EFFECT OF IGNEOUS ROCKS ON SOURCE ROCKS AND HYDROCARBON GENERATION IN THE LANGGU SAG, CENTRAL HEBEI PROVINCE

Organic geochemical data analysis is conducted on source rocks in intrusive igneous rock interval in the Langgu Sag,Central Hebei Province.The results indicate that intrusion of igneous rocks has distinct effect on Ro and H/C atomic ratio and less effect on HC/TOC and I_H,and it only shifts the oil generation peak and upper limit of wet gas belt to an earlier time instead of inducing overmaturation of organic matters.In this way,intrusion of igneous rocks does not damage source rocks or existing oil and gas reservoirs,but increases maturity of organic matters fast by means of short-term baking,and especially for those source rocks at immature-low maturity stage.Therefore,it is ahead of normal evolution stage.In addition,multiple intrusions of igneous rocks can thicken source rocks of hydrocarbon generation stage,which is more favorable for hydrocarbon generation.