Theoretical study and tests on geophone-limestone coupling effect
Shi Zhan-jie1, Tian Gang1, Gu She-feng2, Shen Hong-lei1
1. Department of Geosciences, Zhejiang University, Hangzhou, Zhejiang 310027, China;
2. Exploration and Development Research Institute, Daqing Oilfield, CNPC, Daqing, Heilongjiang 163712, China
Abstract：The geophone-limestone coupling problem is one of the important factors which influence quality of seismic data in marine carbonate outcrops area of South China.In this paper,using multi-freedom degree vibration system theoretical model,we analyze the response characters of geophone-limestone coupling system.Then combining the theoretical results with field test results,we compare seismic data collected from different geophone coupling modes and discuss the geophone-limestone coupling mechanism.The results show that it is "two degrees of freedom coupling vibration system" to make geophone spike insert into limestone ground.And the resonance frequency is very high and coupling system's influence is very little when making geophone spike insert into limestone ground tightly.But seismic acquisition efficiency is low using this geophone coupling mode.The results also show that it is "three degrees of freedom coupling vibration system" to bury geophone on the limestone ground using coupling mediums such as surface soil.And the seismic acquisition efficiency is high using this geophone coupling mode.However,when using the latter geophone coupling mode,we need to select proper coupling medium and reduce contact acreage between coupling medium and limestone ground and coupling medium's height in order to weaken the coupling resonance.
