Tight Oil Forming Mechanism And Source Rock Evaluation

The comprehensive evaluation of the middle Permian’s source rocks hydrocarbon potential in Malang-Tiaohu sag SanTangHu basin, which provides a basis for the further research of Oil and gas accumulation and next optimizing good exploration area. On the basis of analyzing massive amounts of data about lithology、lithofacies and testing,the mechanism of complex lithology source rock forming tight oil is studied, and then make sure the tight oil and gas source of various reservoirs are determined adopting the method of oil source correlation. The main source rock forming tight oil in middle permian strata is confirmed.Finally, source rock comprehensive evaluation is done, especially the geochemistry evaluation about abundance、type and maturity which is very important. and high quality source rock development zone is predictived, which provides the scientific basis for tight oil exploration in SanTangHu basin.The results prove that siliciclastic and carbonate sediments in LuCaogou formation is a new type of source rock, which forming tight oil and gas. The oil in Lucaogou formation is fron source rocks in Lucaogou formation, which is source and reservoir in the same bed. The oil in Tiaohu formation is fron source rocks in Lucaogou formation, which is the lower-generation and up per-storage pattern. Abundance of source rock is up to better-best level in China, source rock type is from I to II1, and maturity is low. The hydrocanbon generation threshold is up to 1900 m,The Hydrocarbon-generation potential of LuCaogou formation is good in Malang sag, and the maximal total hydrocanbon generation rate is411.19mg/g.TOC. high abundance-mature type(A) and high abundance-low mature type(B)of source rocks are developed in the area. the Tiaohu sag is bad. The source rock abundance is in poor to medium level in Tiaohu formation. The type A of the source rocks only are developed around tiao 25 well, the low bundance-mature type(C) of the source rocks are developed in most of the area.And its kerogen type is II2 to III. Its maturity is in Low to mature stage. The hydrocarbon potential is limited.