Well logging course for fourth year Geophysics By

Well logging course for fourth year Geophysics By Dr. Adel Kamel Mohamed

The syllabus of Well Logging course Course Title: principles and application of well logs Objectives: 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 different types of wire line logs. Students should also know how to calculate the petrophysical parameters required formation evaluation (source and reservoir rocks). Course construction: Strategy: 12 lectures. General divisions Chapter 1 Introduction Chapter 2 Borehole Environment & Recording Formats of logs Chapter 3 Electrical Logs Chapter 4 Radioactive Logs Chapter 5 Acoustic Logs Chapter 6 Thermal Logs Chapter 7 Imaging logs Chapter 8 Quick Look Interpretation of Wire line Logs pplication of well logging in different fields (formation evaluation). References: Asquith, G. and Krygwski, D. (2004): Basic well log analysis” The American Association of Petroleum Geologists, Tulsa, Oklahoma. Rider, M. H. (1996): ”The geological interpretation of well logs” 2 nd edition, Blackie and Son Limited, London, UK. Schlumberger (1987): “Principles and application of well logs“ Schlumberger Ltd. , France. Web Site: www. brookes. ac. uk/geology/peg/short course www. chee. uh. edu/petroleum/PETR 6304

Items of lecture Historical overview on the well logging technique. - What is a “Log” - Types of boreholes and well logs. - Well logs; the necessity. - Logging companies. - Objectives 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 Trucks in the past

Types of boreholes § According to Casing operation - Cased holes - Open holes § According to conductivity of the borehole - Conductive (water base drilling mud) - Non-conductive boreholes (oil base mud, air drilled or cased holes)

Cased holes Open holes

Types of well logs Wireline logs (Electrical, Radioactive, Acoustic, mechanical, Thermal and Magnetic logs) Formation Testers (Repeated Formation Tester, Drill Stem Tests)

§ § the necessity - Well logs These measurements are necessary because geological sampling during drilling (cutting sampling) leaves a very imprecise record of the formations encountered. Entire formation samples can be brought to the surface by mechanical coring, but this is both slow and expensive. The results of coring, of course, are unequivocal. Logging is precise, but equivocal, in that it needs interpretation to bring a log to the level of geological or petrophysical experience. However, logs fill the gap between ‘cuttings’ and cores, with experience, calibration and computers, they can almost replace cores, as they certainly contain enough information.

Some Logging Companies § Schlumberger § § § Gearhart Dresser Atlas Welex Haliburton Others

Objectives of wire line logging 1 -Lithology identification 2 -Determination of reservoir characteristics (e. g. porosity, saturation, permeability). 3 -Discrimination between source and non source rocks 4 -Identification the fluid type in the pore space of reservoir rock ( gas, oil, water) 5 -Identification of productive zones. 6 -Determination the depth and thickness of productive zones. 7 -Locating reservoir fluid contacts. 8 -Well to well correlation for determining the lateral extension of subsurface geologic cross sections. 9 -Determination formation dip and hole angle and size.

Principal uses of open hole wireline logs