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This paper was presented at the University of Oklahoma-SPE Production Research Symposium in Norman, Okla., April 29–30, 1963, and is considered the property of the Society of Petroleum Engineers. Permission to published 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 the Journal of Petroleum Technology or the Executive Secretary. Such abstract should contain conspicuous acknowledgement 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 providing proper credit is given that publication and the original presentation of the paper.
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For many years, operators have longed or a little colored boy to go down the hole and tell what he sees. The use of radioisotopes gives us such a little boy, in fact a super little boy, because he can help us to see through casing, and back into the formation.
Because of lack of information, misinformation, misunderstanding, and misuse of radio- isotopes, this unique and powerful tool has received limited use in the oil field. Some of the methods and techniques using radioisotopes in fracturing, remedial cementing, and fluid tracing operations will be reviewed. No particular method will be stressed but each method wail be briefly described along with advantages and disadvantages of the method.
In general, a radioisotope is blended into a material and pumped into the well. After pumping, the well is gamma logged to locate the radioisotope. One can generally use this information to help determine the results of the treatment.
In fracturing operations, several questions require answers:
Where is the fracture [or fractures]?
How wide,, or thick, is the fracture?
What type of fracture [or fractures] was produced?
What direction did the fracture take?
How effective were additives, fracturing techniques, fracture initiation processes, etc.?
Fracture location [depth] has been attempted by two general methods using radioactive propping agents or radioactive fluids.
The radioactive propping agents, of course, are an integral part Of the fracture job. The activity is low and there is practically no danger to personnel, or contamination of the equipment or site. Location of gamma activity indicates the location of the propping agent.
One service company bakes the radioisotope on the actual propping agent used such as sand, metal pellets, walnut hulls, etc., so that it is not removed by well or treating fluids. Approximately one fortieth of the individual grains are radioactive, thus each grain is of low specific activity, and a considerable quantity [2 lb sand required] of propping agent must be present to produce an indication from a gamma detector. This process is effective in either open hole or behind pipe.
