Well construction is necessary part of oil and gas business, and its greenhouse gases (GHG) emissions reduction is becoming important. Today, the main attention is paid to technology, minimizing drilling time and upgrading rig with low-energy equipment. However, often the changes are implemented without establishing the proper baseline. This paper provides the detailed approach how the emissions can be accurately calculated at the well planning stage, aiming to implement most effective actions to reduce it.

The conventional approach to estimate rig site GHG emissions during the well construction relies on thepast data, when the average daily fuel consumption is taken. Instead, the modern workflow was developed,which included the development of the algorithm to evaluate the emission during a specific well constructionactivity. To ensure the accuracy of the predicted values the rig fuel consumption measured with higherfrequency comparing to daily-basis-approach and processed from spud to rig release. The obtained dataallowed to tune the developed algorithm to ensure the high accuracy of the prediction.

As a result, the actual GHG emissions during every operation was obtained. It was understood thatbetween others the drilling and back reaming has the highest fuel consumption rates (as well as emissionrate). The actual values were collected for different hole size at the same depth, for drilling, tripping,circulation, and flat time activities. Additionally, the carbon footprint of the auxiliaries was estimated.

The updated algorithm allows now to have 95% accurate estimation of the rig site emissions duringdrilling program preparation. Previous approach during any decision related to a well construction wasbased on 2 main pillars: the budget and the performance. Now, with this information, it is possible to addthe third component into the equation – the GHG emissions footprint. And better, more balanced decisioncan be made at the planning stage.

The main idea of this approach is to get the low-energy, cost-effective and technically achievable welldesign as a baseline. It will leverage the effect of further implementation of energy transition technologieson top of this basis.

This manuscript presents a new methodology of oil and gas wells engineering bringing the well design on qualitatively new sustainable development level. The ideas, which are formulated in the manuscript, can be implemented in any drilling project worldwide.