The book is devoted to the main issues of the hydrodynamic theory of filtration of homogeneous and heterogeneous liquids related to the modern problems of oil and gas fields development. Methods for calculating the interference of perfect and imperfect wells, issues of formation and stability of water and gas cones, as well as a number of problems of displacement of liquids and gases in porous media are considered. Methods of research of some questions of non-isothermal filtration in relation to problems of thermometry of wells and to methods of thermal influence on a layer are given. The book is intended for students of oil and gas hubs and universities, which study the elements of underground hydro-gasodynamics, as well as for engineering and scientific workers of the oil and gas industry. Separate sections of the book may also be of interest to hydrogeologists, hydrotechnicians and workers of the gas and petrochemical industry, who have to meet with filtration processes in various technological processes.