Automatic determination of lithology from well logs

Journal Article · Tue Sep 01 04:00:00 EDT 1987 · SPE (Society of Petroleum Engineers) Format. Eval.; (United States)

DOI:https://doi.org/10.2118/13290-PA· OSTI ID:5992175

Delfiner, P C; Peyret, O; Serra, O

A procedure combining modern wireline measurements with a lithofacies data base has been developed to produce an automatic lithologic description of the formations crossed by a well. The database lithofacies are defined from petrographic knowledge and translated in terms of log responses. The assignment of depth levels to a lithofacies is done with the data base and with a discriminating function (Bayesian decision rule). External knowledge can be taken into account by use of artificial intelligence methods. A confidence factor is produced for each result. Logs currently in the data base are the density, neutron, sonic transit time, gamma ray, photoelectric cross section, and concentrations of thorium, potassium, and uranium. Major lithofacies groups represented in the data base include sandstones, limestones, dolomites, shales, coals, and evaporites. These are subdivided by introducing cement and special minerals and by considering porosity ranges. The construction of the data base is a critical step. It is largely empirical and requires careful calibration against intervals with well-known lithologies (e.g., from cores). The data base can be tuned to local conditions. The procedure has been tested in several environments and compared with cores and mud log descriptions. A detailed lithologic column can be produced at the wellsite and used in decision making. The results can also serve as input for further geologic studies of facies and sequences or for quantitative evaluation of formations.

• Research Organization: Etudes et Productions Schlumberger
• OSTI ID: 5992175
• Journal Information: SPE (Society of Petroleum Engineers) Format. Eval.; (United States), Journal Name: SPE (Society of Petroleum Engineers) Format. Eval.; (United States) Vol. 2:3; ISSN SFEVE
• Country of Publication: United States
• Language: English

Related Subjects

02 PETROLEUM
020200* -- Petroleum-- Reserves
Geology
& Exploration
03 NATURAL GAS
030200 -- Natural Gas-- Reserves
Geology
& Exploration
99 GENERAL AND MISCELLANEOUS
990210 -- Supercomputers-- (1987-1989)
ALKALINE EARTH METAL COMPOUNDS
ARTIFICIAL INTELLIGENCE
AUTOMATION
BUILDING MATERIALS
CALCIUM CARBONATES
CALCIUM COMPOUNDS
CARBON COMPOUNDS
CARBONACEOUS MATERIALS
CARBONATE MINERALS
CARBONATE ROCKS
CARBONATES
CEMENTS
COAL
DATA BASE MANAGEMENT
DENSITY
DOLOMITE
DRILL CORES
DRILLING FLUIDS
ELECTRIC LOGGING
ENERGY SOURCES
EVAPORITES
FLUIDS
FOSSIL FUELS
FUELS
GAMMA LOGGING
GEOLOGIC DEPOSITS
GEOPHYSICS
KNOWLEDGE BASE
LIMESTONE
LITHOLOGY
MAGNESIUM CARBONATES
MAGNESIUM COMPOUNDS
MANAGEMENT
MATERIALS
MINERAL RESOURCES
MINERALS
NATURAL GAS DEPOSITS
NEUTRON LOGGING
OXYGEN COMPOUNDS
PETROGRAPHY
PETROLEUM DEPOSITS
PHYSICAL PROPERTIES
POROSITY
RADIOACTIVITY LOGGING
RESERVOIR ROCK
RESOURCES
ROCKS
SANDSTONES
SEDIMENTARY ROCKS
SHALES
SONIC LOGGING
WELL LOGGING