As constrained spending has slowed the development and construction of new wells, operators are increasingly reliant on their mature assets. The companies that will be successful are those that can leverage their existing investments to optimize production; reduce health, safety and environmental (HSE) risk; and control costs. One key method to achieve these goals is improved production surveillance and analysis.
Thirty years ago, production monitoring consisted primarily of surface gauges, which were present on only about 10 percent of active wells. Now, most wells have some type of basic monitoring hardware. However, the true value of production monitoring is not realized until monitoring equipment is connected as part of a system for automated control, remote surveillance and production analysis.
Empowering, Not Replacing, Personnel
It is important to understand that intelligent systems are tools that help skilled field personnel do their jobs more effectively. Field personnel are essential to any automated system. To start, they are responsible for setting appropriate parameters to achieve performance goals.
The resulting improvements can be impressive. In a 14,000-well Texas field, automated systems reduced the number of pump strokes by more than 1 million and cut 50,000 on-off cycles per day to reduce wear on components and extend equipment life. In another case, the production from 200 electric submersible pump wells in China was increased 30 percent through the use of real-time automation systems.
Real-time analysis also allows field personnel to more effectively prevent downtime and the resulting production delays. In Argentina, analysis software enabled personnel to make adjustments that increased production on 190 progressing cavity pump (PCP) wells while decreasing pump downtime by 70 percent. In another field, lift system downtime for problem wells was reduced by more than 50 percent.
Enhancing Short- and Long-Term Performance
Automated production monitoring and analysis systems come in two primary types: those that support real-time control and optimization of production operations and those that aggregate and organize large swaths of data to support long-term planning.
Real-time automation systems can autonomously adjust artificial lift systems in response to changing well conditions. For example, pumping rates can be continuously adjusted to match production inflow in order to maximize production while preventing damaging pump-off conditions. Automated controls can also adjust pumping cycles to match fluid conditions. In rod-pumped wells, pumping speeds can be adjusted within the pumping cycle to maximize production on the upstroke without over-running the rods on the downstroke.
Real-time automation systems also enhance HSE performance by mitigating potentially damaging or hazardous downhole conditions, such as rod stick-slip and pressure kicks, before they develop into more serious risks. In some cases, automated systems have prevented catastrophic events by recognizing dangerous conditions and immediately adjusting lift systems to counteract them—all without exposing personnel to additional risk. HSE is further improved by remote surveillance, which eliminates the need for most wellsite visits to monitor production activity and status.
Analysis software manages and examines large amounts of collected data to identify trends and opportunities for planned improvements in operations. Modeling and simulations can predict the impact of declining well pressures on production and cost, enabling operators to consider appropriate changes in production systems. Automated analysis software can also reveal data trends that point to water coning, water encroachment and liquid loading.
By automating certain facets of well monitoring, analysis software improves the efficiency and effectiveness of personnel resources so they can better manage a broader scope of responsibilities. This has an indirect favorable HSE impact since fewer personnel is required to manage assets and fewer visits to the wellsites are required.
Related Surface & Downhole Equipment
Whether the automation system is focused on real-time data, long-term analysis or both, the software must be supported by high-quality monitoring equipment installed at the wellsite. On-site monitoring equipment commonly includes sensors and transmitters connected to a field network that performs system calibration and diagnoses any anomalies. In an automated system, the network organizes and analyzes the data, identifies areas of concern and initiates immediate action as needed—all without the need for human interference.
For example, one type of deliquification system (DLQ) is a remote terminal unit that automates such critical functionality as electronic flow measurement, injection well processes and custody transfer quality measurements. The system can be customized for use on one or multiple wells of various types, from flowing to injection to artificial lift.
Another related technology is variable speed drives (VSDs). For rod pumping applications, one VSD monitors implied pump fillage from the pump card and adjusts the rate to maximize pump fillage. When pump fillage is below the established parameters, the VSD reduces the pumping rate. When pump fillage is above the established point, it increases the rate.
For PCP applications, this VSD automatically and continuously adjusts the pumping rate to match the well inflow. Inflow is calculated based on downhole pressure measurements. The system also enables operators to "soft start" PCP systems to prevent overstressing components when the system is initially turned on. This can be important for preventing system damage after momentary power interruptions.
Downhole sensors also play a role in automated production surveillance. Automatic systems require highly accurate input values to trigger the appropriate response. Despite improvements in surface sensors that infer downhole conditions, direct downhole measurements are the only way to accurately determine downhole conditions such as pressure, temperature and fluid phases. Measuring forces and operating speeds at the surface cannot effectively reflect downhole conditions that are outside of normal operating parameters.
Electronics-based sensors provide cost-effective measurement of downhole pressures, temperatures and vibration, especially in moderate well conditions. They provide feedback of real well conditions more accurately than values that can be calculated or inferred through indirect measurement.
Permanent fiber-optics-based systems provide more sensing options and improved reliability. This is especially important for high-value wells, such as those in unconventional reservoirs, which see strong declines in pressure and production rates soon after starting production. In these fields, it is essential to collect direct measurements of pressure, temperature, flow and liquid levels—something that can only be accomplished using permanent downhole gauges. These values can then be automatically monitored and analyzed using optimization software, which serves to support both daily operations and long-term strategic planning for maximizing production.
Intuitive Displays Enable Fast Action
The form of data presentation is equally important to data quality. For example, software that presents an intuitive visual interface using multiple presentation styles and colors could be helpful. Color-coding leverages learned signals to quickly transmit information from the eyes to the brain. Automation software can be configured to display data in green, yellow or red based on whether the downhole conditions are in the normal range, of some concern or require immediate attention. This enables decision makers to act on the most critical items quickly and with confidence.
Application Example: Intelligent Gas Lift
One area with room for growth is the automation of gas-lift and gas-assisted plunger lift. Intelligent lift systems of this type work by determining the precise amount of gas needed to complete a lift cycle, then injecting only that amount. This reduces the amount of gas needed to complete each lift cycle, which substantially reduces overall lifting costs.
The technology also lowers tubing pressures to encourage greater production inflow since less gas is circulated through the sales-line suction system. Finally, by reducing the demand for injection gas, intelligent gas-lift technology decreases the strain on compression systems, extending the time between maintenance and minimizing downtime related to system failure.
Justifying the Investment in Mature Assets
While it is usually easy to justify installing sensing and control systems on new wells as they are brought online, it can be harder to argue for the same systems on existing wells in mature assets. Typically, the approach is to spend as little as possible on wells that have their best years behind them.
Although permanent fiber optic systems may be out of reach from a cost basis, there are many lower-cost options that can provide meaningful production improvements and reductions in operating costs. The automation of gas lift systems is one example. The use of remote monitoring to reduce wellsite visits is another obvious example.
Even lower-cost solutions must be justified. The most effective way to prove value is to partner with an experienced systems supplier and to start very small—perhaps with a few pilot systems on a basic network— to measure the gains. The system can then be expanded, perhaps gradually, based on the lessons learned from the initial successes. It is not uncommon for operators to use the improved earnings and reduced operating costs from the pilot projects to fund expansion of the systems, from which they can then realize greater benefits.
The combination of real-time and trend data with analysis facilitated by intelligent, automated production systems has many benefits including greater efficiency, higher production and fewer lift-system failures. All of these are proven and justified ways to lower costs—an essential goal for all operators at a time when capital expenditures are scarce.