油气化探技术在川西坳陷油气勘探中的应用

Application of hydrocarbon geochemical exploration technique in oil and gas exploration in western Sichuan depression, China

自"七五"以来,为配合四川盆地的油气勘探,在川西坳陷开展了一系列油气化探工作,对该区油气的发现起到了重要作用。川西坳陷的地质条件有利于微渗漏烃类以较高浓度赋存于土壤中,从而有利于油气地球化学探测方法的使用。选择有代表性的大型气田——新场气田进行近地表地球化学场特征与石油地质关系解剖,结果表明气田上方近地表地球化学异常是客观存在的,与本区独特的地质环境相对应,并优选出勘探天然气的有效指标组合。这些有效的油气化探方法在川西天然气富集区的预测中同样效果显著,以川西新都-金堂地区油气化探详查为例,许多化探异常经钻探后证实具有工业油气流。上述研究表明,油气化探技术在川西坳陷具有良好的应用前景。

Studies of hydrocarbon geochemical exploration have been done in western Sichuan depression in conjugation with oil and gas exploration in Sichuan basin since＇the Seventh Five Year Project＇, which have played an important role in the discovery of oil and gas in this area. Geological condition in western Sichuan depression is favorable for high concentration microseepage hydrocarbon enriched in soil which facilitates surface geochemical dectect. A typical large-scale gas field, namely Xinchang gas field is chosen as the study object for the relationship between characteristics of surface geochemical field and petroleum geology conditions. The results clearly indicate the surface hydrocarbon anomalies do exist and have certain link with deep reservoir, which is corresponding to local geological conditions of this area. A series of practical indicators are thus optimized for natural gas prospecting. Then, they are used to predict the zones with rich hydrocarbon accumulation and yield satisfactory gas-prospecting results, for example, some surface hydrocarbon anomalies are verified to be commercial oil and gas flows in boreholes. The studies mentioned above indicate hydrocarbon geochemical exploration technique has good application prospect in western Sichuan depression.