Abstract

Vertical interference pressure tests in stratified reservoirs have commonly been interpreted using type-curve matching techniques which, although supported by rigorous mathematical formulations describing interlayer communication through low-permeability barriers, depend on graphical procedures that introduce subjectivity and reduce analytical flexibility. This work presents an analytical interpretation methodology for vertical interference pressure tests based on Tiab’s Direct Synthesis (TDS) technique as an alternative to conventional curve-matching approaches. A classical vertical interference model was implemented computationally to generate dimensionless pressure and pressure-derivative responses, allowing systematic evaluation of the effects of the governing dimensionless parameters , and on transient flow behavior. Characteristic points were identified on log-log pressure and pressure-derivative plots, and normalization relationships were developed to collapse responses corresponding to different parameter values into unified trends from which direct analytical expressions were obtained. The proposed methodology enables estimation of vertical communication and individual layer permeabilities directly from pressure transient data without reliance on type-curve matching. Validation using reference and synthetic cases produced consistent parameter estimates and confirmed the applicability of the TDS technique to vertically communicating stratified reservoir systems. The methodology provides an objective and reproducible framework for interpreting vertical interference pressure tests in multilayer reservoirs with vertical communication.

Keywords

TDS