Abstract:
An apparatus for telemetering a downhole parameter from a well. The apparatus comprises a housing having a bore. The apparatus further comprises an annular main valve with an enlarged end positioned within the bore, with the main valve having a center of axis. A restrictor is concentrically disposed within the bore, the restrictor configured to define an annular passage with the main valve. The apparatus also includes: a pressure device for supplying hydraulic pressure to the main valve; a control valve, operatively associated with the restrictor member, for controlling pressure to the main valve; and a solenoid control valve assembly for activating the control valve. In one preferred embodiment, the solenoid control valve assembly comprises a controller for emitting an electrical signal, a coil that receives the electrical signal and generates a magnetic field, a solenoid static pole receptive to the generated magnetic field, and a solenoid moving pole responsive to the magnetic field so that the solenoid moving pole moves in a direction towards the solenoid static pole. A method for communicating a downhole parameter is also disclosed.

Description:
BACKGROUND OF THE INVENTION  
       [0001]     This invention relates to a measurement while drilling tool. More specifically, but without limitation, this invention relates to an apparatus and method for telemetering a down hole parameter from a well.  
         [0002]     Operators drill wells many thousands of feet in the search for hydrocarbons. The wells are expensive and take a significant amount of time to plan. Operators find it important to obtain data about the various subterranean reservoirs once the actual drilling begins. Thus, measurement while drilling (MWD) tools have been developed that gather information about the subterranean reservoirs and telemetry the data to the surface. Engineers and geologist can then use this data in an effort to understand the formations and make plans on completion, sidetracking, abandoning, further drilling etc.  
         [0003]     MWD tools are expensive tools due to their complexity. The tools are designed for a lifetime of 5-7 years, and the tools are routinely made of expensive materials and electronics which require a lot of maintenance by highly trained personnel. Typically, service companies have geographically positioned regional maintenance facilities that perform these tasks. As the use of MWD and LWD tools expanded, several problems have become evident. One problem is that maintenance requires very high levels of training. Mean time between failures (MTBF) has become the standard measurement for evaluating the reliability of the MWD technology, and a central question is when will the tool fail. Another problem is that the maintenance facilities require large spaces and expensive testing equipment. It is not uncommon for a MWD tool to spend as much time traveling to and from these maintenance facilities as it does at the wellsite. In one study, it was found that a MWD tool string spends less than 90 days a year in a well, and the maintenance and logistics cost of a MWD tool can amount to 50% of the annual expense of the system.  
         [0004]     Therefore, it is an object of the present invention to reduce the maintenance and repair time of MWD tools. It is also an object of the present invention to reduce the maintenance and repair cost. It is also an object to manufacture a tool that is less expensive to build, less complex and have higher reliability. These objects, and many others, will be met by the following disclosure.  
       SUMMARY OF THE INVENTION  
       [0005]     An apparatus for telemetering a down hole parameter from a well is disclosed. The apparatus comprises a cylindrical housing having a bore there through. The apparatus further comprises an annular main valve positioned within the bore, with the main valve having a center of axis, and wherein the main valve is in a funnel shape having a tubular inlet and tubular outlet, and a restrictor member concentrically disposed within the bore of the cylindrical housing, wherein the restrictor member is aligned with the center of axis, the restrictor member configured to define an annular passage with the main valve. The apparatus also includes: a hydraulic circuit control pressure passage means for supplying hydraulic pressure to the main valve; control means, operatively associated with the restrictor member, for controlling pressure to the main valve; and a solenoid control valve assembly for activating the control means. It should be noted that the solenoid control valve assembly may also be referred to as the magnetic control valve assembly.  
         [0006]     In one preferred embodiment, the solenoid control valve assembly comprises a controller for emitting an electrical signal, a coil receiving the electrical signal in order to energize the coil and generating a magnetic field, a solenoid static pole receptive to the generated magnetic field, and a solenoid moving pole responsive to the magnetic field so that the solenoid moving pole moves in a direction towards the solenoid static pole. Also, the control means may comprise a shaft operatively associated with the solenoid moving pole, a ball engageable with the shaft, and a ball seat configured to sealingly engage with the ball. The restrictor member may include a restrictor housing having a bolt that is selectively movable within the restrictor housing to vary the size of the annular passage. The restrictor housing further includes an annular screen for allowing passage of a fluid into an annular cavity.  
