ch5 - form pressures (1)
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dTRANSCRIPT
Ch. 5 Pore Pressures and Fracture Pressures
Terminology - Formation Pore Pressures
• Pore Pressure• P-Z Diagrams• Pore Pressure Gradient• Overbalance• Underbalance• Normal Pressure Gradient• Abnormal Pressures
Pore Pressure Profiles
Overbalance
Typical Pressures
Normal Pressures
Overpressure
Underpressure
Importance of Pore Pressures
• Underbalance• Borehole Collapse
• Influx
• Overbalance• Low ROP
• Formation Fracture
• Differential Sticking
Origin of Overpressure• Overpressure
• Incomplete Sediment Compaction
• Faulting
• Phase Changes
• Massive Rocksalt Deposition
• Salt Diaperism
• Tectonic Compression
• Repressuring
• Hydrocarbon Generation
Origin of Subnormal Pressures
• Sub normal Pressure• Thermal Expansion
• Formation Foreshortening
• Depletion
• Precipitation
• Potentiometric Surface
• Epeirogenic Movements
Uncompacted Sands
Formation Foreshortening
Piezometric Surface
Acquifers
Pore Pressures
Abnormally Pressured Sands
Transition Zone
• Shale Caprock
• Salt Caprock
Transition Zones
Formation Fracture Pressure
• Mechanism of Breakdown• Leak-off Test/Limit Test
• Procedure
• Maximum Mudweight
• Maximum ECD• MAASP
• Calculating Fracture Pressure
Fracture Pressure
Leak Off Test
Fracture Test
Leak Off Test
Limit Test
Mechanism of Breakdown
Leak Off Test
Regional Faulting
Poissons Ratio
HPHTWells