complexity of the tool  18  in comparison to traditional MWD or LWD tools. It is intended that the tool  18  be a “fit-for-purpose” tool that is constructed to have those sensors that are desired for a given job but not others that are not required. As a result, the cost and complexity of the tool  18  is minimized. 
   The tool  18  also includes a processing section  50  and a power section  52 . The processing section  50  is operable to receive data concerning the operating conditions sensed by the sensor section  36  and to store and/or transmit the data to a remote receiver, such as the receiver or data acquisition system  22  located at the surface  14 . The processing section  50  preferably includes a digital signal processor  53  and storage medium, shown at  54 , which are operably interconnected with the sensor section  36  to store data obtained from the sensor section  36 . The processor  53  (also referred to as the “control unit” or a “processing unit”) includes one or more microprocessor-based circuits to process measurements made by the sensors in the drilling assembly at least in part, downhole during drilling of the wellbore. 
   The processor section  50  also includes a data transmitter, schematically depicted at  56 . The data transmitter  56  may comprise a mud pulse transmitter, of a type known in the art, for transmitting encoded data signals to the surface  14  using mud pulse telemetry. The data transmitter  56  may also comprise other transmission means known in the art for transmitting such data to the surface. 
   The power section  52  houses a power source  58  for operation of the components within the processor section  50  and the sensor section  36 . In a currently preferred embodiment, the power source  58  is a “mud motor” mechanism that is actuated by the flow of drilling fluid or another fluid downward through the tool string  16  and through the bore  32  of the tool  18 . Such mechanisms utilize a turbine that is rotated by a flow of fluid, such as drilling mud, to generate electrical power. An example of a suitable mechanism of this type is the power source assembly within the 4¾″ CoPilot® tool that is sold commercially by Baker Hughes INTEQ. Other acceptable power sources may also be employed, such as batteries where, for example, fluid in not flowed during the particular downhole operation being performed. 
   A number of exemplary methods and arrangements for implementing the present invention will now be described in order to illustrate the systems and method of the invention.  FIG. 3  depicts a situation wherein it is necessary to fish a section of production tubing  60  and a retrievable packer  62  out of the borehole  12 . This type of fishing operation may be necessary where the production tubing  60  has developed a breach above the location of the packer  62 , and the packer  62  cannot be released using its intended release mechanism. In  FIG. 3 , the borehole  12  is shown lined with casing  64 , and the packer  62  is sealed against the inner wall of the casing  64 . The upper end  66  of the production tubing section  60  has been cut off in an uneven fashion and the upper portion of the production tubing string leading to the surface  14  has been removed. 
   A tool string  16 , which in this instance may comprise a string of production tubing or coiled tubing, is then lowered into the borehole  12  as shown in  FIG. 3 . The condition sensing tool  18  is secured to the lower end of the tool string  18 . In this arrangement, the tool  18  is configured to have at least a weight sensor  38  and torque gauge or sensor  40 . Affixed to the lower end of the tool  18  is an engagement device  68 , which serves as the workpiece  20 . The engagement device  68  is a fishing tool, of a type known in the art, which is configured to engage the upper end  66  of the production tubing section  60 . Then, by pulling upwardly upon, jarring, pressuring up within, and/or by rotating the tool string  16 , the production tubing section  60  and the packer  62  are removed from the borehole  12 . 
   In operation, the weight sensor  38  of the tool  18  detects the amount of upward force exerted upon the engagement device  68  from upward pull on the tool string  16 . If rotation of the tool string  16  is applied in an attempt to remove the tubing string section  60  and packer  62 , then the torque gauge  40  will detect the amount of torque from this rotation that is actually felt at the engagement tool  68 . Alternatively, if the tool string  16  is pressured up in order to help release the tubing string section  60  and packer  62 , detection of bore pressure and annulus pressure would be desirable. This data is then either stored or transmitted to the surface  14  so that an operator can detect whether there is a significant discrepancy between the upward or rotational force being applied at the surface and the forces being received proximate the workpiece  20 . A significant difference may be indicative of a problem that prevents full transmission of such forces, such as an obstruction in the annulus or the tool string  16  being grounded against the borehole  12  in a deviated and/or extremely deep portion of the borehole  12 . 
