SCADA is for Midstream
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As any engineer or operator can tell you, operating a midstream gathering system is a challenge. Along with all the regulatory duties, midstream systems require just as much attention as their upstream counterparts in wellhead production. But the geographic expanse of a midstream system presents a fundamental problem: you can’t be at both ends of the pipeline at once. With pipelines stretching across counties, states, and even countries, midstream operators must get data as quickly as possible. For successful midstream systems, the days of waiting for accounting reconciliation to determine fuel and loss across a gathering system are over. Leveraging the power of a proven system like zdSCADA®, operators can be alerted to potential pipeline leaks in minutes, not weeks, saving time and money.
The Balancing Act
In addition to receipt meters and sales meters, savvy operators monitor all sources of gas consumption. Compressor fuel meters, vapor recovery meters, and flares are just a few of the components contributing to the total system balance. Your system balance is only as good as the completeness of your telemetered devices. Without a robust SCADA solution, operators are left to guesswork and assumptions.
While this plays a part in leak detection (below), it is also essential to good measurement practice. More often than not, imbalances result from measurement error. Anything from an unrecorded plate change, to liquids passing through an orifice plate, can skew system balances. Identifying these problems early makes them easier to address.
Leak Detection
Definitive leak detection on pipelines is, in most cases, not possible. But the emphasis here is on “definitive.” With effective use of SCADA, operators can be alerted to possible leaks due to rising system imbalances or strange pressures. Graphs are especially useful in identifying such situations. Recently a zdSCADA® customer, utilizing a full monitoring program, was alerted to a gas imbalance. Upon inspection by field personnel, it was discovered a vertical separator had a dump valve hanging open, venting gas to the condensate storage tanks. Because this was discovered within a few hours (and not days) of occurrence, the financial and environmental impact of the midstream operations was mitigated.
Unlike gas pipelines, balancing a liquids system is made easier by fluid incompressibility. Hence, no “storage” effect as with gas lines. In either case, SCADA indication of possible leaks requires excellent measurement. All meters must be in proper working order, with synchronized clocks. (Most pipeliners would cheer the abolishment of Daylight Saving Time.) Providing ample measurement and segmenting lines helps. A system with dozens of inlets and multiple outlets is difficult. Segmenting each upstream lateral and mainlines would improve such a situation.
Keeping an Eye on Things
Full tanks can mean shutting in an entire system. Whether it’s condensate tanks at a compressor station or saltwater tanks at a disposal facility, when tanks are full, it’s a problem. SCADA allows close monitoring of tank levels so that loads are called in suitably.
Compressor or pump downtime costs money... big money. “Cry-out” alarms notify operators via text or call so they can immediately address the problem. Effective SCADA-hosting systems will escalate notification until the alarm is acknowledged. This creates the accountability that makes alarm systems effective.
Upstream operators are the “customers” of the pipelines, and the customers need to be kept happy. Rising pressure situations are better noticed first by the pipeline operator. That way, the problem can be resolved before the customer notices. Reports that indicate declining production can make money for both upstream and downstream. Alerting a customer to this gives them the opportunity to address the issue sooner and get volumes back up, to the benefit of both parties.
SCADA can provide clues to upstream operators that may be putting fluids in lines. H2S and CO2 alarms can close valves before these corrosive chemicals get in a pipeline.
A Pig in a Poke (or Pipeline)
The most common use of “pigs” (implements that travel down the inside of pipelines) is to clear liquids from gas pipelines. SCADA systems can alert operators to rising upstream pressures, a typical indicator of excess fluid in lines. This data can be graphed so rising pressure can be understood visually. Pigs can be run before liquid levels create problems.
But, pigging can be a time-consuming process. Most pipeline operators are familiar with the frustrations of slow or “lost” pigs. SCADA can provide the ability to monitor pigging processes, either through pressure changes or pig sensors. Systems can indicate pig arrival at a downstream receiver, so operations personnel can shift their focus to other items.
Playing Defense
Try as we might, upstream operators are going to complain from time to time. Having well-documented, accessible data allows midstream operators to quickly defend their position. A customer complaining about a volume statement may question the meter test and gas analysis. With zdSCADA®, meter tests and gas analysis can be stored alongside volume data for quick retrieval. A few clicks of the mouse, and these documents are sent to the customer – while they are still on the phone!
The Future is Here
The digital age of pipeline operation is here. Tools like SCADA are no longer luxuries, but critical components giving operators the ability to monitor midstream gathering systems faster, with greater accuracy. When properly configured for their system, zdSCADA® can save an operator both time and money.
