Personal hydrogen sulfide gas alarm system

[00002] 1. Field of the Invention

[00003] The subject invention pertains to the hazards of hydrogen sulfide and more specifically to a personal system for responding to an excessive amount of hydrogen sulfide.

[00004] 2. Description of Related Art

[00005] 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 H25, 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.

[00006] 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 monitoring hydrogen sulfide gas at a particular location, but it may be inadequate for protecting an individual moving from one location to another.

[00007] In the case of an outdoor well site that includes a stationary H2S monitor, an undetected problem may occur if a hydrogen sulfide leak is downwind of the H2S monitor, and an oilfield worker is downwind of the leak. The worker may be exposed to the hydrogen sulfide gas, but the monitor may fail to detect the leak.

[00008] Today, H2S monitors, various fault monitoring systems, and wireless communications are used for monitoring conditions at a well site. SCADA (Supervisory Control And Data Acquisition) is perhaps the most common system for monitoring the pumping conditions at a well site and for communicating pumping-related faults to another location. Various transducers that sense a pumping condition (e.g., fluid pressure, fluid level, power failure, etc.) are hardwired to the hardware portion of the SCADA system. Hardwiring a person-carried H2S monitor to a SCADA system, unfortunately, would drastically limit the portability of the H25 monitor. Thus, person-carried H2S monitors are generally stand-alone devices that simply sound an alarm upon sensing a certain concentration of hydrogen sulfide gas. Such an alarm, however, may not necessarily alert outside help.

[00009] Consequently, a need exists for a completely portable, person-carried H2S monitor that can summon help from a remote location. It may be beneficial to have such a system where an existing conventional H2S monitor can be incorporated into a conventional SCADA system, thereby avoiding the cost of an entirely new monitor and communication system.

[00010] It is an object of some embodiments to provide a person-carried H2S monitor that communicates with a stationary fault monitoring system, which in turn communicates with a distant host computer.

[00011] It is an object of some embodiments to provide a personal alarm system where an existing conventional H2S monitor can be incorporated into a conventional SCADA system, thereby avoiding the cost of an entirely new monitor and communication system.

[00012] It is an object of some embodiments to use a microphone to help communicate an H2S fault to a fault monitoring system such as a SCADA system.

[00013] It is an object of some embodiments to provide a signal relay unit with a leaning mode so that the unit can adapt itself to different types of H2S monitors.

[00014] It is an object of some embodiments to provide a signal relay unit with a leaning mode for learning and storing multiple audible alarm patterns so that the unit can respond to a variety of H2S monitors.

[00015] It is an object of some embodiments to store the occurrence of an H2S fault event until a host computer pings the fault monitoring system.

[00016] It is an object of some embodiments to send an inquiry signal or ping a fault monitoring system to establish the location of where an H2S fault may have occurred.

[00017] It is an object of some embodiments to use a SCADA or other type of fault monitoring system to monitor pumping-related faults at fixed locations within a well site and to monitor H2S-related faults at indeterminate locations within the well site.

[00019] FIG. 1 is a schematic diagram illustrating a personal alarm system 10 for detecting hydrogen sulfide gas 12 at a well site 14, which is at a remote location relative to a host computer 16. The term, “remote” refers to a distance of at least ten miles.

[00020] Alarm system 10 comprises a person-carried alarm instrument 18 and a fault monitoring system 20, wherein fault monitoring system 20 is placed (e.g., mounted, parked, installed, set up, etc.) at a generally fixed location at well site 14. System 20 can be any electrical system for receiving, storing and transmitting electrical signals. In some embodiments, fault monitoring system 20 is a conventional SCADA (Supervisory Control And Data Acquisition) system for monitoring and recording the conditions of a well-related operation 22 at well site 14 and making the stored monitored information, particularly well-related faults, available to host computer 16. A pressure sensor 24, for example, may send an operational fault signal 26 when the pumping pressure (or other operational characteristic, such as flow rate, temperature, liquid level, strain, load, etc.) at well site 14 is abnormal. Well-related operation 22 is schematically illustrated to represent operations that include, but are not necessarily limited to, producing gas, water or petroleum; repairing a well; servicing a well; inspecting a well; etc. In some cases, a service vehicle 23 can be used to help facilitate performing well-related operation 22 and can be used to transport system 20 to well site 14.

[00021] In cases where conventional SCADA software is used, host computer 16 accesses the stored monitored information by pinging system 20, whereby an alarm status signal 28 corresponding to fault signal 26 is conveyed to host computer 16 via a wireless communication link 30. Computer 16 can ping fault monitoring system 20 by sending an inquiry signal 32 to system 20 via wireless communication link 30. Inquiry signal 32 and the pinging process enables computer 16 to access well-related data of a particular well site that is at a location known to computer 16.

