Abstract: The Paleogene gypsum-salt rock is extensively developed in the main part of Kuqa Depression, with a maximum thickness of
up to 4000 m. There are diverse deposition patters of the base salt rock but a lack of the unified marker bed. Moreover, influenced by the vertical shear stress and orogenic compression during the uplift of the south Tien Shan Mountains, the gypsum-salt rock experienced intensive plastic creeps, and the complex lithologic association brought difficulties in accurately discriminating the base salt rock. Based on the undercompaction theory, the differences between inter-salt mudstone and base-salt mudstone are summarized. Then the sedimentary pattern of multiple salt lakes is characterized and the zonal sedimentary sequences are identified of the subsalt sequence by using drilling data from 120 wells, as well as the subsalt sedimentary sequence, lithologic association of basal sandstone and residual thickness of the Cretaceous;The cuttings, mud logging and wireline logging data enable to determine the lithologic associations at the base salt layer and establish a lithologic association plate for different zones; The differences between inter-salt mudstone and base-salt mudstone are compared and an on-site identification standard is set up based on the lithology, mineral composition, element composition, wireline logging and seismic facies characteristics; A series of quantitative indexes for discriminating the base salt mudstone are precisely established in various zones by using sedimentary sequences, drilling, mud logging, wireline longing and element geochemistry data; Finally, the micro-drilling time, XRF
logging, and pilot well data are applied to develop an applicable discrimination method and field operation scheme by integrated geology and engineering. The technology ensures the safe and rapid completion of 31 exploration wells, which provides solid technical supports for building the largest production base of ultra-deep natural gas with a production capacity of 30 billion cubic meters.

Key words: discrimination of the base salt, gypsum-salt rock, lithologic association plate, quantitative index, operation process