New Production Tech Averts Failures
Published on Feb 11, 2016
This article was previously published in the January 2016 issue of The American Oil & Gas Reporter. It is reproduced here with permission, by Corinne Westeman.
Unscheduled downtime in oil and gas production operations is a double whammy that results in lost revenues and added costs to repair problems, which erodes bottom-line margins. But in times of low commodity prices especially, any equipment failure or downhole operating condition that disrupts the flow of hydrocarbons to the sales line can be a profit killer. Consequently, operators are zeroed in on improving the efficiency and economic performance of producing assets in all types of plays.
The key metric is cost per barrel of oil equivalent produced, and although every producer has contingencies in place to deal with the unexpected, a well failure is not an option. This is particularly true for resource plays with multiwell pads, where one problem can take production from four or more wells off line and potentially upset operations at downstream processing facilities.
Right on cue, the latest innovations in production technology–from mechanical downhole tools to digital well site monitoring and analysis software–are designed to maximize efficiencies and production flows while minimizing cost and preventing well failures. The VRU Pro™ from FW Murphy is designed specifically for monitoring and controlling the smaller-horsepower compressors used in vapor recovery operations. Certified for Class I, Division 2 hazardous area operations, the controller is configured as a flexible, off-the-shelf solution that requires no programming customization while enabling advanced features such as automatic starting and speed/recycle/capacity control.
Vapor Recovery Controller
Vapor recovery applications are expected to increase markedly in coming years as a result of ever-more stringent emissions restrictions on tank batteries and other production facilities. But vapor recovery also is being driven by the compelling economic proposition that oil and gas companies potentially can turn a regulatory compliance requirement into a new revenue stream by capturing the value of tank vapors, which are often high in Btu content.
“Recognizing that vapor recovery is an emerging market, we talked with oil and gas producers to get feedback on what was needed to optimize the performance of vapor recovery units in the field,” says Roel Rodriguez, product manager, applications solutions for FW Murphy, which is headquartered in Tulsa. “We realized that one of the biggest needs was an electronic controller specifically for VRU operations.”
In response, he says FW Murphy’s engineers went to the drawing board to design the VRU Pro™ for comprehensive signal monitoring and control for the smaller-horsepower rotary screw, scroll and single-stage reciprocating compressors associated with VRU systems. The technology is certified for Class I, Division 2 hazardous area operations using either AC or DC power, Rodriguez points out. Equipped with 18 fit-for-purpose fixed digital, analog, thermocouple and frequency inputs and nine field-effect transistor and analog outputs, he says VRU Pro is rated to operating temperatures of -40 to 185 degrees Fahrenheit.
“The controller provides a highly flexible, all-in-one solution that the operator can buy off the shelf and set up himself however he likes, whether using an electric motor or natural gas engine, or a rotary screw or reciprocating compressor,” Rodriguez details. “Unlike many programmable logic controllers, it requires no custom programming.”
The flexibility is built into the controller’s software architecture by a platform that enables the user to select from a number of preconfigured compressor equipment options using a tactile keypad and backlit 3.8-inch monochrome LCD display. It features CAN J1939 engine communications with a closed-loop proportional integral derivative (PID) algorithm for monitoring and control.
At its base functionality, VRU Pro uses a transducer to monitor tank pressures and automatically start and stop the compressor, according to Rodriguez. The controller keeps the compressor in a ready-to-start condition until tank pressure reaches the preset level. At that point, it starts the compressor to recover the vapors and draw pressure back down to the set point, when it then turns off the compressor. However, depending on the type of compressor and engine package, Rodriguez says the system has the optionality to facilitate a variety of advanced control capabilities, including automatic speed, recycle and capacity control through three-way PID monitoring of suction/discharge pressures and engine loading.
“Not every compressor package has these advanced control options, but the feature sets are built into the control panel and are configurable by the user though the keypad,” Rodriguez remarks. “The controller uses PID to monitor and compare a particular feedback such as suction/discharge pressure or motor current/manifold pressure against a set point value. It continually calculates a correction factor to keep key parameters at their set points to maximize the performance of the entire vapor recovery system.”