IMPROVEMENT OF HYDRA TRANSPORT OF HIGH-VISCOSITY HEAVY OIL IN A TWO-PHASE CORE-ANNULAR FLOW

The paper presents the results of experimental research aimed at developing effective methods of special pumping for collection and long-distance transportation of high-viscosity extra-heavy oils produced from hard-to-recover deposits of natural bitumen and kerogen shale. In order to abandon the widely used «hot methods» of pumping, associated with the risks of thawing of permafrost rocks and high level of greenhouse gas emissions, new methods are proposed for practical realization and increasing the efficiency of the hydrotransport method, which was not obtained in the corresponding period. For its realization the concept and devices for creation of stable water and foam ring flow are developed. To create a water ring, the design of a mixer has been developed, providing water supply tangential to the oil flow, which provides the required current lines. The effect of reducing hydraulic resistance in certain cases can reach more than 80 %, and the pressure drop during hydraulic transport of heavy oil in the water ring is close to pressure losses commensurate with pumping the water itself. To stabilize the structured annular flow «oil in water», the influence of surfactants and polymer additives on the value of hydraulic resistance reduction and stability of the flow structure has been experimentally investigated. It was found that the addition of non-ionogenic polyacrylamide (PAM) to the aqueous phase forming a smoothing film near the wall can increase the stability of the annular flow. The magnitude of hydraulic resistance by adding polymer additive can be significantly reduced simultaneously by stabilizing the two-phase annular flow and damping the turbulence in the near-wall layer. The possibility of creating a stable water-foam annular layer providing additional reduction of hydraulic resistance due to the effect of micro-bubble slippage has been proved. The microstructure of the obtained foam, the influence of temperature, composition of water and oil phases, pipeline surface on its stability and structure were studied. Studies of the microstructure of the foam obtained by the orthogonal method showed that the water-foam layer retains stability at high oil and salt content, and breaks down, flowing to the lower forming pipe, at high oil temperatures. According to the results of the performed research the maximum achievable hydraulic effect of the developed method was evaluated and the main directions of research aimed at increasing the stability of the structured annular flow regime of the flow «oil in water» on the extended horizontal pipelines, including through the use of ultrasonic and magnetic treatment methods, were formed.