   Referring now to  FIG. 4 , there is shown an illustrative anchor latch or threaded arrangement wherein the utility of the devices and methods of the present invention is shown for performing disconnection of threaded components within the borehole  12 . In this instance, a packer element  62  is shown secured against the casing  64  of the borehole  12  and retains a production tubing portion  66  that includes a lower tubing section  69  that is secured by threaded connection  70  to an upper tubing section  72 . The upper tubing section  72  has been cut away as with the production tubing section  60  described earlier. An engagement tool  74 , herein serving as the workpiece  20 , is secured to the condition sensing tool  18  and is configured to fixedly engage the upper end  76  of the upper tubing section  72 . Such an engagement tool  74  is known in the art. It is desired to unthread the threaded connection  70  so that the upper tubing string section can be removed from the borehole  12  and replaced with another tubing string section which can then be threadedly engaged with the lower tubing section  69  to reestablish production within the borehole  12 . Unthreading of the threaded connection  70  depends upon lifting up on the tool string  16  until the compression force, or weight, upon the threaded connection  70  is essentially zero. Otherwise, the threaded connection  70  will be difficult, if not impossible to unthread. Attempting to do so may, in fact, damage the thread, making it impossible to attach another production tubing section later. Conversely, too much lifting up on the tool string  16  will also cause the threaded connection  70  to be difficult or impossible to unthread though rotation of the tool string  16 . Therefore, it is important to be able to sense and determine the amount of tension and compression that is felt proximate the engagement tool  74  with some accuracy. Therefore, the condition sensing tool  18  is configured to sense, at least, weight and torque. In operation, the engagement tool  74  is latched onto the upper section  72  and the operator pulls upward or slacks off on the tool string  16  until the weight reading is essentially zero, indicating that unthreading of the threaded connection  70  may begin. The tool string  16  is then rotated in the direction necessary to unthread the connection  70 . Torque readings from the tool  18  will indicate whether there is a problem in transmitting the rotational forces from rotating the tool string  16  to the engagement tool  74 . 
     FIG. 5  illustrates a situation wherein a portion of wellbore casing  64  is being cut by a casing cutter  80 . Those of skill in the art will understand that it could as easily apply to the cutting of production tubing. The casing cutter  80  is secured to the lower end of the condition sensing tool  18  and includes, essentially a central tubular body  82  with a pair of radially extending cutters  84 . Such cutting tools are well known in the art and are used only in order to illustrate the invention and, therefore, will not be described in detail herein. The casing cutter  80  is shown cutting through the casing  64  and into the surrounding formation  86  by cutters  84 . Because the casing cutter  80  is rotated by rotation of the tool string  16 , it is important to know the direction of rotation, the speed of rotation (RPM), as well as the weight on the casing cutter  80 . In operation, the tool string  16  is rotated to cause the casing cutter  80  to cut the casing  64  to form an opening  88 . The tool  18  is configured to sense at least the speed (RPM) and direction of rotation proximate the casing cutter  80  to ensure that the opening  88  is properly cut. Measurements of the torque applied to the casing cutter  80  and weight upon the casing cutter  80  are also important and are preferably sensed by the tool  18 . 
   Referring now to  FIG. 6 , an underreaming situation is illustrated that incorporates the devices and methods of the present invention. An underreamer device  90  is affixed to the lower end of the tool  18 . The underreamer device  90 , as is known in the art, includes a tubular body  92  with a plurality of underreamer arms  94  which are pivotally connected to the body  92  and move radially outwardly to cut the formation  86  when the underreamer body  92  is rotated about its longitudinal axis. Underreaming is used when it is desired to enlarge the diameter of the borehole  12  at a certain point. In an underreamer operation, it is important to monitor the torque forces proximate the underreamer  90 . Thus, the tool  18  is configured to at least sense torque forces proximate the underreamer  90 . Preferably, the tool  18  is also configured to sense weight, rate of rotation (RPM), and direction of rotation. 
   Turning now to  FIG. 7 , there is shown an arrangement wherein a packer  100  is being retrieved from a set position within the borehole  12 . The condition sensing tool  18  is secured to the lower end of the tool string  16 , and an engagement tool  102  is affixed to the lower end of the condition sensing tool  18 . The engagement tool  102  is configured to latch onto the packer  100  and unset it for removal from the borehole  12 . The tool string  16  is lowered into the borehole  12  until the engagement tool  102  becomes securely latched onto the packer  100 . The packer  100  is typically released from engagement with the wall of the borehole  12  by pulling upwardly on the tool string  16  and/or by rotating the tool string  16  so as to apply tension and torque to the packer  100 . In this instance, then, the tool  18  should be configured to measure at least tension/compression (weight) and torque proximate the packer  100 . 
     FIG. 8  illustrates an exemplary pilot milling arrangement wherein a rotary pilot mill  104  is secured to the condition sensing tool  18  and tool string  16 . The mill  104  has a generally cylindrical central body  106  with a number of radially-extending milling blades  108 . The body  106  presents a nose section  110 . The mill  104  is shown in contact with the upper end of a tubular member  112  that has become stuck in the borehole  12 . It is desired to mill away the tubular member  112  by rotation of the mill  104  so as to cause the milling blades  108  to cut the tubular member  112  away. Thus, the mill  104  is set down atop the tubular member  112  so that the nose  110  is inserted into the tubular member  112  and the blades  108  contact the upper end of the tubular member  12 . During operation, drilling mud is circulated down through the tool string  16 , tool  18  and mill  104 . The drilling mud exits the mill  104  proximate the location where the blades  108  contact the tubular member  112  and serves to lubricate the cutting process and/or provide a means to circulate cuttings to the surface via the wellbore fluid in the annulus. 
