Fault activity and hydrocarbon accumulation significance of structural belt in northern Kuqa Depression

The tectonic belt in northern Kuqa Depression has a long period of fault activity and multi-stage superposition, which has an important influence on hydrocarbon accumulation.Through the combination of growth index profile method, typical profile elongation (or compression ratio) method and structural equilibrium profile method, the development characteristics, active periods and hydrocarbon accumulation significance of faults in the northern Kuqa Depression are studied.The results show that there are three types of faults in the northern Kuqa Depression: early thrust fault, late thrust fault and long-term active fault.There are five periods of fault activity, which are paleogene (E), Neogene Jidike Formation (N₁j), Kangcun Formation (N₁k), Kuqa Formation (N₂k) and Quaternary (Q) respectively.N₁j, N₁k and N₂k are the key periods of fault activity.The fault activity will lead to the thickening of the source rocks in the Kezilenuer Formation (J₂kz), which is conducive to the formation of multiple types of structural and lithologic traps.The fault active periods (N₁j, N₁k, N₂k) match well with the main hydrocarbon generation and expulsion periods (E, N₁j, N₁k, N₂k) of source rocks.The fault activity is beneficial to the formation and accumulation of oil and gas reservoir Yinan 2 and Tundong 2, but it also lead to the escape of oil and gas escape from Yinan 4 and Yishen 4 Wells, resulting in the destruction of reservoir forming and preservation conditions.The fingdings are of great significance to the analysis of hydrocarbon accumulation process in this area.