Abstract：Based on well logging and seismic data,through observation of core and thin section and scanning electron microscopy,combined with test results of porosity,permeability,trace elements and isotopes,the stratigraphical correlation,sedimentary characteristics,reservoir characteristics and diagenesis of the gas reservoir in Member 2 of Lower Triassic Jialingjiang Formation in Heba area,northeastern Sichuan Basin were analyzed.The results showed that:(1)The Member 2 of Jialingjiang Formation can be divided into Upper,Middle,and Lower Sub-Members, and the main reservoir developed in the Middle Sub-Member dolostone of restricted platform which was dominated by intra-platform shoal,tidal flat and lagoon microfacies.The intra-platform shoal mainly located in the middle of Heba area and was the most favorable sedimentary microfacies for reservoir development.(2)Reservoir rocks mainly include residual (algae-) sand-sized introclast dolostone and fine silt-zized crystalline dolostone with intercrystal(dissolved)pores and intragranular dissolved pores.It was dominated by Ⅲ-type reservoir with low porosity and low permeability.The reservoir space type is fracture-porosity type.(3)Several types of diagenesis were developed,such as micritization,dissolution,cementation or filling,dolomitization,compaction-pressolution and fracturing.The reservoir was mainly controlled by penecontemporaneous meteoric dissolution,burial dissolution and tectonic fracture.(4)The penecontemporaneous meteoric dissolution was the key factor controlling the development of reservoir pores in granular carbonate rocks of the Member 2 of Jialingjiang Formation,and some burial diagenesis,such as dolomitization and burial dissolution,promoted the development of reservoir pores.Thus,the favorable exploration targets were distributed in microtopography uplands and areas where faults and fractures developed.
Li Hongtao,Wu Wenbo,You Yuchun et al. Sedimentary characteristics and diagenesis of the gas reservoir in theLower Triassic Jialingjiang Formation in Heba area, Sichuan Basin[J]. JOPC, 2014, 16(1): 103-114.
