Abstract:

worIn recent years, multiple types of high density methane inclusions have been discovered in northeast Sichuan. The geological occurrences of methane inclusions were investigated, and their microscopic Raman spectra were analyzed. Pyrobitumenbearing high density methane inclusions occur in Triassic carbonate and clastic reservoir rocks in Puguang gas field,and were postulated resulting from later stage high temperature cracking of oil inclusions trapped at early stage of oil reservoir formation; H2Sbearing, instead of pyrobitumenbearing, high density methane inclusions occur in carbonate reservoir rocks in the well Puguang 5, indicating that CH4 inclusions and “TSR”formed H2S fluid inclusions were trapped in newly grown calcite crystals at the stage of high temperature cracking of old oil reservoirs; abundant high density methane inclusions and small quantity of light hydrocarbon inclusions occur in lower Silurian siliceous rocks drilled from the well Wuke 1, indicating that the organicrich lower Silurian black shale showing high maturation contains high pressure methane and light hydrocarbon in its geological history. These different types of high density methane inclusions listed above show different genetic mechanisms and different high temperature and high pressure conditions. The authors believe that the results would be helpful for exploration and assessment of gas resulting from cracking of old oil reservoirs and gas from Silurian shale in northeast Sichuan.

Key words:  high density methane inclusions, microRaman spectroscopic analysis, hightemperature cracking of crude oil and gas form shell