«Geology, geophysics and development of oil and gas fields»

A method for assessing residual reserves of high-viscous oil with their subsequent involvement into development by wells with a dual system of wellbores

UDC: 552.578.2:532.13+622.276.1/.4(470.43)
DOI: 10.33285/2413-5011-2023-5(377)-40-48

Authors:

¹ Institute of Oil and Gas Technologies of Samara State Technical University, Samara, Russia

Keywords: high-viscous oil, residual reserves, water cut, oil saturation, dual wellbores system

Annotation:

Analytical dependencies are proposed for non-Newtonian oil systems that make it possible to theoretically relate the water cut index to the current water and oil saturation of the pore space. They help to calculate the index of the density of non-linearly viscous-plastic oil reserves at the stage of watering the C-I formation of the Bobrikov horizon of one of the fields in the north of the Samara region. It is shown that, taking into account the rheological factor influence on the mechanism of oil displacement by water, the amount of residual oil in the pores, according to the forecast, can significantly exceed the value determined by means of using the model of both phases Newtonian flow. At the same time, the dynamics of reservoir watering and the degree of oil displacement are additionally determined by the actual pressure gradient. As a result of the operational localization of residual oil reserves, areas have been identified that can be operated by wells with a dual system of wellbores. This technical solution provides periodic thermobaric impact on the reservoir and the production of residual oil outside the zone of the rock expected damage. The effective degree of heating corresponds to a temperature of 60 °C, which is confirmed by laboratory studies and analytical calculations based on the model of radial filtration of non-linear viscous-plastic oil. After turning off watered interlayers, the second wellbore drilling and targeted heating, additional annual oil production is estimated at 3,5 thousand tons per well.

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