A Review of Formation Evaluation
Authors: Walstrom J.E. 
Published: December 2007

This paper was prepared for the 43rd Annual California Regional Meeting of the Society of Petroleum Engineers of AIME to be held in Bakersfield, Calif., Nov. 8–10, 1972. Permission to copy is restricted to an abstract of not more than 300 words. Illustrations may not be copied. The abstract should contain conspicuous acknowledgment of where and by whom the paper is presented. Publication elsewhere after publication in the JOURNAL OF PETROLEUM TECHNOLOGY or the SOCIETY OF publication in the JOURNAL OF PETROLEUM TECHNOLOGY or the SOCIETY OF PETROLEUM ENGINEERS JOURNAL is usually granted upon requested to the Editor PETROLEUM ENGINEERS JOURNAL is usually granted upon requested to the Editor of the appropriate journal, provided agreement to give proper credit is made.

Discussion of this paper is invited. Three copies of any discussion should be sent to the Society of Petroleum Engineers Office. Such discussions may be presented at the above meeting and, with the paper, may be considered for publication in one of the two SPE magazines.

A principal purpose of this paper is to define what we mean by "formation evaluation", indicate the objectives of this science and to point out the direction it may take in the next ten or twenty years. The paper is based primarily on the author's own experience primarily on the author's own experience within Standard Oil Company of California and also on his long association and relationships with the service companies.

SCOPE, DEFINITIONS, AND OBJECTIVES

The evaluation of subsurface formations as applied to oil well drilling began about 50 years ago and is now approximately a one-quarter billion dollar per year business. In general, it includes all coring, logging, mud logging, testing and sampling procedures. It includes log interpretation methods and laboratory analyses related to subsurface evaluation of the formations including an analysis of their contained fluids. In certain circumstances, casing is set to more definitely evaluate the formations and therefore this operation is also included in formation evaluation.

The principal objectives of formation evaluation are to evaluate the presence or absence of commercial quantities of hydrocarbons in formations penetrated by, or lying near, the wellbore and to determine the static and dynamic characteristics of productive reservoirs. Another objective of productive reservoirs. Another objective of formation evaluation is to detect small quantities of hydrocarbons which nevertheless may be very significant from an exploratory standpoint. A further objective is to provide a comparison of an interval in one provide a comparison of an interval in one well to the correlative interval in another well.

Formation evaluation is a term involving many types of well operations and is clearly more inclusive than the term well logging which encompasses only a certain class of well operations. The term petrophysics generally implies the physics of sedimentary rocks. Formation evaluation utilizes petrophysical relationships and therefore clearly petrophysical relationships and therefore clearly encompasses this body of knowledge.

The factor that usually decides the success of a new formation evaluation tool is the increased amount of oil or gas that is produced as a result of its use. If this produced as a result of its use. If this amount is sufficiently large, the economics of providing the service, by the service companies; and the utilization of the service, by the oil companies, will both be satisfactory.