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Reservorios con sobrepresión en la Formación Mina del Carmen. Identificación y delimitación de la anomalía como soporte para la extensión del desarrollo - Cuenca del Golfo San Jorge, Argentina

By: Language: Español Publication details: 2018Description: 24 p. ; 1-25Subject(s): DDC classification:
  • 068.82 553.28 C62 2018 0015650
Online resources: In: Summary: When basins are filled by sediments the fluid pore pressure increases following the hydrostatic gradient. Compaction reduces pore size while water leaks through surface. Positive or negative deviations from hydrostatic pressure gradient are considered anomalous pressure behavior. Once water leakage processes finish due to sedimentation rate, the fluid retention depth is reached. From here to lower stratigraphic units, pore pressure should increase in a closely parallel trend to the lithostatic pressures gradient.Regional stress variation and poral fluid volume change are some of the variables which define an overpressure situation. However, when specific data is scare, the recognition of the normal gradient (to be used as reference) and the acknowledgement of the unique features of each field, are keys to first identify an overpressure scenario. Based on open-hole reservoir pressure measurements, a reservoir fluid pressure anomaly behavior was identified in northern El Huemul field. This anomaly is evidenced by a break between two different pressure gradients. Shallower stratigraphic intervals are characterized by an hydrostatic gradient while deeper formations present a sharp deviation toward an overpressure situation. This break was initially identified around Mina del Carmen Formation (MDC) top (eastern part of the field). Toward Western blocks, where MDC top deepens slightly, the intersection between the two-pressure gradients deepens as well, though it does so more abruptly. Most of the oil bearing reservoirs are restricted to MDC. Hydrocarbon is characterized by 35-43°API oil range with no biodegradation fingerprints (highly mature source rock). These features allow to place hydrocarbon expulsion, migration and trapping during late stages of the basin silting, when sedimentary units and fault system framework had likely reached their current configuration. The block architecture is characterized by a normal fault system running in W-E direction. The main structure normally does not affect the complete stratigraphic column, but only the upper section of MDC. At the same time, it is remarkable that the break between the two pressure gradients is regularly accompanying the upper tip of the faults. Static or dynamic equilibrium pressure states could explain the current pressure situation of the field. Absence of source rock real pressure data or other significative variables, hinder the chances to define the most likely scenario. Nevertheless, the identified spatial association of MDC Fm., faults termination and the presence of oil and gas bearing, over-pressurized reservoirs, empirically allows to reduce risks when new well locations are defined in the block
Item type: Congresos (trabajos presentados) List(s) this item appears in: Conexplo 2018
Holdings
Current library Call number Status Barcode
IAPG-Colección 068.82 553.28 C62 2018 0015650 (Browse shelf(Opens below)) Not for loan 200065056

When basins are filled by sediments the fluid pore pressure increases following the hydrostatic gradient. Compaction reduces pore size while water leaks through surface. Positive or negative deviations from hydrostatic pressure gradient are considered anomalous pressure behavior. Once water leakage processes finish due to sedimentation rate, the fluid retention depth is reached. From here to lower stratigraphic units, pore pressure should increase in a closely parallel trend to the lithostatic pressures gradient.Regional stress variation and poral fluid volume change are some of the variables which define an overpressure situation. However, when specific data is scare, the recognition of the normal gradient (to be used as reference) and the acknowledgement of the unique features of each field, are keys to first identify an overpressure scenario. Based on open-hole reservoir pressure measurements, a reservoir fluid pressure anomaly behavior was identified in northern El Huemul field. This anomaly is evidenced by a break between two different pressure gradients. Shallower stratigraphic intervals are characterized by an hydrostatic gradient while deeper formations present a sharp deviation toward an overpressure situation. This break was initially identified around Mina del Carmen Formation (MDC) top (eastern part of the field). Toward Western blocks, where MDC top deepens slightly, the intersection between the two-pressure gradients deepens as well, though it does so more abruptly. Most of the oil bearing reservoirs are restricted to MDC. Hydrocarbon is characterized by 35-43°API oil range with no biodegradation fingerprints (highly mature source rock). These features allow to place hydrocarbon expulsion, migration and trapping during late stages of the basin silting, when sedimentary units and fault system framework had likely reached their current configuration. The block architecture is characterized by a normal fault system running in W-E direction. The main structure normally does not affect the complete stratigraphic column, but only the upper section of MDC. At the same time, it is remarkable that the break between the two pressure gradients is regularly accompanying the upper tip of the faults. Static or dynamic equilibrium pressure states could explain the current pressure situation of the field. Absence of source rock real pressure data or other significative variables, hinder the chances to define the most likely scenario. Nevertheless, the identified spatial association of MDC Fm., faults termination and the presence of oil and gas bearing, over-pressurized reservoirs, empirically allows to reduce risks when new well locations are defined in the block



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