@Article{ee.2026.077029,
AUTHOR = {Zheng Zhang, Zhenning Qiao, Jianbo Du, Yanfeng Gao, Yu Zhao, Yi Yang, Zhibo Xu},
TITLE = {Wellbore Fluid Temperature Sensitivity Analysis of Deepwater Hydrate Drilling Based on Dual-Wall Drill String Dual-Gradient Technology},
JOURNAL = {Energy Engineering},
VOLUME = {},
YEAR = {},
NUMBER = {},
PAGES = {{pages}},
URL = {http://www.techscience.com/energy/online/detail/26278},
ISSN = {1546-0118},
ABSTRACT = {To inhibit hydrate reconfiguration during deepwater dual-wall drill string dual-gradient reverse circulation drilling, accurate wellbore thermal profile characterization is critical. In this study, a novel two-dimensional transient heat field model is established. Unlike previous steady-state or one-dimensional approaches, this model explicitly captures the radial-axial thermal coupling and the transient ‘shallow-section heating’ effect unique to the dual-wall, counter-current flow architecture, providing a more accurate tool for hydrate stability assessment. A comprehensive numerical sensitivity study shows the system exhibits strong thermal decoupling. Circulating medium injection temperature governs the outlet temperature, where a <mml:math id="mml-ieqn-1"><mml:msup><mml:mi>6</mml:mi><mml:mrow><mml:mo>∘</mml:mo></mml:mrow></mml:msup><mml:mrow><mml:mtext>C</mml:mtext></mml:mrow></mml:math> inlet rise elevates the outlet by 24.1%, while the bottom-hole temperature change is negligible at <mml:math id="mml-ieqn-2"><mml:msup><mml:mi>0.011</mml:mi><mml:mrow><mml:mo>∘</mml:mo></mml:mrow></mml:msup><mml:mrow><mml:mtext>C</mml:mtext></mml:mrow></mml:math>. Circulation duration critically affects transient heating in the shallow seawater section; extending reverse circulation from 4 to 8 <mml:math id="mml-ieqn-3"><mml:mrow><mml:mtext>h</mml:mtext></mml:mrow></mml:math> raises the mudline annulus temperature by 24.7%. This “shallow-section heating” is diametrically opposed to conventional circulation models. Notably, the geothermal gradient is the dominant factor for bottom-hole temperature, where an incremental increase of <mml:math id="mml-ieqn-4"><mml:msup><mml:mi>0.004</mml:mi><mml:mrow><mml:mo>∘</mml:mo></mml:mrow></mml:msup><mml:mrow><mml:mtext>C</mml:mtext></mml:mrow><mml:mrow><mml:mo>/</mml:mo></mml:mrow><mml:mrow><mml:mtext>m</mml:mtext></mml:mrow></mml:math> induces a corresponding <mml:math id="mml-ieqn-5"><mml:msup><mml:mi>5.19</mml:mi><mml:mrow><mml:mo>∘</mml:mo></mml:mrow></mml:msup><mml:mrow><mml:mtext>C</mml:mtext></mml:mrow></mml:math> bottom-hole temperature elevation. Fluid thermal properties are main control parameters for the mudline’s hydrate-sensitive zone. High thermal inertia (from density or specific heat capacity) elevates the mudline return temperature by up to 16.9%, whereas high thermal conductivity causes a sharp 17.0% temperature reduction. These quantitative research results lay a theoretical basis for optimizing circulating medium parameters and thermal anomaly diagnosis of the dual-wall drill string dual-gradient hydrate production system, thereby improving operational safety and production efficiency.},
DOI = {10.32604/ee.2026.077029}
}