Types of logs

Over time, many different types of logs have been developed to collect data about wellbores and subsurface formations. This article provides an overview of how various log types correspond to reservoir characteristics. It also provides links to articles discussing the various types of logs and selected applications in depth.

Relating log types and reservoir characteristics

Fig. 1 summarizes a number of specialized logging methods and how they relate to reservoir characteristics and the techniques for measuring them.

Fig.1 – This chart is separated into three concentric areas: the middle annular area indicates the subsurface properties to be evaluated, the innermost area indicates the specialized logging tools discussed here, and the outermost area indicates the logging tools discussed in other subchapters of this Handbook. The corresponding innermost and outermost areas show how the different tools complement each other in the investigation of particular subsurface properties.

Types of logs

·         Resistivity and spontaneous (SP) logging

·         Electrode resistivity devices

·         Induction logging

·         Microresistivity logs

·         Spontaneous (SP) log

·         Acoustic logging

·         Cement bond logs

·         Nuclear logging

·         Gamma ray logs

·         Spectral gamma ray logs

·         Density logging

·         Neutron porosity logs

·         Pulsed neutron lifetime logs

·         Carbon oxygen logs

·         Geochemical logs

·         Nuclear magnetic resonance (NMR) logging

·         Mud logging

·         Sonic logging

·         Specialty logs

·         Openhole caliper logs

·         Casing collar locator

·         Casing inspection logs

·         Borehole imaging

·         Borehole gravimetry

·         Downhole magnetic surveys

·         Production logging

·         Temperature logging

·         Radioactive tracer logging

·         Noise logging

·         Fluid capacitance logging

·         Focused gamma ray density logging

·         Unfocused gamma ray density logging

·         Diverting spinner flowmeter

·         Continuous and fullbore spinner flowmeters