Abstract: During horizontal well drilling process, people often mix oil or organic additives into drilling fluid, which may have interference on gas measured indication and impact on the discovery and evaluation of oil and gas shows. The traditional solution is deducting part of the gas measured values based on experience, and regarding the deducting part as the gas measured values in response to oil?emulsion drilling fluid, which does not realize the proper measurement or quantitative elimination of strata oil?gas indication value. The relative content of each component is different between gas measured values from the strata and the oil?emulsion drilling fluid, by which such a proper quantitative elimination that may objectively reflect in?situ hydrocarbon?bearing information can be made through calculations. This approach has been successfully applied to Shengli oilfield, Zhongyuan oilfield, northeastern Sichuan and Xinjiang, etc, without increasing costs and complex calculations, thus can be widespread for use in gas logging with mixed oil?emulsion drilling fluids