Method predicts frae gradient for abnormally pressured formations

Journal Article · Wed Jan 01 00:00:00 EST 1986 · Pet. Eng. Int.; (United States)

OSTI ID:5847939

Constant, W D; Bourgoyne, A T

When drilling offshore wells with abnormally pressured zones, the prediction of fracture pressure gradients is essential from both an economic and safety standpoint. In wildcat areas, high reliance must be placed on fracture gradient correlations. The following method, an extension of Eaton's approach, fits stress ratio to depth exponentially and calculates variable overburden stress with depth, based on the exponential trend of average porosity from bulk density logging methods. The Poisson's ratio trend, taken from Eaton's data, may not be the same for all geographical areas, but field data can be fitted by the same method. Then, for a given well or area, plots can be made for rapid prediction of fracture pressure gradients. The working equations, and the Basic computer program which employs them, allows calculation of fracture pressure gradients for a given area, with pore pressure, sediment depth, air gap, and water depth being the only variables. The technique is ideally suited for implementation in the field.

• Research Organization: Louisiana State Univ., Baton Rouge, LA
• OSTI ID: 5847939
• Journal Information: Pet. Eng. Int.; (United States), Vol. 58:1
• Country of Publication: United States
• Language: English

Related Subjects

02 PETROLEUM
42 ENGINEERING
OFFSHORE DRILLING
FRACTURE MECHANICS
GEOPRESSURE ANOMALIES
PRESSURE GRADIENTS
OIL WELLS
BASIC
COMPUTER CALCULATIONS
DEPTH
ECONOMICS
EQUATIONS
GAMMA-GAMMA LOGGING
GRAPHS
POISSON RATIO
POROSITY
PROGRAMMING
SAFETY
STRESS ANALYSIS
DIMENSIONS
DRILLING
MECHANICAL PROPERTIES
MECHANICS
PROGRAMMING LANGUAGES
RADIOACTIVITY LOGGING
WELL LOGGING
WELLS
020300* - Petroleum- Drilling & Production
423000 - Engineering- Marine Engineering- (1980-)