Study of tertiary methods for enhancing oil recovery in carbonate reservoir fields

Background: The dynamic development of the oil and gas industry is of key importance for the economy of Kazakhstan. The country's long-term strategy for the development of the oil and gas complex is aimed at increasing oil and gas production. However, every year oil companies are faced with a decrease in easily accessible reserves, which forces them to develop hard-to-recover reserves, including fracture-pore-type reservoirs of carbonate deposits. In Kazakhstan, there are many fields with fractured porous reservoirs that are at a late stage of development, which requires their detailed study to improve oil recovery.

Aim: The purpose of this work is the scientific substantiation of new technological approaches, aimed at increasing the final oil recovery factor, based on research and analysis of the world experience in oil production from fractured porous carbonate reservoirs.

Materials and methods: As part of this study, the works have been carried out to model the injection of various agents, in particular gas and water, into the carbonate formations, which includes the creation of detailed geological and hydrodynamic models, taking into account the features of the fractured pore structure of carbonate formations, and simulations for various scenarios for the injection of agents with the use of the ECLIPSE™ software product (Schlumberger). Gas has been injected into different parts of the reservoir to assess the impact on the efficiency of oil displacement.

Results: A study of the field, using a sector model, has shown that the greatest production volumes are achieved when perforating the upper part of the formation. In this case, there is a mixing of the flow of injected gas and oil, which significantly increases the efficiency of oil production. Options with perforation into the middle and lower parts of the formation demonstrate less efficient piston gas displacement. Experimental modeling of water injection into a carbonate reservoir has revealed that water injection leads to uneven fluid movement due to a developed fracture system. An analysis of the tracer studies has confirmed that the injection well has a significant impact on the formation of a stable water cut channel, especially in the southern part of the facility, which leads to an increase in the water cut of the produced product.

Conclusion: The modeling has shown that gas injection with the perforation of the upper part of the formation provides the greatest hydrocarbon production. Optimizing the perforation interval is an important factor for increasing production in the future development strategies. The water injection experiment has revealed that a developed system of fractures in carbonate reservoirs leads to uneven fluid movement, increasing the water cut of the produced product. The use of the flow diversion technologies can reduce this effect and increase production efficiency. Different stimulation techniques for the carbonate reservoirs show significant differences in oil recovery factors, highlighting the importance of modeling for optimizing the production processes.