How to establish a proper CO₂ budget

If you want to reduce your emissions, you need to know the amount of CO₂ you produce today, and what you will produce tomorrow based on business as usual. You need to forecast your emissions to establish a proper CO₂  budget. This is key to reach the UN ESG Goal 13.

The purpose of emissions forecasting is to provide a comprehensive understanding of the different variables and operations that may affect emissions over time, and in this manner develop emission mitigation strategies and plans. Thorough emissions forecasting is a powerful tool in understanding the current state of emissions and their future development, the significant drivers that cause emissions, as well as their role in regulating emissions. One can only control and reduce their environmental impact by understanding it first.

Oil and gas production and export are energy demanding operations and the power necessary is usually produced with gas turbines onboard. Engines are also used but on a much smaller scale. The produced natural gas is the primary fuel source and some diesel is also used. As a result of the combustion process CO₂, methane and NOx emissions are released to the atmosphere.

Power is necessary to drive big compressors and water pumps. Compressors provide high-pressure gas for gas lift and gas injection which is used to enhance the pressure in the formation to increase petroleum production. Gas compressors also boost the pressure of the produced gas that will be exported via pipelines. Water injection is another method to increase the pressure in the formation to enhance petroleum production.

In NEMS we call these energy-demanding activities, such as gas injection and water injection “unit operations”. We develop energy models for all unit operations on an asset. This also includes unit operations with smaller energy needs, such as thrusters on an FPSO or oil-fired boilers. These models reflect the situation today and possible changes in the future. They are tested annually and updated to guarantee that any possible changes that might affect the energy demand today or in the future are covered.

A good energy model must be dynamic as the asset conditions will change over time.

Many factors will be effective in determining the faith of emissions.

Our models account for

• the changes inactivity, such as gas and water injection volumes and oil and gas production volumes
• a complex web of streams that will be handled at the platform and different units (satellite fields, tie-ins)
• what production phase the field is at (start-up, peak, tail)
• minimum and maximum load of compressors (the level of gas in the system, re-circulation, etc.)
• planned and approved technological changes such as the installation of a subsea compressor or re-bundling of old compressors, installation of emission control units
• energy optimization measures
• operating conditions (how many gas turbines are used together simultaneously, what factors are detrimental in defining this)
• implementation of new emissions monitoring and measurement systems

In 2019 alone, we calibrated energy models for about 50 installations on the Norwegian continental shelf. This is more than 80% of all the installations in entire Norway.

Flaring of gas causes CO₂  emissions and we also prepare estimations for flare volumes and corresponding CO₂ budget.

Besides CO₂, NOx and CH₄ emissions from combustion, other emissions also occur while producing oil. Gas leaks from valves, flanges, etc., cold vents, oil loading, and storage operations cause emissions of nmVOC and CH₄. Cold vents are the main source of methane. Cold vents can be anywhere in the process such as compressors (compressor seals), produced water system, gas stripping systems, etc. NEMS has carried out a very comprehensive study in Norwegian oil fields, as well as refineries and onshore processing plants regarding cold vents and gas leaks. We consulted in defining possible emissions sources and developing the most accurate methods for estimating such emissions. Therefore, we have the most up to date knowledge on how to prepare estimations for such emissions.

In other words, our emission forecasts are very detailed, tailor-made for individual oil and gas platforms and are very comprehensive as they include all emissions that are released to the atmosphere during oil and gas production per operation.

NEMS has more than 20 years of experience in emissions forecasting. In Norway, the oil and gas industry is subject to RNB (Revised National Budget) reporting. The regime covers annual forecasts for CO₂, NO_x, CH₄ and NMVOC emissions, fuel gas and diesel consumption. Reported emissions data to the Norwegian Petroleum Directorate is an important basis for the Norwegian authorities to monitor the industry and thus set new requirements and emission abatement strategies. In 2019 alone NEMS delivered around 300 forecasts for the RNB reporting, this covers almost the entire Norwegian shelf.