Abstract:
A mobile system travels with a work crew to various remote well sites and monitors the presence of H2S (hydrogen sulfide gas) at those sites. If the concentration of H2S reaches a toxic level, the system notifies a distant host computer of not only the problem but also where the problem exists. Help can then be dispatched to the known area. In some embodiments, the system notifies the work crew when help is on the way.

Description:
BACKGROUND OF THE INVENTION  
         [0001]    1. Field of the Invention  
           [0002]    The subject invention pertains to the hazards of hydrogen sulfide and more specifically to a system for responding to an excessive amount of hydrogen sulfide at a well site.  
           [0003]    2. Description of Related Art  
           [0004]    Hydrogen sulfide, H2S, is a toxic gas that often accompanies the production of gas, oil and water. H2S can usually be contained, but if it escapes, an H2S monitor can be used for alerting personnel in the area. In response to sensing about 10 to 20 ppm of H2S, typical H2S monitors will sound an alarm that warns of the danger. Once the alarm sounds, personnel often have sufficient time to vacate the area. In some cases, however, someone or everyone in the area may be overcome by the gas and fall to the ground. Since H2S is heavier than air, an unconscious person lying on the ground may continue breathing the toxic gas. If outside help is not quickly summoned to the area, eventually those continuing to breath the gas may die.  
           [0005]    U.S. Pat. No. 6,252,510 discloses an H2S system that calls for outside help upon sensing an excessive amount of H2S at a distant location. The system appears to be designed for an established chemical plant where the H2S monitor is at a fixed, known location. Such a system may be fine for such an application because the location of the H2S monitor is known, thus the location where medical assistance is needed is also known.  
           [0006]    However, in the case of an oilfield crew working among numerous remote oilfields, the location of the crew may be unknown to those that may otherwise be able to dispatch help to where it is needed. Thus, oilfield workers may be left stranded in an emergency and have to rely solely on their own ability to help themselves.  
           [0007]    It is conceivable to install a dedicated H2S monitor at each and every oilfield; however, such an approach would be unnecessarily expensive because the vast majority of oilfields operate unattended. Often, an H2S monitor and an emergency call-out alarm is only needed when a work crew or other personnel are in the area.  
           [0008]    Consequently, a need exists for an H2S monitor that can not only travel with a work crew but also communicate to outside help the location of the monitor.  
         SUMMARY OF THE INVENTION  
         [0009]    To improve the safety of a work crew that travels among numerous oilfields, it is an object of some embodiments of the invention to provide an H2S monitor system that can travel with the crew and transmit to a designated host computer information that indicates the location of the crew.  
           [0010]    In some embodiments, the H2S sensor is carried by a service rig or truck used by the work crew.  
           [0011]    In some embodiments, the H2S system calls for help via a wireless communication link between the H2S monitor and the designated host computer.  
           [0012]    In some embodiments, the host computer is notified of an alarm or fault after the host computer first sends an inquiry signal to the H2S system.  
           [0013]    In some embodiments, the H2S system provides an opportunity to deactivate an alarm within a certain time delay.  
           [0014]    In some embodiments, the system communicates to a host computer the location of the H2S monitor using a global positioning system.  
           [0015]    In some embodiments, the system communicates to a host computer the location of the H2S monitor using an LBS system.  
           [0016]    In some embodiments, the system communicates to a host computer a fault in the H2S system.  
           [0017]    In some embodiments, the H2S system employs an NDB transmitter that directs help to the area where the H2S monitor detected a high level of hydrogen sulfide gas.  
           [0018]    In some embodiments, the H2S system provides a reassurance signal that informs a work crew that help is on the way.  
           [0019]    One or more of these and other objects of the invention are provided by a mobile system for responding to hydrogen sulfide at a plurality of well sites that are remote relative to a host computer. In response to detecting an excessive concentration of hydrogen sulfide, the system communicates that information as well as the location of the problem to the host computer. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0020]    [0020]FIG. 1 is a schematic diagram of a mobile system for responding to a hazardous concentration of hydrogen sulfide gas.  
