Abstract: The application of formation test data at Well T in Tarim basin is examined, indicating that condensate gas readily condensed and dropped out in the reservoir when pressure was lowered, part of it couldn't be produced to the surface because it was adsorbed on the surface of rock, causing a drop in its productivity. Thus .condensate gas reservoir must be produced at stabilized pressure. When gavs and condensate mixtures are produced from individual layers in different pressure systems, it may cause influx of fluid in the high pressure bed back into the low pressure bed.reducing the overall productivity of gas and condensate mixture. In this case, individual beds should be produced using different well patterns. For the oil reservoir with vertical permeability similar to horizontal permeability, if is suitable to improve its productivity by means of horizontal well technology. Under all circumstances, deviated well with hole deviation of over 40° has a higher productivity than vertical well.

Key words: Tarim basin, Formation test, Well test interpretation