2019 AAPG Annual Convention and Exhibition:

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Reconstruction and Forward Modeling of Deep Water Basins on the Hyperextended Atlantic Margins

Abstract

Hyperextended deep-water margins are recognized worldwide and in recent years have been associated with a number of major oil discoveries. As these margins hold the potential for future exciting new discoveries, it is important when de-risking deep-water exploration to recognize their key structural features and understand their tectonic evolution from pre-rift to eventual breakup or failed rift. We present a new approach to modelling and analysis of deep-water basins on hyperextended continental margins and show that the tectonic processes associated with hyperextension exert an important influence on hydrocarbon discoveries. The foundation for our new approach to modelling and analysis of hyperextended margins is the construction of a palinspastic deformable plate reconstruction model that quantifies the amount, timing and direction of crustal extension across conjugate margins through time. This provides us with a set of retro-deformed beta grids of crustal stretching for key tectonostratigraphic intervals. These grids are used to calculate inputs into the forward modelling of the tectonic evolution of hyperextended margins from the pre-rift configuration output from the palinspastic deformable plate reconstruction. Forward modelling the initial tectonic and subsequent thermal subsidence with input from a palinspastic deformable plate reconstruction sheds new light on basin subsidence history and connectivity, and provides a way to quantify the amount of flexural isostatic uplift of the basin margins through time. Using this method, we have analyzed different hydrocarbon play types associated with hyperextended Atlantic margins. A propagating series of rift, hyperextension and breakup events from the Equatorial Atlantic to the Labrador Sea and from the Rockall and Porcupine basins to the Barents Shelf have been analyzed to develop a detailed tectonic model. This region includes important discoveries associated with hyperextension on the margins of the Bjørnøya Basin and the Loppa High in the SW Barents Shelf, and on the margins of the hyperextended Orphan Basin in the Flemish Pass on the Newfoundland margin. We have modelled basin geometry and connectivity in these basins and on their conjugate margins through time, tectonic subsidence rates, and periods and amounts of flexural uplift and erosion. This information can be used to re-assess new areas of interest for hydrocarbon exploration in the deep water basins of the Atlantic and Arctic margins.