Abstract
Fluvial deposits of the Castissent Formation (late Ypresian) form part of the Eocene infill of the Tremp-Graus piggyback basin. The Castissent Formation has been subdivided into three complexes (A, B, and C). This project focuses on the proximal fluvial-sandstones of Complex A in the Mas de Faro outcrop (NE Iberian Peninsula). There, three amalgamated channel belts are exposed in a 15–24 m thick succession that passes upwards from sandy braided-river deposits (A1-A2) to coarse-grained meandering-river deposits (A3). Sedimentary heterogeneities within these deposits are characterised and their impact on oil recovery in a reservoir analogue are estimated using field descriptions, virtual outcrop interpretation, a 3D geocellular facies model and fluid-flow simulations. Petrophysical values of different facies types were derived from well data through analogous fluvial deposits of the Eiriksson Formation, in the Norwegian North Sea. Facies analysis show a waning succession of gravel channel lags, unit-bar and dune deposits in A1; a basal mud-clast channel lag, unit-bars and dune deposits in A2, and a coarse-grained point-bar succession in A3. Flow simulation shows: a) fingering of the waterfront related to the gravel channel lag and unit-bars of A1 and A2, and the gravel bars, scour-and-fill deposits and dunes of A3, which act as thief zones hindering efficient sweeping of the intervals immediately above; b) segregation of the injected fluids towards the base of the channel belts due to the fining-upwards successions; and c) vertical compartmentalization due to a relatively impermeable barrier at mud-clast channel lag beds. Permeability contrasts trapped 35% of the original oil in place after 0.5–0.6 pore volumes were injected.
Original language | English |
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Pages (from-to) | 661-680 |
Number of pages | 20 |
Journal | Marine and Petroleum Geology |
Volume | 103 |
Early online date | 16 Feb 2019 |
DOIs | |
Publication status | Published - 1 May 2019 |
Bibliographical note
Thanks, are given to Schlumberger for the donation of the Petrel E&P licenses, to the Virtual Outcrop Geology Group for the donation of LIME licenses, to Petroleum Experts for the donation of MOVE licenses, to Innovmetric for the donation of the Polyworks license and to Agisoft for the donation of the Agisoft Photoscan license. Magda Chmielewska is acknowledged for the technical support during the virtual outcrop processing. Support from the Ministerio de Economía y Competitividad (Project SEROS CGL2014-55900-P) and from the Generalitat de Catalunya (2017SGR596) is gratefully acknowledged. Thanks to reviewers Brian Willis and César Viseras and also to the Associate Editor Luca Colombera for their constructive comments, which have improved the content of this paper.Keywords
- Sandy braided river
- Coarse-grained point bar
- Sedimentary heterogeneity
- 3D geocellular models
- Flow simulation
- Thief zones
- Compartmentalization
- Original oil in place