[00022] In other cases, however, fault monitoring system 20 provides alarm signal 28 over wireless communication link 30 without having to first be pinged. In such cases, system 20 may also provide a well location signal 35 that indicates the location of well site 14. Well location signal 35 can be in the form of an address, APIN or well number, or a gps reading (coordinates of a conventional global positioning system). Host computer 16 is thus informed of the H2S fault and its location.

[00023] Another wireless communication link 34 places fault monitoring system 20 in communication with person-carried alarm instrument 18. The term, “person-carried” refers to an item having one or more features that makes the item readily carried by a person. Such person-carried features include, but are not limited to, a belt clip, pocket clip, strap, compact size, lightweight, etc. Alarm instrument 18 is shown being carried by an oilfield worker 36, so instrument 18 actually travels or moves relative to fault monitoring system 20.

[00024] Upon sensing that a concentration of hydrogen sulfide gas 12 has reached a predetermined limit (e.g., 10 ppm), person-carried alarm instrument 18 provides a trigger signal 38. Wireless communication link 34 conveys trigger signal 38 to fault monitoring system 20, and fault monitoring system 20, in turn, provides an alarm status signal 40. The other wireless communication link 30 then conveys alarm status signal 40, and in some cases well location signal 35 and well-related operation data such as alarm status signal 28, to one or more designated host computers 16. In some embodiments, alarm status signals 28 and 40 are both communicated to computer 16 upon computer 16 pinging fault monitoring system 20. Alarm status 40 corresponds to trigger signal 38, so host computer 16 is notified that a hydrogen sulfide gas problem has occurred at well site 14. Thus, host computer 16 can be used for dispatching assistance to well site 14.

[00025] Wireless communication link 34 can be of various forms including, but not limited to, radio waves, infrared, spread spectrum, etc. Communication link 34 can have a range of a few hundred feet, which is appreciably less than that of communication link 30. Communication link 30 has a range of several miles, which can be achieved using technology such as satellite communications, radio waves, cell phone technology, etc. In some embodiments, communication with one or more host computers 16 involves the use of the Internet.

[00026] Alarm instrument 18 can be a single unit or may comprise two separate units. With two separate units, alarm instrument 18 may comprise a conventional H2S monitor 42 and a signal relay unit 44 Signal relay unit 44 provides a way for a conventional H2S monitor to communicate with a conventional SCADA system, such as fault monitoring system 20. The functional relationships of fault monitoring system 20, H23 monitor 42, and signal relay unit 44 can be further understood with a description of their operation.

[00027] When H2S monitor 42 senses that the concentration of hydrogen sulfide gas 12 exceeds a predetermined allowable limit, monitor 42, being a conventional H2S monitor, sounds an audible alarm signal 46. Signal relay unit 44 includes a microphone 48 that detects alarm signal 46, and signal relay unit 44 responds by generating trigger signal 38. A receiver 50 associated with fault monitoring system 20 receives trigger signal 38 and responds by recording the event on fault monitoring system 20. The H2S fault is recorded or stored to ensure that the awareness of the event is not lost before computer 16 pings fault monitoring system 20 or before alarm status signal 40 is communicated to computer 16. For instance, if computer 16 only pings fault monitoring system 20 once every ten minutes, computer 16 should receive alarm status signal 40 even if alarm signal 46 were cleared prior to system 20 being pinged. The step of recording the event can be carried out by tripping a conventional latch relay or storing the event on some other type of a memory (e.g., integrated circuit) of system 20. Such a memory or latch relay is schematically illustrated by numeral 52.

[00028] Since existing conventional H2S monitors may provide different sounding alarm signals, signal relay unit 44 includes a learning mode 54 for teaching unit 44 to recognize the sound of a particular alarm signal and to distinguish that sound from other extraneous or background sounds. When operating in learning mode 54, signal relay unit 44 listens to alarm signal 46 and stores its various attributes, which may include, but are not limited to, pitch, volume, waveform, tone, pulsating pattern, etc. Afterwards, signal relay unit 44 is returned to its normal operating mode where unit 44 listens for the alarm signal it just learned to recognize while in its learning mode. Such a learning process is based on common voice recognition technology, which is practiced by Sensory, Inc. of Santa Clara, Calif.

[00029] In some cases, signal relay unit 44 can be taught to recognize several different audible alarm patterns. This allows unit 44 to be paired up with different models of H2S monitors without having to repeat the learning process for each individual H2S monitor. Signal relay unit 44 would then emit trigger signal 38 if any one of several known alarm patterns were detected.

[00030] 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. Also, it should be noted that the various elements, such as those represented by numerals 16, 20, 22, 23, and 36 are drawn out of scale to show more or less detail depending on the need. Therefore, the scope of the invention is to be determined by reference to the claims, which follow.