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The influence of environmental salinity on the cement plug mechanical strength in a function of time |
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The influence of environmental salinity on the cement plug mechanical strength in a function of time Author: J. Wilk
The results of laboratory tests on determining the influence of time on the mechanical strength of cement plug (used for drilling) with respect to the salinity of the seasoning environment have been discussed and analysed in the paper. They way in which the mechanical strength of the plug has changed has been traced in the first three months following the end of cement setting. The results were also viewed in the perspective of years. The portland cement 350 was used for the experiments. The water-to-cement ratios of the analysed slurries were: 0.45, 0.50 and 0.55. The plug samples were stored in: distilled water, tap water of definite chemical composition, 4% NaCl water solution, 20% NaCl water solution and NaCl water solution saturated in normal conditions. The results of laboratory experiments were listed in four Tables and 12 Figures. The analysis of the obtained results has shown that the mineralisation degree (salinity) of the environment in which the plug has been disposed is negligible for short periods of time (up to 3 months). For longer periods (3 years and more) the mechanical strength has a dropping tendency with the increasing mineralisation of the environment surrounding and saturating the plug. The laboratory tests were performed within the framework of the own research programme No. 10.190.233 realised at the Department of Drilling, Faculty of Drilling, Oil and Gas, UMM.
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2011