Process Control & Engineering

The field of Process Control in upstream Oil and Gas is one where issues and benefits are frequently underestimated. CORE has complemented the Process Control offering with a Process Engineering capability

CORE

Although the upstream process systems are generally straightforward, the operating requirements for production systems are becoming more restrictive.

We provide solutions that support the customer’s business objectives, from conceptual stage through to safe and profitable operation.

The following constraints place increasing importance on efficient process control

Slugging from multiphase subsea tiebacks
Increasing reliance of mature fields on gas lift
Tighter legislative requirements for produced water, flaring and energy reduction.
Alarm rate limitations
Turndown issues

Under the Process Engineering umbrella CORE offer:

Process Optimisation

Process Safety and

Dynamic Simulation/Modelling Services.

Uptime

Small reductions in uptime obviously cause significant revenue losses. For mature assets, this is increasingly important due to prolonged restart durations following even a short shutdown.

Production trips are a major environmental challenge due to associated flaring and restart instability that invariably affects produced water system efficiency. High BS&W readings are also a common occurrence on restart as operations personnel struggle to maintain high quality produced water for overboard discharge.

Stability and Slugging

Production declines from mature assets have been supplemented in many cases by third party production, usually from a subsea tie back. A combination of well, terrain and riser based slugging is usually a major challenge for most assets as this unstable feed is invariably a cause of topside instability.

The impact of slugging differs greatly from asset to asset and CORE has extensive experience of improving topsides stability thus ensuring production is maximised. The slugging encountered on most assets (and wave instability on FPSOs) is not a major problem and the effect can be handled within the surge volume of the separator or by minor adjustments to the compressor capacity. Improved produced water quality, zero flaring and stable oil/condensate export flowrates can usually be achieved.

 

However, as the magnitude of the slugs increase, the impact on the topsides stability is more severe and further intervention is required. This requires a slug suppression technique to be adopted to regulate the flow through the riser. This type of system is complex to optimise and if not designed or set up correctly, it will dramatically increase instability in the multiphase pipeline, increase topside instability and therefore production deferral.

Throughput Enhancement

CORE can provide assistance with throughput enhancement trials such as low pressure separation trials, gas lift trials, produced water optimisation or low flaring trials.

One of the major benefits of having CORE on-site is the ability to rapidly solve instability problems or throughput limitations that may occur during the trial and this may prevent the trial from being halted.

Oil platforms that utilise gas lift become totally reliant on gas compression for achieving target production figures.

Gas Compression

Gas compression uptime, performance and throughput usually becomes more critical as an offshore asset matures.

Gas platforms in particular have increased compression duty requirements as depletion occurs.

Oil platforms that utilise gas lift become totally reliant on gas compression for achieving target production figures.

Gas compression uptime and throughput directly correlate with oil production volumes. Oil platforms with declining gas profiles are challenging with the gas compression system having to operate at low throughputs, particularly on start-up when high gas lift pressures are required.

Therefore, efficient and stable compression systems are the cornerstone of achieving good production and low flaring figures for all assets. Compression and gas turbine systems are usually the most complex systems on an offshore installation.

Core has extensive experience in improving the operation of gas compression systems in the UK and overseas. Typical problems addressed include:

Compressors surging during instability, startup or during shutdown/rundown. A fast trend of a compressor surge is shown below.

Compressor instability on single and multistage compressors due to overly aggressive or overly complicated compressor OEM control software designs.

Conservative setup of compression control systems by OEM vendors due to warranty obligation concerns.

Gas compression capacity and loadshare controls being too complicated and operated in manual as a result.

Inefficient operation due to antisurge control valves being operated partially open with excessive recycling and capacity/energy efficiency losses.

Core can assist any client achieve improved operation of their gas compression systems and this can take one of many forms:

Design/peer reviews prior to installation.

Review of vendor or OEM design/software designs.

Factory Acceptance Test attendance.

Startup and commissioning.

Surge, performance testing and loadsharing system setup.

Compressor mapping, fouling calculations and debottleneck/re-wheel studies.

Training.

Separation/Oil Export

Separation systems usually present few problems if the feed flow to the plant is stable. However, if feed flow is unstable during normal operation or during well start-up, inefficient separation can result.