         [0021]    [0021]FIG. 2 is one example of an algorithm of a micro-controller that determines a system&#39;s response to a hazardous concentration of hydrogen sulfide gas.  
         [0022]    [0022]FIG. 3 is another example of an algorithm of a micro-controller that determines a system&#39;s response to a hazardous concentration of hydrogen sulfide gas. 
     
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0023]    [0023]FIG. 1 is a schematic diagram illustrating a mobile system  10  for responding to hydrogen sulfide gas detected at a plurality of well sites. The plurality of well sites may include, for example, a first well site  12  with a first well bore  14 , and a second well site  16  with a second well bore  18 . A broken line  20  indicates that well sites  12  and  16  are remote relative to each other, wherein the term, “remote” used herein and throughout refers to a distance of at least ten miles.  
         [0024]    System  10  and its various components are made mobile by virtue of a truck  20  that carries a variety of equipment to the various well sites. A typically stationary H2S monitor, for instance, is considered a mobile H2S monitor because the monitor is carried by truck  20 . The term, “truck” refers to any wheeled vehicle used to facilitate installing, disassembling, repairing, or otherwise servicing a well. A left-central area of FIG. 1 shows truck  20  at well site  12 , and a lower-right area of FIG. 1 shows truck  20  at well site  16 .  
         [0025]    Mobile system  10  primarily pertains to the safety-related equipment on truck  20 . In some cases, the safety-related equipment on truck  20  includes one or more of the following: a mobile hydrogen sulfide monitor  22 , its primary power supply  24  and its backup power supply  26 ; a first alarm  28 ; a second alarm  30 ; a mobile transmitter  32 , a GPS unit  34  (Global Positioning System); an LBS system  36  (Location-Based Services system); and a mobile NDB transmitter  38  (Non-Directional Radiobeacon).  
         [0026]    Hydrogen sulfide monitor  22  is schematically illustrated to represent any device that provides an alarm in response to sensing that hydrogen sulfide gas has exceeded a predetermined limit. Such hydrogen sulfide monitors are well known to those skilled in the art.  
         [0027]    Alarms  28  and  30  are schematically illustrated to represent a single-unit alarm or the alternate embodiment of two separate alarm units. In some embodiments, the single-unit can only generate a single alarm (audible or visible), and in other embodiments, the single-unit can selectively emit two or more distinguishable alarms (e.g., high pitch and low pitch).  
         [0028]    A controller  40  coordinates and controls the operation and interaction of the safety-related equipment. Controller  40  is schematically illustrated to represent any appropriate logic processor. Examples of controller  40  include, but are not limited to, a personal computer, microprocessor, microcomputer, PC, desktop computer, laptop computer, notebook computer, handheld computer, portable computer, PDA device (e.g., a personal digital assistant, PLC (programmable logic controller), analog electrical circuit, digital electrical circuit, and various combinations thereof. Controller  40  may include appropriate I/O devices such as I/O boards, I/O modules, A/D converters, drivers, etc. Such devices are well known to those skilled in the art.  
         [0029]    In operation, truck  20  may travel to well site  12  to service the well. While there, controller  40  controls the operation of the safety-related equipment according to some predetermined control algorithm. In some embodiments, for example, controller  40  operates according to the algorithm of FIG. 2.  
         [0030]    In FIG. 2, decision block  42  first determines whether H2S monitor  22  is functioning properly or whether some monitor-related fault has occurred. The fault refers to a malfunction rather than a hydrogen sulfide triggered event. In some cases, for example, a current transformer in communication with controller  40  may determine that H2S monitor  22  has switched from its primary power supply  24  (e.g., the truck&#39;s main battery) over to backup power supply  26  (e.g., dedicated backup battery for monitor  22 ).  
         [0031]    If a monitor-related fault occurs, control block  44  commands transmitter  32  to transmit an H2S fault signal  46  and a location signal  48  over a wireless communication link  50  to a remote designated host computer  52   a , which could be at a central dispatch office or some other distant location. Knowing the location and nature of the problem, the dispatch office can respond accordingly. Transmitter  32  is schematically illustrated to represent any device for enabling the transmission and/or receiving of signals through air. Examples of transmitter  32  include, but are not limited to, a transceiver, antenna, parabolic dish, cellular phone, modem, etc.  
