Terra Nova is situated on the Grand Banks, 350 km. east-southeast of St. John's, Newfoundland. The reservoir package at Terra Nova consists of 6 or more sandstone depositional cycles within the Late Jurassic Jeanne d'Arc Formation. Each cycle is initiated by periodic tectonic uplifts, resulting in the formation of incised valleys. The valleys were filled by the rapid progradation of conglomerates (alluvial fans, fan deltas and channels) from a marginal southeasterly direction, and of sands (sandy braid-plain to braid-delta) from the uplifted head of the basin to the southwest. As the sediment supply diminished after each tectonic episode, each depositional sequence was drowned as the braid-plain was transgressed.

The reservoir model consists of multiple layers used to reflect the internal sequence stratigraphy. Detailed centimeter scale facies interpretation, in conjunction with extensive probe permeameter measurements formed the building blocks for reservoir characterization and geostatistical modelling. Five lithofacies types were chosen to represent the reservoir heterogeneity. Utilizing a non-stationary approach, lateral lithofacies' variations were simulated in the model using multiple vertical lithofacies proportion curves to construct a proportion matrix which was constrained by well data and lithofacies isopach maps for each reservoir unit. Different proportion matrices were simulated for assessment of model uncertainty and agreement with geological maps.

Petrophysical attributes were selected randomly from distributions of petrophysical properties for each lithofacies. These were applied to the geological model in a probabilistic fashion. The model was then upscaled and faulted to its present day position to form the input framework for reservoir simulation. The results of this work were used to develop a drilling and depletion strategy for the Terra Nova oil field.

AAPG Search and Discovery Article #90928©1999 AAPG Annual Convention, San Antonio, Texas