G emala Field, Block Tuban located at East Java basin whereas the area of the carbonate development at Tuban Formation which attained the age of Late Oligocene – Late Miocene. Gemala Field has 2 wells i.e. SKW-1 and SKW-2 which have data core, well log, and 3D Seismic to be used for determining the facies lithology as well as the sedimentation and facies distribution in lateral manner by using the sequence stratigraphy method. Based on the analysis of the core at the SKW-2 well, by the depth of 6810.0’-6929.0’ (MD), it is found 3 main facies lithology contained of Packestone facies, Bindstone fasies, and Wackestone facies which in accordance to the rocks characteristics and fossil contents and its minerals, they are included into the carbonate reef buid-up system. The formed facies sedimentation is included in the carbonate platform zone which consisted of Open Marine Shelf facies, Platform Margin Organic Reef facies, and Platform Foreslope facies. The result of the log interpretation shown that there is a marker like flooding surface which can be devided into 2 parasequence set, i.e. parasequence 1 which is bounded by marker FS1-FS2 and parasequence 2 which is bounded by marker FS2-FS3. There also found 2 system tracts i.e. Highstand System Tract (HST) and Transgresive System Tract (TST). The result of the seismic interpretation, it is shown the pattern of reflection termination like onlap on the carbonate build-up with mounded pattern, chaotic pattern until free reflection and high continuity back-self.