| Most of our country reservoirs have complex oil reservoirs and fluid properties,in the later stage of the development process,the nitrogen is injected to enhanced oil recovery,but the rules for nitrogen movement is not unclear,require for inter well gas injection monitoring,not only can provide timely and effective support for the adjustment of gas injection measures,but also can reduce development risks and difficulties.However,at present,the research of gas tracer both at home and abroad tends to be applied in the field,lack of corresponding laboratory evaluation method,thus,it's very important to build a set of evaluation method for gas tracer.In this paper,we first carry out the detection and optimization of gas tracer after which the stability evaluation and diffusion experiments of gas tracer were performed and the laboratory method used to evaluate gas tracer combined with software simulation is constructed.After those research,got the following understanding.The optimization of gas tracer is realized by using the established program which is based on comprehensive dynamic evaluation model.Different from the previous methods through the laboratory experiment to carry out the screening of the tracer,the method is simpler and more effective,successfully screened out four kind of gas tracer for our paper research:sulfur hexafluoride?Octafluorocyclobutane?1,1,1-Trifluoroethane and 1,1,1,2,3,3,3-Heptafluoropropane.When studying the stability of gas tracer,a new idea was put forward:when application GC-MS,choose the full scan mode,we can figure out the stability of the selected gas tracer by search the new wave,the experiments shows that the four kind of gas trace have great stability under formation condition.Combine with software to simulation and laboratory experiments,the gas tracer under formation condition was studied,the results show that the four kind of gas tracer were insoluble in water but soluble in oil,and the partition coefficient is also small both in water-gas and oil-gas.In the beginning of the experiment,the experimental vessels with three sizes were designed by using Fluent software to stimulate the unsteady flow of gas tracer.the results show that the the time of unsteady flow decreased with narrowing the diameter of the experimental vessel,which is beneficial to obtain more accurate results.In the experiments for gas tracer diffusion coefficient,by monitoring the pressure of the vessel,then using the mathematic model to solve,we finally get the gas tracer diffusion coefficient of 4 gas tracers in oil under the formation condition. |
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