The Golden Zone temperature distribution of petroleum: part 2

Our previous study published in 2023 examined the estimated ultimate recovery (EUR) of conventionally recoverable oil, gas and condensate in 1175 of the Earth's largest reservoirs in relation to reservoir temperature and showed that 74% occurs within the ‘Golden Zone’ (GZ) temperature range of 60–120 ± 2°C, with only 6% at higher temperatures. This present article examines the temperature distribution of EUR in 18 geographical regions not covered earlier, including six with EUR distributions skewed towards low temperatures and three with distributions skewed towards high temperatures. A fuller explanation is provided here as to why diagenetic processes are thought to be the main causes of overpressure in deeply buried reservoirs, and a new model is proposed for how the opening of the Arctic and North Atlantic oceans led to the uplift of Arctic continental margins, with possible negative consequences for Arctic exploration potential. Particular attention is given to examples of large reservoirs at temperatures outside the GZ in order to examine the possible factors favouring these occurrences. Most low-temperature cases can be ascribed to tectonic uplift and cooling subsequent to petroleum accumulation, whereas most of the high-temperature reservoirs have low–moderate fluid pressure consistent with preservation of hydrocarbon columns due to open lateral drainage. It is clear that reservoir temperature is a useful parameter for exploration risk analysis but one that should be calibrated using available analogues relevant for each area of interest.