(1) the external force of the cement mortar on the casing
In the formula, pco --External force of cement mortar on casing，ρc - Cement slurry or drilling fluid density (2) The pressure inside the casing
Mechanical Mechanism of Casing Damage in Thermal Recovery Wells
4th ：Casing load and casing stress
1. the external pressure of the casing and the casing pressure and the stress generated in the casing.
In the formula, pci -The pressure inside the casing，pcic -easing pressure，ρo -Casing fluid density
Mechanical Mechanism of Casing Damage in Thermal Recovery Wells
also consistent with the borehole of the bending, bending stress generated in the casing.
(5) Thermal stress. The stress caused by the temperature variation of the formation and
Third : coordinate system
According to the hypothesis (1), select the
column coordinate system, the coordinate origin is selected at the wellhead, and the Z axis along the axis of the borehole is down. The r axis along the shaft radially outward
Mechanical Mechanism of Casing Damage in Thermal Recovery Wells
2. Mechanical analysis of casing in thermal recovery wells
(1) Internal pressure; Internal pressure refers to the pressure on the inner wall of the
casing during the steam injection process
Mechanical Mechanism of Casing Damage in Thermal Recovery Wells
Second : Fundamental Assumptions
(1) the radius of the casing is very small relative to the radius of the hole; (2) the material of the casing and the formation rock is linear elastic, homogeneous and isotropic, and in the range of small deformation; (3) the coefficient of linear expansion of casing and formation rocks is constant; (4) the casing and the formation are in the plane strain state when the steam injection, and the casing is in the plane stress state when the cement is injected (5) meet the Mises criteria of casing damage.
action of the self weight of the casing and the buoyancy of the cement paste. It is formed in the process of cement injection.
(4) Bending stress. Due to the curvature of the borehole, when the casing is in place, it is
Mechanical Mechanism of Casing Damage in Thermal Recovery Wells
1. Factors and analysis of casing failure
With the continuous development of heavy oil production, the casing damage is more and more serious. The main problems in the exploitation of heavy oil are casing deformation, fault and leakage. For this purpose, domestic and foreign experts have conducted a more indepth study of thermal recovery casing damage. According to the analysis of experts at home and abroad in recent decades, as well as the analysis of the Shengli Oilfield casing damage data, the reasons of thermal recovery well casing damage can be summarized as following three aspects. Engineering technology factor
Mechanical Mechanism of Casing Damage in Thermal Recovery Wells Contents
Preface
1. Factors and analysis of casing failure
2. Mechanical analysis of casing in thermal recovery wells
LOGO
Tubular Mechanics in Oil-Gas
Mechanical Mechanism of Casing Damage in Thermal Recovery Wells
Reporter ：RenWenming Supervisor ：Professor Li Zifeng Date ：7/10/2016
(3) Radial Stress and Tangential Stress in Casing Under Internal Pressure and External Pressure According to the theory of thick wall cylinder :
Geological factors
Casing Damage
Corrosion factor
Mechanical Mechanism of Casing Damage in Thermal Recovery Wells
1. Factors and analysis of casing failure
force is the force of cement stone and casing after the cement stone is solidified.
(3) Initial axial force; The initial axial force in the casing is the result of the combined
Mechanical Mechanism of Casing Damage in Thermal Recovery Wells
2. Mechanical analysis of casing in thermal recovery wells
Thermal recovery well thermal stress lead to casing damage is actually steam injection temperature field during the process of the tube wall heat should force and surrounding rock stress field change, causing external loads, cause the casing stress caused by casing damage. Theoretical analysis of casing stress in heat injection process First :Casing in oil well production process, by the role of the following forces: (1) Internal pressure; (2) Outer force of the casing; (3) Initial axial force; (4) Bending stress.; (5) Thermalpreventing casing damage