Transient temperature field model of shut-in offshore wells

Key words:  drilling  offshore  transient temperature field  shut-in  insulated oil tubing

Abstract:

Based on transient heat transfer mechanism involved in shut-in offshore oil wells, the temperature governing equations for areas including inside the wellbore, interface between the wellbore and sea water or formation, and formation were developed. According to production tubing structure and the geometry characteristics of wellbore heat transfer physical model, discrete equations for nodes at wellbore axis, oil tubing bottom, inner area and interface between wellbore and sea water were established respectively using implicit finite volume patterns and the alternate-direction method. A stable and convergent numerical simulation method was proposed to solve transient temperature field. The results show that the wellbore temperature decreases rapidly at the initial stage, and then it decreases slowly with shut-in periods extending. In addition, the affected radius is less than 3m after shut-in 24h, and the wholesome temperature field is recovered to the origin one after shut-in about 106.1h. The relative error between simulated results and test data of a cased well in South China Sea is less than 3％.