Sensors and automation passively participate in our everyday lives to improve comfort, add safety and reliability, and increase the efficiency of needed products and services. As the use of sensors and automation has proliferated throughout various industry sectors, these products have become reliable, economical and easy to maintain and service. Experienced personnel and suppliers can create, adapt or integrate their products and services for almost any application. The challenge becomes how we collect, correlate and translate this data into actionable information.
The oil and gas industry is no stranger to the advanced uses of sensors, automation and data collection, especially in the discovery process, high volume producing wells, regulatory reporting and custody transfer. However, lower producing wells and older, more established producing regions have not been as willing to make these critical investments for the following reasons:
- Economics does not justify the expense and support of these technologies
- Entrenched policies and procedures are hard to adapt to new technologies
- Bad prior experience when poor implementation caused more problems than it solved
These barriers to implementation need to be resolved by addressing the real costs of inaction and overcoming entrenchment and prior experience. The alternatives to doing nothing are not attractive and lead to greater regulatory involvement, higher insurance costs, lower productivity and lost production. Perhaps the greatest risks from reckless behavior are the loss of good will and a community's willingness to permit operations in an area. For instance, consider a sensor installed to prevent a leaking seal from polluting a well site. The real cost of a single cleanup operation would cover the cost of installing the sensor and automation systems deployed across a significant portion of the operating area. The cost of lost production and employee productivity are significant costs to include in the total equation. Operators too often believe that the impact is minimal and accept the risk. However, the risks are often much larger than realized; once an incident occurs, it will curb growth and new opportunities.
When approaching the described barriers, operators should start with a small project. Some good steps include:
- Understand what problem or solution needs to be solved
- Consider the current needs and what might be needed in the future
- Resist the urge to over-engineer the requirements
- Setup a timeline as to how long the pilot should last to receive a good assessment
- Define what will be understood as a success
Suppliers are often willing to conduct no obligation trials where the system can be tested in a real world environment. The operator gets a chance to experience a system in operation and know the supplier's ability to deliver, support and service the equipment. Pick a project or site with a reasonable chance of success that the supplier and operator personnel can easily access. If successful, pick a challenging second pilot site that will let the supplier showcase his solution and help justify the system's deployment. This second site should also replicate conditions like weather, power condition, pumping fluid properties and pumping pressures characteristic of a large sample of wells in the field.
Even the best systems often require some adjustment and tuning to receive the full benefit of the implementation. However, if the supplier has to continue working on implementation problems or operations personnel have to repeatedly return to a site, the chances of success in full deployment are slim. Be willing to accept failure and start with another supplier or solution.
Location and Types of Sensors
For oil wells, there are several key locations for placing sensors, including:
- Downhole at Pump Depth
- Pump intake pressure
- Pump discharge pressure
- Fluid level
- Pump rotation direction
- The Well Head
- Flow line pressure
- Flow line flow
- Casing pressure
- Packing/seal pressure and temperature
- Rod temperature and vibration
- Rod load
- Rod torque
- Primary Mover
- Motor temperature
- Motor RPM
- Rod RPM or Strokes Per Minute (SPM)
- Rod Location
- Variable Frequency (Speed) Drive
- Cabinet temperature
- Heat sink temperature
- Incoming service power voltage
- Internal DC Bus voltage
- Motor current
- Motor torque
- Energy consumption
Each of these data points can be valuable in understanding the health, operational status and pump optimization levels of each site.
Many of the described sensors are readily available without a large amount of investment; however, the challenge is to report the collected information back to a central location for reporting and monitoring. Building the central server and supporting the software are additional cost variables that can add significant cost to any deployment. If more sensors are deployed and measurements are taken frequently, they need to be transmitted via some method back to the central location. The challenge for operators is the cost of building out a data network and managing the network saturation of this information. In addition, it can be difficult to build a data network because of the physical location and area terrain. Equipment, contractors and licenses can all add significant expense to a monitoring and control network if the wrong solution is selected.
Local Intelligence and Data Repository
The solution to saturation is local intelligence implemented in software that can analyze information and determine based on predefined rules if local automated action is needed. For example, if the torque applied to a rod string for a downhole progressing cavity pump (PCP) exceeds the permitted level, the variable frequency drive (VFD) should have sufficient automation to decide on the appropriate action. Whether or not a data network is available, the VFD can take action and report the reasons for it.
Argentina well site in environmentally sensitive area
The most critical sensor data items can be frequently reported to a central location. However, many data points are not as critical and can be stored locally. If a problem occurs, the central software systems can request details for a specific time period or a technician can review the details once he arrives onsite for root cause problem determination and analysis. This can be done if the local site has a data logging system that collects sensor values and stores them locally. Memory and processing power to collect and store millions of data points is available for almost any type of deployment and budget.
Overwhelmed with Options
Many suppliers have solutions and services to help facility operators accomplish the described objectives, but many organizations do not have the resources available to do the necessary research and investigation to assemble the parts to make a complete system. Finding a supplier with the skill and proven systems built out is a smart, cost effective approach.
The right supplier should have a solution for total site visibility and control specifically optimized for PCP deployments. The system should be built around a VFD with software optimized for PCP applications. The VFD should include a control computer that receives all of the available sensor information and stores a year's worth of data in local memory. The system should store data and evaluate the values to make an appropriate speed decision for pump optimization, site environmental protection and personnel safety. Any time a problem occurs, an operator can connect locally or through a network to analyze highly detailed data through a built-in web server. Internet Explorer or a similar browser can be used to review, graph and download detailed data to a local PC. Sensors can be connected to the control computer as needed.
Components necessary to automate a remote well site with automatic protection and centralized monitoring and optimization
An optional satellite-based service can be added to work in any location around the world and automatically integrate with a supplier's Internet site. Authorized users can log on to a website and view the engineering design for the pump deployed at a particular site, view the manufacturing test results, document the installation details and view the system's operating conditions.
Sufficient products and services exist in the market to address the needs of virtually any oilfield operator. These products have proven themselves in the market as good tools to protect investments and improve efficiencies. Making good choices requires some effort, but the payoff will be a successful deployment and an operational environment positioned for growth and profitability.
Pumps & Systems, December 2009