Advancing CO₂ Huff-and-Puff Simulation in Tight Reservoirs: Critical Gaps and Optimization Strategies

Abstract

This study provides a critical evaluation of CO₂ Huff-and-Puff (HnP) modeling for enhanced oil recovery in tight reservoirs, with particular attention given to the methodology adopted in a previous study on this topic. Although their findings indicating an optimal 21-day soaking period and two injection cycles yielding a 22.96% recovery factor are consistent with empirical data, the predictive reliability of their model is limited by several methodological simplifications. Notable shortcomings comprise oversimplified fracture representation, insufficient petrophysical characterization, unvalidated immiscibility assumptions, static injection parameters, and limited sensitivity analysis. To overcome these constraints, an integrated modeling framework is proposed, which includes: explicit fracture modeling using Embedded and Discrete Fracture Models (EDFM/DFM); rigorous miscibility evaluation through Equation of State (EOS) modeling and slim-tube experiments; dynamic injection protocols; advanced parametric analysis employing Design of Experiments (DOE); and integrated techno-economic and carbon intensity assessments. This refined approach illustrates how the integration of established EOR and fractured reservoir modeling principles can lead to more reliable and operationally feasible field development strategies.