--> Abstract: Static and Dynamic Modelling of a Complex Alluvial-Fluvial Reservoir (Middle Jurassic Lotena Formation, Aguada Toledo Field, Neuquen Basin, Argentina), by Barros, Pablo; Giunta, David; Godino, Georgina; Loss, Laura; Martino, Luis; Morettini, Elena; Santana, Teresa; Serrano, German; Thompson, Anthony; and Massaferro, Jose Luis; #90166 (2013)

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Static and Dynamic Modelling of a Complex Alluvial-Fluvial Reservoir (Middle Jurassic Lotena Formation, Aguada Toledo Field, Neuquén Basin, Argentina)

Barros, Pablo; Giunta, David; Godino, Georgina; Loss, Laura; Martino, Luis; Morettini, Elena1; Santana, Teresa; Serrano, German; Thompson, Anthony; and Massaferro, Jose Luis
1[email protected]

The Aguada Toledo Field consists of a fault-bounded E-W anticline structure, producing oil (5MMbbls) from a mixed alluvial-fluvial system (Middle Jurassic Lotena Formation). In order to expand current waterflooding development to the northern sector of the field, an integrated reservoir model was built.

Seismic interpretation shows that four main tectonic phases have affected the structural evolution of the field: 1) Bajocian compression generating the E-W fault-bounded palaeo-high structure 2) Callovian tectonic inversion reactivating the main fault system through extensional growth faulting at the time of Lotena deposition; 3) Tithonian-Berriasian compression and uplift generating folding and truncation/erosion of Lotena at the centre of the field; 4) Tertiary compression resulting in the current Aguada Toldeo anticline structure.

Core analysis reveals the existence of four main accommodation cycles (C1-C4) deposited in an alluvial-fluvial environment. C1, C3 and C4 consist of fluvial sands fining upward into flood-plain shales interpreted as retrograding fluvial-dominated cycles associated to periods of tectonic quiescence. C2 consists of erosive alluvial conglomerates/coarse sands fining upward into over-bank finer sands interpreted as a prograding alluvial cycle associated to active tectonic pulses.

Based on this structural and stratigraphic framework, we generated a static model where proximal-distal facies arrangement, especially in the prograding C2, determined a deterioration of reservoir properties, moving away from the main active fault.

Dynamic modelling identified that pressure regimes between northern and southern sectors of simulated area were not in communication, confirming the existence of erosion and truncation across the structure, and of facies-associated reservoir property variations. The general degradation of reservoir properties to the north of the field was confirmed, and refinement of correlation at sub-cycle level required. Initial dynamic realizations proved to be overestimating reservoir net to gross due to log resolution issues. The modelling of cemented beds observed in core (cross-bedded fluvial facies), initially not captured in the static model, was critical to replicate reservoir behavior and decrease excessive reservoir volumes.

This case study shows the importance of integrated approaches and of static-dynamic iterations to identify areas of reservoir property variation impacting waterflood development.

 

AAPG Search and Discovery Article #90166©2013 AAPG International Conference & Exhibition, Cartagena, Colombia, 8-11 September 2013