Surveillance and precision control optimizes well performance.
by Bobby Mason & Ted Wilke, SPOC Automation
March 28, 2016

A handful of surface and downhole problems cause the majority of pump system failures, which result in shorter run life, higher maintenance costs and deferred production. Problems like pump off and cycling, fluid pound, mechanical stress, overheating and power fluctuations are commonplace. Optimized well performance requires constant surveillance and precision control. Instrumentation, control and monitoring systems enable production teams to quickly identify problems and minimize their impact. Operators and production engineers can measure and trend well behavior precisely to fine tune results and increase reliability. The first benefit of remote monitoring is early problem detection. Even if production team members are away from a well, they know its current condition. The next benefit is being able to respond to problems remotely in real time to control well equipment and processes. Identifying potential problems and opportunities to improve production proactively is the ultimate benefit. Trending lets the production team adjust operations to maximize both equipment run life and production. One company improved field performance so much that they were able to replace a planned injection well with another production well.

well equipmentPersonnel can respond to problems remotely in real-time to control well equipment. (Images courtesy of SPOC Automation)

Gas Interference

Gas is a big problem for all pump systems. It impedes production and causes a cascade of problems, including debris accumulation during shutoff and mechanical stress on restart. In the case of electric submersible pumps (ESPs), gas creates cavitation that erodes impellers and can cause cycling. In turn, this can lead to high motor temperature because the cooling, lubricating, production liquids are replaced with gas. Pump run life and production can be severely impacted. In some instances, run life may be reduced by 30 to 50 percent. To avert gas interference, or at least catch it early, operators need to carefully monitor intake and discharge pressures, process flow (using flow meters on flow lines), motor amps and motor torque. These four measures provide sufficient insight into gas interference and downhole equipment to predict performance issues. Trending systems make this process much easier by recording data and making it available on mobile devices. By analyzing the data across time, operators can determine what is happening at the well and take steps to address the issue. Often, this can be automated so that alerts are dispatched when key limits are exceeded. Even corrective action can be automated, for example, increasing pump speed in response to low intake pressure relative to discharge pressure.

Fluid Pound

Gas may also be the cause of fluid pound in beam pumping systems. The load cell of a traditional pump-off controller mistakes gas for low fillage and triggers a pump slowdown that can lead to gas lock. To avoid pump off, operators set pump fillage limits as low as 70 percent. This is below optimal production levels, and the equipment pounds fluid every single stroke every single day, leading to premature wear and catastrophic failure. A better alternative is to track and trend motor torque, which drops in the presence of gas. If extremely erratic spacing occurs between drops in motor torque, gas is almost always present. The gas must be cleared, and this requires faster pumping. Trending systems can successfully differentiate these sudden changes from gradual ones anticipated by the production curve.

High Temperature

Heat is another destructive force for motor windings and insulation. Monitoring the health of both downhole and surface equipment is paramount. Equipment wear is rapid when temperature exceeds the motor specs. However, high temperature is usually a symptom of an underlying problem. Simply addressing high temperature by shutting down or easing back may actually worsen the condition rather than resolve it. For example, an ESP motor can overheat if it is run at a high ratio of pump load to horsepower rating. Similarly, low voltage may decrease 
fluid flow, reducing heat transfer away from the equipment. A motor can overheat quickly. Alerts can indicate rising motor temperatures. A quick analysis of well data can identify the cause of the temperature increase and set the course for resolution. Because the whole production team can access the data, the pump personnel can wait for analysis by other team members and return for maintenance scheduling as needed. Catastrophic failure situations can be avoided.

The whole production team can access the data for analysis with appropriate user permissions.The whole production team can access the data for analysis with appropriate user permissions.

Oversize Pumps

Before pump installation, calculations are usually performed to properly size the pump and surface system. The installed system is typically larger than the ideal application size to ensure that the operator has sufficient flow. After all, many specifications are estimated or unknown, and tamping down the system’s operation is often less risky than increasing its specifications. Trending data helps operators understand the dynamics of the well during initial pump sizing. The production team analyzes performance data trends to determine the optimal parameters for flow, pressure, torque and voltage. This in-depth analysis is virtually impossible to achieve any other way. Once the designed system is installed, trending analysis is used to dynamically tune operations for current conditions. The range of pressure and the tightness of control allow operators the greatest flexibility in adapting to both short- and long-term conditions.

Field Efficiency

Remote monitoring provides the current status of every connected well in near real time. Trending data shows personnel if problem wells exist or if any crossover effects are occurring between wells. Operators can trend individual wells against others and against a whole field. For example, in a field with an injection pump that feeds several beam pumps, operators can change the injection pump’s speed or pressure and see the effects across all the pumps in the field or for a particular well that is problematic.

Warranty Dispute Evidence

Operators are increasingly using trend data to ensure that equipment operates within manufacturing specifications and safety limits. One company had a failure on a hydraulic pump that was outfitted with data instrumentation and monitoring. The operator downloaded all the performance data that had been recorded since the equipment was installed, which proved to the manufacturer that the pump had been operated within its designed parameters.

Voltage Fluctuations

Voltage spikes can damage pumping equipment and shorten its life. Voltage drops are more common and may cause overheating because of reduced fluid flow. Remote monitoring allows operators or other personnel to 
track and analyze the voltage data, revealing patterns that otherwise might be undetected.

Water Management

Good management reduces the cost of sourcing and delivering water to wells. Fluid flows from pond to pond through piping to wells and is moved by shallow water and floating pumps. The flow rates into and between these storage areas must be sufficient to ensure continuous flow to hydraulic fracturing trucks. Operators can track and trend the flow and other attributes to ensure that the rates are correct at all times, which is crucial for these high-pressure operations.

Beyond Tally Books

Tracking well data has become significantly easier in recent years. Instead of carrying tally books, pump personnel can use a tablet or smartphone to check wells’ status and receive alerts. Instrumentation is available to measure most data points, including:

  • Temperature
  • Pressure
  • Flow
  • Tank levels
  • Voltage
  • Amperage
  • Motor torque

These measures are correlated back into a control system with basic operating parameters that enable the equipment to respond to predictable changes without manual intervention. The pump personnel’s notes are digital and available to anyone with access rights. These notes indicate when a problem occurred and what adjustments were made. They reveal to operators if a problem is recurring, what settings were used in the past and other important data. Digital notes are easily sent to new field personnel. This mobility makes adjusting resources and filling gaps in coverage easier. The use of digital systems for trending and analysis will continue, and standards, such as supervisory control and data acquisition (SCADA), allow 
for easier collection and rapid sharing 
of information. Data are knowledge, 
and knowledge is powerful. Trending data empowers the production team to make the best decisions and maximize oilfield performance.