Six equations of state (including ours) were compared for their thermodynamic property prediction accuracy for reservoir fluid systems. This was done using their percentage absolute deviation to search for and establish a trend in accuracy for each on conventional wells which will give a clue to their applicability to HPHT (High Pressure High Temperature) PVT modeling. A group of three showed fairly good accuracy with a trend of improvement up to about 1800 psi. Another set of two interestingly showed very similar trends with continuous improvement in accuracy as pressure increased making them potential candidates for high pressure reservoir PVT modeling. One equation of state (EOS) however showed an irregular error trend.