Abstract: PVT data of gas condensate reservoir provide important parameters for reservoir numerical modeling and recovery planing. For various reasons, however, representative PVT samples of the initial development phase are often not available. Phasestate restoration is one of the methods usually used to solve this problem; but systematic study on the theories behind phase-
state restoration is lacking. In the present work, the general principles of phase-state restoration of gas condensate reservoirs and their application to the Yinmai Well 7 in Tarimu basin are given. After data matching, phase-state restoration was performed directly on the effluents from the well at different
formation pressure drawdowns. Restoration was also performed on mixed separator oil and gas samples assuming the GOR of the initial production phase or assuming a formation pressure equal to the dew pressure. Comparison is made on the influence of the two types of restoration on the fluids as being representative of the initial formation fluids.

Key words: gas condensate reservoir, PVT analysis, phase-state restoration