Field Evaluation Of Microbial Problems And Their Control
Authors: Whitesell L.B. 
Published: December 2007

This paper is to be presented at the Seventh Annual Meeting of Rocky Mountain Petroleum Engineers of AIME May 25–26, 1961, in Farmington, N.M., and is considered the property of the Society of Petroleum Engineers. Permission to publish is hereby restricted to an abstract of not more than 300 words, with no illustrations, unless the paper is specifically released to the press by the Editor of JOURNAL OF PETROLEUM TECHNOLOGY or the Executive Secretary. Such abstract should contain conspicuous acknowledgment of where and by whom the paper is presented. Publication elsewhere after publication in JOURNAL OF PETROLEUM TECHNOLOGY or SOCIETY OF PETROLEUM ENGINEERS JOURNAL is granted on request, providing proper credit is given that publication and the original presentation of the paper.
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 considered for publication in one of the two SPE magazines with the paper.

Abstract
One of the problems facing the waterflood operator is that of evaluating the effectiveness of a microbial control treatment. Usually this problem is solved by sending samples of water to a microbiological laboratory for counting. In many cases it takes several days for the sample to reach the laboratory, thus making it impossible for an accurate evaluation of the treatment Another method of solving this problem has been by setting up a laboratory in the field. While effective, this method is often very expensive and can be done only at infrequent intervals.
Continental's solution to this problem has been the development of a "suitcase laboratory" which is portable and can be used by the field engineer. By the use of serum bottles of media and sterile disposable syringes an accurate, on the spot examination of the water can be made. Provisions have also been made in the "suitcase laboratory" to allow the running of pertinent chemical analyses and bactericide evaluations.

Introduction
The microbiological examination of water-flood injection waters is a valuable aid to the field engineer in evaluating his operating problems. Transporting water samples brings about a change in the microbial population. This may lead to erroneous data upon which the engineer will base his evaluation. To alleviate this problem, a "suitcase laboratory" has been developed which permits microbiological examinations to be made in the field.

METHODS OF MICROBIOLOGICAL ANALYSIS OF WATER
A. Microscopic Examination makes it possible to detect significant numbers of microbes which may not respond to usual laboratory cultivation media. It also permits an estimation of the number of organisms present as an aid in preparing plate count dilutions. B. Plate Count Technique is designed to cultivate or grow the general aerobic bacterial population. By this means, bacterial colonies develop which can be counted visually. The number of bacteria present in the original water sample then can be calculated. C. Extinction Dilution Technique is to dilute a measured quantity of water until it is improbable that any of the original bacterial population is still present. When this diluting is done in a systematic or serial manner into a nutrient medium, it is possible to establish a growth-no growth range for the bacteria. That is, the greatest dilution which theoretically contains but a single organism. This organism multiplies in the nutrient diluting solution and imparts a cloudiness or turbidity.