A Computerized Method of Sand Coating
Authors: Ershaghi Iraj , Plasch William 
Published: December 2007

This paper was prepared for the 44th Annual Fall Meeting of the of the Society of Petroleum Engineers of AIME, to be held in Denver, Colo., Sept. 28-Oct. 1, 1969. 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 PETROLEUM ENGINEERS JOURNAL is usually granted upon request 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 discussion may be presented at the above meeting and, with the paper, may be considered for publication in one of the two SPE magazines.

A computerized method of sand counting has been developed using SP or gamma-ray curves. This method is independent of the SP base-line or level of natural radioactivity.

The computer examines the character of the curves and establishes the bed boundary by the two-thirds rule or any other applicable rule.

This method, when used with the computed log, provides a further refinement of the sand count by deleting zones of very low porosity. Additional modification can be easily made with regard to water saturation and dispersed shale.

A brief literature review on the techniques proposed by others is also presented.

Introduction

The basic tools of a log analyst are a few equations and several different assumptions. The type and number of assumptions depends upon the logging experience of the interpreter. To the extent that certain universal rules and equations exist, log interpretation does not create severe problems. However, in many cases a log analyst has to solve critical problems through the use of personal experience and imagination. The involvement of personal judgment in the interpretation of well logs often creates controversial situations.

A good example develops during unitization of producing properties. Questions of policy concerning unit operation are normally agreed upon in advance by a committee representing unit interest owners. One of the major problems for these committees is to reconcile differences in sand-counting techniques.

It is not always difficult to agree on some sort of rules for sand counting. Manual application of these rules to long sections of well logs without being influenced by several interpreters' judgment creates the problem. Therefore, any automation which can be applied to sand counting is desirable from unitization standpoint.

There is another way to look at this problem. Through the use of high-speed problem. Through the use of high-speed computers calculation of basic properties such as saturation and porosity can now be carried out for a long section of a well in few seconds. To do this we need to properly locate porous beds so that unnecessary computations for shale will be eliminated. The zone selection is normally done by the log analyst. The task, which is very time-consuming in the case of thinly interbedded permeable and impervious strata., can be accomplished through the use of a computerized method for sand counting.