         [0007]     The cylindrical housing is configured to have an annular flow area for the hydraulic circuit control passage means that communicates pressure from the pressure means to the main valve through the cylindrical housing. In one preferred embodiment, the hydraulic circuit control passage means includes a passage through said static pole and through the ball seat in order to act against the main valve. Additionally, as the coil de-energizes, the shaft, via the moving pole, returns and the ball is allowed to return to seal against the ball seat so that the main valve moves from a first position to a second position thereby enlarging the annular passage.  
         [0008]     A method of communicating a down hole parameter is also disclosed. The method comprises providing a down hole apparatus, the down hole apparatus including: a cylindrical housing having a bore; an annular main valve positioned within the bore, the main valve having a center of axis, and wherein the main valve has a first end disposed within the bore and an enlarged second end, and wherein the main valve is movable from a first position to a second position; a restrictor member concentrically disposed within the bore of the enlarged second end of the main valve, wherein the restrictor member being aligned with the center of axis, and wherein the main valve has the first end disposed within the bore and the enlarged second end configured to form an annular passage about the restrictor member; hydraulic circuit control pressure passage means for supplying hydraulic pressure to the main valve.  
         [0009]     The method further includes flowing the drilling fluid through the bore, emitting an electrical signal with a controller, and receiving the electrical signal with a coil. The method further includes generating a magnetic field, receiving the magnetic field at a solenoid static pole so that the solenoid static pole is magnetized, and moving a solenoid moving pole in response to the generated magnetic field in the direction of the solenoid static pole. The method further includes moving a shaft, the shaft being operatively attached to the solenoid moving pole. The method further comprises displacing a ball that is seated within a ball seat, allowing pressure from an annular cavity to pass through a hydraulic circuit control pressure passage means which includes through the ball seat and displace the main valve from the first position to the second position, and decreasing the annular passage between the main valve and the restrictor member thereby causing a pressure pulse to be created within the bore of the cylindrical housing indicative of the downhole parameter.  
         [0010]     In one preferred embodiment, the step of flowing the drilling fluid through the bore includes channeling the turbulent flow of the drilling fluid through the enlarged second end of the main valve and into the annular passage. The method may further comprise emitting a second electrical impulse signal with the controller, terminating the second electrical signal to the coil so that the magnetic field is terminated, moving the ball onto the ball seat by the pressure within the annular cavity via the pressure within the cavity, terminating the flow through the hydraulic circuit control pressure passage means and moving the main valve from the second position to the first position via the pressure within the bore of the cylindrical housing.  
         [0011]     An advantage of the present invention is that the design allows for fewer parts and a shorter tool length. Another advantage is that the components of the system are designed in modules, wherein the modules can be replaced with a new module. Another advantage is that no field service technicians are needed, eliminating maintenance problems. Because the tool is designed to go straight from manufacturing to the rig, much higher utilization rates will be achieved.  
         [0012]     A feature of the present invention includes the annular main valve, wherein the funnel shape of the main valve contains all violent, turbulent flow caused by pulsers, and in doing so, it contains all the erosion within its surface that is made of very hard ceramic or tungsten carbide material. Another feature is the ball control valve that utilizes a poppet valve constructed of a separate ball and shaft that allows the ball to seat perfectly by eliminating concentricity issues. Another feature is that the present design is very well suited for fluids with high solid contents.  
         [0013]     Yet another feature is the annular screen element that allows a large inlet area for a relatively small axial height, thus allowing the overall length to be significantly shorter than current designs. Still yet another feature is that the annular solenoid doughnut shape provides the geometry best suited to minimize overall valve length. Another feature is the annular control valve. Still yet another feature is the control valve ball seat, pilot driven main valve, and exit that are nearly aligned to minimize axial packaging requirements. Thus, the shortest (minimum axial length) possible valve is obtained. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0014]      FIG. 1A  is a perspective view of the drill collar housing containing the down hole apparatus and drill bit.  
         [0015]      FIG. 1B  is a perspective view of the drill bit and drill collar housing seen in  FIG. 1A  taken from view I-I.  
