Abstract: During the process of drilling or drill pipe sticking, the influence of oil emulsion drilling fluid on geochemical logging and its varying degrees of pollution on rock sam- ples can not be avoided.Through simulation experiment, the influence of oil emulsion drilling fluid on geochemical logging,and its pollution degree on core,cuttings and sidewall coring are carefully analyzed.The results indicate that its influence on core and cutting samples can be neg- lected.However,reservoir evaluation can not be carried out due to its bad influence on sidewall coring samples. Meanwhile,geochemical logging is found to be capable of anti-pollution and identify hydrocarbon show with on- site logging practice of 2 wells.