Genetic Types of Deep Natural Gas in Guxi Fault Zone in Jiyang Depression

Key words: 
• deep natural gas /
• genetic type /
• ternary geochemicaltracing system /
• Guxi fault zone /
• Jiyang Depression

Abstract: The deep natural gas in Guxi fault zone is of the characteristics such as multisource and complex genesis. In view of this problem, based on the analysis of source rocks characteristics, the ternary geochemicaltracing system of natural gas and biomarkers of associated oil were used in order to clarify the geochemical characteristics and genesis of natural gas in the area, combining with analysis on geologic condition of gas pools. It is proposed that the natural gas in Guxi fault zone shows certain regularities and shifts from oiltyped gas to coaltype gas from west to east. Gas in Boshen 6 buried hill is the mixture of highmatured oiltype gas from upper Es4 source rocks in Bonan subsag and oilassociated gas from lower Es3 source rocks. Natural gas from Bogu 4 buried hill mainly consists of highmatured oiltype gas sourced by upper Es4 source rocks, mixed with coaltyped gas. Gas in the second row of Gubei buried hill is the mixture of coaltype and oiltype gas, and natural gas from the third and forth rows is mainly composed of coaltype gas generated by the upper Paleozoic source rocks.