Application of tomography technology to provide precise level measurements, optimizing separation efficiency, reducing chemical consumption, and minimizing environmental impact.
Srini Kamandahalli, Ramsey J White and Ashiff Khan, Saudi Aramco
OVERVIEW
Naturally, crude oil is produced along with water and gas. At the beginning of the crude-water-gas separation stage, fluids enter high-pressure production traps (HPPTs), which are typically three-phase separators, from trunk lines via the inlet manifolds and where all three phases of fluids—crude oil, gas, and water—are separated. The separated oil is further degassed in a low-pressure production trap (LPPT), where two-phase separation occurs. After that, it goes through the desalting train for emulsion separation and crude desalting, while the produced water is de-oiled in a water-oil separator (WOSEP) before injection into the reservoir for pressure maintenance.
The oil-water interface is one of the key parameters to be monitored and controlled in the HPPT to maintain adequate separation and to prevent significant oil-in-water and water-in-oil emulsions from impacting crude and water quality, respectively. The presently used level instruments, such as guided wave radar (GWR) transmitters, do not offer detailed profiles of the level. This hinders smooth operations and frequently causes water to carry over to downstream equipment. To aid in oil and water separation, a demulsifier chemical is injected into the inlet of the separation vessel. The amount of water in the oil is evaluated via lab sampling, and then the quantity of demulsifier dosage is controlled and optimized. Over-injection of a demulsifier can also result in reverse oil-in-water emulsions. Hence, optimum demulsifier dosing is necessary. The GWR measurement readings cannot be used for demulsifier control, due to measurement imperfections and the lack of real-time reading capabilities.
This article discusses an innovative and precise monitoring solution for the emulsion layer in high-pressure production traps (HPPT) within an upstream gas oil separation plant (GOSP). The objective is to furnish a precise level measurement to improve the HPPT separation efficiency. The innovative level measurement device utilizes “Tomography” technology, which relies on electric measurements, rather than radioactive sources, providing comprehensive cross-sectional and longitudinal imaging of the fluid profile within the HPPT, in real time.
The Tomography system produces extensive and graphical representations of HPPT oil, gas, water, emulsion, and solid layers. These representations are subsequently exhibited on the local computer (Fig. 1) and central control room. This innovative method of level measuring aims to optimize interface level monitoring, management, apply the correct quantity of demulsifier, and preventing operational disruptions in downstream equipment, such as dehydrators, desalters, and water-oil separators. The new sensors of tomography technology have no moving parts, making them low-maintenance, easier to install, and more cost-effective. They function properly, even in the presence of sensor contamination.
By utilizing this novel approach, we have enhanced the engineering and professional standards significantly by revolutionizing the HPPT level control process. This has been exemplified through tangible instances of its application, ensuring the safety of the process by mitigating operational workforce’s exposure to radioactive materials. Furthermore, our efforts have contributed to societal welfare by enhancing the quality of crude oil and water, minimizing chemical consumption and waste to benefit the environment, increasing the lifespan of the equipment, and support in achieving Scope 1 emission reduction targets.
TOMOGRAPHY PROFILER
The implementation of emulsion layer measurement is a unique method and, first, in our company, consists of several GOSPs. The implemented solution is a groundbreaking innovation for the industry. Conventionally, GOSP operations rely on guided wave radar technology to measure the level of HPPT. The other more reliable level measurements, such as using radiometric technology, are rarely used, due to the inherent risks involved with it of exposure to operating and maintenance personnel, as well as the high costs associated.
Traditional measurement devices, such as Guided Wave Radar (GWR), use microwaves, and the important feature of microwaves is that their reflection depends on the energy reflection property of the material, and the measurement is limited to a single layer. Whereas, the tomography technology is based on electric measurements instead of the microwaves and radioactive sources. The process data provided by electric measurement is more comprehensive, due to multi-point measurement with full cross-sectional and longitudinal imaging measurements, as opposed to the conventional practice of utilizing radioactive sources.
The data obtained through this method are more extensive, as they involve multi-point measurements, along with complete cross-sectional and longitudinal imaging of the targeted area in real time. Our engineering team, composed of proficient process engineers and control engineers from various disciplines, initiated an endeavor to ascertain and deploy a highly resilient system for the measurement of the emulsion layer. It would accurately measure the emulsion layer thickness and could be employed for demulsifier optimization and to maintain the optimal interface level.