         [0016]      FIG. 2  is a cross-sectional view of the drill collar housing containing the down hole apparatus seen in  FIG. 1A  taken along line A-A of  FIG. 1B .  
         [0017]      FIG. 3  is a cross-sectional view of the drill collar housing containing the down hole apparatus seen in  FIG. 1A  taken along line B-B of  FIG. 1B .  
         [0018]      FIG. 4A  is a cross-sectional view of the drill collar housing containing the down hole apparatus seen in  FIG. 1A  taken along line C-C of  FIG. 1B .  
         [0019]      FIG. 4B  is an enlarged view of the pressure bulkhead seen in  FIG. 4A .  
         [0020]      FIG. 5  is an enlarged view of the detail area “D” seen in  FIG. 2 .  
         [0021]      FIG. 6  is an enlarged view of the detail area “E” seen in  FIG. 2 .  
         [0022]      FIG. 7  is an enlarged view of the detail area “F” seen in  FIG. 6 .  
         [0023]      FIG. 8  is an enlarged view of the detail area “D” seen in  FIG. 2 .  
         [0024]      FIG. 9  is a schematic representation of the down hole apparatus being used in a well bore.  
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0025]     Referring now to  FIG. 1A , a perspective view of the drill collar housing  2  containing the down hole apparatus and drill bit  4 . As understood by those of ordinary skill in the art, the drill collar housing  2  is connected to the drill bit  4 .  FIG. 1B  is a perspective view of the drill collar housing seen in  FIG. 1A  taken from view I-I. More specifically,  FIG. 1B  depicts the lines A-A, B-B, and C-C which will described in more detail later in the application.  
         [0026]     Referring now to  FIG. 2 , a cross-sectional view of the drill collar housing containing the down hole apparatus, drill collar housing  2  and drill bit  4  seen in  FIG. 1A  taken along line A-A of  FIG. 1B  will now be described. It should be noted that like numbers appearing in the various drawings refer to like components. More specifically,  FIG. 2  depicts the battery and electronics section  6  to power and control the tool. The electronics section  6  includes a controller for processing collected down hole data, storing the data and generating outputs to the various electronic components.  FIG. 2  also depicts the sensors  8  to make measurements, such as directional survey sensors and/or gamma ray sensors. A communications port  10  is provided in order to talk to the tool before and after being used in the drill string. The pressure housing  12  is shown, wherein the pressure housing  12  is used to package sensors, batteries, and electronics.  FIG. 2  also depicts the drill collar housing  14  that connects to the remainder of the drill string.  FIG. 2  also depicts the detail ovals D, E and F which will be discussed later in the application. The down hole pulser apparatus is seen generally at  16 , and is generally contained within the detail box D.  
         [0027]      FIG. 3  is a cross-sectional view of the drill collar housing  2  taken along line B-B of  FIG. 1B .  FIG. 3  depicts the battery and electronics section  6 , the pressure housing  12  and the communications port  10 , as well as the downhole pulser apparatus  16  (hereinafter pulser  16 ).  
         [0028]      FIG. 4A  is a cross-sectional view of the drill collar housing  2  containing the pulser  16  taken along line C-C of  FIG. 1B . The pressure bulkhead  18  is also shown in  FIG. 4A .  FIG. 4B  is an enlarged view of the pressure bulkhead  18  seen in  FIG. 4A . The pressure bulkhead  18  is used to provide electrical power to the solenoid, but isolate internals of the pressure housing  12  from fluid pressure exposure. The pressure bulkhead  18  contains a single conductor with first prong  20  that is connected to the battery and electronic section  6  and a second prong  22  that connects to the solenoid coil that will be described in greater detail later in the application. There are two pressure bulkheads  18  (one is not shown), one for each electrical termination of the solenoid coil.  
