Numerical Simulation Research On Medium And Low Temperature Fluid Thermal Power Generation In SAGD

Steam assisted gravity drainage technology(SAGD)is a heavy oil thermal recovery technology.A large amount of medium and low temperature fluid will be produced during the oil recovery process,and the rest of the heat recovery potential is vast.As the world pays more and more attention to energy efficiency and environmental protection,waste heat recovery has become a solution to reduce energy consumption,improve efficiency,and have good economic benefits.Therefore,carrying out corresponding analysis,design,and research has essential economic value and environmental benefits.Thermovoltaic power generation(TEG)can directly convert heat energy into electricity.In addition,TEG has the advantages of scalability,small size,no emissions,no moving parts,quietness,and environmental protection.Based on the above analysis,this research proposes using thermovoltaic power generation technology to recover the waste heat utilization of the low-temperature fluid in SAGD to realize distributed power generation at the wellhead,and the generated electricity can be used for crude oil transportation at the wellhead.In this thesis,a corresponding thermovoltaic power generation model is established based on the TEG experimental device.Numerical simulations are carried out using different boundary conditions.It is found that the simulation results using the constant flow boundary have a higher degree of fit with the experimental data.On this basis,simulation calculations with different chip numbers were carried out,and the relevant numerical simulation results were verified with experimental data.For the temperature≥170 ℃,a scheme of waste heat recovery and utilization using co-generation technology for direct power generation is proposed.For SAGD flue gas waste heat is not conducive to direct collection and use;make full use of some of the existing oilfield infrastructure.It does not affect the operation of the original system or equipment.Two waste heat recovery schemes are proposed for winding spiral tube heat exchangers on the outer wall of the chimney and installing concentric tube heat exchangers:first,use the heat exchanger to exchange the waste heat.170 ℃ fluid,and then use thermovoltaic power generation technology to generate electricity.Aiming at the waste heat utilization of the produced fluid of SAGD,a corresponding thermovoltaic power generation model was established,and the output power and thermoelectric conversion efficiency were simulated and calculated.The flow rate of the thermal fluid was 0.13kg/s,and the temperature was 280 and 180 ℃,respectively.According to the relevant simulation data under the conditions,the TEG device with 144 chips on the six layers can output 1699.64 and632.88 W,respectively,and the thermoelectric efficiency is 9.52%and 2.19%,respectively.The power generation of a single well is 16.9-28.2 kW.For the spiral tube heat exchange system,the research results show that under the same other conditions,the heat absorbed by cold water increases with the increase in the number of winding turns,the diameter of the spiral tube,and the decrease of the tube wall thickness.And the heat transfer performance of the spiral tube increases from high to low order is copper,aluminum,iron,and steel.For the concentric tube heat exchange system,the heat exchange efficiency decreases with the increase of the radius of the sleeve and first increases and then decreases with the rise of the cold water flow rate.The heat exchange efficiency can reach the maximum efficiency of 91.1%at 1 kg/s.