A New Classification of Gas-Condensate Reservoirs Based on Joule-Thomson Inversion Envelope Interaction

Abstract Gas-condensate reservoirs are traditionally classified using phase-envelope features (critical point, cricondentherm, and dew-point behavior). However, wells exhibiting similar phase envelopes may follow different pressure–temperature trajectories during drawdown because the Joule–Thomson (JT) effect can either cool or heat the flowing gas depending on the sign of the JT coefficient. This work proposes a practical subdivision within gas-condensate systems based on the interaction between the phase envelope and the JT inversion locus (μJT = 0). A unified Peng–Robinson (PR) equation-of-state workflow is applied to (1) reproduce the phase envelope and (2) compute the inversion curve from the same compositional description, avoiding inconsistencies arising from mixed models. The proposed descriptor is defined as ΔPinv = Py – Pinv(Ty), where Pinv(Ty) is the inversion pressure at reservoir temperature. Positive ΔPinv indicates μJT < 0 (warming tendency under near-isenthalpic pressure drops), while negative ΔPinv indicates μJT > 0 (cooling tendency). Three HPHT wells (I-1, B-1, and E-23) are used to illustrate the concept: I-1 and B-1 operate in the μJT < 0 regime, whereas E-23 falls in the μJT > 0 regime. This subdivision provides direct guidance for choke strategy, near-well condensate-management priorities, and compositional simulation practices in HPHT gas-condensate developments.