Specifics of cyclic water flooding for development systems made up with horizontal wells

UDK: 622.276.1/.4
DOI: 10.24887/0028-2448-2021-7-86-89
Key words: horizontal well, cyclic water flooding, reservoir permeability, production well, water cut, injection well, intermittent production, cyclic sampling
Authors: M.M. Veliev (Vietsovpetro JV, the Socialist Republic Vietnam, Vung Tau), A.N. Ivanov (Vietsovpetro JV, the Socialist Republic Vietnam, Vung Tau), I.V. Vladimirov (Ufa State Petroleum Technological University, RF, Ufa), E.M. Veliev (Oktyabrsky Branch of Ufa State Petroleum Technological University, RF, Oktyabrsky), V.V. Mukhametshin (Oktyabrsky Branch of Ufa State Petroleum Technological University, RF, Oktyabrsky)

In research and scientific-technical publications, the matters of selecting the optimal parameters for the unsteady stimulation technology usually refer to determine the parameters of the reservoir pressure maintenance system. It is only in recent times, the studies and technologies for applying the unsteady (cyclic) operation of producers for increasing the oil recovery from layerwise heterogeneous reservoirs started to appear. This article describes the processes to change the profiles of pressure and saturation in the layerwise permeably heterogeneous reservoir for modelled zone during the unsteady operation of producers. Based on hydrodynamic modelling of intermittent operation of a production horizontal well, which produces from layerwise non-uniform permeable formation with highly viscous oil, it is shown, that in the layerwise heterogeneous porous reservoir with a significant non-uniformity of permeable area along the cross section, an intermittent production of a horizontal well leads to an increased oil rate and some reduced water cut of produced products. Despite positive increment in oil flowrate during intermittent well operation, the rate of oil reserves recovery reduces due to idle time, cumulative oil production is below the base value. Increment value of oil flowrate during intermittent well operation depends on its “initial” water cut. It is found that, the higher the “initial” water cut, the lower the oil flowrate increment during intermittent production. Once the intermittent flooding is complete, the well remains higher (in comparison to the base level) oil flowrate for a limited period of time, however, after a while the oil flowrate reduces below the base level or equals it, while the water cut goes up to the base level and in certain cases above it. It is shown, that the intermittent (cyclic) water flooding in the production well influences the neighbouring wells, and this effect depends on mutual location of production and injection wells. It is found, that the changes in the process parameters of “remote” wells during intermittent operation of the neighbouring wells, mostly relates not to the unsteady stimulation (even though there is some effect), but to the increase of the reservoir pressure in an inter-well area and to the directional change of filtration flows by the lateral. Besides, the intermittent operations of the well leads both to occurrence of interlayer cross-flows of reservoir fluids and to the change of flow direction by lateral (more intense production from the reservoir area between the producers).


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