| In 2018,China's dependence on foreign oil increased to 69.8%;the dependence on natural gas rose to 45.3%.Conventional oil and gas resources have been difficult to meet the needs of national development,and more oil and gas resources are urgently needed to meet the growing domestic energy demand.At the same time,China's oil shale resources are abundant.The national oil shale resources are 719.937 billion tons,which is converted into shale oil resources of 47.6 billion tons,1.5 times that of conventional oil and gas resources.If the oil shale oil and gas resources can be effectively utilized,it is of great significance to alleviate China's energy shortage and ensure national energy security.The key to the effective use of oil shale is the development technology of oil shale.After years of research and production,oil shale ground refining oil production and combustion power generation technology are relatively mature,but only for the exploitation of shallow oil shale resources,the economic cost of developing oil shale as energy is too high.In addition,the environmental pollution during the mining process is also very serious.In recent years,oil shale in-situ mining technology has received more and more attention.The in-situ mining technique of oil shale refers to the technique in which the oil shale is not mined out of the ground,and is directly heated in situ to generate oil and gas,and then the oil and gas are extracted from the ground.While reducing the economic cost of oil shale resource mining,it also avoids environmental pollution problems.There are many influencing factors for in-situ pyrolysis of oil shale.By using computer to simulate the in-situ pyrolysis process of oil shale,the cost and time required for field test of different mining modes can be reduced,and different geological conditions and mining can be simulated.The influence of the mode on its mining effect is of great significance for the in situ pyrolysis of oil shale.The following research was carried out on the hydrocarbon generation process of oil shale in situ using numerical simulation technology:1.Using the pyrolysis experimental data of three different types of oil shale in Fushun,Maoming and Colorado as the comparison,mathematical modeling and numerical simulation of the first-class,parallel-level and series-level pyrolysis models of the general package were carried out using MATLAB software.Study and analyze the differences and laws between different oil shale simulation results in different pyrolysis models.It is found that the general-package pyrolysis model is suitable for type I kerogen oil shale,and the higher the H/C ratio,the closer the calculation result is to reality;the parallel first-order pyrolysis model can simulate different types of oil shale well.Suitable for oil shale with low H/C and O/C ratios;the series first-stage pyrolysis model has the best simulation effect,and the oil/shale ratio with larger O/C ratio is in the series first-stage pyrolysis model.The better the simulation results in.2.Using the numerical simulation software ANSYS to model the six modes of multi-well injection and single well injection,the equilateral triangle,square and regular hexagonal well groups,and simulate the temperature field;solve the oil page by MATLAB software.The chemical reaction kinetics equation of rock hydrocarbons was used to obtain the hydrocarbon generation amount of oil shale in situ under the corresponding time,and the input and output results of different well locations were compared.The simulation results show that the hydrocarbon generation effect of multi-well injection scheme is better than that of single well;the net value of hydrocarbon shale hydrocarbon generation is the 20 th month of the six well model,which is 1141.85 tons;the second is the fourth well mode.25 months,103.63 tons;the last 22 months of the Mitsui model,878.95 tons;multi-well injection mode,the energy return rate of each mode is 2.73,1.74 and 2.05,respectively,energy return in single well injection mode the rate is 1.418. |
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