Monitoring and evaluation of energy use in oil treatment facilities

Monitoreo y evaluación del uso de la energía en estaciones de tratamiento de crudo

Laura Milena Corredor-Rojas ^a, Ariel Uribe-Rodríguez ^b, Juan Carlos Cobos-Gómez ^c

Instituto Colombiano del Petróleo, Ecopetrol S.A, Colombia. ^aLaura.corredor@ecopetrol.com.co, ^bAriel.uribe@ecopetrol.com.co, ^cJuan.cobos@ecopetrol.com.co

Received: March 11^th, 2015. Received in revised form: January 23^th, 2015. Accepted: May 25^th, 2016.

Abstract
The paper presents the steps required to undertake an energy audit in oil treatment facilities and presents key energy performance indicators that can be applied to benchmarking and monitoring of this type of system. The proposed indicators are classified into the five following categories: production, consumption, efficiency, cost and reliability indicators. The paper also presents some general initiatives, short, medium or long term, that are classified according to their maturity and their economic benefits in order to increase energy efficiency.

Keywords: Production facilities, Key performance indicators, Energy performance.

Resumen
El artículo presenta los pasos a seguir para realizar una auditoría energética en estaciones de tratamiento de crudo y los indicadores claves de desempeño energético que pueden ser aplicados para el monitoreo y el desarrollo de estudios comparativos de éste tipo de sistemas. Los indicadores propuestos se agrupan en 5 categorías que son indicadores de producción, consumo, eficiencia, costo y confiabilidad. También se presentan algunas iniciativas generales orientadas a incrementar la eficiencia energética de las estaciones las cuales se clasifican de acuerdo a su plazo de amortización y a sus beneficios económicos en iniciativas de corto, mediano o largo plazo.

Palabras clave: Facilidades de producción, indicadores energéticos, gestión energética.

1. Introduction

Production Facilities include processes, equipment and required materials to collect, separate, handle, characterize and measure oil, gas and water from producing wells. Considering that energy use has a very important role in the process cost, the following general strategies should be taking in account to optimize energy consumption, starting from the design phase [1]:

]]> Evaluation and quantification of the thermodynamic constraints of treatment processes and the selection of the processes with minimal energy requirements.
• Selection of the process units with operation conditions similar to the ones used in the reservoir, which allow the reduction of heat exchange processes.
• Avoid hot fluids transportation to minimize energy losses.
• Evaluation of the use of direct contact heat exchangers instead of indirect heat contact exchangers.
• Maximization of fuel efficiency through heat recovery by steam generation (if cogeneration is required).
• Maximization of heat integration between processes to minimize external heating or cooling.
• Selection of equipment such as heaters and pumps that are highly efficient.

When oil treatment facilities are in operation, energy optimization is performed by applying a methodology to systematically monitor the processed energy performance and identify technological alternatives for optimization. The general applied methodology steps for the evaluation of energy management are shown in Fig. 1.

2. Energy audit: Types and methodologies

• Set the global energy consumption of the processes.
• Build the energy consumption baseline.
• Identify energy losses that can be corrected through operative and maintenance actions.
]]> Estimate the savings
• Categorize areas depending on investments and savings.

2.2. Detailed audit

The detailed audit involves all the components of the preliminary audit, including tests and measurements to evaluate the energy use and its losses, as well as evaluating the economy for the proposed changes. It also incorporates the assessment of how much energy should be used in each process and operative function by using computer modeling simulations [5]. The detailed audit is divided into 3 stages which are: pre-audit, audit and post-audit. Fig. 2 presents the processes that are to be followed in each stage. Each process will be later explained for oil treatment facilities [6].

3. Information required for energy analysis of oil treatment facilities

Tables 1 and 2 present the required information to perform an energy audit in oil treatment facilities.

Energy use diagrams are presented in Fig. 3. These apply to a treatment facility without crude heating processes.

The analysis should include energy consumption per process, calculation of current and optimal yields of processes, the list of equipment with higher energy consumption and the key performance indicators' approaches (KPIs).