         [0029]     Referring now to  FIG. 5 , an enlarged view of the detail area “D” as seen in  FIG. 2 , and in particular the pulser  16  seen in  FIG. 2 , will now be described.  FIG. 5  depicts the screen and restrictor housing  24  with the annular screen  26  disposed therein. As those of ordinary skill in the art recognize, the drilling fluid is pumped down the drill string, as denoted by arrow “AA”. The screen  26  allows the liquid part of the drilling fluid flow to pass and keeps the larger particles from going into the hydraulic circuit control passage and the solenoid control valve assembly, as will be more fully described later.  FIG. 5  also depicts the annular control housing  28  which provides the large annular area for the hydraulic circuit control passage that feeds the main valve  30  with drilling fluid, as will be more fully explained. The main valve  30  contains an outer diameter portion and an inner diameter portion.  FIG. 5  shows the connection point of the screen  26  and restrictor housing  24  and the annular control housing  28  at threads  34 .  FIG. 5  further depicts the restrictor bolt  36  which supports the main valve restrictor  37  and provides a means to adjust the axial position used to set the size of the pressure pulse. As seen in  FIG. 5 , the main valve  30  is in a funnel shape. In other words, the first end  38  has a larger inner diameter than the second end  40 , and wherein end  38  acts as a tubular inlet and end  40  acts as a tubular outlet for the drilling fluid.  
         [0030]     The restrictor housing  24  holds the restrictor  37  and screen  26  and provides a passage for the drilling fluid from the center of the drill pipe to the annulus cavity between the restrictor  37  and the main valve  30 . The restrictor  37  provides the restriction on the inner conical surface of the main valve for the flow of the drilling fluid. If the main valve  30  moves forward enough, the main valve  30  could contact the restrictor  37  and completely shut off the flow of the drilling fluid. In the embodiment shown, however, this could not happen because there is a physical stop upstream of the main valve that stops it from contacting the restrictor. As will be more fully explained later in the application, the solenoid control valve assembly opens and closes and causes flow or no flow through the hydraulic circuit control passage. The restrictor  37  will be attached to the annular control housing  28  as shown in  FIG. 5 . The drilling fluid coming down the bore of the drill pipe will divert about the diverter, out of the opening “O”, and back into the bore of the main valve  30 .  
         [0031]      FIG. 5  further depicts the solenoid control valve assembly which includes the solenoid static pole  42 , and wherein the solenoid static pole  42  contains certain cavities, seen generally at  44  that contain hydraulic oil. The solenoid static pole  42  is operatively associated with the solenoid coil  46 , and wherein the solenoid coil  46  is connected to the solenoid coil housing  48 . As shown in  FIG. 5 , the solenoid coil housing  48  is positioned within the drill collar housing  2 . The pulser  16  also includes the main valve bearing housing  50 , and wherein the main valve bearing housing  50  is operatively connected to the annular control housing  28 . The main valve upper bearing  52  and the main valve lower bearing  54  are adjacent and cooperate with the main valve bearing housing  50 , and wherein the bearings  52  and  54  serve the purpose of positioning the main valve  30  concentric within the main valve bearing housing  50 . The solenoid moving pole  56  is shown disposed between the main valve bearing housing  50  and the poppet shaft  58 . The solenoid coil  46  is the winding that when current flows through it, it creates a magnetic field in the iron-rich materials that form a path around the coil  46 . The magnetic field produces a magnetic force that attracts the solenoid moving pole  56  to the solenoid static pole  42 . As seen in  FIG. 8 , lack of this force causes the axial gap “G” to open.  
         [0032]     Returning to  FIG. 5 , the restrictor sleeve  60  covers the axial gap between the restrictor  37  and the restrictor bolt  36 . The restrictor  37  is made of very hard material such as ceramic or tungsten carbide. Also,  FIG. 5  depicts the pressure pipe plug  64  that is used to fill and isolate the control valve cavity  44  which is filled with clean hydraulic fluid. The rubber compensating sleeve  66  compensates for hydraulic fluid contraction and expansion within cavity  44  due to temperature and pressure.  
         [0033]     It should be noted that as shown in  FIG. 5 , the most preferred embodiment depicts a ball on the left side and the right side as well as a shaft on the left side and the right side that are attached to one moving pole (which is cylindrical). Only the right side ball and shaft have been described.  
