The definition of oil displacement mechanism is one of major questions in problem of reservoir processes: or as mixed oilwater flow, when oil and water phase relative permeability (kro and krw) of water flood zones are specified; or as piston flow, when takes place frontal drive of oil by stream of approaching water.
Phase relative permeability for water and oil are usually defined on the basis of learning filtering of oil-water mixtures through a core. Just on the basis of such experiments the curves of phase relative permeability to oil and water are performed, which then used in the different design documents and projects of field development.
At the same time it is known, for example, that using modern methods of engineering inclusive reservoir simulation model are large difficulties at history matching with applying of such relative permeability curves of filtered fluids. Frequently forced variation of parameters of filtering at history matching results in concurrence of calculated and actual indexs to development at final parameters of filtering much distinguished from source, obtained in laboratory conditions.
It is necessary to mark also, that in the literature last years many papers have appeared that the core is a poor material that only on its basis to plan field development because of unrepresentative of coring, as a result of which it does not mirror property of all reservoir system; high created gradients of stresses at studies in laboratory conditions as contrasted to actual; strictly oriented directivity of flow of fluid through a core with impossibility of an estimation of anisotropy of formations on permeability and etc.
In a paper the features of extraction of oil reserves on some fields of Western Siberia are reviewed. Is shown, that as a whole on fields there are complex processes of fluid flow, where are formed as regions of water inrushes with consequent catastrophic watering out of individual wells, and zones of oil displacement with waterless wells, working a long time, and recovery of reserves in such zones much greater, than initial oil reserves in drained areas of these wells. It is impossible to explain by widespread assumptions about influencing reformative phase relative permeability or complex heterogeneity of oil reservoir. Formed zones of oil displacement to durable waterless operation of wells, as a rule, are connected with frontal drive. The examples of operation of some horizontal wells with high oil recovery factor (more than 0.5) in area of their drainage. The results of numerous production and injection well testing and conducting of hydrolistenings testify to such nature of water-oil displacement.
The concrete offers on rational field development methods are made, when the piston condition of water-oil displacement is organized predominantly.
Water-oil displacement is well-know technology of oil-field development connected with slitting of reservoirs by injection wells on separate blocks and injection in these wells of water. As a result the displaced oil is countervailed by the displacement agent - water. At that energy state of reservoir does not change and the average reservoir pressure is close to initial reservoir pressure. It is one of the major factors of rational field development of reservoirs. The modern projects of field development are founded on that principle of move of displacement front, when it is considered, that at water entry in reservoir, there is blending water to oil. As a result in water flood zone the share current of an oil-in-water mixture is carried out. In laboratory conditions, in result of pumping of oil-water mixtures with different oil-water proportions the phase permeability on oil and on water are instituted. And, as a rule, permeability on separate phases turns out much below absolute permeability of formation. Fig.1 shows the typical phase relative permeability curves.