The results of previous studies of filtration in low-permeability reservoirs are presented in this article. The factors influencing the filtration characteristics are analyzed, such as capillary pressure and intermolecular interaction forces; presence of water and clay minerals in the reservoir; rock and fluid microstructure; change of stress state in rock. Particular attention is paid to the non-linear effects of filtration in low-permeability reservoirs. The deviation from the linear filtration law is associated with the presence of an initial pressure gradient. The article describes how to determine the initial pressure gradient. Experimental and theoretical versions of definitions of the lower limit of applicability of Darcy law are reviewed. The effect of deviation from Darcy law at the lower boundary on well performance and the effectiveness of well stimulation techniques are described. It is concluded that traditional field development methods, which are based on Darcy's law and the Laplace capillary pressure equation, require considerable adjustment in low-permeability reservoirs. The current criteria for classifying low permeability reservoirs do not meet the conditions for practical development, so variants of reservoir classification are given in the text. It was established that rocks with a gas permeability of less than 0.004 μm2 should be classified as reservoirs with a low filtration potential. A plan for creating a scientific and methodological base for predicting filtration properties in low-permeability reservoirs has been developed. This scientific and methodological base will make it possible to prepare draft amendments to regulatory documents. Creating favourable conditions for the development of reservoirs with permeability of less than 0.004 μm2 will increase recoverable oil reserves by 4 billion tons at developed and explored fields.
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