The production phase of an E&P project can last for decades. In fact, managing fields from first oil to abandonment is how the E&P business ultimately makes money. Companies are always striving for the best in class methodologies in design, project management, drilling, and reservoir analysis to maximize production.
The production process is the “manufacturing” portion of the E&P business. Operational Excellence technologies and methodologies, which first gained prominence in refining and other process industries, can help achieve the goal of maximizing production to ensure the promised return on investment for a field development.
Operational Excellence helps maximize production from existing assets by controlling costs and safely operating at optimal levels. That is why these techniques now are being applied in the production phase of E&P projects.
For the purpose of applying Operational Excellence techniques in the production of mature assets, it makes sense to focus on three key concepts:
Making sure the “right” information is available at the “right” time for the “right” people;
Using models to support better operating decisions – extending engineering models used to design and build production facilities to support/optimize operating decisions; and
Applying advanced process control (APC) – dynamic control systems to maintain optimum performance. E&P companies have been inundated with data for many years, and as technology continues to provide more advanced monitoring systems, the problem is growing. While data provide an important starting point, there is a problem if the data never become useful as actionable information. Sifting through data is not productive. Decision-making is expedited only when decision makers have access to the data that have an actionable context. In short, success depends upon getting the “right” data to the “right” people in the “right” form at the “right” time.
Defining a solution
The primary goal of any producer is to increase production. One way to increase volume is to leverage data with engineering models of the gathering system, separator effectiveness, and gas processing efficiency and use those models to optimize the production process. To achieve this goal, data infrastructure needs to be in place.
A distributed control system (DCS) is the foundation of that data infrastructure and normally captures most of the field instrumentation values. However, many companies also have added a data historian that collects select data from DCS systems and other sources (e.g. lab and model calculated data), time stamps it, and “historizes” the information so different users can visualize it. This allows operators and engineers to quickly understand how the process is performing and calculate key performance indicators. While E&P production facilities usually are fairly straightforward from a processing standpoint, they can be very complex hydraulically because of variations in well production.
Production and beyond
Adapting quickly to a changing environment helps optimize production. The oil and gas industry uses first principle simulation models to design facilities but have not always used models to understand the complex interaction of composition, temperature, pressure and flow rate; i.e. to make the “right” data into actionable information. Models enable operators to understand how to set variables to optimize facilities in near real time. Models can include wells, gathering pipelines, separation plants, and gas processing plants. The handover of as-built models from the design and construction team to support operating decisions over the life of the field is a best practice.
In an actual case on a field with three wells connected to a common gathering system, the operator determined compressor settings to operate at an optimum rate of about 28 MMcf/d. By modeling the network of pipelines as well as choke valves at the wells and compressor and considering the cost of compressor operations and inlet pressure requirements at the gas plant, the operator was able to increase production to 31 MMcf/d (11%) by adjusting the compressor speed and the well choke valve settings. Having the models also enabled the operator to consider the impact of bigger compressors, changes to the inlet pressure to the gas plant, and the impact on reservoir performance.
This example is for a basic gathering network; others are more complex with multiple gathering system legs, more wells, and more variability in composition. In such cases, models are essential because changes can have unexpected consequences.
In addition to production applications, there are other opportunities for model support in operations:
Used as the basis for “soft sensor” calculations; e.g.
used to predict pressures, flows, and compositions at
key points in the process, which can help avoid slugging problems and over-pressure situations; and
Used to track the composition of the produced fluids through the system, which can help environmental reporting.
Controlling at the optimum point
APC systems reduce the variability of key operating parameters so a facility can operate closer to its optimum. APC facilitates increased production rates without increased capital spend and provides the ability to operate a facility safely by returning to steady operation more quickly. The end result is a higher average production rate.
Progressive E&P companies are applying APC to achieve production increases from 2% to 10%, with paybacks often measured in weeks. Despite the potential for significant results, the rate of adoption has been unusually slow. Fortunately, the barriers that once existed have largely been removed. For example, E&P assets are now better instrumented, and APC comes with a more robust suite of tools that makes it easier to implement, deploy, and monitor remotely.
In general, the objective for a production facility is to minimize the differential pressure between wellhead and separators. Achieving this goal requires that separator pressure be minimized subject to constraints, something that APC is ideally suited to do. APC handles more complicated constraints such as gas lift, multiphase flow, and slugging by using correlations first developed through either empirical testing or through the development of first-principle simulation models.
Mature fields offer a source of increased production and new reserves. Operations Excellence technologies and methodologies applied to these assets can effect significant production increases.
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