Abstract: A system for designing a casing string for an oil well, a gas well, an oil and gas well, and/or a geothermal well. The system comprises a processor, a non-transitory memory storing a casing string design, wherein the casing string design comprises at least one section of UOE-type pipe, a downhole environment simulation application stored in the non-transitory memory that, when executed by the processor determines downhole conditions based on the casing string design, wherein the downhole conditions comprise a downhole temperature, and a casing collapse strength modeling application stored in the non-transitory memory that, when executed by the processor, analyzes collapse strength of the casing string based on the downhole temperature and based on a UOE-type pipe collapse strength model and presents a collapse strength report on the casing string design based on analyzing the collapse strength of the casing string.

Abstract: A well operation simulator predicts temperature and pressure profiles of a multi-tubing completion well for well design. The simulator is comprised of modules, which when executed, determine a first set of design limits based on stress conditions arising from the temperature and pressure profiles from a multi-tubing drilling module and a multi -tubing production module for drilling and production operations. A multi-tubing multi-string module predicts the annular fluid expansion (AFE) and annular pressure buildup (APB) of the multi-tubing well from the previously calculated temperature profile, pressure profile, and stress conditions and determines a second set of design limits with the AFE/APB effects in addition to the temperature profile and pressure profile predicted from multi-tubing drilling module and multi-tubing production module.