The northward subduction of the Neo-Tethys oceanic crust triggered multiple magmatic activities in the West Myanmar Arc,which in turn influenced the deposition of sedimentary pyroclastic rocks from the Cretaceous to E...The northward subduction of the Neo-Tethys oceanic crust triggered multiple magmatic activities in the West Myanmar Arc,which in turn influenced the deposition of sedimentary pyroclastic rocks from the Cretaceous to Eocene strata in the Central Myanmar Basin(CMB).The pore structure of these lithologic reservoirs is complex and rich in tuffaceous sandstone,which plays an adverse role in reservoir development in this region.To understand the development characteristics and genetic mechanism of the pyroclastic rocks within three sets of reservoirs in this area,a comprehensive analysis was conducted through borehole core observations,thin section identification,scanning electron microscope analysis,and mercury injection tests.The tuffaceous sandstone from the upper Cretaceous to the Eocene is dominated by intermediate-acid volcanic rock debris.The pyroclastic rocks exhibit evident chloritization and ironization,with residual intergranular pores being the principal type accompanied by a smaller amount of intergranular dissolved pores and intragranular dissolved pores.The highest porosity is observed in the Eocene tuffaceous sandstone,ranging from 8%to 12%.The Late Cretaceous to Paleocene sandstones exhibit lower porosity levels of only 4%-6%.These reservoirs are characterized by their low porosity and low-permeability.Despite the presence of a good source rock in this area,the volcanic debris particles filling the pores,as well as their subsequent devitrification,chloritization,and limonite mineralization,result in pore throat blockage and narrowing.The reservoirs in this area are small in size,exhibit poor reservoir connectivity and lateral continuity,and fail to meet the necessary conditions for commercial-scale hydrocarbon accumulation and migration.展开更多
基金Supported by the National Natural Science Foundation of China(No.92055203)。
文摘The northward subduction of the Neo-Tethys oceanic crust triggered multiple magmatic activities in the West Myanmar Arc,which in turn influenced the deposition of sedimentary pyroclastic rocks from the Cretaceous to Eocene strata in the Central Myanmar Basin(CMB).The pore structure of these lithologic reservoirs is complex and rich in tuffaceous sandstone,which plays an adverse role in reservoir development in this region.To understand the development characteristics and genetic mechanism of the pyroclastic rocks within three sets of reservoirs in this area,a comprehensive analysis was conducted through borehole core observations,thin section identification,scanning electron microscope analysis,and mercury injection tests.The tuffaceous sandstone from the upper Cretaceous to the Eocene is dominated by intermediate-acid volcanic rock debris.The pyroclastic rocks exhibit evident chloritization and ironization,with residual intergranular pores being the principal type accompanied by a smaller amount of intergranular dissolved pores and intragranular dissolved pores.The highest porosity is observed in the Eocene tuffaceous sandstone,ranging from 8%to 12%.The Late Cretaceous to Paleocene sandstones exhibit lower porosity levels of only 4%-6%.These reservoirs are characterized by their low porosity and low-permeability.Despite the presence of a good source rock in this area,the volcanic debris particles filling the pores,as well as their subsequent devitrification,chloritization,and limonite mineralization,result in pore throat blockage and narrowing.The reservoirs in this area are small in size,exhibit poor reservoir connectivity and lateral continuity,and fail to meet the necessary conditions for commercial-scale hydrocarbon accumulation and migration.
