Evaluation Of Construction Defects On Casing Collapse

Evaluation Of Construction Defects On Casing Collapse

Casing Collapse against salt layer, always made prevalent major problem of the oil fields which causes increase of costs to oil companies. Majority of reservoirs in south west of Iran are below Gachsaran formation and this formation bring aboundant problems and cause collapse contingency for well in this field. This problem can be seen not only at drilling time in some formations but also after the completion and production may cause problems. Studying of casing collapse according to the two views geomechanics and mechanics of solids needs of the countryʹs oil industry and this method is one of the best ways to predict such problems and offer optimum solution. Construction defects such as ovality and eccentricity may be exist during the construction in casing. This imperfection affect on the strength casing collapse. The main objective of this paper is to examine the behaviour of casing collapse with considering the formation properties such as salt rock creep and casing imperfection Simultaneously. Numerical simulations were applied to evaluate the casing collapse strength. The data belongs to one of the wells in Southwest part of Iran. The effect of casing eccentricity and ovality of casing were investigated. In this study, finite element simulation was used through the use of ABAQUS software to model of formation, cement and casing, against salt layer and the failure of casings in well. The results of this study show construction defects such as ovality and eccentricity can greatly reduce the strength of casing collapse. This reduces the resistance to the extent that the casing at the time of installation due to high plastic strain will collapse and also it was found that the pipe imperfections is more effective than rock salt creep in casing collapse