Analysis and application of carbon-bearing rate of reservoirs in the Puguang gas field, northeastern Sichuan Basin

With wells Puguang 2 and 6 in the Puguang gas field as the research objects by choosing organic carbon as characterization reservoir carbon (indirectly reflecting the bitumen contents), this paper discusses the relationship between bitumen contents and lithologic characteristics, reservoir characteristics, and calculates the volume of paleooil and oil cracked gas. The study shows that the organic carbon contents of the reservoirs are related to lithologic characteristics. Due to variations in the particle size or structure of rocks, the porosity of the reservoirs varies, furthermore, it will influence the contents of organic carbon. And the relationship between these two parameters is positive. Based on the analysis, the relationship between total organic carbon (TOC) and the contents of reservoir bitumen also appears to be positive. The volume of paleo-oil and cracked gas of the Changxing-Feixian’guan Formation are respectively 495 million tons and 360.4 billion m³ through the calculation of reservoir’s organic carbon. Therefore, the relationship between carbon-bearing rate and characteristics of the reservoirs can be used to indirectly evaluate reservoir types. Besides, the carbon-bearing rate of the reservoirs also reflects the contents of reservoir bitumen, paleo-oil as well as natural gas. It makes a new approach for the study of the types of reservoirs and the amounts of paleo-oil and oil cracked gas in northeastern Sichuan Basin.