Casing Design - Theory and Practice

FUNDAMENTAL ASPECTS OF CASING DESIGN. Purpose of Casing. Types of Casing. Cassion pipe. Conductor pipe. Surface casing. Intermediate casing. Production casing. Liners. Pipe Body Manufacturing. Seamless pipe. Welded pipe. Pipe treatment. Dimensions and weight of casing and steel grades. Diameters and wall thickness. Joint length. Makeup loss. Pipe weight. Steel grade. Casing Couplings and Thread Elements. Basic design features. API couplings. Proprietry couplings. PERFORMANCE PROPERTIES OF CASING UNDER LOAD CONDITIONS. Tension. Suspended weight. Bending force. Shock load. Drag force. Pressure testing. Burst Pressure. Collapse Pressure. Elastic collapse. Ideally plastic collapse. Collapse behaviour in the elastoplastic transition range. Critical collapse strength for oilfield tubular goods. API collapse formula. Calculation of collapse pressure according to Clinedinst (1977). Collapse pressure calculations according to Krug and Marx (1980). Biaxial Loading. Collapse strength under biaxial load. Determination of collapse strength under biaxial load using the modified approach. Casing Buckling. Causes of casing buckling. Buckling load. Axial force due to the pipe weight. Piston force. Axial force due to changes in drilling fluid specific weight and surface pressure. Axial force due to temperature change. Surface force. Total effective axial force. Critical buckling force. Prevention of casing buckling. PRINCIPLES OF CASING DESIGN. Setting Depth. Casing for intermediate section of the well. Surface casing string. Conductor pipe. Casing String Sizes. Production tubing string. Number of casing strings. Drilling conditions. Selection of Casing Weight, Grade and Couplings. Surface casing (16-in.). Intermediate casing (13^3/8-in. pipe). Drilling liner (9^5/8-in. pipe). Production casing (7-in. pipe). Conductor pipe (26-in. pipe). CASING DESIGN FOR SPECIAL APPLICATIONS. Casing Design in Deviated and Horizontal Wells. Frictional drag force. Buildup section. Slant section. Drop-off section. 2-D versus 3-D approach to drag force analysis. Borehole friction factor. Evaluation of axial tension in deviated wells. Application of 2-D model in horizontal wells. Problems with Wells Drilled through Massive Salt-Sections. Collapse resistance for composite casing. Elastic range. Yield range. Effect of non-uniform loading. Design of composite casing. Steam Stimulation Wells. Stresses in casing under cyclic thermal loading. Stress distribution in a composite pipe. Design criteria for casing in stimulated wells. Prediction of casing temperature in wells with steam stimulation. Heat transfer mechanism in the wellbore. Determining the rate of heat transfer from the wellbore to the formation. Practical application of wellbore heat transfer model. Variable tubing temperature. Protection of the casing from severe thermal stresses. Casing setting methods. Cement. Casing coupling and casing grade. Insulated tubing with packed-off annulus.COMPUTER AIDED CASING DESIGN. Optimizing the Cost of the Casing Design. Concept of the minimum cost combination casing string. Graphical approach to casing design. Casing design optimization in vertical wells. General theory of casing optimization. Casing cost optimization in directional wells. Other applications of optimized casing design. AN INTRODUCTION TO CORROSION AND PROTECTION OF CASING. Corrosion Agents in Drilling and Production Fluids. Electrochemical corrosion. Corrosion of Steel. Types of corrosion. External casing corrosion. Corrosion inspection tools. Protection of Casing from Corrosion. Wellhead insulation. Casing cementing. Completion fluids. Cathodic protection of casing. Steel grades. Casing leaks.