Seals, Reservoirs And Prospect Assessments For E&P

INSTRUCTOR: Selim Shaker, PhD
DISCIPLINE: Geoscience, Engineering
CEUS: 2.4


WHO SHOULD ATTEND: Geologists, geophysicists, drilling and reservoir engineers, well log analysts, managers, and support staff involved in exploration, development and drilling.

COURSE DESCRIPTION: The optimum trap is a reservoir capable of confining and economically delivering hydrocarbon under a competent sealed cap and /or faulted structural closure. Sealing competence is essential for trapping, migration, lateral and vertical distribution of hydrocarbons in a prospective reservoir. The sealing capacity also impacts reservoir flow rate and the driving mechanism of the natural flow, and the secondary recovery process. Subsurface geopressure compartmentalization plays an essential role in determining seals and reservoir characteristics.

This course demonstrates how to use measured pressure data from wire-line tests (MDTs, RFTs etc.) and production tests (DST’s) to design pressure-depth plots which reveal permeability barriers (sealed), communications, and breached reservoir (seal failure).
It will also examine how seismic velocities (RMS) and well logs’ petrophysical properties establish the predicted pore pressure in the seals. Moreover, participants will gain the fundamental knowledge of predicting pore-fracture pressure and the drilling tolerance window that leads to successful drilling prognosis to the targeted formation.

Hands-on experience will be provided by several class projects. Analog and digital data (Excel software) will be utilized to assess and evaluate prospect risk. Participants will make an analytical scheme for the development phase of the whole prospect. Before drilling risk assessment and post drilling appraisal methods will be clarified and how to salvage a prospect with a dry hole wildcat will be discussed.


  • Understand the causes, concepts and graphic representations of vertical and horizontal compartmentalization due to reservoirs partitioned by seals.
  • Comprehend pressure gradient in seals versus reservoirs and the causes of disparity between measured and predicted values.
  • Recognize sealed vs. breached reservoirs.
  • Calculate hydrocarbon column in four way vs. three way faulted closures.
  • Evaluate and assess the risk of a prospect pre and post drilling.



  • Subsurface Compartmentalization:
    • Vertical and lateral subsurface compartments
    • Pressure gradient behavior in seals vs. reservoirs
    • Causes of pressure transgression and regression across seals
  • Reservoirs:
    • Direct and pertinent measurements of pore pressure
    • QC, calibrate and validate measured data for analysis
    • Graphic representations (PSI and PPG MWE), including some of their pitfalls
    • Calculate fluids and gas densities(types ) and the water-hydrocarbon contacts
    • Predict driving mechanisms type (water or depletion drive)
    • Estimate hydraulic head for production forecast (natural and secondary)
    • Monitor reservoir pressure (BHP) for production forecast and recharge
  • Cap Seals (four ways)
    • Lithology, age and pressure decay
    • Seismic velocity – Well logs and calibration of prediction model
    • Sealing capacity vs. hydrocarbon retention capacity calculations.
  • Fault Seals. (Faulted three ways)
    • Fault types: their rock mechanics and pressure yield
    • Cross fault beds-juxtaposition, fault geometry and hydrocarbon spills
    • Capillary pressure vs. excess pressure across faults
    • Shale smear potential seal: calculations and uncertainty
    • Counter- regional dip and fault seal
    • Pulsed sealed fault leakage
  • Prospect Evaluation
    • Pre drilling
      • Strat-Geopressure Fairways
      • Predict sealing capacity from seismic and offset wells
      • Velocity vs. AVO, AVG
    • Post drilling
      • Appraise success and /or failure
      • Define hydrocarbon, type, thickness, lateral extension and down-dip limits
      • Calculate excess pressure, communication and reservoir permeability
      • Identify bypass pay zone
      • QC and assess assessments of pre-drill DHI, AVO, low resistivity pay
      • Identify additional sealed structural closures in the same prospect for future E & P.