Comparative Analysis and Optimization of Driller’s and Engineer’s Methods for Surface Pressure Prediction in Well Control: Case Study of the XYZ Niger Delta Field

This study presents the development and optimization of predictive models for annular surface pressure (ASP) during well control operations, integrating detailed gas composition analysis and advanced numerical modeling. Eight natural gas samples were collected from producing wells in the XYZ Field of the Niger Delta and analyzed via gas chromatography, following GPA 2286, to determine molecular compositions and compute gas densities and pressure gradients critical for accurate simulation inputs. Well data and mud rheology, including parameters derived from the Herschel-Bulkley model, provided the basis for calculating annular frictional pressure losses during influx circulation. Well control models for the Driller’s and Engineer’s Methods were formulated based on pressure balance principles and subsequently optimized using a Multi-Objective Genetic Algorithm (MOGA). The optimization aimed to identify the minimum wellbore pressures at specific depths under constraints of kick volume (30–100 bbl) and kick intensity (0.5–1.5 psi/ft). Simulation results revealed that the minimum kick pressure in the wellbore is strongly influenced by prompt detection and accurate pore pressure estimation, consistent with prior findings emphasizing early intervention in kick management. The Driller’s Method produced higher maximum surface pressures (peaking at 838 psi) and more significant standpipe pressure fluctuations compared to the Engineer’s Method, which maintained lower pressures and required shorter circulation times, corroborating earlier research. Simulations examining the effect of kick volume showed that a 50 bbl influx kept surface pressure below the Maximum Allowable Annular Surface Pressure (MAASP) of 758 psi, whereas a 100 bbl kick elevated surface pressure to 839 psi, exceeding the MAASP and resulting in simulated formation fracturing. Additionally, varying kick intensities demonstrated that lower kick intensities significantly reduce annular surface pressures and circulation time, underscoring the importance of diagnosing kick mechanisms accurately to avoid excessive mud weights and unnecessary formation stress. Overall, the study demonstrates that although the Driller’s Method is operationally simpler, the Engineer’s Method offers superior performance in maintaining lower annular surface pressures and standpipe stability. The optimized models and simulation outcomes provide valuable tools for predicting worst-case surface pressures during well control planning, contributing to safer and more efficient well designs in the Niger Delta and similar high-pressure environments.