Patent Publication Number: US-8122906-B2

Title: Pressure driven apparatus for sequential control of a cementing head

Description:
BACKGROUND OF THE INVENTION 
     I. Technical Field 
     The invention relates to a pressure-driven apparatus, such as pneumatically/hydraulically, for sequentially controlling a multiphase operation, e.g. of a cementing head. 
     II. Description of the Related Art 
     From the patent literature, the following is cited as prior art: 
     EP A2 837.216 discloses a cementing head comprising drop balls being held back by a rotary sleeve actuated by hydraulic or pneumatic pressure. The sleeve is rotated so as to open a port, allowing the ball to fall down the well. 
     The currently used method of operating a cementing head offshore: 
     The currently used system is manually operated, i.e. an operator must be lifted 5 to 15 meters above the drilling floor in a riding belt depending on how the cementing head is positioned. When the operator has been lifted up to the cementing head, he turns a handle ½ turn, after which he will be lowered down to the drilling floor. This operation is repeated an additional two times in order to release a cementing plug before and after a cementing job. 
     The Norwegian Petroleum Directorate has imposed a regulation that this operation is to be carried out by remote control, and that no riding belt is to be used for lifting workers up in the air on offshore installations. 
     SUMMARY OF THE INVENTION 
     In order to comply with this requirement, according to the invention, a pressure-driven, such as pneumatically/hydraulically driven, apparatus for the sequential control of the multiphase operation of the cementing head has been developed. 
     The present application relates to a pressure-driven, preferably pneumatically driven apparatus for the sequential control of a multiphase operation, e.g. of a cementing head, the apparatus being characterized in the features set forth in the claims. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIGS. 1A ,  1 B show the control apparatus, and 
         FIGS. 2A ,  2 B show the control procedure. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       FIG. 1A  shows the apparatus in a side view. A transmission arm  3  comprising a pawl  4  is supported on a cam shaft  9  connected to a pawl cylinder  1  having an integrated spring force or some other return load mechanism as well as three directional control valves,  8 ,  8 ′,  8 ″, and  8   n  having a spring return and roller  7 , which is operated by cam plates  6 ,  6 ′,  6 ″, and  6   n  of cam shaft  9 . 
       FIG. 1B  shows the apparatus in a top view in which a cam shaft  9  with cam plates  6 ,  6 ′, and  6 ″ that are staggered relative to each other in a predetermined angle to a pawl disk  5  supported in bearings  10  and  10 ′. Each time the system is supplied with pressure, pawl cylinder  1  with return spring  2  will rotate cam shaft  9  through pawl disk  5  to a particular angular position in the same rotational direction, and thereby operate directional valves  8 ,  8 ′,  8 ″, and  8   n  with rollers  7  operated by cam plates  6 ,  6 ′,  6 ″, and  6   n . A pawl disk  5  comprising a predetermined number of catch levers may include one or more wheels. 
     At the initiation of an operating procedure, none of the valves has been operated, and all valves on the cementing head are in their closed positions. 
     When pressurized air or another pressurized medium, e.g. hydraulic, is supplied to the sequence controller, pawl cylinder  1  will rotate cam shaft  9  forward to a predetermined angular position, whereby a first directional control valve  8  applies pressure to an actuator present and the first cementing valve or another valve will open for a predefined period of time until a timer control shuts off the pressure supply and the pressure bleeds off through a drain valve and the pawl cylinder  1  returns to the starting position. 
     On the next time pressure is supplied to pawl cylinder  1 , cam shaft  9  with cam plates  6 ,  6 ′,  6 ″, and  6   n  is rotated further by the predetermined angle, and the second cementing valve or another valve is opened so that both valves are open for a predetermined period of time until a timer relay shuts off the pressure supply and the pressure bleeds off and pawl cylinder  1  returns to the starting position, and on the third and/or following time pressure is supplied, cam shaft  9  is rotated in the same rotational direction to a predetermined angular position and a third directional control valve  8 ″ applies pressure to the actuator, so that all three cementing valves are open for a predetermined period of time until the timer relay shuts off the pressure supply and the pressure is discharged and pawl cylinder  1  returns to the starting position. When pressure is supplied to pawl cylinder  1  after all phases has been completed, cam shaft  9  is rotated further to the predetermined angular position, arriving at the starting position in which all directional valves are in their closed positions. 
     Additional information is provided as follows: 
       FIG. 2A  shows a control panel including:
         a valve  21  for supplying pressurized air to a cementing head  30     a timer relay  29  for setting the operating time for actuators of cementing head  30     two valves  22 ,  23 , each having a key  22 ′,  23 ′ for initiating the operation of the cementing head or a test valve  24 .   two valves  25 ,  26  having a flush-mounted push button  25 ′,  26 ′ and a spring return  27  for sequentially controlling cementing head  30     a valve  28  having a rotary button for locking and closing/opening test valve  24         

     Sequential procedure: 
     In order to apply pressure to the sequential control, initially a key-operated valve  22  must be energized by turning the key. Then both sequential valves  25 ,  26  must be depressed at the same time. Following this, pressure will be supplied to a port on valve  21 , and through this port to a timer relay  29  for setting the operating time for the actuators of cementing head  30 . Then, valve  23  with key  23 ′ must be closed/locked until the next sequence is run. In the meantime, cement is carried to the fill area. When the time period set for timer relay  29  has expired, a control pulse is sent to a port of valve  21 , which shuts off the pressure and drains cementing head  30 . 
     Safety measures: 
     Should an operator inadvertently depress the sequentially operated valves  25 ,  26  while the timer relay is engaged or the key-operated valves  22 ,  23  are locked, this will have no effect on the operation. 
     The multiphase operation is characterized in a predetermined repeatable sequence for operating actuators/valves in that a cam shaft is rotated a fixed number of angular increments and a fixed number of cam plates until all phases has been completed, so that the actuators/valves are operated as described herein, meaning that each time cementing is to be carried out, the above operation is repeated. 
       FIG. 2B  shows a side view of a cementing head  30  including a test valve  24 .