De-Risking Jurassic and Cretaceous Leads With the Integrated Interpretation of 3-D EM, 2-D Seismic and Well Data in North Flemish Pass Basin, East Canada

Abstract

The North Flemish Pass is located north of the oil producing Jeanne d'Arc Basin, and likewise is a structurally complex Mesozoic rift basin offshore eastern Canada. The basin comprises a series of tilted fault blocks, fault bounded horsts, and inversion anticlines forming potential traps for hydrocarbons. A regional 3D EM data was inverted to 3D resistivity volumes. The recorded data recovered resistivity anomalies across drilled Jurassic oil discoveries. In addition, anomalies are mapped in open acreage and within the Cretaceous stratigraphic unit which is a known play in the Jeanne d'Arc Basin, but not proven in the Flemish Pass. Additionally, 3D MT data acquired simultaneously, reveal new geologic insights at the sub-regional scale. Lateral resistivity differences were observed between sub-basins and anticlines. In the west the anticline is interpreted as cored by a mobile lithology such as shale and not Paleozoic metamorphic rocks. In contrast, to the east, we interpret that deep sub-basins are characterized by in-folded resistive rocks, possibly Paleozoic rocks. At the basin to sub-basin scale we have identified dominant resistive features at Jurassic and Cretaceous stratigraphic levels on leased and open acreage. The anomalies are integrated with 2D seismic and available well data. 3D EM data show excellent lateral resolution, resistivity anomalies stop abruptly at faults, and stratigraphic boundaries. EM data are sensitive to resistors of a certain threshold in size, determined by both the background resistivity and the reservoir properties such as depth, areal extent, pay thickness, and resistivity. This implies that the strength and size of the anomaly can be indicative of the net rock volume. Well logs allow us to evaluate the resistivity range of a hydrocarbon-filled versus a water-wet sandstone. In this paper, we present the anomaly recovered over the Bay du Nord and Harpoon discoveries, how it correlates with well data and show the estimated areal extent of the accumulation. We discuss potential leads and how by integrating EM data in an early phase of exploration, drilling risk can be reduced and pre-drill volumetric estimates are improved. We conclude that 3D inversion of the EM data and the integration of all available data sets can significantly improve and better frame the interpretation of the major anticlines that underlie the oil discoveries and the generation of new leads at both the prospect and sub-regional scale offshore East Canada.

AAPG Datapages/Search and Discovery Article #90259 ©2016 AAPG Annual Convention and Exhibition, Calgary, Alberta, Canada, June 19-22, 2016