No abstract

New data on the mechanisms of intermediate layer formation in petroleum emulsions are reported. The possibility of structural phase transitions preceding the inversion points of these multicomponent media was experimentally demonstrated. Many features of these transitions are similar to the phase transitions in model dispersions of the Winsor III type. In manufacturing processes, the formation of undesirable "intermediate layers' can be interpreted as the appearance of a bicontinuous phase at ratios of the volume fractions of water and crude close to unity. In acceptance, storage, and preparation of crude oil for refining, important volumes of crude-containing sludges, which are valuable hydrocarbon feedstock, are formed [1], although they are traditionally considered a source of environmental pollution. Prolonged storage of crude mixed with stratal water, contact with atmospheric oxygen, the presence of solid particles and hydrophobized resins and asphaltenes and waxes favor the formation of such sludges as "intermediate layers," which are very stable petroleum emulsions [2]. More exhaustive studies of the mechanisms of formation of intermediate layers in oil emulsions are necessaryto develop effective technologies for the utilization and processing of such sludges. We report the results of such studies here.We investigated mixtures of crude oil and stratal water sampled from well 60 (Tula stratum) in the Aktanysh field. The stratal water phase had a density of ρ w = 1153.9 kg/m 3 at 20°C, which corresponds to a salt content of close to 150 g/liter. The degassed petroleum phase had a density at 20°C of ρ p = 902.2 kg/m 3 and a viscosity of 64.80 mm 2 /sec and contained 5.59% waxes, 19.25% resins, 8.89% asphaltenes, and 3.68% sulfur.The ratio of the total resin and asphaltene content to the wax content in the crude was equal to 5.03. Based on this index, the crude can be classified as high-resin crude [3]. In turn, based on the difference in the densities r w -ρ p = 251.7 kg/m 3 , the mixtures are classified as tending to form difficult to separate emulsions [4].The properties of the water-oil emulsions were determined in the 5-50°C temperature range characteristic of the Aktanysh field. The volume fraction x of aqueous phase in the emulsions did not exceed 0.6.

There are many equations of steady inflow of fluid to the wells depending on the type of well, presence or absence of artificial or natural fractures passing through the well, different degrees of drilling-in of the wellbores. For some complex cases, analytical solutions describing the inflow of fluid to the well have not yet been obtained. An alternative to many equations is the use of numerical methods, but this approach has a significant disadvantage – a considerable counting time. In this regard, it is important to develop a more general analytical approach to describe different types of wells with different formation drilling-in and presence or absence of fractures. Creation of this method is possible during modeling of fractures by a set of nodes-vertical wells passing from a roof to floor, and modeling of a wellbore (wellbores, perforation) by a set of nodes – spheres close to each other. As a result, based on this approach, a calculation algorithm was developed and widely tested, in which total inflow to the well consists of the flow rate of each node taking into account the interference between the nodes and considering the impermeable roof and floor of the formation. Performed modeling confirmed a number of known patterns for horizontal wells, perforation, partial drilling-in of a formation, and also allowed solving a number of problems.

No abstract

No abstract