Well logging The Bore Hole

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Slide 1

WELL LOG (The Bore Hole Image)

What is well Logging

Well log is a continuous record of measurement made in bore hole respond to variation in some physical properties of rocks through which the bore hole is drilled.

Traditionally Logs are display on girded papers shown in figure.

Now a days the log may be taken as films, images, and in digital format.

Slide 2

History

1912 Conrad Schlumberger give the idea of using electrical measurements to map subsurface rock bodies.

in 1919 Conrad Schlumberger and his brother Marcel begin work on well logs.

The first electrical resistivity well log was taken in France, in 1927.

The instrument which was use for this purpose is called SONDE, the sond was stopped at periodic intervals in bore hole and the and resistivity was plotted on graph paper.

In 1929 the electrical resistivity logs are introduce on commercial scale in Venezuela, USA and Russia

For correlation and identification of Hydrocarbon bearing strata.

The photographic – film recorder was developed in 1936 the curves were SN,LN AND LAT

The dip meter log were developed in 1930

The Gamma Ray and Neutron Log were begin in 1941

Slide 3

Logging units

Logging service companies utilize a variety of logging units, depending on the location (onshore or offshore) and requirements of the logging run. Each unit will contain the following components:

logging cable

winch to raise and lower the cable in the well

self-contained 120-volt AC generator

set of surface control panels

set of downhole tools (sondes and cartridges)

digital recording system

Slide 4

Work Flow Chart

Slide 5

Slide 6

depth to lithological boundaries

lithology identification

minerals grade/quality

inter-borehole correlation

structure mapping

dip determination

rock strength

in-situ stress orientation

fracture frequency

porosity

fluid salinity

Slide 7

Depth Of Investigation Of Logging Tools

Slide 8

Log interpretation objectives

The objective of log interpretation depends very much on the user. Quantitative analysis of well logs provides the analyst with values for a variety of primary parameters, such as: