地球化学烃场随时间演化及地质作用（温度场、应力场、水动力场）的变化而发生空间上的转移，作为现今地球化学烃场的地下聚集体和深部烃类物质场源的油气藏，其演化过程也是深部烃场场源（油气藏）与场内介质进行物质交换与能量转移的过程，这必将带来场内介质(岩层、岩性等)的变化，进而在油气藏分布区域形成地球化学烃场效应。油气藏上方化探异常是地球化学烃场效应最为直接的近地表表现形式之一，影响化探异常的因素是：油气藏属性特征、化探指标属性特征（指标物理化学性质）、输导体系（地层、构造）、近地表介质条件等。油气化探实例说明：滤波数据处理技术、多方法和多指标的组合匹配使用可降低非深部烃源因素对化探异常的影响，提高化探异常反映深部油气藏的真实性和可靠性。

The space distribution of the hydrocarbon geochemical field changes with time evolution and geological processes such as geothermal field, stress field and hydrodynamic field. The hydrocarbon field source is the underground hydrocarbon congeries, and its evolution is in the exchange of matter and the transformation of energy between hydrocarbon and its surrounding medium. So changes of the terrane and the lithology around the hydrocarbon take place because of their interaction, and they will impose geochemical effects on near surface. The abnormality of geochemical indexes over a reservoir is regarded as one of the most direct effects incurred by the geochemical field. The factors influencing geochemical exploration include the attribute of the reservoir, the attribute of geochemical index (the character of geochemical index), the transportation system (terrane and the fractured formation), and the environment of the earth surface. The successful examples of geochemical exploration display that the combination use of data smoothing, multi-methods and multi-index do well in reducing the interferences of shallow hydrocarbon factors to the geochemical exploration abnormality, increasing the reliability of abnormal signals for targeting deep oil and gas reservoirs.