Abstract: Because of the special geological structures in Tarim basin, it is quite complicated that the case of formation water comes forth by carbonate formation testing. The water coming from carbonate rocks or reservoirs could be divided into seven aqueous types by its geochemistry characteristic and water status. The source of the water has been confirmed according to its geochemistry characteristics, reference formation water characteristic parameters and water classification by taking the carbonate buried hill reservoir of Ordovician in Lunnan area of Tarim basin as an example. The main factor that influences the water analysis is the sampling condition. It is concluded that the key to properly determine the real aqueous source is to rightly use the information from formation testing and comprehensively understand the geological characteristic and the water occurrence. This method for distinguishing formation water and searching for the real aqueous sources is of some significance to other similar strata for reference.

Key words: Tarim basin, carbonate rock, formation testing, formation water, extraneous water