Well logging course for fourth year

Geophysics

By Dr. Adel Kamel Mohamed

The syllabus of Well Logging courseThe syllabus of Well Logging courseCourse TitleCourse Title:: principles and application of well logs principles and application of well logsObjectives:Objectives: At the end of this course, the students should be able to understand the basics of At the end of this course, the students should be able to understand the basics of

borehole geophysics, theory of measurements, interpretations and applications of the borehole geophysics, theory of measurements, interpretations and applications of the different types of wire line logs. Students should also know how to calculate the different types of wire line logs. Students should also know how to calculate the petrophysical parameters required for formation evaluation (source and reservoir rocks).petrophysical parameters required for formation evaluation (source and reservoir rocks).

Course constructionCourse construction::StrategyStrategy: 12 lectures: 12 lectures . .

General divisionsGeneral divisionsChapter 1 IntroductionChapter 1 IntroductionChapter 2 Borehole Environment & Recording Formats of logsChapter 2 Borehole Environment & Recording Formats of logsChapter 3 Electrical Logs Chapter 3 Electrical Logs Chapter 4 Radioactive Logs Chapter 4 Radioactive Logs Chapter 5 Acoustic LogsChapter 5 Acoustic LogsChapter 6 Thermal Logs Chapter 6 Thermal Logs Chapter 7 Imaging logs Chapter 7 Imaging logs Chapter 8 Quick Look Interpretation of Wire line LogsChapter 8 Quick Look Interpretation of Wire line Logs

Chapter 9 Application of well logging in different fields (formation evaluation)Chapter 9 Application of well logging in different fields (formation evaluation) . . ReferencesReferences::

Asquith, G. and Krygwski, D. (2004): Basic well log analysis” The American Association of Asquith, G. and Krygwski, D. (2004): Basic well log analysis” The American Association of Petroleum Geologists, Tulsa, OklahomaPetroleum Geologists, Tulsa, Oklahoma . .

Rider, M.H. (1996):”The geological interpretation of well logs” 2nd edition, Blackie and Son Rider, M.H. (1996):”The geological interpretation of well logs” 2nd edition, Blackie and Son Limited, London, UKLimited, London, UK..Schlumberger (1987): “Principles and application of well logs“ Schlumberger Ltd., FranceSchlumberger (1987): “Principles and application of well logs“ Schlumberger Ltd., France..Web Site:Web Site: www.brookes.ac.uk/geology/peg/short course www.brookes.ac.uk/geology/peg/short course

www.chee.uh.edu/petroleum/PETR6304www.chee.uh.edu/petroleum/PETR6304

Items of lectureItems of lecture Historical overview on the well logging technique.Historical overview on the well logging technique.- What is a “Log”What is a “Log”- Types of boreholes and well logs.Types of boreholes and well logs.- Well logs; the necessity.Well logs; the necessity.- Logging companies.Logging companies.- Objectives of wire line logs.Objectives of wire line logs.- Principal uses of wire line logs.Principal uses of wire line logs.

Figure shown represents the first well

logging record by Henri Doll in 1927

Schlumberger Logging Schlumberger Logging Trucks in the pastTrucks in the past

Types of boreholesTypes of boreholes According to Casing operationAccording to Casing operation - Cased holes- Cased holes - Open holes- Open holes According to conductivity of the boreholeAccording to conductivity of the borehole - Conductive (water base drilling mud)- Conductive (water base drilling mud) - Non-conductive boreholes (oil base mud, air - Non-conductive boreholes (oil base mud, air

drilled or cased holes)drilled or cased holes)

Cased holes Open holesCased holes Open holes

Types of well logsTypes of well logs

Wireline logs Wireline logs (Electrical, Radioactive, Acoustic, (Electrical, Radioactive, Acoustic,

mechanical, Thermal and Magnetic logs)mechanical, Thermal and Magnetic logs)

Formation TestersFormation Testers (Repeated Formation Tester, Drill Stem (Repeated Formation Tester, Drill Stem

Tests)Tests)

Well logsWell logs- - the necessitythe necessity These measurements are necessary because These measurements are necessary because

geological sampling during drilling (cutting geological sampling during drilling (cutting sampling) leaves a very imprecise record of the sampling) leaves a very imprecise record of the formations encountered. formations encountered.

Entire formation samples can be brought to the Entire formation samples can be brought to the surface by mechanical coring, but this is both surface by mechanical coring, but this is both slow and expensive.slow and expensive.

The results of coring, of course, are unequivocal. The results of coring, of course, are unequivocal. Logging is precise, but equivocal, in that it needs Logging is precise, but equivocal, in that it needs interpretation to bring a log to the level of interpretation to bring a log to the level of geological or petrophysical experience. geological or petrophysical experience.

However, logs fill the gap between ‘cuttings’ and However, logs fill the gap between ‘cuttings’ and cores, with experience, calibration and cores, with experience, calibration and computers, they can almost replace cores, as they computers, they can almost replace cores, as they certainly contain enough information.certainly contain enough information.

Some Logging CompaniesSome Logging Companies SchlumbergerSchlumberger GearhartGearhart Dresser AtlasDresser Atlas WelexWelex HaliburtonHaliburton Others Others

Objectives of wire line loggingObjectives of wire line logging1-Lithology identification1-Lithology identification2-Determination of reservoir characteristics (e.g. 2-Determination of reservoir characteristics (e.g.

porosity, saturation, permeability).porosity, saturation, permeability).3-Discrimination between source and non source rocks 3-Discrimination between source and non source rocks 4-Identification the fluid type in the pore space of 4-Identification the fluid type in the pore space of

reservoir rock ( gas, oil, water)reservoir rock ( gas, oil, water)5-Identification of productive zones.5-Identification of productive zones.6-Determination the depth and thickness of productive 6-Determination the depth and thickness of productive

zones.zones.7-Locating reservoir fluid contacts.7-Locating reservoir fluid contacts.8-Well to well correlation for determining the lateral 8-Well to well correlation for determining the lateral

extension of subsurface geologic cross sections.extension of subsurface geologic cross sections.9-Determination formation dip and hole angle and size.9-Determination formation dip and hole angle and size.

Principal uses of open hole wireline logsPrincipal uses of open hole wireline logs