利用土壤游离烃技术判别油气藏性质及保存条件

摘要：土壤游离烃技术通过直接检测受地表景观介质变化影响小的游离态轻烃异常来获取地下油气信息。塔里木盆地试验区已知油气藏上方具有良好的游离烃化探异常显示，干燥系数在840~1989之间，显示游离烃异常与深部油气的热演化相关。土壤游离烃组分平衡系数、湿度系数、特征系数等指标预测与判断地下油气藏性质的结果与实际地质结果相吻合。近地表游离烃的甲烷/丙烷指标均值高达25~116，由北向南依次增大，说明油气藏埋藏深度依次增大。丁烷异构比和戊烷异构比特征显示雅克拉油气区有机质成熟度最高。结果表明：游离烃的轻烃组分和含量变化特征能够预测与判断地下油气藏的位置、性质、有机质成熟度和保存条件。

Application of Soil Free Hydrocarbon to Distinguish Properties and Preservation Conditions of Oil and Gas

Abstract: Soil free hydrocarbon technique by directly detecting free light hydrocarbon anomalies affected by the landscape medium of little influence is introduced to obtain underground oil information in this paper. The known petroleum reservoir has a good show of free hydrocarbon geochemical anomalies in the test area in Tarim Basin, the aridity coefficient between 840 and 1989 of which indicates that free hydrocarbon geochemical anomalies is related to the thermal evolution of deep oil and gas. The underground oil and gas reservoir properties predicted and judged by the balance coefficient, soil humidity coefficient and characteristic coefficient of free hydrocarbon component are consistent with the actual geological results. The average of CH4/C3H8 index of near surface free hydrocarbon from north to south is between 25 and 116,which illustrates that the depth of oil and gas reservoir increases in turn. The feature of the butane heterogeneous ration and pentane heterogeneous ration shows that Yakela petroleum region has the highest maturity of organic matter. The result indicates that the component and the content variation of free hydrocarbon can forecast and judge the location, character, maturity of organic matter and preservation condition of underground oil and gas reservoir.