Pore Pressure Prediction

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Well Planning and Drilling Hazards

Seismic Pore Pressure Prediction (PPP) provides volumetric estimates of pore pressure across reservoirs, fields and even at the basin scale. These can be used by geologists and reservoir engineers to improve understanding of hydrocarbon basins, identify potential drilling hazards and improve well positioning.

CGG combines expertise in high-resolution seismic velocities, petrophysical modelling and well data integration to deliver a range of seismic pore pressure services.

Seismic Interval Velocity

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Predicted Overpressure

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Pore Pressure Prediction (PPP) for a proposed well in the Central North Sea.
High-Pressure High-Temperature area.

The base chalk (marked with a white arrow) acts as a seal creating substantial overpressure in the reservoirs below. Accurate, high-resolution velocities from dense, automated picking are used as the basis for the prediction.

A lithology-dependent normal compaction trend has been used to improve the accuracy of the predicted pressures within and below the chalk. The resulting well prognosis indicates that the well trajectory avoids hazardous, highly over-pressured zones.

Features

Pore Pressure
Highlight from a basin-scale pore pressure study offshore Nigeria, showing a pressure contrast across a sealing fault (1).

The reservoir (2) sits above over-pressured shales (3) in a transitional interval containing some higher pressure layers.
  • High-resolution seismic velocities
  • Integrated workflow from seismic to petrophysics
  • Rigorous calibration of velocities and rock physics model with well data
  • Spatially varying and lithology-dependent rock physics model

Benefits

Well calibrated field-scale pore pressure volumes for:

  • Development well planning
  • Calculation of safe mud-weight window
  • Drilling hazard prediction

Basin-scale pore pressure volumes for:

  • Improved exploration well positioning
  • Source maturation modelling
  • Seal recognition and hydrocarbon migration modelling

Basin-Scale Prediction Enhances Exploration

Pore pressure prediction can also be performed across large areas and used as a more qualitative exploration tool at a basin scale. These large volumes provide an overview of pressure and fluid behaviour within the basin and can be used to identify important features, such as the behaviour of faults (see example). In this context pore-pressure prediction becomes a tool for geologists and can help in understanding regional basin dynamics and the identification and de-risking of new prospects.

PPP01Figure: Pore pressure prediction using seismic interval velocity calibrated to well log data and pressure tests (GoM example).

PPP02Figure: Comparison of deep water pore pressure estimation based on analysis of composite data from multiple wells and dense seismic velocity field (GoM example).

Although pore pressure analysis is best known for the role it plays in prediction of geo-hazards and regulatory compliance, it is also important in the role of calibrating seismic-based stress analysis from azimuthal seismic, especially in resource plays. Pore pressure analysis from conventional well logs provides two of the three principal stresses, vertical stress and minimum horizontal stress. When calibrated to well tests and core data, pore pressure analysis can also provide the ratio of minimum-to-maximum horizontal stress, leading to both estimates maximum horizontal stress, closure pressure, and fracture gradients. CGG works with the Baker-Hughes Alliance to provide outstanding pore pressure prediction in shale plays.

PPP03Figure: Typical elements of stress analysis from azimuthal seismic.  Pore pressure estimation plays a critical role in this work.


GeoConsulting - Reservoir Characterization

Integrated Reservoir Characterization

Geophysicics, petrophysicists, geologists and engineers: a unique breadth of experience and capabilities.

GeoConsulting - Reservoir Petrophysics

Reservoir Petrophysics

We link elastic and petrophysics properties to extract more value from seismic volumes.

GeoConsulting - Shale Science

Shale Science

Take a scientific approach to shales. Our team predicts the most promising zones and optimizes development, drilling and completion programs.
GeoConsulting - Geophysical Services (SRC)

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