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Improved Reservoir Characterization of Señal Picada Field, Neuquén Basin, SW Argentina: Assessing the EOR Potential of a Mixed Carbonate/Siliciclastic System

Gomez Rivarola, Laura1; Mykietiuk, Karina; Bernhardt, Carolina; Mendoza, Marcos; Borghi, Pablo; Garcia Briceño, Maria Eugenia; Manestar, Gaston; and Thompson, Anthony
1[email protected]

Señal Picada is located in the northeastern margin of the Neuquen Foreland Basin, SW Argentina. The field was discovered in 1965 with 474 wells drilled to date (263 active producers & 93 inyectors). So far 22 Mm3 of oil have been produced. Since 1983 it has been producing by secondary recovery and water cut is currently 96%.

Oil production comes from Loma Montosa Fm (Valanginian) which is a 250 meter-thick carbonate/silicicastic unit. Four intermediate scale accommodation cycles were recognized from core interpretation forming an overall regressive/transgressive trend. The building blocks of these main cycles are ten smaller scale cycles. Basal cycles are characterized as mainly regressive, with dominant bioclastic packstones/grainstones. Upper cycles consist of interbedded siliciclastic and carbonatic beds. Transgresive cycles are characterized by oolitic grainstones, whereas cross to flat-bedded arkosic sands dominate the regressive cycles.

These defined cycle hierarchies were used to build the correlation framework for the static model. The lateral and vertical distribution of the interpreted lithofacies was captured by stochastic facies modelling. Petrophysical properties were populated within the stratigraphic cyclicity.

To characterize such a large reservoir within a reasonable time frame, it was decided to study a sector of the field in the vicinity of an excellent quality core that has recently been acquired. By focusing on a sector, iterations and run times were far more rapid. From this sector model it was possible to identify a number of key issues,

  • The productive intervals are stratified and not in vertical connectivity with each other.
  • The sharp boundaries seen in core between reservoir and non reservoir rock were not initially replicated in the static model due to the lower resolution of well logs, affecting the determination of water saturation.
  • Within the correlation of the productive sands non reservoir facies needed to be modeled explicitly to explain dynamic behaviour.

    With these learnings, it was possible to build a robust full field static model while simultaneously fine tuning the history match of the sector model.

    A number of incremental primary and secondary opportunities were identified. However by far the largest potential lies in the clean productive sand intervals with low clay content which as a result of this study, were identified as being continuous and hence having strong EOR potential.

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