Geopressure and Prospect's Risk Assessment
by Selim Simon Shaker
Duration: Two days
Intended Audience: Geophysicists, geologists, petrophysicists, drilling and reservoir engineers, geopressure modelers, hydro-geologists, rock-mechanic scientists, geosciences technicians and almost all technical personnel in the oil patch. This course is designed for explorationists and technical personnel that are keen on appraisal in house and farm in/out prospects.
A viable prospect is contingent on hydrocarbon source, a reservoir that can contain and deliver, competent seal, and drillable well trajectory. These amalgamated aspects are chiefly a consequence of the subsurface geopressure vertical and lateral partitions. Moreover, successful drilling relies on accurate prediction of pore–fracture (PPP-FP) pressure within the drilling tolerance window and their safety limitations. Geophysics plays an essential function of appraising the prospect's risk.
Each participant will gain experience in the usage of the 2/3D seismic and petrophysical data to evaluate geopressure partitions and prospect's trapping integrity and reserve potentials. Moreover, they will learn to calculate seal effectiveness and predict pore pressure using Excel Work Sheets.
Throughout the two day course, the integrated petrophysical properties to the subsurface geological, rock mechanics and hydrodynamic models will be examined. Conceptual Models and simple algorithm are used for prediction calculations.
- Explain the integrated process of prospect generation.
- Demonstrate the four geopressure zones and their models.
- Discuss the measured pore (MPP) / fracture (FP) pressure tools, charts, and plots.
- Explain the difference between the effective stress models and their algorithms.
- Demonstrate simple Excel Sheets for the interpretation of pore and fracture pressure, seal effectiveness and hydrocarbon column height (no software).
Geophysical Data for PPP (Before Drilling):
- Select and QC seismic velocity.
- Design the transformation model based on stacking, RMS, Dix velocities and other petrophysical properties e.g. ΔT, R, ρ, VSP of offset wells.
- Distinguish velocity trends in normally, hydrodynamically and geopressured systems.
- Incorporate the offset well log data and measured PP (RFT's, MDT's).
- Calculate the pre-drilling mud weight and casing seats in bare dry hole vs. potential producer.
During and post drilling assessment:
- Calibrate the pre-drilling prediction seismic model with the real time data.
- Identify challenging intervals along the well bore trajectory.
- Appraise the success of finding hydrocarbon and lessons learned due to failure.
- Diagnose seal failure and reservoir breach on seismic displays during prospect generation.
- Recognize compartmentalization, transgression, regression and communication.
- Appraise potential reserves in four vs. faulted three way closures.
- Assess drilling challenges in deepwater.
- Recognize the supra and subsalt impact on the geopressure and trapping mechanism.
- Distinguish the PSDM blind zone due to shale – sand velocity crossing over and AVO assessment.
- Appraise the potential of the under explored and bypass pay zones in the untested structural segments in the prospect and play concept.
Worldwide case histories will be discussed. Exercises follow each segment of this course in form of Q&A.
Selim Simon Shaker