Oil and Gas Production from non-Conventional Reserves

Production and Transformation of Primary Energy

The attention from the main oil companies to all those hydrocarbon resources not yet exploited and/or difficult to recover is always keen. The reasons are to be found in the still high dependence of the major economies on fossil fuels and in the ever-increasing estimates of oil production (approximately 91 mb / d in 2020 and between 88 and 103 those estimated at 2030 in the various IEA scenarios, [1] ). In addition, the progress of extraction techniques makes it economically accessible to exploit deposits and resources that were not until a few years ago. If we consider that the current recovery factor achievable with the best extraction technique hardly exceeds 50% of the hydrocarbons present in the reservoir and that only 25% of the estimated resources belong to the category of 'conventional' hydrocarbons, it is immediate to understand the impact on the energy market of the so-called 'unconventional' sources. Generally speaking, extra heavy hydrocarbons (extra heavy oil), shale (shale oil and gas or tight tight oil), sandstone (oil-sands and natural bitumen), coal bed methane) and, from hydrates (hydrate methane). The main deposits are located in Canada (oil sands, Alberta, about 60% of Canadian hydrocarbon production comes from unconventional sources), Venezuela (extra heavy oil, Orinoco river basin), Indonesia, USA, Russia, Kazakhstan , Oman, China and Mexico. The actual extent of these resources is still uncertain, so much so that there are different estimates, some of which are conflicting. In this regard, the International Energy Agency (IEA) estimates that by 2020, approximately 4.097 billion barrels of the total 6. 206 are attributable to unconventional resources (total reserves amount to 1753 billion barrels) and that approximately 384 of the 809 trillions of m3 are linked to unconventional gaseous fractions (tight gas, shale gas and coalbed methane) (the total reserves amount to about 221 trillion m3). In this regard, the gradual reduction over the years of conventional hydrocarbon production in favor of non-conventional hydrocarbon production should also be considered (it is estimated that the latter will register, in the period 2020-2040, an increase of 33% and 70%, respectively for the oil and gas).

The main producers of tight oil and shale gas are currently the United States and Canada while other countries such as Argentina and China are successfully starting their own extraction activities. As of 2014, only four countries, namely the United States, Canada, Argentina and China, were found to be producers of commercial quantities of hydrocarbons from shale (both oil and gas) and tight oil (hydrocarbons from compact sand or sandstone). In the same vein, in 2015, Algeria, Australia, Colombia, Mexico, Poland and Russia started their respective explorations, not reaching, for the moment, commercially viable production levels. In the medium to long term, forecasts by the US Energy Information Administration (US-EIA) still see the United States as the world's largest producer and the appearance on the market of countries such as Russia and Argentina.

Generally speaking, oil production from conventional fields is much simpler and less invasive than that from unconventional fields. In the extraction from the former it is usual to use techniques in which the effect of natural evacuation of the reserve prevails, while in the second case, the most widely used techniques are the so-called 'cold' ones (mainly by surface extraction). However, the recovery factor achievable in such cases is rather low. Substantial improvements are now obtainable thanks to the use of more sophisticated techniques (Enhanced Oil Recovery, EOR) which combine the introduction of additional energy into the well with the adoption of appropriate management strategies. The achievable efficiencies in such cases range from a minimum value of 10% (Water Flooding), up to 70-80% (SAGD and THAI techniques).

28-07-2022

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