Field Examples of Nuclear Magnetism Logging

Field examples are presented from various operating areas which demonstrate the capability of the nuclear magnetism log to operate under most drilling and formation conditions. On the basis of these examples, it is shown thatthe free fluid index of nuclear magnetism logging provides a superior means of reservoir rock definition, yields a measure of formation permeability and productivity and is an excellent correlation tool andhydrocarbon and water can be differentiated with good reliability. Operational factors are discussed along with methods of interpretation of original data. Introduction In Sept., 1959, Brown and Gamson presented a paper concerning the application of nuclear magnetism to oil-well logging. Some early examples of field performance were discussed along with a detailed explanation of the basic phenomenon as it applies to down-hole operations. It is the purpose of this paper to discuss the operations of nuclear magnetism logging (NML) and to present additional field results. As will be evident, NML is in the early stages of development, and its full significance is yet to be realized. Its ability to define fluid-bearing zones is well established. In addition, considerable evidence suggests its application as a permeability or productivity index, its ability to distinguish hydrocarbon and water zones, and its capability of operating in all borehole conditions. Certain operational problems of a commercial NML must still be evaluated. Only a limited number of logs have been conducted with a recently completed prototype tool, and continuous changes are being made for more satisfactory operation.