         [0034]     Referring now to  FIG. 6 , an enlarged view of the detail area “E” seen in  FIG. 2  will now be described. This view shows, among other things, the main valve bearing housing  50 , and slidably adjacent to it, the solenoid moving pole  56 . The main valve bearing  54  is disposed between the main valve  30  and the main valve bearing housing  50 .  FIG. 6  also depicts the cavity  44 . The first end  38  of main valve  30  depicts the enlarged inner diameter while the second end  40  depicts the smaller inner diameter. Thus, main valve  30  is in the shape of a funnel. The shaft  58  has a bottom  67   a  that will engage with the top end of the set screw as will be explained later in the application.  
         [0035]      FIG. 7  is an enlarged view of the detail area “F” seen in  FIG. 6 . The control valve ball  68  is positioned adjacent the control valve poppet shaft  58 , and wherein the ball  68  is separate from shaft  58  and the ball  68  will seal-off in the seat  70 . A control valve shaft sleeve  72  is pressed onto the control valve poppet shaft  58 , and the control valve poppet bearing  74  is disposed about sleeve  72 . A control valve wiper and seal  75  is also included. The control valve return spring  76  pushes the moving pole  56  back into its lower position when the current in the solenoid is removed and the magnetic field is turned off. The spring  76  engages the retaining ring  78 . The setscrew  80  is used to adjust the critical gap of the solenoid that defines how far the ball  68  moves. The set screw  80  that is threaded into the moving pole will engage with the bottom  67   a  of the shaft  58  so that movement of the moving pole  56  moves the set screw  80  which in turn engages and moves the shaft  58 .  
         [0036]     As seen in  FIG. 7 , the control valve ball guide rails  84  contain the control valve ball  68  by providing for a large unobstructed inlet flow area when the ball is unseated. The arrows “BB” depicts the hydraulic circuit control passageway which allows the pressure to act against the main valve  30 .  
         [0037]     It should be noted that  FIGS. 5, 6 ,  7  show the situation where the shaft  58  has displaced the ball  68  due to the magnetic movement means, and in particular, the solenoid moving pole  56 . As noted earlier, the shoulder  67   a  is engaged with moving pole  56  which causes shaft  58  to move upward.  FIG. 8  is an enlarged view of the detail area “D” seen in  FIG. 2 . In  FIG. 8 , the ball has resumed its position on the control valve seat  70  so that the hydraulic pressure is no longer communicated through the hydraulic circuit control pressure passage “BB” and against the main valve  30  (i.e. the hydraulic circuit control pressure passageway is closed), which is due to the termination of the magnetic field. In other words, in  FIG. 8 , the solenoid moving pole  56  has returned to its initial position. When the coil is de-energized, the control valve ball  68  seals against the seat  70 , and the shaft  58  is in its lowered position due to the de-energized coil. The shaft  58  has returned to this lowered position due to the biasing action of spring  76 . Hence,  FIG. 8  depicts a view of the detail area “D” seen in  FIG. 2 , wherein the ball  68  is seated on the seat  70 . The annular passage is denoted by the letters “AP”.  
         [0038]     Referring back to  FIGS. 5, 6 , and  7  collectively, the pressure profile within the pulser  16  will now be described. P 1  denotes the pressure of the drill pipe fluid flow just upstream or at the inlet of the pulser  16 . P 2  is the pressure of the annular cavity AC 1  filtered by the screen  26 . P 3  signifies the pressure of the annular cavity AC 2  formed by the main valve  30 . P 4  is the pressure of the primary drilling fluid flow in the bore of the main valve  30  downstream from the restrictor  37 . Also, P 5  is the oil pressure of the internal cavities  44  of the solenoid control valve assembly.  
         [0039]     According to the teachings of the present invention, there are two (2) states for the pulser  16 . In the first state, there is no flow through the hydraulic circuit control passage “BB”. The control valve ball  68  seals against the control valve ball seat  70  and prevents any flow through the hydraulic circuit control passage. The main valve  30  is pushed downstream against the mechanical stop  86  (seen expressly in  FIG. 5 ). In this state, there is a minimum of pressure drop through the pulser  16 . This minimum pressure drop, which has been found to be usually less than 100 psi, is the hydraulic power used to drive the main valve&#39;s  30  movement to the upward (restricted) position. The annular cavity AC 2  of the main valve  30  has a pressure P 3 , which equals its bore pressure P 4 .  