   In milling operations such as the one shown in  FIG. 8 , it is helpful to be able to detect the torque forces, direction of rotation, weight (i.e., axial tension and/or compression forces exerted on the mill by the tool string  16 ), and speed of rotation for the mill  104 . Thus, the tool  18  should be configured to at least detect these downhole operating parameters. Additionally, the amount of bounce of the mill  104  may be determined by incorporating a vibration sensor (not shown), of a type known in the art, into the sensor section  36  of the tool  18 . The sensed information is then used to make adjustments to the milling procedure (i.e., a change in RPM, setting down on or lifting up on the mill) to improve the milling procedure. 
     FIG. 9  illustrates a washover retrieval operation incorporating devices and method of the present invention. In this instance, a bottom hole assembly (BHA)  118  has become stuck in the borehole  12 . The BHA  118  includes a drill bit  120  and drill pipe section  122  extending upwardly therefrom. The drill pipe section  122  is a stub portion of the drill pipe string that remains after the rest of the drill string has been cut away and removed. The BHA  118  is but one example of a component that might become stuck in the wellbore. Other components that might become lodged or stuck in the borehole  12  include screens, liners, drill pipe sections, tubing sections and so forth. 
   Secured to the lower end of the tool string  16  is the condition sensing tool  18  and a washover tool  124 , which serves as the workpiece  20 . The washover tool  124  includes a rotary shoe  126  with annular cutting edge  128  that is designed for cutting away the formation around the stuck BHA  118 . In this way the stuck component  118  is washed over and easier to remove. In this operation, it is desirable to know, in particular, the torque forces experienced proximate the washover tool  124 . Thus, the condition sensing tool  18  should be configured to sense at least torque forces. Preferably, the tool  18  is also configured to sense RPM and direction of rotation in order to help prevent inadvertent twisting off of or damage to the washover tool  124  or to the stuck component. 
   It is noted that the data acquisition system  22  preferably includes a graphical display,  23  in  FIG. 1 , of a type known in the art, thereby permitting a human operator to observe indications of downhole operating conditions and make adjustments to the downhole operation (i.e., by adjusting the rate of rotation or set down weight) in response thereto. The effect of the adjustment will be detected by the downhole sensors of the tool  18  and then transmitted to the surface  14  where it will be received by the data acquisition system  22 . Thus, it can be seen that a closed-loop system is provided for control of non-drilling applications based upon sensed data. 
   It is further noted that the display and data acquisition system  22  may comprise a suitably programmed personal computer, as opposed to the “rigfloor” displays that are associated with MWD and LWD systems. Because there are fewer and less complex parameters to measure and monitor than with a typical MWD or LWD system, a less complex and expensive display and acquisition system is required. 
   In a further aspect of the invention, automated or semi-automated control of the non-drilling processes is possible utilizing a closed loop system. The processor  53  processes measurements made by the sensors in the condition sensing tool  18 , at least in part, downhole during operations within the wellbore  12 . The processed signals or the computed results are transmitted to the surface  14  by the transmitter  56  of the condition-sensing tool  18 . These signals or results are received at the surface  14  by the data acquisition system  22  and provided to the controller  24 . The controller  24  then controls downhole operations in response to the signals or results provided to it. 
   The processor  53  may also control the operation of the sensors and other devices in the tool string  16 . The processor  53  within the tool  18  may also process signals from the various sensors in the condition sensing tool  18  and also control their operation. The processor  53  also can control other devices associated with the tool  18 , such as the devices casing cutter  80  or the underreamer  90 . A separate processor may be used for each sensor or device. Each sensor may also have additional circuitry for its unique operations. The processor  53  preferably contains one or more microprocessors or micro-controllers for processing signals and data and for performing control functions, solid state memory units for storing programmed instructions, models (which may be interactive models) and data, and other necessary control circuits. The microprocessors control the operations of the various sensors, provide communication among the downhole sensors and may provide two-way data and signal communication between the tool  18  and the surface  14  equipment via two-way mud pulse telemetry. 
   The surface controller  24  receives signals from the downhole sensors and devices and processes such signals according to programmed instructions provided to the controller  24 . The controller  24  displays desired drilling parameters and other information on a display/monitor  23  that is utilized by an operator to control the drilling operations. The controller  24  preferably contains a computer, memory for storing data, recorder for recording data and other necessary peripherals. The controller  24  may also include a simulation model and processes data according to programmed instructions. The controller  24  may also be adapted to activate alarms when certain unsafe or undesirable operating conditions occur. 
   While, in the described embodiments, the condition sensing tool  18  is shown to be directly connected to the workpiece  20 , this may not always be so. It is possible that a cross-over tool or some other component may be secured intermediately between the workpiece  20  and the tool  18 . 
   The foregoing description is directed to particular embodiments of the present invention for the purpose of illustration and explanation. It will be apparent, however, to one skilled in the art that many modifications and changes to the embodiment set forth above are possible without departing from the scope and the spirit of the invention.