The paper presents an invariant flow rate measurement system for individual components for a flow that consists of oil, water, and gas. The proposed flow measurement system is a continuation of the work of the authors, which is based on the application of the multichannelling principle of invariance theory. The paper proposes and discusses the structure of the invariant system for measuring the flow rate of oil-water-gas, analytical expressions are obtained for the implementation of algorithms for measuring the flow rate of individual substances that make up the flow. The uncertainty of the flow rate measurement results was assessed separately for oil, water, and gas. In this work, it is shown that by selecting flow meters of the main and additional channels with an uncertainty of less than 0.5 %, for almost any ratio of components in the additional pipeline, it is possible to measure the flow rate of water or oil with an uncertainty of less than 3 %, and the flow rate of the gas fraction in free form can be measured with an uncertainty value of less than 1 %. The paper discusses the practical aspects of the implementation of an industrial prototype of the system and the characteristics that affect its accuracy and efficiency.