A study on hydrocarbon generation potential of deep source rocks and gas sources in Changling Fault Depression, Songliao Basin

Through natural gas exploration in the Changling Fault Depression, abundant natural gas flows were obtained and high-quality source rocks were also reveiled. Based on bulk analyses, organic matter abundance, organic matter type and thermal maturity of the source rocks were studied systematically. At the same time, gas generating intensity and gas generating quantity were quantitatively analyzed by using basin modeling technologies. The results indicated that gas source rocks of the Shahezi Formation are characterized by abundant organic matter and dark mudstone distributions and high-over thermal maturity. They possess high gas generating intensity with the biggest value surpassing 500×108 m3/km2, and large gas generating quantity, accounting from 74.40% of the total amount. The Yingcheng Formation has good gas-source rocks with moderate dark mudstone and relatively high organic matter. It has type-III organic matter and low-over thermal maturity. The gas generating intensity is moderate, between 20×108 and 60×108 m3/km2. The gas generating quantity is 13.63% of the total amount. The Huoshiling Formation has relatively good source rocks with limited dark mudstone and low organic matter. It has type-III kerogen and over-thermal maturity. The gas generating quantity is 7.10% of the total amount. The Denglouku Formation has poor-gas source rocks, and is characterized by undeveloped dark mudstone and low organic matter abundance. It has type-III organic matter and low-high thermal maturity. Hydrocarbon gases in the Changling Fault Depression mainly originated from the Shahezi Formation, and secondarily from the Yingcheng Formation. The contribution of the Huoshiling Formation gas source rocks is relatively small. © 2011 Science Press, Institute of Geochemistry, CAS and Springer Berlin Heidelberg.