Prediction of fracture gradients from log derived elastic moduli

Journal Article · Fri Sep 01 00:00:00 EDT 1972 · Log Anal.; (United States)

OSTI ID:6048975

MacPherson, L A; Berry, L N

Thirty-five measured fracture gradients in 10 fields are included in this study. The procedure utilizes all plugback operations from open hole, both into surface pipe and production strings or liners. Sonic and density logs have been obtained where possible from wells in the fields with measured breakdown gradients. Unfortunately, offshore logistics, risks, costs, and particularly hole conditions in highly deviated, geopressure penetrations often preclude obtaining desired porosity logs. Values for M calculated from logs should be related to tensile strength, elasticity and possibly the stress configuration around the well bore. Elastic moduli circulated from logs have been compared with trends of measured fracture gradients in 10 offshore fields and a correlation is shown to exist. Measured fracture gradients in 11 offshore fields show differing trends of gradient with depth for each field. These empirically determined gradients appear to be related to sand-shale ratio, depth to geopressures, sediment age, and geographic distribution. Within each field, at equivalent depths, lower mud weights usually fracture at lower pressures. Based on limited data, breakdowns in geopressured intervals show only slight departures from normal pressure trends in the direction of increased fracture gradient with increase in geopressures.

• Research Organization: Shell Oil Co.
• OSTI ID: 6048975
• Journal Information: Log Anal.; (United States), Vol. 13:5
• Country of Publication: United States
• Language: English

Related Subjects

02 PETROLEUM
OIL WELLS
WELL LOGGING
PRESSURE GRADIENTS
FORECASTING
ELASTICITY
FRACTURING
GAMMA-GAMMA LOGGING
MATHEMATICS
MECHANICAL PROPERTIES
PETROLEUM
RADIOACTIVITY LOGGING
TESTING
COMMINUTION
ENERGY SOURCES
FOSSIL FUELS
FUELS
TENSILE PROPERTIES
WELLS
020300* - Petroleum- Drilling & Production