| The high viscosity of heavy oil brings great difficulties to produce and gather heavy oil.Some heavy oil single wells in Xinjiang Oilfield adopt steam-incorporated heat-collecting technology,resulting in waste of energy resources of a large number of high-quality steam.In response to this phenomenon,Xinjiang Oilfield began to study the single-well water-incorporating and gathering process and carried out pilot tests,which have significant energy-saving effects.However,there is still space for further saving high-quality steam and improving the cost performance of the water mixing process.The key point is that the gathering boundary of Xinjiang thermal oil in different oil properties and different water conditions is not yet clear.In view of the above problems,the indoor loop simulation experiment is tested,combined with field experimental research and theoretical analysis,the gathering process and its main operating parameter boundary suitable for thermal recovery of heavy oil are established,which provides theoretical basis and technical support for the rational design and operation and operation optimization of the hot oil heavy oil gathering and transportation process in Xinjiang Oilfield.The study mainly carries out the following work:(1)In accordance with relevant standards,the basic composition,density,and moisture content and viscosity-temperature characteristics of heavy oil in Xinjiang 980195 well and heavy oil in T98170 well are tested and analyzed.The results show that the heavy oil in 980195 well is ordinary heavy oil,and the heavy oil T98170 well is extra heavy oil.The two aqueous crude oils are pseudoplastic fluids at low temperatures and Newtonian fluids at high temperatures;both dehydrated crude oils are Newtonian fluids in the test temperature range.(2)Two heavy oil heating and water mixing are simulated by the loop system.The effects of flow rate and temperature on the pressure drop gradient and effective viscosity of the heavy oil pipe are analyzed.The pressure drop of the mixture in the test tube at different water cuts,temperatures and flow rates are measured in the water-in-the-loop experiment.Based on the existing oil-water two-phase flow model,the effective viscosity of the tube flow is calculated,and the reversed point of the two heavy oils is determined.In addition,the relationship between pressure drop,flow rate and cycle time is analyzed.The effects of flow rate,water content and temperature on the pressure drop gradient and effective viscosity of heavy oil pipe are analyzed.The results show that the heavy oil in 980195 well can be transported normally when the temperature is higher than 65?,and the heavy oil in T98170 well can be transported normally when temperature is higher than 85?.The reversed point of the two heavy oils is 50%.Before the reverse phase,the fluidity of the two heavy oils is poor.It is necessary to mix water to 20%?25%higher than the reverse point to ensure the safe transportation.(3)Based on the flow similarity criterion of the loop and the on-site gathering pipeline,the unit pressure drop of the collecting fluid under different working conditions is predicted,and the gathering radius of the two heavy oils is predicted according to the wellhead back pressure requirement.According to the experimental data,the water-incorporated layout is made,and the gathering and transporting boundaries of the two heavy oils are determined.Combine the actual situation and the production data of the site,the water mixing process is fully evaluated from a technical and economic perspective.The results show that the optimum water mixing rate of heavy oil in 980195 well is 60%,the optimum water mixing rate of heavy oil in T98170 well is 70%,and the temperature of water mixing to single well should be higher than 650C.The process can save natural gas by 1579.89×104 m3/a,save water by 27.36×104 m3/a,and reduce CO2 emissions by 101.1×104 t/a.The energy saving effect is remarkable and economically feasible. |
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