Discovery of oil seepage from the Middle Triassic of Luoping area, eastern Yunnan, China

Oil seepage was discovered for the first time from thin-bedded micritic limestone of the second member of the Guanling Formation in Luoping area through 1∶50000 regional geological mapping. Oil seepage distributes mainly in crystal caves. Coexistence of dry asphalt and thickened is observed. Organic geochemical analyses show that the contents of chloroform bitumen "A" is 67×10-6 and sapropel-based type Ⅰ is the primary type of organic matter. The kerogen vitrinite reflectance R0 is 2.84% and Tmax = 568 ℃ indicating a higher maturity of the organic matter. The discovery of oil seepage in Luoping area is of great significance in further evaluation and exploration of oil and gas in Nanpanjiang Basin.