PREDICTED AND MEASURED PETROPHYSICAL AND GEOCHEMICAL CHARACTERISTICS OF THE EGRET MEMBER OIL SOURCE-ROCK, JEANNE-DARC BASIN, OFFSHORE EASTERN CANADA

The DELTAlog R wireline log technique has been used to predict high ve rtical resolution geochemical profiles for 17 well penetrations of the Upper Jurassic Egret Member source rock of the Jeanne d'Arc Basin, of fshore Newfoundland. The predictions are compared with Rock-Eval data obtained from the same interval. High resolution comparison of the com puted total organic carbon (TOC) curves with gamma ray logs implies th at the source rock layers in the Egret Member are mainly shale/claysto ne and the non-source rock layers are limestone/marl (to the south) an d siltstone/sandstone (to the north). These comparisons also indicate that in the mature area some coarse-grained non-source rock layers are filled with hydrocarbons, implying primary migration of oil/gas. Usin g the average computed TOC value, the thickness of the Egret Member an d the average formation density, the mass of organic carbon was calcul ated at 19 well locations and regional variations examined. Areas with a great mass of organic carbon were identified. The present mass of o rganic carbon is primarily related to the amount of organic matter bei ng deposited and preserved, but the expulsion of oil/gas may also exer t a control. Using 1 wt.% as the lower limit for a source rock, it was observed that the percentage of non-source rock in the Egret Member i s generally higher in immature wells (LOM less-than-or-equal-to 7) tha n in mature wells, probably as a result of hydrocarbon migration/expul sion after maturation.