This would lead to enhancing the oil-water separation efficiency and decreasing crude processing expenses. The first step in our implementation strategy involved carrying out a comprehensive evaluation of the HPPT performance, separation efficiency, and process disturbances in downstream equipment. This analysis established the basis for creating a quest for highly reliable level measurement of the HPPT separator, to enhance separation efficiency and minimize demulsifier usage.
The market research has indicated that tomography technology could be used for measuring the thickness of emulsion layers. The installed profiler relies on electrical tomography (ET), allowing for comprehensive imaging of a process area (such as a pipe, separator, or tank) without the need for a radioactive source. In electrical tomography (ET), a low-voltage electrical signal is administered to the target by employing several electrodes positioned within the sensor. This will generate an electrical potential within the subject area of measurement.
The form of the potential distribution is contingent upon the distribution of permittivity and conductivity found in materials (such as water, oil, gas, etc.) within the target. The sensors are capable of measuring electrically conducting and non-conducting materials, thus providing a comprehensive tomographic image of the vessel. With appropriate mathematical models and data processing algorithms, it enables the visualization of the entire HPPT while also offering measurement signals and AI-driven trends.
LEVEL PROFILER IMPLEMENTATION
The project’s impact extends beyond internal operations or inter-departmental relationships within the firm; it will also assist global energy reliability and environmental sustainability. The project assures a regular and stable supply of high-quality oil to the global market by cementing the company’s position as a reliable crude oil provider while adhering to demanding quality standards. This dependability leads to stable energy markets, which promote global economic growth and progress.
Furthermore, the project supports Saudi Aramco’s commitment to environmental stewardship by streamlining chemical injection operations and eliminating chemical waste. The initiative decreases the company’s environmental footprint by introducing automated demulsifier control, based on emulsion thickness measurement, minimizing chemical usage and waste. This reduction in chemical usage reduces not just operational expenses but also the environmental impact on chemical manufacturing and disposal.
Additionally, the project improves water management techniques by providing consistent water quality for subsurface injection. The initiative reduces the danger of process upsets and contamination by optimizing water separation processes in upstream HPPT separators, thereby protecting groundwater resources and ecosystems. This part of the project demonstrates Saudi Aramco’s commitment to sustainable water management and environmental conservation.
In general, the project’s impact on society is multifaceted, including economic, environmental and technological aspects. By increasing oil quality for dependable global supply, maintaining water quality for subsurface injection, and decreasing chemical waste, the project illustrates Saudi Aramco’s commitment to excellence, sustainability, and societal responsibility on a global scale.
SUSTAINABILITY
To ensure appropriate focus on sustainability and environmental impact, our project team implemented several steps throughout the development and implementation phases of the tomography-level profiler. Primarily, one of the key objectives of developing the solution is to “enhance economic, environmental, and social sustainability,” in addition to ease of operation. The potential economic benefits of the technology include cost savings in procurement and installation, reduced chemical usage, and operational efficiencies. Additionally, it had to have an environmental impact by reducing chemical waste and minimizing the environmental footprint. Social sustainability considerations were also integrated, ensuring that the technology aligns with corporate objectives to become a global energy supplier.
In addition, strong monitoring and assessment procedures were implemented to assess the technology’s actual worth. This entailed monitoring important performance metrics, such as demulsifier cost savings; crude quality parameters, such as basic sediment and water; salt-in-crude; and water quality parameters, such as oil in water. Stakeholders, including operations, maintenance and management, were involved throughout the project, providing comments and input to ensure that the technology met their needs and concerns. This collaborative approach instilled a sense of ownership and accountability, resulting in continual improvement and optimization of the technology’s sustainability outcomes, notably in terms of water quality before disposal.
PROCESS SAFETY
Process safety is managed by following the company’s established management of change (MOC) process, the Safety Management Guide (SMG), and risk assessors. The risks are evaluated for the new change prior to its implementation. Moreover, process safety is ensured by conducting “revaluation” and “re-doing” of risk assessment at periodic intervals to ensure compliance with the process in accordance with the latest industry standards. Considerations are made toward incidents that occurred worldwide to ensure continual improvement in process safety management for every step taken. Risk communication, training, and knowledge sharing are integral parts of risk management during this enhancement.
