Characteristics of clastic rock reservoir accumulation in Avat area of the Tarim Basin

Through the analyses of reservoir rock fluid inclusions in different layers of important drilling wells in Avat area of the Tarim Basin, we found that hydrocarbon charges had occurred in the Paleozoic-Cenozoic clastic reservoirs. For the Silurian reservoirs, hydrocarbon charges took place during the late Caledonian, the late Hercynian, and the Himalayan. For the Devonian reservoirs, there were two charging periods:the late Hercynian and the Himalayan. For the Triassic and Paleogene reservoirs, hydrocarbon charges took place during the late Himalayan. However, reservoirs failed to form due to the poor matching relation between hydrocarbon source and traps, poor preservation conditions, and the missing of hydrocarbon migrating faults. The analyses of source rocks and tectonic evolution history showed that, the Paleozoic carbonate and clastic rocks formed primary oil and gas pools while the Mesozoic clastic rocks formed secondary oil and gas pools in the transition zone between the Awat Sag and palaeo high. Stratigraphic and lithologic traps with oil source faults are favorable exploration targets.