Studies Of The Exploration Technology Of Interior Lake Heterogeneous Carbonate Reservoirs

The exploration history for hydrocarbon resources at home and abroad have proved that nowadays, people pay more and more attention to the exploration for complex reservoirs and carbonate reservoirs, which gradually become the main targets of exploration and increasing reserves and production during the advances of human society.The interior lake carbonate reservoirs of Daanzai member in Sichuan Basin were formed in the lean hydrocarbon geological settings, its reservoir is typically interior lake carbonate buildup, which is rarely seen both at home and abroad. Due to its strongly heterogeneous characteristics, its reservoir formation feature, hydrocarbon distribution pattern, trap characteristics and the suitable exploration technology are quite different from other conventional reservoirs and marine carbonate reservoirs. For this special and complex interior lake heterogeneous carbonate reservoirs, based on the basic knowledge of the petroleum geology, the main factors controlling the reservoir formation have been identified, reservoir formation model and geological model having been established, and the petroleum accumulation pattern having been indicated in this study. Furthermore, according to the summary of the recent exploration practice, a series of exploration methods including the geological prediction method for reservoirs, seismic identification and prediction methods for reservoirs and reservoir engineering technology have been established thereafter.The main achievements and innovation in this study are listed as follows:The mixed sedimentary buildup of shell limestone and clastic rock was the product of interior depression lake sediments formed in the particular geohistory during the process of formation and evolution of Sichuan Basin. The basin formation, evolution and regional framework macroscopically controlled the distribution of the sedimentary faciestract, vertical changes in sedimentary facies sequence, the relation between the characteristics of source - reservoir- seal and their assemblage, local structure characteristics, diagenetic history and reservoir formation history and the particularity and complexity of the reservoirs.Oil - bearing interval of Daanzai member is characterized by its self- origin, self- storage and relatively separate hydrocarbon system. In this hydrocarbon system, three main factors including the low abundance level of hydrocarbon resources, the strongly heterogeneous reservoirs and the interbedded lamina of shale and shell limestone resulted in the particularity and complexity of the Daanzai reservoirs.The long time opposing reaction caused by the rigid basement uplift of central Sichuan Basin has made the oil and gas bearing interval mainly distribute in the uplift - slope position in the geohistory, the...