<p>The oil field development in the Russian Federation is growing annually. A third of hydrocarbons is produced offshore. In Russia, offshore oil production takes place in the Sea of Okhotsk and the Baltic, Caspian, and Pechora Seas. Offshore oil production is a technologically complex process, thus increasing the importance of creating safe processes for the extraction, transportation, and refining of petroleum products. Failure to adhere to safety regulations and neglecting annual diagnostic and repair work may give rise to conditions that trigger man-made accidents resulting to natural disasters. The consequences of emergency oil spills lead to the destruction of flora and fauna in the environment. Completely eliminating an oil spill requires significant economic, technological, and time resources. Marine oil spills create submerged plumes, which spread hydrocarbons into the environment. Prediction of the behavior of such submerged plumes can expedite the oil spill response. This paper studies the problem of the emergence of a petroleum leak source. This oil leak source can be formed as a result of damage to an oil pipeline. According to the formulation of the problem, this source is located at the bottom of a water body and is characterized by oil volumetric flow rate, temperature, density, etc. The problem considers the characteristics of the medium characterized by a shallow depth of the oil pipeline, so hydrate formation is not taken into account. The problem is solved by the integral Lagrangian control volume method. According to this method, a submerged jet is modeled as a sequence of cylindrical control volumes, each with its own characteristics, such as radius, height, density, water/oil ratio, temperature, velocity, etc. These parameters are recalculated depending on the movement of the control volume. This submerged jet is also affected by environmental characteristics, such as water temperature and salinity, and the presence of underwater currents. As a result, a mathematical model was constructed containing the fundamental equations describing oil flow processes, taking into account the entrainment of surrounding liquid in the jet. The accuracy of the model was ensured by a detailed consideration of a refined entrainment parameter. The mathematical model was used to calculate various scenarios of water entrainment in the jet during oil spills. Graphs were constructed to identify the dependences of thermophysical characteristics.</p>