         [0032]    Location signal  48  can be provided in various ways, such as by employing GPS unit  34  or LBS system  36 . GPS unit  34  is a satellite-based system that identifies a location&#39;s global coordinates. LBS system  36  determines the location of transmitter  32  when transmitter  32  is part of a network of similar transmitters, as is the case with cellular phone technology. The LBS system employs triangulation of multiple transmitters to identify the location of a particular transmitter, such as transmitter  32 . Both GPS and LBS systems are well known to those skilled in the art.  
         [0033]    If a monitor-related fault does not exist, and H2S monitor  22  is functioning properly on its primary power supply  24 , then control logic transfers to block  54 , which clears or terminates H2S fault signal  46 .  
         [0034]    Next, the control logic transfers to decision block  56 . In response to input from H2S monitor  22 , decision block  56  determines whether H2S monitor  22  detects a concentration of hydrogen sulfide gas  58  that exceeds a predetermined, allowable limit. If the H2S level is below the limit, the control logic returns to decision block  42 .  
         [0035]    If, however, the concentration of H2S exceeds the allowable limit, block  60  initiates a time delay (e.g., 30 seconds, 60 seconds, two minutes, or whatever), and block  62  activates alarm  28 . In some embodiments, the time delay of block  60  is a programmed value that could be set to any value greater than or equal to zero. Blocks  64  and  66  provide a limited opportunity for someone to abort the H2S alarm/call-out sequence. If someone resets or disables the process by actuating a reset switch  68  within the time delay defined by block  64 , then block  70  deactivates alarm  28 , block  72  resets and terminates the time delay, and the control logic returns to decision block  42 .  
         [0036]    If decision block  64  determines that the time delay has run its course without being reset, then the control logic transfers to block  74 . Block  74  sets a counter-N to one, and block  76  commands transmitter  32  to transmit an alarm signal  78  over wireless communication link  50  to one or more host computers, such as host computer  52   a . Likewise, block  80  commands transmitter  32  to transmit location signal  48  to host computer  52   a , so the host computer is made aware that H2S monitor  22  was triggered at well site  12 . In other words, someone beyond the well site knows that an H2S alarm was triggered and knows the location where it was triggered.  
         [0037]    It should be noted that the communication of the alarm and its location to one or more host computers can be carried out using conventional wireless communication technology including, but not limited to, analog or digital cell phone, pager, Internet, etc.  
         [0038]    If the information was successfully conveyed to host computer  52   a , a person at computer  52   a  can dispatch a rescue team  82  (e.g., helicopter, ambulance, etc.) to well site  12  and send an acknowledgement signal  84  back to well site  12  via a transmitter  86  (or transceiver, etc.), communication link  50 , and transmitter  32  (or an appropriate receiver or transceiver at well site  12 ). Once controller  40  receives acknowledgement signal  84  as determined by a decision block  90 , a block  88  discontinues an alarm signal  28 ′ and block  92  activates a reassurance signal  30 ′. Reassurance signal  30 ′ is preferably an audible signal that can be differentiated from alarm signal  28 ′. Reassurance signal  30 ′ notifies those at well site  12  that help is on the way.  
         [0039]    To direct rescue team  82  to well site  12 , block  94  may, in some embodiments, command transmitter  38  to emit an NBD signal  94 . The rescue team, in turn, has a conventional ADF set (Automatic Direction Finder set) which points to the source of NDB signal  94 , whereby the ADF and NDB system helps guide the rescue team to well site  12 .  
         [0040]    Once help has arrived, decision block  96  resets system  10 , block  98  terminates the transmission of NDB signal  94 , block  100  ensures counter-N is set to one, block  102  discontinues reassurance signal  30 ′, block  70  ensures alarm  28  is turned off, block  72  ensures that the time delay is reset, and control returns to decision block  42 .  
