What Is Well Logging?

Logging, also called geophysical logging, is a method of measuring geophysical parameters by using geophysical characteristics such as electrochemical characteristics, electrical conductivity characteristics, acoustic characteristics, and radioactivity of rock formations, and belongs to one of the applied geophysical methods. ^{[1] In} oil drilling, logging must be performed after drilling to the designed well depth, also known as completion electrical survey, to obtain various petroleum geological and engineering technical data, as raw data for completion and development of oil fields Logging is conventionally called open-hole logging. The second series of logging performed after casing in an oil well is conventionally called production logging or development logging. The development of production logging has generally experienced analog logging, digital logging, CNC logging, imaging Four stages of logging.

According to the geological and geophysical conditions, the comprehensive logging method can be selected reasonably, and the drilling can be studied in detail.

There are many logging methods. Electricity, sound, and radioactivity are the three basic methods. Special methods include

Summary of the main applications of logging

1) Use geophysical logging information for stratigraphic sequence division and calibration.

2) Use the logging data to study the fine geological structure and faults of oil and gas reservoirs.

3) Guided by the basic theory of tectonic geology, through the analysis of tectonic stress, make full use of well logging information to carry out quantitative research on fractured reservoir zones, and understand the development and distribution rules of fractures.

4) Research on geophysical logging and sedimentology, integrating other geological data, analyzing sedimentary microfacies, and establishing the sedimentary environment and paleocurrent direction.

Utilization of logging mineral resources

Geophysical logging is a method and basis for solving problems related to mineral resource geology, engineering geology, disaster geology, and ecological environment. It is a conditional and indirect reflection of the actual geological conditions in the well. Logging information must be further processed and converted into geology Information, engineering information, disaster geology, ecological environment and other information can achieve the purpose of understanding and solving problems.

1) Use geophysical logging information to interpret and evaluate oil, gas, and water layers, and calculate the porosity, permeability, and oil (gas) saturation of oil-bearing rock series.

2) Use logging information to postgraduate the reservoir, caprock, and oil and gas production, storage, and capping combinations.

3) Use logging information to study oil reserve parameters, underground fluid properties, and distribution.

Other applications of logging

Logging can also be used for quantitative analysis of modern in-situ stress fields, predicting and monitoring formation pressure and fracture pressure, and providing a basis for the rational development of oil and gas and scientific drilling. Geophysical logging is a technological discipline that is still rapidly developing. With the increasing difficulty in the development of mineral resources such as oil and gas and the rapid development of science and technology, new logging theories, new methods, and new technologies are constantly emerging and developing. ^[2]