The discovery of new reserves of oil and gas located at great distances from the coast, with increasingly stringent regulations for safety, energy efficiency, environment and quality of products, poses new technological challenges for automation and control. Advanced control systems can play an important role to improve stability and profitability. The main objectives of advanced control systems are:
Maximize the production;
Ensure the specification of products;
Minimize energy consumption;
Minimize the process variability which increases safety and minimizes the flare (loss of products);
Minimize operational costs, operating the equipment in a stable environment thus reducing the number of unscheduled stops resulting in lower maintenance and logistics costs.
Although advanced control system is a reality in many industrial areas (refineries, petrochemicals and gas plants), it is not widely used for offshore production units. There are many causes that justify why advanced control is not widely utilized in offshore platforms, like:
A platform has many transients (shutdown, different well alignments, etc.), many disturbances (slugs), uncertainties and noise.
Oil and gas production is never in a steady state because it is a time-varying process (gas-oil-rate, water cut, sand production, gas coning, water coning, etc.).
Few instruments available, for example there aren't many pressures and temperatures instruments inside subsea pipelines and wells, etc.
There are no advanced control specialists onboard to install and keep these tools working properly.
This paper will present some solutions to promote the use of advanced control on a platform, for example:
New control strategies to minimize the effects of transients (adaptive algorithms to find out optimum PID tuning) and disturbances (anti-slug control) and also new algorithms to optimize the process.
A methodology in order to help the implementation of these tools that change the way the operators interacts with the production process.
This paper will show and discuss some results of the implementations of these advanced control systems in offshore platforms, emphasizing the gains of stability and profitability. The offshore plants are becoming more complex and require these advanced tools to support the operators.
The regulatory and advanced control, as well as real time optimization systems can provide many advantages for the industrial units, as improved stability and safety, respect to constraints and higher profitability. Figure 1 shows a schematic automation pyramid containing the regulatory and advanced control layers.