Experimental and numerical simulation of in-situ tube expansion for deep gas wells

Growing energy demand is forcing the petroleum industry to reevaluate resources found in unconventional gas formations and utilizing low-production zones. Extracting oil and gas from these difficult and deep reservoirs require new knowledge which should lead to develop solutions in lifting those reserves to the surface. Centuries-old manufacturing process of tube forming has found an interesting and extended application in petroleum well drilling and delivery. The in-situ expansion of tube is aimed at expanding its diameter by pushing or pulling a mandrel through it. The expansion process is strongly nonlinear due to material and contact nonlinearities. The goal is to achieve desired tube expansion smoothly as well as maintain minimum post expansion material and mechanical properties. The objective of this research is to conduct experiments to expand the tube under simulated downhole conditions. Finite element analysis is also used to simulate the expansion process, and the results are compared with experimental data. The force required for expanding the tube, thickness reduction in tube wall thickness, and length shortening under fixed-free end condition are estimated. Good agreements were found between numerical and experimental results. Thickness reduction greater than 12% lowers collapse strength by 50% making it unsuitable for deep wells.