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Technical Specifications Oil & Gas Journal article on Wellhead Monitors

The Gas-Injection Wellhead Monitor (WHM) is specifically designed to sense and control the wellhead variables of a gas-lift production site. The unit adjusts the gas-lift injection flow to match an operator determined flow rate, and computes estimated gas-oil-water production in real-time. Communication is possible to a centrally located computer, allowing the results to be easily gathered for analysis. Trending of flow data by a master computer can be particularly useful in the early detection of well problems.

Intended for use in remote locations, the WHM features ultra-low power consumption and lightweight subassemblies. A built-in solar panel can drive an active production well for up to seven cloudy days. Hence, the unit is especially attractive in off-shore or similar areas where electric power is not available, and portability is important.

The WHM consists of two major components. First is the Remote Terminal Unit, containing the electronics and transducers necessary to determine gas flow rates and issue control commands. Divided into two subassemblies, each is housed in separate enclosures for ease of maintenance. Tube connections are provided for gas inputs. Second is the Meter Run/Control Valve, containing the mechanical pieces needed to measure and control the actual gas flow.


General Operating Information

The WHM directly measures the following orifice/nozzle flow parameters: Temperature inputs are provided by the user via pipeline grade thermocouples. RTD's may be used as an option. In addition, the user must provide the production side orifice/nozzle meter run. The WHM contains all other material. Hence, installation is accomplished via 1500 lb. ANSI-rated flanges, direct to field piping. The standard WHM uses schedule 80 pipe and is rated for 2500 lb. operation pressure.

Actual flow calculations may be modified, based upon individual customer requirements. AGA#3/NX19/AG#8-style equations can be readily handled, via programming in high-level language. The user may enter the various calculation constants from the local display, a lap-top computer plug-in port, or from a master computer via a communication link. Control of the valve is accomplished by a proprietary Proportional Time algorithm, requiring some variables to be modified at installation time. Normal operation needs only a setpoint valve.

In addition to normal reporting of flow rates, pressures and temperatures, the WHM can calculate estimated gas-oil-water production. While not intended to substitute for a test separator, this information can be extremely useful for trending purposes in order to detect well problems in their early stages.

The WHM accumulates the data from a well for up to 5 days before it must be picked up by a computer for analysis. Optional expansion capabilities can increase this storage time to 10 days.

Custom Support

IAR recognizes that each field location may have unique problems or specific preferences for a mode of operation. Both hardware and software support is available to modify a WHM to fit these needs. Extra status and analog readings can be added to expand well analysis. Master stations, based upon 386-style computers, can be supported as well. For example, WHM's can be commanded by a host system to terminate injection gas flow to low producer wells in times of gas shortages. Specially modified WHM's can act as intermediate data collectors, storing data up to 5 days for up to 25 wells. Advantages offered by such an application include reduced communication demand placed on a master computer, local field control and ease of battery backup. IAR encourages close cooperation in order to find the best use of the WHM product within the user's organization. International Automation Resources, Inc., IAR, WHM, Well Head Monitor, Oil Field Automation, RTU, Gas Lift Injection