From imperfect measurements of a few physical properties representing a tiny fraction of the reservoir, significant interpretations are made by geologists, engineers, and geophysicists. As the geophysicist begins to focus more on field delineation rather than broad exploration, it becomes even more important to understand the potential as well as limitations of borehole measurements.

Basic physical measurements in the borehole provide far more information than the usual reservoir parameters such as porosity, fluid type, and saturation. Log responses such as self potential, natural radioactivity, resistivity, acoustic travel time, and density also provide invaluable clues to lithology,

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depositional environment, and correlation. Wireline measurements together with direct measurements of the rock in the form of cuttings and cores must be understood by the geologist and geophysicist using them to achieve the proper confidence in their interpretation.

Examples of some of the limitations of borehole measurements illustrate a wide variety of problems that can occur. However, with understanding of these limitations, remarkably sound interpretation can be made.

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