Characterizing thin-bedded, low-N/G tough gas reservoirs through reservoir-analogue and core studies

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Characterising thin-bedded, low-N/G

tough gas reservoirs through

reservoir-analogue and core studies

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Outline

• Context and motivation

• Project aims

• Data acquisition

• Contemporary reservoir analogues

Río Colorado fluvial system, Altiplano Basin, Bolivia

• Outcrop reservoir analogues

Cajigár and Huesca fluvial systems, Ebro Basin, Spain

• Subsurface data

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Context and motivation

• Fine-grained sedimentary rock intervals discarded as non-permeable ‘waste zones’

• Thin-bedded, fine-grained sand bodies formed in continental (fluvial) depositional

environment

• Successions may contain ‘hidden treasures’, accessible at low investment costs

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Project aims

• Develop a thorough understanding of the depositional

processes and their associated boundary conditions in low-N/G fluvial intervals

• Link the reservoir architecture of the targeted fine-grained fluvial intervals to their expression in 1-D well penetrations

• Predict and quantify the reservoir potential of these deposits from subsurface data alone and develop high-resolution

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Contemporary reservoir analogue

Río Colorado fluvial system, Altiplano Basin, Bolivia • Altiplano Basin

• Cenozoic Basin with vulcanic, evaporitic and clastic infill • Semi-arid climate

• Fieldwork area

• 450km south of La Paz • Río Colorado fluvial system • Fringing the Salar de Uyuni

• Ongoing deposition (active system)

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Contemporary reservoir analogue

Río Colorado fluvial system, Altiplano Basin, Bolivia • Lower coastal plain • Meandering channels • Crevasse splays and terminal lobes

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• Acquired data

• Morphology and size • Laquer peels

• Sediment samples

Contemporary reservoir analogue

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Contemporary reservoir analogue

Parallel lamination

Climbing ripples

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Contemporary reservoir analogue

• ~ 3km burial • Mean GS: 11 - 27μm • Φ: 5 - 7% • k: 0.05 - 0.13mD • ~ 3km burial • Mean GS: 11 - 22μm • Φ: 5 - 7% • k: 0.04 - 0.12mD • Simulated burial

• Porosity: Kominz et al., 2011

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Outcrop reservoir analogue

• Cajigár fluvial system

• NAC12 poster presentation

Outcrop-analogue study for tough gas reservoir modelling: thin-bedded fluvial crevasse-splay sandstone, Cajigár Fm, NE Spain

Lisanne Bouman and Niels Noordijk

• Huesca fluvial system (Quicena)

• Upcoming fieldwork

Lithostratigraphical logs

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Subsurface data

• NLOG public data

• Well-logs • Seismics

• Petrophysical core plug analyses

• GdF & NAM

• Slabbed cores

• Early results

• Sub-log-scale sand/silt alternations

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Data integration and modelling

• Devise generic models of single- and stacked-lobe deposition

• Link lobe architecture and stacking to 1D expression in well penetrations

• Compose a ‘cookbook’ workflow for the upraisal of gas-bearing stacked crevasse-splay deposits in low N/G fluvial intervals from field data

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Laboratory work

Laser particle-size analysis

Removal of organic matter and carbonates

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Processing and analysis

Distribution of silt component grain size

• Grain size decreases from proximal and axial towards lobe edges

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Processing and analysis

Distribution of clay component

• Clay component increases in distal parts of lobe