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Results
Abstract It is extremely difficult to produce heavy oil from an ultra-deep reservoir due to the long lifting path and the high flowing resistance in the wellbore. During its path to the surface along the production string, the reservoir fluid becomes more viscous resulting from heat loss and evolution of the dissolved gas, and thus movement of reservoir fluid slows down and stops at certain position inside the production string. In this paper, jet pumping has been selected and successfully applied to produce heavy oil from Lungu reservoir, Tarim Oilfield, with a maximum depth of 5950 m. Various power fluids have been examined for their capacities to reduce viscosity of the heavy oil in the production string. Hot water fails to reduce the viscosity of the reservoir fluid due to the significant heat loss along the wellbore, while adding chemicals to water (i.e., activated water) suffers from high material costs. Blending light oil with the reservoir fluid in the wellbore is found to optimally reduce viscosity of the reservoir fluid by more than 1600 times and has been applied in Lungu reservoir. Well configurations for jet pumping technique are designed and analyzed. A theoretical model is formulated to calculate the pressure, temperature, viscosity distributions along the production string, which are subsequently used to determine the key operational parameters, such as the quantity and pressure of the power fluid at the wellhead and the M ratio (ratio of the reservoir fluid to the power fluid). Sensitivity analysis indicates that the viscosity of the light oil and M ratio impose a significant impact on performance of the jet pumping. Field applications show that the jet pumping driven by light oil is a viable and efficient technique to lift heavy oil from the ultra-deep heavy oil reservoir.
- Asia > China (0.94)
- North America (0.68)
- Reservoir Description and Dynamics > Unconventional and Complex Reservoirs > Oil sand, oil shale, bitumen (1.00)
- Reservoir Description and Dynamics > Fluid Characterization > Fluid modeling, equations of state (1.00)
- Production and Well Operations > Artificial Lift Systems > Hydraulic and jet pumps (1.00)
Abstract The relative permeability is a crucial parameter for accurately evaluating reservoir performance. Two-phase relative permeability curves are normally obtained by either directly or indirectly interpreting the displacement experiment data. As for the direct interpretation, the core samples are assumed to be homogeneous, while the capillary forces are normally neglected. Although the indirect interpreting approach is able to take heterogeneity of the core sample into account, calculating the derivatives of the objective functions through the graphical or numerical methods is prone to considerable errors. In this paper, a new method is developed to calculate the absolute and relative permeability from unsteady-state, two-phase immiscible displacement experiments. The permeability data is determined by history matching the experimentally observed pressure drop, production data and water saturation profiles via the ensemble Kalman filter (EnKF) algorithm. The power-law model is utilized to represent the relative permeability. Both the absolute and relative permeability are calculated simultaneously by assimilating the observed data. The newly developed method is validated using a numerical coreflooding experiment. It has been found that estimations of absolute and relative permeability are improved progressively as more observation data are assimilated. In addition, this method is convenient to be implemented as the derivative of the objective function is not required.
- Research Report > Experimental Study (0.34)
- Overview > Innovation (0.34)
- Oceania > Timor-Leste > Timor Sea > Bonaparte Basin > Oliver Field (0.93)
- Oceania > Australia > Timor Sea > Bonaparte Basin > Oliver Field (0.93)