         [0040]     In the second state, there is flow through the hydraulic circuit control passage “BB”. The flow goes through the screen  26 , then past the control valve ball  68  and ball seat  70  and finally, through a hole  88  in the main valve  30 . The opening area of the control valve ball  68  and ball seat  70  of the solenoid control valve assembly is much larger than the hole  88  through the main valve  30 . When flow begins in the hydraulic circuit control passage “BB, there is a pressure increase in the annular cavity AC 2  of the main valve, that is, P 3  increases to the value of P 2 . That is, the annular pressure of the main valve  30  now experiences the upstream inlet pressure of the pulser  16 . This pressure increase causes the main valve  30  to move forward. As the main valve  30  moves forward, it closes the distance (space) between the main valve  30  and the restrictor  37  (i.e. the area of the annular passage decreases). This increases the pressure drop across the tool and more specifically through the restriction between the restrictor  37  and the main valve  30 . This causes a pressure pulse that travels at the speed of sound upstream to the drilling rig. The main valve  30  then stops movement as it hits the upstream physical stop  90 , which is the radial end of the annular control housing  28 .  
         [0041]     In operation, the solenoid control valve assembly starts operation in the closed position (i.e. the first state). The control flow through the hydraulic circuit control passage “BB” is shut-off. The net pressure on the main valve  30  is biased downward and so the main valve  30  rest on the downstream stop  86 . As understood by those of ordinary skill in the art, the electronics encode sensor data into pressure pulses. Also as well understood by those of ordinary skill in the art, there are many algorithms to encode the sensor data. When it is time to send a pulse, the electronics (controller) send the necessary current and voltage to the solenoid coil  46 , which pulls in the moving pole  56  to stop against the static pole  42 .  
         [0042]     The moving pole  56  pushes the poppet shaft  58 , which pushes the ball  68  off the sealing seat  70 . As mentioned earlier, this allows a free flow through the hydraulic circuit control passage BB, which is through the screen  26 , through the annular space AC 1 , through the ball seat  70 , and past the poppet shaft  58 , into the annular cavity AC 2  of the main valve in order for the hydraulic pressure to act against the radial surface “S” (on the outer diameter portion of the main valve  30 ). This control flow is restricted through the small exit hole  88  of the main valve  30  resulting in the system pressure drop being experienced in the AC 2 . This flow provides an increase in pressure in the annular cavity AC 2  of the main valve  30 , which creates an imbalance and starts moving the main valve  30  upstream. This movement continues until the main valve  30  hits the up-hole physical stop  90 . When the movement stops, there is a tighter restriction in the annular passage “AP” i.e. the flow area between the main valve  30  and the restrictor  37 . This restriction causes an increase in pressure above the tool, which can be seen at the surface. After a short time interval (anywhere from 1/10 of a second or greater, depending on the code format), the electronics shuts off the current to the solenoid, which allows the moving pole  56  to return to its un-energized state using the spring force  76 . This action shuts-off flow through the hydraulic circuit control passage “BB”, since the ball  68  seats again on the seat  70 . The system is again back to the original first state. The main valve  30  then returns to the original position due to the force of the drilling fluid moving down the drill string.  
         [0043]     Referring now to  FIG. 9 , a schematic representation of the downhole apparatus being used in a well bore  100  will now be described. Hence, the bit  4 , which is connected to the drill collar housing  2 , has drilled the well bore  100 , and the operator is performing measurement while drilling operations. A drill string  102  is attached at one end to the rig  104  and at the other end is connected to the drill collar housing  2  (as noted earlier, the down hole apparatus  16  is positioned within the drill collar housing). The fluid flow of the drilling fluid within the well bore  100  is shown by the arrows “AA”, which is known as circulating. As taught by the present disclosure, the downhole sensors are collecting data, and the data is being processed down hole, and ultimately, the information is telemetered via pressure pulses through the fluid column to the surface.  
         [0044]     Although the present invention has been described in terms of specific embodiments, it is anticipated that alterations and modifications thereof will no doubt become apparent to those skilled in the art. It is therefore intended that the following claims be interpreted as covering all such alterations and modifications as fall within the true spirit and scope of the invention.