Design And Study Of Shale Gas Concent Sensor Based On Surface Plasmon Resonance Technology

In recent years, energy contradiction between supply and demand increases sharply with the rapid development of global economy. As important kind of unconventional oil and gas resources, shale gas has a high priority and its development and utilization has become the important guarantee to resolve the contradiction between supply and demand of energy. Shale gas has significant strategic importance for the sustainable development of the country. Compared with the developed countries in Europe and America, shale gas exploration and development in our country is still in its infancy. Shale gas is a kind of natural gas existing in the forms of free gas and adsorbed gas which occurs in the organic rich shale of micro-nanometer pore gas. The free state of shale gas accounts for about 20%. At present, the main formation coring method is used to evaluate the adsorption state of shale content. However, the free state of shale gas is prone to erosion in the process of running coring, which cannot accurately reflect shale gas reserves. Therefore, test methods to carry out the free content of shale gas and new research on sensor method have great importance for evaluating the shale gas reserves accurately.Based on the design requirements of shale gas concentration sensor, this paper puts forward optical fiber surface plasmon resonance method to design the system of shale gas content by using numerical method to study the effect of surface plasmon resonance sensor spectral characteristics, which provides theoretical basis for design content of shale gas sensor. The simulation results of optical fiber surface plasmon resonance show that the resonance peak is increased with the refractive index of the surrounding medium, the depth of the resonance peak absorption peak increases first and then gradually becomes shallow with the increase of the silver film thickness. Moreover, the silver film thickness which either too thick or too thin is not conductive to stimulate the phenomenon of surface plasmon resonance.Using the discrete dipole approximation method, the research on extinction properties of metal and metal/oxide core-shell nanostructure has been taken. The results indicate that the LSPR peak is red shifted and the extinction spectrum becomes broader with the increase of core-shell ratio. The relationship between peak wavelength and core-shell ratio are substantially linear when compared with the fitting curve. Besides, the main factors affecting the extinction efficiency are gradually replaced from scattering efficiency to absorption efficiency.Additionally, the extinction spectrum is red shifted with the increase of the silver nanoparticle core-shell ratio and the refractive index of the surrounding medium and the resonance peak of larger nanoshell is located at longer wavelength with the same core-shell ratio. It is also found that electron transfer is existed between the compound nano-core and the silver nanoshell accordingly, the level of reduced surface electronic density of silver nanoshell with the same size from the highest to lowest is CdS/Ag, ZnS/Ag, ITO/Ag.