Dessert Lithofacies Study of Fengxi Tight Oil in Qaidam Basin

Abstract Two kinds of sweet spots were deposited in the shallow-semi-deep lake subfacies during N1-N21 in Fengxi area of Qaidam Basin, but it is not clear which kind of sweet spots are dessert targets. The lithofacies of Fengxi tight oil sweet spot is analyzed from geological and engineering angles, and the optimal target of exploration and development is obtained. From the source rock quality, lithology characteristics, reservoir property, oil content and so on, the geological sweet spot analysis is carried out. The engineering dessert mainly adopts triaxial compression experiment to obtain rock mechanics parameters. Through fracturing physical model experiment, the fracture growth morphology under different geological and engineering conditions is simulated, and the law of hydraulic fracture growth is explored. The structure of algal limestone is dominated by clumps, complex fabric, poor stratification, and high fracture complexity after fracturing. The stratification of laminar lime-dolomite rock is strong, the fracture is easy to spread along the bedding after fracturing, and the fracture complexity is low. Considering the pore structure and post-compaction complexity of the reservoir, it is suggested that algae limestone should be selected as the sweet rock for exploration and development in the Fengxi tight oil area.