The analytical procedure is shown in Fig. 91.

111.3.3. Recommendations

It is recommended that a reference solution (sample with known tracer concentration in the brine of the target reservoir) should be prepared and applied in an actual scale test, in order to obtain very reliable results through the use of the above analytical procedures. The concentration of the tracer in the reference solution should be at a similar level to that in the samples collected from the field.

III.4. ANALYSIS OF RADIOLABELLED [Co(CN)6]3- IN SAMPLES OF PRODUCED WATER

There are several radioisotopes that can be used to label the [Co(CN)6]3- compound: 56Co, 57Co, 58Co, 60Co and 14C.

III.4.1. Method

Enrichment of radiolabelled [Co(CN)6]3- in reservoir brine is conducted by anion exchange column chromatography. The absorption efficiency of the

lOOOmLbrine

_____ 1 _________________

Filtration by 0.45 p m filter paper

I

Adjust pH to 5-6 by HCL and Na.^COj

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Loading to а Ф5.х100тт glass column with about 1g No. 717 resin (80-100 meshes)

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Seal the column

________________ 1 ___________________________

Gamma counting or spectral gamma analysis of the column
Well Type Detector

FIG. 92. Analytical procedure for analysis of radiolabelled [Co(CN) 6]3 in samples of produced water.

[Co(CN)6]3 to the resin is more than 99%. The analysis method consists of three steps:

(1) Sample purification by filtration;

(2) Use of No. 717 anion exchange resin column enrichment;

(3) Gamma counting or spectral gamma analysis.