In this stage, KPIs play an important role because they are control tools that allow the planned goals to be monitored. The indicators should provide enough and relevant information to not bias the analysis, and in addition they should allow for decision-making and effective processes control. In order to do this, an indicator must at least comply with features that are internationally recognized by the acronym SMART (Specific, Measurable, Actionable, Relevance, Timely). The suggested steps to formulate or adjust the indicators are:

• Set the variables required for measurement.
• Identification of the benchmarks.
• Set the target to be measured.
• Identification over what information is required from the target.
• Identification of people for whom this information is useful.
]]>

There are two kinds of indicators: management and results. Management indicators measure how the process is performing in terms of resource optimization. This kind of indicator is used to detect what is happening and is used to take appropriate actions to improve the situation. Results indicators are associated with management goals as well as the efficiency and effectiveness of their achievement. This kind of indicator is used to measure situations when they have already occurred and to take appropriate measures to prevent reoccurrences. The proposed KPIs for oil treatment facilities are presented in Table 3.



The analysis of energy consumption can be performed based on both internal and external benchmarking performance studies. Internal studies include the analysis of historical data and trends, while external audits are undertaken based on data or indicators obtained from systems or similar processes. Comparative factors to be taken into account for external analysis are the maximum capacity of the station, the technologies used in the processes and the quality specifications for both raw and treated products. Benchmarking studies allow:

• Quantification of fixed and variable energy consumption according to production levels.
• Comparison of the usability factor with other facilities.
• Identification of gaps and best practices.
• Establishment of the basis for monitoring and goal setting.
• Quantification of the target variability margin for consumption and energy cost.
]]> 5. Identifying opportunities for optimization

The last step in the energy auditing process is to recommend an action plan to optimize the use of energy, the cost of operation and to reduce emissions. The plan should include the period of implementation for each initiative and the investments' payback period [7].

Initiatives for energy management can be classified as short, medium or long term, depending on their maturity and their economic benefits. Short-term projects are those that must be performed quickly to resolve a compliance issue regarding air quality, or that have a very short payback period (a high rate of return).

The projects that are to be carried out for environmental reasons are sometimes to be implemented in the future, but are still classified as short-term because the work should begin as soon as possible [8]. Initiatives with high rates of return should be classified according to their ease of implementation. If little or no capital is required, projects should be performed immediately. If projects require time and capital but have a high rate of return, they should be started as soon as possible.

The medium-term initiatives have periods of economic return that is usually between one to three years. Because they require capital investment, they should be retested to make sure they are economically feasible [8].

The long-term initiatives are characterized by simple economic returns over three years. If capital investment is large or the return is small, initiatives are classified as having a low priority. However, it is important not to dismiss such initiatives because they may have changes in energy costs, in technologies and environmental regulations: situations that make their implementation imperative.

The reduction in energy costs associated with short-term initiatives is between 10 and 20%, while initiatives with a repayment period of two years or less offer additional reductions: between 20 and 30% [9].

Some initiatives to optimize treatment facilities are presented in Fig. 4. The size of the installation will determine whether an initiative is short, medium or long term [10-13].



 

]]> 6. Conclusions

An energy audit quantifies the consumption and energy costs of industrial processes, in order to identify gaps and establish a plan of initiatives to reduce losses, maximize efficiency, optimize energy supply and costs associated with processes. Energy auditing affects three key factors: profitability, through the optimization of energy consumption; productivity through optimization of equipment and processes; and performance, to use energy rationally.

Structuring an optimization plan is one of the most important steps in an energy audit. The initiatives proposed in this article are focused on improving models to contract the purchase of electricity and fuel, improve power quality, reduce energy loss from processes and equipment, include and track maintenance plans and improve operating conditions' control systems. Additionally, they can help to minimize emissions associated with the processes.

The sustainability of the audit's results of will be ensured through monitoring and control of key performance indicators, accompanied by an energy management program. Additionally, these indicators will allow comparative studies with other treatment facilities that have similar characteristics (production capacity, used technologies in processes, crude and products quality).

