Recognition of Cambrian Pre-salt Source Rock in the Central and Western Part of Tarim Basin

The mudstones of lower Cambrian Yuertus Formation in the central and western part of Tarim Basin have been regarded as the major source rocks,with little consideration to the carbonate rocks of Xiaoerbruk Formation.However,the observation of field outcrops and drilling cores,together with the data of pyrolysis analysis,demonstrates the lagoon facies carbonate rocks of Xiaoerbruk Formation is also one of the major Cambrian pre-salt source rocks by the facts that it is more stable in the lateral distribution,thicker,relatively high content of organic matter,advantageous type of organic matter as well as high maturity.