PDSS help keep an eye on operations

The global push is on to optimize hydrocarbon production. For some time now, the digital oil field has been envisioned by many as a way to maximize production. One of the byproducts of digital oilfield efforts, however, has been a resulting explosion of data. Some surveillance systems generate up to two terabytes of new well and field data each day. For operators and petroleum engineers this is a mixed blessing.

A recent industry survey reveals 44% of oil and gas operations professionals suffer from information overload. Many of them say the effort to search for and retrieve relevant and timely information from varying data sources, both structured and unstructured, robs them of day-to-day operational productivity.

Built-in domain expertise and realistic graphical representations of the production process make the PDSS easy to navigate. (Images courtesy of NSI Upstream)

Today there is an industry push to develop surveillance and monitoring systems to deliver targeted and useful information – information that often is buried in the massive amounts of production data. This select information, made available anytime, anywhere by real-time production decision support and monitoring technology, provides value to business decision-makers, enabling them to respond more quickly to opportunities and threats from a business and operations point of view.

Real-time PDSS
Today’s production decisions support systems (PDSS) are designed to facilitate effective operational monitoring of oil and gas companies’ critical assets. The emergence of ready and reliable data communications capabilities such as the Internet, company intranets, and very small-aperture terminal satellite communications to remote field locations has enabled information to be made available to a variety of disciplines anywhere in real time.

Production engineers, reservoir engineers, operations personnel, and managers have the ability to see and discuss real-time data on their desktops from locations sometimes hundreds or thousands of miles from the producing platform or field. They also have the advantage of simultaneously overlaying real-time and historical information from anywhere in the production process train to identify trends and emerging issues that might otherwise go unnoticed.

Also, effective PDSS provide users with virtually unlimited flexibility to compare, overlay, and visualize all aspects of the production environment in the system in real time. This capability allows them to determine cause and effect and make critical production decisions quickly and more accurately.

Using these expanded capabilities, operators have been able to avoid extended shutdowns, intervention costs, and deferred production in locations worldwide. For offshore producers, with heightened challenges and risks, remote real-time operations surveillance and analysis take on even greater importance.

Avoiding hydrate shutdown
When a senior production engineer gave the word for operations personnel to make a minor choke change to an offshore Gulf of Mexico (GoM) subsea oil well, he was concerned with what happened next – nothing.

The engineer knew that the well had not responded to the choke change because he was monitoring the operation – in real time from his home several hundred miles from the well – using an advanced PDSS with a powerful suite of upstream applications and data analysis tools.

With the advanced analysis capabilities, the engineer customized the PDSS display within seconds to show trends of four pressures together on one screen:
• Boarding valve pressure;
• Flowline pressure downstream of the choke;
• Flowing tubing pressure; and
• Flowing bottomhole pressure.

An ad hoc example of multiple historical and real-time data points overlaid to help users determine cause and effect and make critical production decisions quickly and more accurately.

The boarding valve pressure had been nearly constant (except when they adjusted the operating pressure at the platform), while the flowline pressure downstream of the choke had been steadily increasing since about five weeks before this event. This increased pressure seemed to have been influencing the flowing tubing pressure and flowing bottomhole pressure, which quickly led him to suspect a flow assurance type of obstruction, either hydrates or paraffin wax, somewhere between the tree and the boarding valve.

With a simple click, the engineer was able to capture this graph from the system and email it to a team of chemical vendors and flow assurance experts. Quick research and analysis by the team of previous well and flowline treatments pointed to a much higher likelihood of hydrates, and operations began pumping methanol. Within 24 hours of initial detection, well production had resumed pre-incident production levels.

“A well shut-in and intervention might have easily taken a month or more, costing the company in flowline intervention charges and lost production,” the engineer said. “The savings in lost production alone amounts to more than US $4 million.”

Collaboration enables rapid response
A team of oilfield professionals at a large independent producer was observing a new offshore GoM gas well, designed to produce 25 MMcf/d, start up and come online.

The three co-workers – a production operator on the offshore platform, a field engineer in Houston, and the corporate SCADA supervisor in Calgary – were watching the action in real time, from their respective locations, using a PDSS.

In this implementation, which the operating company has deployed throughout the GoM, the PDSS is integrated with a programmable logic controller. This integration makes it part of the well and platform process control and safety system, thereby allowing the operator to monitor operations, rapidly identify issues, and execute changes to resolve them quickly.

On this occasion, as the colleagues looked on from their respective locations, they did not like what they saw: The new well’s flowing tubing pressure was falling fast.

The problem first was identified on the PDSS wellhead screen. Within seconds, a trend chart of flowing tubing pressure was created, allowing the team to see and graphically monitor that key indicator.

The three immediately were on a conference, discussing the problem while continuing to monitor the situation in real time. Because they were looking at the same data in the PDSS, they were able to analyze the problem and devise a solution.

Based on the well shut-in tubing pressure and the current hydraulic pressure on the control line of the tubing retrievable surface-controlled subsurface safety valve (SCSSV), they determined that the SCSSV was not fully opened, significantly restricting the well flow.

They collaborated on a solution and agreed that the production operator should shut in the well and bleed off the SCSSV hydraulics to zero. The new required hydraulic pressure was calculated, the production operator applied that new pressure, and the SCSSV was opened fully.

The well was brought back online with normal decline characteristics – in less than one hour of detecting the problem.

If the team had not been able to see and fix the problem early on, the situation likely would have escalated, requiring expensive solutions. For example, had the SCSSV been damaged (a likely scenario if the problem had not been caught quickly enough), they would have had to bring the rig back to the platform, pull the tubing, and replace the malfunctioning SCSSV, at a cost of $3 million for the rig plus parts and deferred production.

Clear benefits
By implementing PDSS technology, operators reduce risk and increase the speed of production decision-making by enhancing the ability to organize and visualize data trends from disparate sources on a single screen, more quickly determine cause and effect, and facilitate the sharing of real-time information among production and engineering professionals onshore, offshore, at home, or headquarters locations anywhere in the world.

These capabilities enable costs savings, prevention of future problems, and the ability to exceed production and profitability targets – a true competitive advantage in today’s global oil and gas production environment.