Well Log Techniques

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Exploration Technique: Well Log Techniques

Exploration Technique Information
Exploration Group: Downhole Techniques
Exploration Sub Group: Well Log Techniques
Parent Exploration Technique: Downhole Techniques
Information Provided by Technique
Lithology: depth and thickness of formations; lithology and porosity can be inferred
Stratigraphic/Structural: reservoir thickness, reservoir geometry, borehole geometry
Hydrological: permeability and fluid composition can be inferred
Thermal: direct temperature measurements; thermal conductivity and heat capacity
Well Log Techniques:
Well logging is the measurement of formation properties versus depth in a borehole.
Other definitions:Wikipedia Reegle

Well logging, also known as wireline logging, is a method of data collection in the borehole environment which enables the determination of subsurface physical properties and reservoir parameters. Measurements are collected versus depth along a well and there are many different types of wireline tools depending on the physical property of interest. In general, well logs respond to variations in rock matrix and pore fluid composition.

Well logs are acknowledged as legal documents which record the history of a well through the drilling stages and up to its completion. The well logs record physical properties of the borehole which must then be petrophysically interpreted to obtain the associated rock and fluid properties of the well.[1]

The standard well logs are the temperature log, the caliper log, and the resistivity log.[2]
Use in Geothermal Exploration
Well logging supports geothermal resource development in the exploration, assessment and exploitation phases of a well.[3]

Example of lithology and geophysical logs from a high-temperature well in Iceland.[2]

Potential Pitfalls
For geothermal well logging, the temperature capabilities of the downhole instruments can be a limiting factor in their application. Geothermal well conditions may require tools rated to 260 degrees Celsius (500 degrees Fahrenheit) or greater.[1]

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