Research Of SAGD Steam Chamber Expansion Law Based On Heavy Oil-Water Aquathermolysis

Heavy oil recovery by SAGD process is accompanied by significant production of hydrogen sulfide,carbon dioxide,methane and hydrogen due to the injection of steam to the reservoir.Therefore,conducting the formation rules of gas production by aquathermolysis reaction and the effect of generated gas on the expansion of the steam chamber research,which is of great importance in forecasting production potential of H₂S and CO₂ and revealing the SAGD performance.Firstly,this thesis conducted thermal simulation experiments of aquathermolysis to research the effect of reaction conditions with and without core minerals on produced gas composition.It has been determined that the aquathermolysis reaches its equilibrium after approximately 5⁷ days.The content of gas production of H₂S,CO₂ and CH₄ is significantly higher with core minerals,which indicates core minerals have a good catalytic effect on aquathermolysis and may participate in reaction.Secondly,the kinetic of the heavy oil-water aquathermolysis reactions were estimated according to the experiment datas.The reaction orders of generated H₂S,CO₂,CH₄,H₂,CO,C₂₊parallel reactions were 1.0,0.8,1.2,1.0,0.8 and 1.0 respectively,and apparent activation energies were 46.8597 kJ/mol,6.3563 kJ/mol,16.9021 kJ/mol,67.4028 kJ/mol,23.9857 kJ/mol and 14.7354 kJ/mol respectively,which were decreased by 24.9%,68.3%,33.4%,16.5%,26.5%and 44.4%respectively.It is noted that the obtained kinetic parameters are valid for temperatures below 300??Finally,the reactions were encoded into the reservoir simulation model and conducted numerical simulation of SAGD process with and without aquathermolysis reaction by CMG software.Results show that in comparison to the case without reactions,the majority of the reactive zone is in the liquid pool around the production well.The numerical simulation results with this model show good agreement with field data.The top three of cumulative production was CH₄,CO₂ and C₂₊.There is also higher H₂S accumulation at the top of reservoir as the process evolves,which can benefit the process in that it provides an insulative gas layer between the chamber and the cap rock and lead to better cSOR.The evolution of the gas concentration shows that at the edge of the chamber,the generation rates of product gas from the reaction was greater than that at any other part of the chamber,where poor heat transfer hinderd steam chamber growth.This is evident from the reduction in size of the high temperature zones as the process,which resulted in a decrease in the overall oil rate and cumulative oil produced in the case with reaction.