The Petroleum System of Northern Kashi Sag in Tarim Basin and Exploration Direction

摘要

Northern Kashi Sag is located on the northwestern periphery of Tarim Basin, China. This block has been explored for a half century, and Akmomu gas reservoir was discovered in 2001. In Northern Kashi Sag, organic-rich intervals mainly occur in Carboniferous, Lower Permian and Jurassic. Lower Cretaceous Kezilesu Formation(K_1kz) is dominated by braid river succession and is best in big thickness of 385-862m, high porosity of 14.90% and high permeability of 207.00×10~(-3)μm~2. The first grade cap rocks are gypsolyte and mud-gypsolyte in upper Cretaceous and Paleogene with thickness of 100-200m. Two Petroleum Systems are identified, and one is J_(2y)-N_(1p), Yangye Formation (J_(2y)) serves as source rock, and Neogene Pakabulake(N_(1p)) as reservoir rock. Another is C_1+P_1by-K_1kz petroleum system, Lower Carboniferous and Lower Permian Biyoulieti Formation(P_1by) serve as source rock, and Kezilesu Formation (K_1kz) as reservoir rock. J_(2y)-N_(1p) petroleum system contains abundant oil sand resource. In 2001, Akmomu gas reservoir was discovered by AK＃_1 in C_1+P_1by-K_1kz petroleum system.