Oilfields produce more greenhouse gases as they age

Oil fields produce up to ten times more greenhouse gases for the same amount of oil as they age, researchers in the USA find.

It’s no secret that we need to reduce the volume of greenhouse gases produced globally. Greenhouse gases, such as carbon dioxide, trap rays from the sun in our atmosphere and ultimately cause a global rise in temperature.

But academic research about the greenhouse gases produced by oil fields themselves is lacking. Most studies focus on comparing greenhouse gas emissions from renewable energy sources with the burning of fossil fuels, yet up to one quarter of the greenhouse gas emissions from some countries come just from their oil fields. And in the rare cases where oil field emissions have been studied academically, researchers have tended to use only “snapshot data” that fails to account for how oil field emissions change over time.

According to two Stanford-based scientists, this is a major oversight. Mohammad Masnadi and Adam Brandt looked at greenhouse gas emissions from 25 of the world’s largest oilfields over a 55 year period using software developed specifically for this purpose.

Their algorithm uses computer modelling to calculate how much energy is consumed at each stage of the oil production process - extraction, refinement and transportation - for a given oil field in a given year. Brandt and Masnadi then used this figure to estimate the carbon footprint of oil field during the same period.

The pair collected over 50 different data points for each oil field for each year for their analysis, which, as Masnadi says “is a lot of data”. Acquiring it was also a challenge.

Most oil fields don't routinely release this information, and the data are available are skewed by records from UK, Canadian and Norwegian oil fields because these countries have transparency laws in place that require oil production data to be made publicly available.

Nevertheless, the Stanford duo found that, as an oil field ages, the oil source becomes harder to get at and it takes more energy to extract the same volume of oil. Remarkably, they saw the same trend across all 25 unique oil fields, which means that factors like the geographical location, oil quality and extraction processes have relatively little impact upon this trend.

Brandt finds this trend alarming, because most of the information used by policymakers and investors is often taken from a period when an oil field was much more efficient.

This could mislead policymakers into concluding that an oil field is more efficient than it really is, and it could bias calculations against greener, renewable alternatives...