Analysis of the processes of casing leaks formation during well operation in Surgutneftegas OJSC

UDK: 193:622.276.012.05
DOI: 10.24887/0028-2448-2018-3-62-65
Key words: well repair, casing leaks, carbon dioxide, Cenomanian water, interval of casing leaks, well logging, corrosion rate, direction of corrosion development, partial pressure
Authors: I.I. Ryabkov (Tyumen Branch of SurgutNIPIneft, RF, Tyumen)

This article describes the problem of casings leaks in wells of Surgutneftegas related to corrosion processes during the exploitation. It is shown the number of wells with casings leaks that revealed in primary period (less than 10 years) of wells operations increases. The article presents the results of production casing research for estimating corrosion progress direction and depth of its location in wells. The reasons that influences on corrosion location in different kind of wells have been explaining. The different speeds of casings corrosion in wells that are working in the same regime have been noting. The possible factors that are contributing to increasing and decreasing of corrosion speed in well conditions had been considered. The conducted analysis results about degree of influences considered factors to casing leakage formation had been showed. The justification of internal corrosion progressing for production casing and absence of dominant influence of Cenomanian water on casing leakage formation had been stated. The solubility of carbon dioxide in water depending from pressure and temperature values has been considering. It supposed to be that speed of corrosion of production casing will be increase with depth of well, since with increasing of depth the hydrostatic pressure is increase, so quantity of formed carbonic acid is increase too. Results of research of corrosion depositions from internal surface of casings that are confirming of results of researchers who are gave a data about carbon dioxide type of corrosion in wells of Western Siberia have been showing.

Based on conducted work the general factors that are resulting to acceleration of corrosion processes in well have been marked out; the statement about influence of electric submersible pump as a main factor that resulting to production casing leakage have not been confirmed; the influence of aggregate of factors of significantly accelerates the corrosion processes have been marked.


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