         [0041]    Referring back to decision block  90 , if the first host computer  52   a  fails to acknowledge alarm signal  78  within a predetermined reasonable time (e.g., 15 seconds), then block  104  increments counter-N, and blocks  76  and  80  transmit alarm signal  78  and location signal  48  to another designated host computer  52   b . In some embodiments, the “predetermined reasonable time” specified in block  90  is a programmed value that could be set to any value greater than or equal to zero seconds. If the predetermined reasonable time is zero seconds, then all the host computers are notified of the problem simultaneously. The first host computer to respond could then notify the other host computers that the problem is being attended to. The first responding computer, for instance, could send a message over the Internet that notifies the other computers that the first responding computer has already responded to the alarm. If the predetermined reasonable time is greater than zero, then the incrementing of counter-N and sequential calling of other designated host computers  52   a  can continue until a host computer is successfully notified of the problem. When a host computer is reached, its response could be the same as just described with reference to host computer  52   a.    
         [0042]    The process just described is similar regardless of whether truck  20  is at well site  12  or  16 . However, the location-related information will of course be different and unique for each well site.  
         [0043]    In an alternate embodiment, controller  40  follows the logical sequence presented by the algorithm of FIG. 3. In this case, a decision block  106  determines whether host computer  52   a  has sent an inquiry signal  108  via communication link  50 . If so, block  110  commands transmitter  32  to transmit H2S alarm signal  78  provided an H2S hazard relay has been latched. The H2S hazard relay is a conventional latch relay that is latched whenever H2S monitor senses that the concentration of H2S  58  exceeds the allowable limit. Similarly, block  112  commands transmitter  32  to transmit fault signal  46  if an H2S fault relay has been latched. The H2S fault relay is a conventional latch relay that is latched whenever controller  40  determines that a malfunction has occurred with H2S monitor  22 . The malfunction could simply be the H2S monitor switching over to its backup power supply  26 .  
         [0044]    After block  112  or if inquiry signal  108  has not been received, the logic transfers to decision block  114 . Block  114  determines whether a fault exists with H2S monitor  22 . If so, block  116  latches the H2S fault relay. Otherwise, block  118  ensures that the fault relay is unlatched.  
         [0045]    Next, decision block  120  determines whether the H2S hazard relay is latched. If latched, the logic transfers to a decision block  122 , which determines whether system  10  is reset. If system  10  has not been reset, block  122  returns the logic to block  106 . Otherwise, block  122  directs the logic to blocks  124 ,  126  and  128 , which respectively unlatches the H2S hazard relay, resets a time delay, and stops alarm  28 . After block  128 , the logic returns to block  106 .  
         [0046]    Referring back to decision block  120 , if the H2S hazard relay is not latched, a decision block  130  determines whether H2S monitor  22  detects a concentration of hydrogen sulfide that exceeds an allowable limit. If the hydrogen sulfide does not exceed the limit, the control logic returns to block  106 .  
         [0047]    If, however, the hydrogen sulfide does exceed the allowable limit, block  132  starts a time delay, and block  134  activates alarm  28 . If no one resets alarm  28  within the allowed time delay as determined by blocks  136  and  138 , then a block  140  latches the H2S hazard relay and returns the logic to decision block  122 . If someone clears alarm  28  before the time delay expires, then the control logic returns to block  124 . The process continues for as long as it is needed.  
         [0048]    With the control algorithm of FIG. 3, host computer  52   a  knows the location of the alarm and fault activity because it is computer  52   a  that sends a unique inquiry signal  108  to each of the various well sites. In other words, computer  52   a  sends out one particular inquiry signal  108  to obtain the alarm and fault status of well site  12 , and computer  52   a  sends out a different inquiry signal  108 ′ to obtain the status of well site  16 .  
         [0049]    Although the invention is described with reference to a preferred embodiment, it should be appreciated by those skilled in the art that other variations are well within the scope of the invention. Therefore, the scope of the invention is to be determined by reference to the claims, which follow.