Journal issues: 1/2014
Experimental determination of corrosion effect on rod string material strength characteristics in different wetting conditions
An experiment was conducted in order to determine the influence of rod string wetting with corrodent agent (formation water) and rod string novelty on the rate of development of surface corrosion, with further evaluation of each sample destruction degree on the basis of regular photofixation of the sample area affected by corrosion processes. Similarities in corrosion processes were identified, typical for offshore drilling platforms and periodic highly watered stock of sucker rod pumping units, having plunger pair leakage in conditions of Western Siberia. A comparative analysis of the defectograms produced as a result of inspection of test samples with Vektoskop-S electromagnetic detector was conducted before and after the experiment, resulting in determination of micro crack growth characteristics on the surface of sucker rods, depending on the parameters considered and appropriate conditions of Western Siberia. According to the results of the inspection, depth of each micro crack was measured with further integration of the data obtained and construction of appropriate diagrams such as micro crack growth rate dependence on initial depth of its penetration into the sucker rod metal and micro crack depth growth rate dependence on wetting value (N). A series of experiments were conducted in order to determine the effect of rod metal corrosion and micro crack depth growth in different wetting conditions and novelty on rod string strength characteristics, by measuring maximum plastic deformation load to rupture and rod diameter in the spot of rupture. Influence of sucker rod wetting with salt water on micro crack depth growth was determined depending on the initial depth of micro crack penetration and the wetting agent characteristics. Based on the results of static tension of all test samples, the most vulnerable element in coupling – square – fillet system was identified and the role of corrosion processes in rod string coupling parting statistics was evaluated in conditions of the region under consideration. A generalized comparative analysis of the effect produced by various novelty and wetting combinations on rod string metal strength characteristics and micro crack development was conducted.
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corrosion; micro cracks; rod string; sucker rod parting.; wetting; колонна штанг; коррозия; микротрещины; обрыв штанг.; смачивание DOI 10.17122/ogbus-2014-1-94-113 References to this article (GOST) M.A. Kochekov. Experimental determination of corrosion effect on rod string material strength characteristics in different wetting conditions // Electronic scientific journal "Oil and Gas Business". 2014. №1. P.94-113. URL: http://ogbus.ru/authors/KochekovMA/KochekovMA_2.pdf