Solid bitumens are distributed widely in the organic reef and bank-facies reservoir of marine-facies carbonate in the northeast of the Sichuan basin.This paper focused on the solid bitumens of Upper-Permian Changxing Formation and Lower-Triassic Feixianguan Formation reservoirs in the Puguang Gas Field.Based on our observation under microscope,their contents and the volumetric proportions of the solid bitumens to reservoir pore,this study analyzed genesis and forming period,finally calculated the density of palaeo-reservoirs.The solid bitumens of Feixianguan Formation in the Puguang Gas Field occurs mainly as circular banded in pores and dissolved pores and walls in oolitic dolomite and remnant oolitic dolomite.The content ranges from 1.11 % to 5.73%,averaging to 2.92%.The solid bitumens of Changxing biogenetic reef reservoir occurs mostly as patches in various dissolved pores,with the contents ranging from 0.31% to 11.72%(averaging to 3.57%).The contents of the solid bitumen are decreasing with depth.Volumetric proportions between solid bitumen and reservoir pore is about 22% for the Feixianguan reservoir and 43%~56% for the Changxing reservoir.The solid bitumen of the Puguang Gas Field is thermal evolution in origin and had two forming periods.The solid bitumen of Feixianguan reservoir was generated from cracking of light oil palaeo-reservoir,while the solid bitumen of Changxing reservoir was generated from cracking of heavy oil palaeo-reservoir.