Study On The Phase And Process Of In-situ Combustion Exhaust Gases Injection

In recent years,with the continuous development of heavy oil recovery,as an effective replacement technology for heavy oil thermal recovery,in-situ combustion process has been widely used in shengli,liaohe,xinjiang and other oilfields.However,with the output increases,the treatment and utilization of fireflood gas became a key issue in the in-situ combustion technology series gradually.How to deal with the exhaust gas with high efficiency,low cost and zero emission has become an important factor restricting the expansion of fire-flooding industrialization.It is necessary to explore and attempt the in-situ combustion exhaust gases reinjection process.In this paper,the exhaust gas from the pilot area of in-situ combustion was used as the gas source for the key technology research,the related theory and method system of the exhaust gas reinjection of in-situ combustion was established to improve the overall development benefit of heavy oil recovery.First,in view of the HQ well area in-situ combustion exhaust gases components,analyzing the generation mechanism of exhaust gas and the characteristic of components,then using the international simulation software HYSYS analysis.During the research,it was found that the HYSYS automatic generation tool could not accurately describe the influence of moisture content on the phase diagram of in-situ combustion exhaust gas.Therefore,it is necessary to develop corresponding physical property and phase analysis software for the exhaust gas of in-situ combustion.Secondly,the physical properties and phase state models of in-situ combustion exhaust gases are established based on phase equilibrium and state equation,and a software platform for physical properties and phase state analysis of in-situ combustion exhaust gases is developed.The hydrothermal parameters of the exhaust gases in a larger temperature and pressure range are analyzed and calculated during the reinjection process are realized.Based on the independently developed software,the physical properties and phase change process parameters of in-situ combustion exhaust gases in the HQ well area were analyzed,the actual moisture content of it was studied,and the phase diagram of dry or wet gases components was drawn,and the relationship between pressure/temperature and dew point change was studied in depth.At the same time,orthogonal analysis was used to calculate the phase diagram changes caused by component fluctuations in the field,and the actual influence range of various factors on the analysis of working conditions was considered.The practical engineering technology provides the foundation for the later design of the injection system.Finally,based on the study of physical properties and phase change in the injection process,the field data of the HQ well area pilot test station were adopted.Through technical and economic comparison,it was determined whether the dehydration pretreatment process was needed in the exhaust gas injection process,and the specific pretreatment process and parameter boundaries of each process were defined.According to the characteristics of different types of compressors,the physical property change factors of the exhaust gas during the pressurization and the adaptability of equipment material to the exhaust gas compression condition,the combination mode,pressure matching condition and compression series setting of different types of compressors were studied in detail.For the exhaust gas components of pilot test,a preliminary set of complete reinjection process plan is designed,including pipe transportation,dehydration scheme,pressurization,wellhead pressure regulation and injection wellbore flow analysis.The research content covers each process part of the reinjection system,which has important guiding significance for later production.