| dc.description.abstract | The development of underground oil and gas resources involves significant heat transfer between fluid, downhole tubulars and the surrounding formation. Understanding the heat transfer between wellbore and the surrounding formation has significant impacts for all thermal related operations. Different engineers need to understand the heat transfer for different purposes: drilling engineers need to know the temperature profiles in the wellbore during drilling mud circulation for drilling mud properties variance; reservoir engineers need to know the fluid temperature distribution in the reservoir; production engineers need to know the temperature profiles in the wellbore for downhole equipment efficiency and flow assurance purposes. Studying the heat transfer during drilling, completion and reservoir development periods are necessary and challenging. Usually the “rule-of-thumb” value or complicated numerical simulation is either not reliable or impractical. This research studies the heat transfer during drilling, completion and reservoir development periods. Specifically, it includes four parts: (1) the temperature profiles during drilling circulation (2) transient temperature behavior during clean-up period (3) fluid nonisothermal behavior during reservoir development, and (4) fluid flow in the wellbore during production. All the models are solved either fully analytically or semi-analytically with several reasonable assumptions and provide engineers an easy way to estimate and make quick decisions. This research concentrates on offshore assets due to their complication since heat transfer is occurring in between the wellbore and the positive surrounding temperature gradient (formation) and the negative surrounding temperature gradient (seawater). A real offshore well is used to illustrate the approach. iii In addition, this research also applied the heat transfer between the wellbore and the formation to geothermal resource recovery. Abandoned oil wells can be further recompleted as a closed-loop heat exchanger for underground geothermal resource recovery. This engineering operation not only minimizes the cost associated with drilling a new well, but also avoids the pollution associated with drilling and completion. Three different models are proposed and compared: a fully analytical model, a semi-numerical model and a fully numerical model. The research found that the fully analytical model is an ideal choice for designing and optimizing geothermal energy recovery from abandoned oil wells. | |