Unstable oil export is particularly evident when oil or condensate export volumes reduce to below the minimum flow protection requirements for booster and export pumps. This frequently results in pump instability, inefficient operation and metering mis-measurements. It is also common for Operations to have problems with proving of the metering streams.

Produced Water

Tighter legislative requirements have made produced water treatment systems far more important for an offshore installation.

CORE has extensive experience of all produced water plant, including:

Hydrocyclones.

Plate Skimmer vessels.

Induced Gas Flotation units and modern compact units.

Degassers.

Wallnut shell filters.

Produced Water Re-Injection Systems.

Water Injection

Reservoir support using water injection is of significant importance on many oil production facilities. Efficient operation of the filtration and deaeration systems is essential if the correct water injection specification is to be achieved.

The operation of de-aerator towers and multiple pump sets can be difficult under plant upset conditions.

Gas Treatment

Gas Treatment facilities on offshore platforms generally contain glycol systems for gas dehydration. These systems have a number of commonly encountered problems that reduce efficiency, stability or uptime. These can usually be solved quickly.

NGL recovery, cold plants and H2S removal (such as amine) systems are less common systems offshore although they can be problematical. This is usually due to the highly energy efficient or “looping” design that makes the plant interactive and sensitive to control.

Utilities

Utility systems on offshore installations, typically seawater, cooling medium, heating medium, firewater and fuel gas/diesel systems can be the source of major problems.

CORE has extensive experience of solving:

Seawater system instability problems.

Hydraulic surge during firepump start-up.

Turbine fuel changeover failures.

Hot stopping of power generation turbines during load rejection.

Debottlenecking and optimisation of seawater and cooling medium systems.

Energy Efficiency

The energy consumption on an oil and gas installation is considerable. Typically, between 3% and 10% of the energy produced from the reservoir is consumed on the asset.

Operating companies are now more accountable regarding the energy consumption and subsequent emissions that are released into the environment.

There is a close correlation between low energy consumption and smooth running of plant. Typically, a plant that has high uptime, smooth topsides operation and low component failures also has low flaring, low emissions and high energy efficiency.

We provide solutions that support the customer’s business objectives, from conceptual stage through to safe and profitable operation.

Design

CORE has complemented the Process Control offering with a Process Engineering capability.

We provide solutions that support the customer’s business objectives, from conceptual stage through to safe and profitable operation.

Under the Process Engineering umbrella CORE offer Process Optimisation, Process Safety and Dynamic Simulation/Modelling Services.

Operations

The nature of the feed to an offshore processing facility frequently deviates from design assumptions and there is always a desire to push the limit.

Also, the integration of several processing units into an overall process may have been poorly considered leading to chronic operational issues and unwanted downtime.

Commissioning

Process commissioning is a key activity for any new plant and it is important that any issues are identified and dealt with while Project resources are available rather than after hand over to a hard pressed Operations team.

Core has taken key lead positions in commissioning and start-up teams and has also provided the link to the Operations team including ongoing training after handover.

Optimisation

Process Optimisation is always a desirable goal for any company but it is often attempted when the process is suffering with basic issues.

Each new offshore installation tends to be custom built to an extent with new design features that can present new challenges to even experienced operations personnel. Conversely, the design basis for old installations may be lost in the midst of time and may include items that no longer exist elsewhere.

Process Safety has increased in prominence in recent years and is now a key aspect for offshore operations.

Safety

This is a highly technical subject that can impose a high workload on busy operational teams. It also needs to be a cornerstone of process design activities. CORE provide a range of services in this area including the provision of Facilitators, Scribes and Independent Engineers for review meetings. Typical areas are Risk Analysis, HAZID and HAZOP and SIL/LOPA/Fault Trees.

Simulation

CORE has extensive experience in producing steady state design models as well as creating models for existing plant.

We also construct dynamic simulation models and use these to assess a system for various operating scenarios. This ability is enhanced by ready access to in-house Process Control engineers to assist in control loop configuration and assessment.

WE’RE READY, ARE YOU?

We’re here to help you with the day-to-day challenges you’re facing in your operations – get in touch to see how we can help.