 

References

[1] Nardella, N,D. Improving energy efficiency in thermal oil recovery surface facilities [On line]. Montreal, 2010. [date of reference November 15^th of 2014]. Available at: http://www.worldenergy.org/documents/congresspapers/201.pdf. World energy congress.         [ Links ]

[2] Negri, et al., Improving energy efficiency in upstream facilities. Conference paper. Offshore mediterranean conference and exhibition, march 23-25, 2011.         [ Links ]

]]>

[3] Tyers, B. and Franklin, N., Monitoreo y seguimiento del uso de la energía. Arpel, 2002.         [ Links ]

[4] Bureau of Energy Efficiency. General aspects of energy management and energy audit [On line]. [date of reference November 15^th of 2014]. Available at: http://www.bsr.org/reports/bsr-energy-management-handbook.pdf. 2005.         [ Links ]

[5] Turner, W. and Doty, S., Energy management handbook. Atlanta: The Fairmont press, 2007.         [ Links ]

[6] Seai., Energy efficient design methodology [On line]. 2002. [date of reference November 16^th of 2014]. Available at: www.seai.ie        [ Links ]

[7] Thumann, A. and Mehta, D., Handbook of energy engineering. The Fairmont press, 2001.         [ Links ]

[8] Tyers, B. and Franklin, N. Implementación de programas de gestión de energía en la industria del petróleo y el gas. Arpel, 1999.         [ Links ]

[9] Kreith, F. and Goswami, D., Handbook of energy efficiency and renewable energy. Taylor & Francis group, London, UK, 2007. DOI: 10.1201/9781420003482        [ Links ]

[10] New Jersey State Department of Environmental Protection. Establishing an energy management program and identifying energy savings opportunities. The State University of New Jersey, New Jersey, USA, 2000.         [ Links ]

[11] Murray, D et al., Evaluación de proyectos relacionados con la energía. Arpel, 1999.         [ Links ]

[12] Thumann, A. and Woodroof, E., Handbook of financing energy projects. Atlanta: The Fairmont press, 2005.         [ Links ]

[13] Capehart, B., Turner, W. and Kennedy, W. Guide to energy management, third edition. The Fairmont press, Atlanta, USA, 2000.         [ Links ]

]]>  

L.M. Corredor-Rojas, gained her BSc in Chemical Engineering in 2004 and her MSc. degree in Chemical Engineering in 2008, all from the Industrial University of Santander, Colombia. From 2004 she worked in the Colombian Petroleum Institute (ICP) in the operational analysis of non-catalytic processes. Since 2009 she has worked at the same institute but in the implementation of alternatives to optimize the efficiency and cost of the processes associated with production and processing of crude oil. ORCID: 0000-0001-7981-1460.

A. Uribe-Rodriguez, gained his BSc in Chemical Engineering in 2001 and his MSc. degree in Computer Science in 2004, both from the Universidad Industrial de Santander (UIS), Colombia. Since 2004, he has been working as a researcher at the Colombian Petroleum Institute (ICP) on the analysis of refining schemes, and energy planning and optimization of oil production processes. For the last three years, he focused on optimizing upstream costs and the possible inclusion of bioenergy as a renewable energy source for production processes. ORCID: 0000-0001-5950-8923.

J.C. Cobos-Gómez, gained his BSc in Chemical Engineering in 1996 from the Universidad Industrial de Santander, Colombia. He was awarded the qualification of specialist manager in energy resources from the Autonomous University of Bucaramanga in 2006 and the qualification of specialist project manager (PFM) in 2010. He has worked on projects involving the optimization of industrial services, distillation, catalytic cracking of paraffins at a refinery in Barrancabermeja. He is currently leading the project "Emerging technologies to improve heavy oil crudes" at the Colombian Petroleum Institute (ICP). ORCID: 0000-0002-0014-0754.

]]> 1 2010 2 march 23-25, 2011 3 2002 4 2005 5 2007 6 Seai 2002 7 2001 8 1999 9 2007 10 New Jersey State Department of Environmental Protection. 2000 11 1999 12 2005 13 2000 third