BENEFITS OF INSTALLED PROFILERS
The innovative technique of “Precision Control: Measuring Emulsion Layers for Enhanced Separator Interface” provides several key benefits. First, it showcases engineering and professional expertise by addressing a long-standing industry challenge: the absence of multi-layer fluid profile measurement. Tomography profilers accurately measure and differentiate gas, oil, emulsion, water, and solid layers within the HPPT. This capability helps to reduce or eliminate process upsets, a frequent issue with existing GWR level readings that are often inadequate and imprecise, leading to process disruptions, off-spec outputs, recycling, and other inefficiencies.
Precise measurements are essential for optimizing demulsifier dosing, based on emulsion layer thickness; however, current GWR values cannot be used reliably, due to their lack of accuracy. Tomography readings, on the other hand, will be leveraged for this purpose, offering significant economic benefits. When all available parameters of the new profilers are fully utilized, HPPT separation efficiency will improve considerably, resulting in fewer process upsets and enhanced crude oil quality.
Additionally, the adoption of tomography technology alleviates health, safety and environmental (HSE) concerns by eliminating the need for radioactive sources, which are currently relied upon for accurate measurements. Unlike conventional methods that depend on radioactive material, tomography provides a safe alternative. Moreover, tomography profilers are cost-effective, as they require only a spare nozzle for inserting the long probe (Fig. 2), eliminating the need for expensive vessel modifications.
Beyond economic advantages, this project contributes to societal well-being by ensuring a consistent supply of high-quality crude oil on a global scale. It also enhances sustainability by reducing chemical waste and improving water quality for subsurface injection. These environmental and economic benefits align closely with our company’s goals, supporting both operational efficiency and corporate responsibility.
RESULTS AND CONCLUSION
HPPT level measurement is critical in GOSP operations. Accurate level measurement in real time aids in the design of a reliable oil-water interface level control. The tomography technology is based on electric measurements, and the process data provided by this method are more comprehensive, due to multi-point measurement with full cross-sectional and longitudinal imaging of the target area in real time (Fig. 3). It provides a conductance profile in real time, as shown in Fig. 4, and the oil-water interface level can be monitored easily.
The emulsion layer thickness measurement will improve demulsifier optimization by focusing on applying the correct amount and automating the process. The project also saves money by enhancing the quality of the oil produced and the water that is injected into the reservoir. The new level measurement devices improve process safety by removing the use of radioactive sources. Overall, it improves the oil production process, lowers operational costs, improves safety, and encourages environmental stewardship. WO
SRINI KAMANDAHALLI is an operations engineering professional at Saudi Aramco with 30 years of experience in process engineering and plant operation in the petrochemical, oil and gas, and chemical process plant industries. He holds professional engineering registrations with the Saudi Council of Engineers in Saudi Arabia and the Province of Alberta in Canada. He holds an M.Eng. degree in chemical and petrochemical engineering from the University of Calgary in Canada, as well as a Bachelor's degree in chemical engineering from Bangalore University in India.
RAMSEY J. WHITE is a chemical engineer and serves as a Facilities Planning consultant and Process Engineering team leader in the Southern Area Oil Producing Technical Support Department at Saudi Aramco. He brings over 26 years of professional experience, including 18 years at Saudi Aramco, where he has led efforts in risk analysis, strategy development, energy optimization, process troubleshooting and GOSP upgrade and technology deployment projects. Before joining Saudi Aramco, Mr. White worked with SNC-Lavalin in Houston as a process engineer on various petrochemical and refinery upgrade projects. He holds an M.Sc. degree in chemical engineering from the University of Houston and a B.Sc. degree in chemistry from the American University in Cairo.
DR. ASHIFF KHAN is an operations engineering specialist at Saudi Aramco, with 23 years of expertise in process engineering, operations engineering, and project management. He holds a Bachelor's degree in chemical engineering, supplemented by six postgraduate qualifications in Management, Data Science, and Law. Dr. Ashiff’s PhD research focused on the application and management of Big Data / AI in the chemical industry. He holds 11 patents, has published numerous papers in reputable journals, and has obtained several international certifications.