Study on the Annular Pressure Prediction Method for Ultra-Deep Well Hydraulic Lift Dual-Gradient Drilling


== Abstract ==

<p>With the ongoing advancement of oil and gas exploration into deep and ultra-deep formations in China, precise wellbore pressure control under complex geological conditions has become a critical technical challenge for safe drilling operations. To overcome the limitations of existing dual-gradient drilling (DGD) technologies&mdash;particularly their poor applicability and limited pressure regulation capability in land-based drilling&mdash;this study introduces an innovative hydraulic-lift dual-gradient drilling annular flow model, tailored for ultra-deep vertical wells. The model accounts for solid&ndash;liquid phase separation flow characteristics and the hydraulic-lift effect of downhole dual-gradient pumps. The Stability Enhancing Two-Step (SETS) method is employed to solve the strongly nonlinear, coupled governing equations, significantly improving computational stability and efficiency. Experimental validation reveals that the model&rsquo;s predicted pressure distribution closely matches measured data, with a maximum average error of only 16.4%, confirming the model&rsquo;s accuracy and applicability. Additionally, this study systematically analyzes the impact of key parameters&mdash;such as drilling fluid flow rate, viscosity, lift pump speed, and the number of pump sections&mdash;on bottomhole pressure regulation, providing valuable insights into their influence on annular pressure behavior. The findings offer a solid theoretical foundation for optimizing drilling parameters and ensuring safe, efficient drilling in ultra-deep wells under challenging geological conditions.OPEN ACCESS Received: 16/07/2025 Accepted: 19/08/2025</p>



== Document ==
<pdf>Media:Draft_Sanchez Pinedo_304533580-9190-document.pdf</pdf>