Study of factors of influence on creep law of extended reach well in salt rock layer
Authors:
Huang Haoyong, Institute of Petroleum Engineering, China University of Petroleum (East China), Qingdao, Shandong, China
Cheng Yuanfang, Institute of Petroleum Engineering, China University of Petroleum (East China), Qingdao, Shandong, China
Chang Xin, Institute of Petroleum Engineering, China University of Petroleum (East China), Qingdao, Shandong, China
Yan Chuanliang, Institute of Petroleum Engineering, China University of Petroleum (East China), Qingdao, Shandong, China
Abstract:
Purpose. The authors aim to develop a new 3D analytical creep model for directional wells, and to identify the rules of wellbore shrinkage under the action of stress in thick salt-gypsum layer in Middle East fields, which will reduce the risk of drilling sticking accidents during the process of drilling of an extended reach well.
Methodology. Based on the viscoelastic theory, the Kelvin-Voigt creep model was applied to deduce a new three-dimen- sional analytical creep model for extended reach well, by combining the inclined shaft lining stress formula in the rectangular coordinate system and cylindrical coordinate system. By means of this model, the creep law of salt rock under different drilling fluid density, creep time, azimuth, and well drift angle has been quantitatively analyzed.
Findings. The new three-dimensional analytical creep model for an extended reach well has been derived. The relationship between the borehole radial displacement of salt rock layer and different influencing factors, such as the inclination angle, the azimuth angle, drilling fluid density and the borehole spud time, has been analyzed.
Originality. The three-dimensional analytical creep model for extended reach well describing adequately the relationship between salt rock layer creep law and influencing factors, which is different from the current analysis models that are usually studied by 2D plane analysis model or finite element method for numerical simulation, has been developed.
Practical value. The three-dimensional analytical creep model has been created for determining the rules of wellbore shrinkage under different influencing factors. The results of the analysis of the salt rock layer creep can provide significant guidance for extended reach well to be drilled through salt rock layer successfully.
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