Enhancing Reservoir Characterization in Complex Laminated Formations: A Multiscale Evaluation of Wireline Formation Pressure Testing Using Mangahewa Field Case Study

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Abstract Formation characterization is essential for maximizing production and hydrocarbon recovery. It requires analyzing reservoir properties across multiple scales using tools with varying radii of investigation. In cases where traditional well testing methods like Drill Stem Testing (DST) are limited by cost, environmental concerns, or operational constraints, Wireline Formation Pressure Testing (WFPT) offers a viable alternative for near-wellbore evaluation. This case study assesses the reliability of reservoir parameters derived from pretest pressure data, using permeability as a proxy. The analysis benchmarks WFPT results against core data, log-based models, and DST across several zones within the laminated Mangahewa Formation in New Zealand's Taranaki Basin to evaluate interpretation accuracy in complex reservoirs. This study focuses on the laminated, gas-bearing intervals of the Mangahewa Formation in the Taranaki Basin, where a spherical flow interpretation model was developed to extract both average permeability and anisotropy effects from WFPT pretest pressure responses. Permeability estimates were benchmarked against core plug measurements, NMR log interpretations, porosity-permeability transform models, and DST results. Six distinct reservoir intervals (MaD1-A, MaD1-B, MaC3, MaB1, MaA5u, MaA5l) in the Mangahewa-12 well were evaluated to assess the method's reliability in complex, heterogeneous formations. WFPT-derived permeabilities ranged from sub-millidarcy to 60 mD and showed good agreement with core and NMR data in moderate-permeability zones. However, in tighter, anisotropic layers, WFPT diverged from log-based models, which tended to underestimate reservoir quality. DST results consistently reported lower permeabilities due to larger-scale averaging and completion skin effects. Pressure derivative analysis identified transitional flow regimes, including hemispherical and anisotropic behavior, though interpretation was occasionally constrained by short test durations and noise. These results demonstrate the quantitative value of WFPT for characterizing permeability and near-wellbore conditions in laminated reservoirs. The findings also emphasize the need for multiscale data integration and highlight key limitations and best practices for WFPT interpretation in complex geological settings. This study delivers a detailed, zone-by-zone assessment of WFPT performance in a tight, laminated gas reservoir, highlighting how geological heterogeneity, flow geometry, and operational constraints influence permeability interpretation. By integrating analytical solutions, numerical simulations, log-based transforms, core data, and DST results across six distinct intervals, the analysis reinforces the value of a multi-method approach for reliable reservoir characterization in complex formations. The findings clarify both the strengths and limitations of WFPT in tight gas settings and offer practical guidance for its application in similarly challenging reservoirs.

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