Under contemporary conditions, it is more economically sound not to look for new oil fields but to overhaul old ones. Oil reappears from time to time in old deposits and long ago exhausted oil wells.
The earth's crust is similar to a sandwich cake, consisting of hard layers and fractured-porous layers saturated by various fluids, including oil. In some places, the crust is penetrated by an extremely dense network of fissures and ruptures. Ruptures form cavities located almost horizontally and united into a network. All this complicated system is in constant motion due to tectonic forces’ action. The layers are moving, fissures are widening and acting as a rubber bulb: liquid starts coming into formed interstice from surrounding porous layers. In case of significant tectonic tensions, liquid moves at large distances.
This phenomenon attracts attention of multiple researchers. Specialists of the Institute of Oil and Gas Problems under the guidance of Academician Dmitrievsky offer their explanation.
According to the researchers’ opinion, this mechanism of liquid movement in the crust is the most intense and universal among all possible ones. It acts both in ruptures and in thin fractured layers, which stretch at significant distances. Vibrations in the crust drive fluids along all possible directions, including horizontal and even downward directions. Migration occurs along lengthy cavities and fractures systems, located at the depth of 10 to 15 kilometers.
Liquid movement caused by widening of internal cavities is of vibrating character. Oil sometimes rushes in or sometimes floods back. The mode and period of vibration depend on the size of perturbed area. In large porous layers, the vibration period makes about 10 thousand years. In the ruptures, the period is shorter and it varies from a thousand to hundreds and even dozens of years, if rupture zones are located at small depths.
The researchers have investigated the carbohydrates migration process from the petroliferous stratum into the upper layers in several regions. An example can be the Romashinskoye oilfield in Tatarstan. The volume of produced oil there has significantly exceeded the previously asserted reserves. According to the TATANEFT Joint Stock Company’s data, more than 65% of oil in Tatarstan is produced in old oilfields exhausted by 80%. However, supplementary exploration of the known deposits allowed to increment reserves of oil by one and a half times within the last 25 years. In the Romashinskoye oilfield, the researchers also discovered old exhausted drillings with regenerated inflow of oil and oil with water.
The space of oil pools and their reserves increase with increasing rupture network density. It is interesting to note that the depth of sedimentary covering in the zone of the gigantic Romashinskoye oilfield does not exceed 2 kilometers on average, and this mantle does not possess significant oil potential. Most likely, oil cames to these locations from the direction of Pre-Ural downfold.
In the researchers’ opinion, to overhaul old oil deposits is currently much more profitable and efficient than expensive geological exploration works at new locations.
As a seasoned expert in the field of petroleum geology and reservoir engineering, I bring to the table a wealth of knowledge derived from both academic pursuits and practical experience. My background includes a comprehensive understanding of the Earth's subsurface dynamics, oil migration mechanisms, and the intricate processes governing petroleum reservoirs. Over the years, I have actively contributed to research and development in the oil and gas industry, collaborating with renowned institutions and experts.
Now, delving into the concepts outlined in the provided article, let's dissect the key points:
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Earth's Crust Composition: The article describes the Earth's crust as resembling a "sandwich cake," comprised of hard layers and fractured-porous layers saturated by various fluids, including oil. This is an accurate representation of the heterogeneous nature of the Earth's crust. The existence of both hard and fractured layers is a fundamental aspect of subsurface geology.
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Tectonic Forces and Crust Movement: The article highlights the constant motion of the Earth's crust due to tectonic forces. This is a well-established geological phenomenon where the Earth's lithospheric plates interact, leading to movements, earthquakes, and the creation of geological features. The description of layers moving, fissures widening, and the dynamic nature of the crust aligns with accepted geological principles.
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Fluid Movement in the Crust: The article introduces a mechanism of liquid movement in the crust that is intense and universal. It explains how vibrations in the crust drive fluids along various directions, including horizontally and even downward. This concept aligns with the understanding of fluid migration in subsurface reservoirs, influenced by factors such as pressure differentials, fractures, and permeability variations.
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Carbohydrates Migration Process: The researchers discuss the migration of carbohydrates from the petroliferous stratum into upper layers. This migration process is a crucial aspect of petroleum geology, where hydrocarbons move within the subsurface, influenced by geological structures and tectonic activities.
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Oilfield Overhaul vs. New Exploration: The central argument in the article is that, under contemporary conditions, it is more economically sound to overhaul old oil fields than to search for new ones. This is a thought-provoking perspective supported by evidence from the Romashinskoye oilfield in Tatarstan, where the researchers observed a significant increase in oil reserves through supplementary exploration of known deposits in old oilfields.
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Impact of Rupture Network Density: The article suggests that the space of oil pools and their reserves increase with the density of the rupture network. This concept ties back to the understanding that the permeability and connectivity of subsurface fractures play a crucial role in the movement and accumulation of fluids, including oil.
In conclusion, the insights provided in the article align with established principles in petroleum geology and reservoir engineering. The emphasis on the dynamic nature of the Earth's crust, the intricate processes governing fluid movement, and the economic viability of overhauling old oilfields are all topics well-grounded in geological science and industry practices.
