Geology _ Geophysics in Oil Exploration

The log is commonly referred to as the photo electric

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Unformatted text preview: loration Well Logging: History: • 1912 Conrad Schlumberger gave 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 • In 1929 the electrical resistivity logs are introduce on commercial scale in Venezuela, USA and Russia. • The photographic – film recorder was developed in 1936 the curves were SN, LN AND LAT. • The dip meter log was developed in 1930. • The Gamma Ray and Neutron Log were begun in 1941. Well logging: It is also known as borehole logging is the practice of making a detailed record (a well log) of the geologic formations penetrated by a borehole. The log may be based either on visual inspection of samples brought to the surface (geological logs) or on physical measurements made by instruments lowered into the borehole (geophysical logs). An interpretation of these measurements is then made to locate and quantify potential depth zones containing oil and gas (hydrocarbons). Logging tools developed over years to measure the electrical, acoustic, radioactive, electromagnetic, and other properties of the rocks and their contained fluids. It is called also wireline logging due to the wireline cable which carries at its end the instruments & lower it into the well. The measured well log consists of: • LOG HEADER: includes all information about the well logged and information necessary to describe the environment the measurement has been informed in (e.g. drilling mud parameters). Tool sketches and remarks informing about specific events during the logging operation complete the header. • MAIN LOG: main display of measurement performed. • LOG TRAILER: includes tool/computation parameter table and calibration records. Wireline cables consist mainly of two layers: • Outer Wire rope: to provide strength to cable to carry the in...
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