American Institute of Mining, Metallurgical, and Petroleum Engineers, Inc. Abstract The paper contains information on the results of some calculations describing the influence of cold water injection on oil output from a multilayered oil reservoir. It is shown that there exists a real possibility of a complete or almost complete loss in productivity of a low-permeable sublayer adjacent to a highly permeable one, due to the filtration resistances permeable one, due to the filtration resistances redistribution under the influence of thermal interference of different sublayers. Introduction All large oil fields are exploited with the application of water injection in order to maintain the interlayer pressure. Usually each oil reservoir consists of a number of productive layers separated by relatively thin impermeable layers. Different neighboring productive layers are exploited simultaneously, being open by a well of unique face. If the temperature of the injected water is lower than the initial temperature of the reservoir, the water injection can lead to the essential cooling of a relatively small permeable sublayer in front of an oil-water contact permeable sublayer in front of an oil-water contact moving inside it, but behind that in the most permeable layer. This is a consequence of permeable layer. This is a consequence of thermal interference of different productive layers. If the volume of water injected into different productive layers can be maintained on a prescribed level, proportional to their physical permeability, such a cooling does not physical permeability, such a cooling does not lead to any sufficiently essential effects as well as heating of the stratum by injection of hot water. Unfortunately, in practice, the prescribed value is the pressure of injection on prescribed value is the pressure of injection on but not the distribution of water between different productive layers of the oil reservoir. By such a real system of speration the cooling (as well as heating) leads to a redistribution of resistances of oil and water to filtration. This redistribution may lead in some real cases to complete loss of productivity of low permeable sublayers or, in any case, to its almost permeable sublayers or, in any case, to its almost complete loss. Such a catastrophic consequence of cold water injection into multilayered oil reservoirs can be prevented by heating the injected water approximately to the initial temperature of the oil reservoir, and this action is economically admissible. Naturally such treatment must be applied from the beginning of the oil reservoir's exploitation. Our aim consists of the demonstration of results of a number of calculations that were fulfilled some years ago on the base of the spatial developed methods. All these results were published in the author's book.