| At present, most of the oil fields in the world are being in latter phase of Secondaryrecovery and early phase tertiary recovery; they are produced by artificial supply of energy.Main injected fluid is water. So it is important to obtain the flow distributing of the injectedwater in between with the water injection well to the corresponding oil production wells, toget the heterogeneity features of the pattern, and to study the residual oil information of thepattern. Inter-well tracer test is identified an effective technology to achieve the purposes.In the inter-well tracer test, a tracer is injected together with injected water. It cantrack the movement of the injected water and provide immediate measure of its flowdynamics such as flow direction, velocity, swept volume and recovery ratio. Throughcomprehensive investigation of tracer responses and with the aid of computer simulation,extra information can be obtained on geologic features of the reservoir as well asresidual/remaining oil saturation in it. These outputs can be used directly for reservoirmanagement on enhanced oil recovery. So inter-well tracer test is calling more and moreattention by the oil field engineers and managers.In the development and application of inter-well tracer test, preparation of new tracersand their analysis method are the base and important content in for the technology. Thereare several kinds of radioisotope labeled [*Co(CN)6]3-. The chemical has good stability andconsidered a perfect waterflood tracer material for the inter-well tracer test. In this paper,we chose the preparation and analysis method of K3[58Co(C N)6] for research. In detail, theresearch contents of this paper include three aspects:First of all, through using MINI reactor of CIAE to irradiate target material of NiO,the production procedure of 58COCl2 is established. The research contents included targetpreparation, target irradiation, target dissolution and the separation of Ni2+ and Co2+. Therecovery efficiency of all procedure was more than 97%.Secondly, the synthesis of 58Co tagged K3[Co(CN)6] is completed by use of 58COCl2 and KCN. The prepared 58Co tagged K3[Co(CN)6] is evaluated by comparison with theK3[Co(CN)6] provided by the Jersey company using Scanning Electron Microscope. Theresult shows that they have a consistent scanning chart. Through studying thethermodynamics stability and the chemical stability of this tracer, the result shows thistracer is adapted to sandstone reservoir of lower than 120℃temperature and carbonatereservoir of lower than 100℃temperature.At last, this paper studied the method for analysis of 58Co tagged K3[Co(CN)6] in theinter-well tracer test. Measurement method is established for 1000ml K3[58Co(CN)6]sample from oil field. Sample is enriched by 717 anion exchange resin. The enrichmentefficiency of this method is above 98%. After enrichment, 58Co tagged K3[Co(CN)6] isdetected by a high purity germaniumγdetector with minimum detection limit of 0.05Bq/L.The calibration curve of measurement is established from 0.05 to 10Bq/L (R2≥0.9982).The content of this paper is not published in China. Although there are many papersabout using this tracer to inter-well tracer test in other countries, the preparation of thistracer and the analysis method of this tracer were never published in other countries as well.The paper formed an important base is both synthesis and analysis of using 57(60)Co tagged[*Co(CN)6]3- as reservoir waterflood tracer. It is expected that the research results of thispaper will be widely used in the future. |
PDF Full Text Request