On the basis of detailed stratigraphic sedimentary description, as well as about 10000 analytic data and 3000 shallow-drilling reservoir samples from 4 outcropped profiles and 4 wells, it is believed that a braided delta depositional system was well developed in the Lower Jurassic. The major reservoir sand bodies are braided distributary channels of delta plain subfacies and subaqueous distributary channels of delta front subfacies. With the Tuziluk area as the boundary, the eastern and western parts of this suite of reservoirs are notably different in diagenesis, properties and forming mechanisms of the reservoirs. This research shows that the grain size of sandstone, stratigraphic burial history and lateral tectonic compression are the critical factors causing the difference. In time domain, the grain size of sandstone affects the reservoirs, while in space domain the remarkably difference of reservoir properties is controlled by the stratigraphic burial history and lateral tectonic compression.