The authors focus on the ultra-low permeability reservoirs of Chang 4+5 reservoir period of Yanchang Group, Jing’an oil field, Ordos Basin. Cores, thin sections, wireline logs, and imaging logs were used to understand depositional systems, reservoirs and to furtherly characterize vertical and horizontal distribution patterns of sandstones. The results show that main reservoirs of Chang 4+5 of Yanchang Group are composed of medium-tofine grained arkose. Parallel beddings and cross beddings are common. Interpartical pores and a few fractures are main reservoir spaces and reservoir quality is poor. Sand bodies are uniformly distributed in the horizontal direction with brand shape and thickness between 2 to 5 meters. Front delta is the main sedimentary subfacies. Distributary main channel, distributary shallow channel, distributary shoal, and inner distributary bay are four main sedimentary microfacies. In the vertical direction, distributary main channels and distributary shallow channels are distributed reciprocally related to the variation of hydrodynamic power. The research result is a guidance on the hydrocarbon exploration in this region.

Rice calli keep proliferating constantly without differentiation on N₆ medium, but can be induced to differentiate to form roots when they are treated with ABA. Basing on this physiological feature, RNAs were extracted from the calli cultured on mediums with or without ABA respectively, and hybridized with the rice cDNA microarray. By analyzing the cDNA microarray data, The authors totally obtained 271 genes associated with root differentiation from calli, including 107 up-regulated genes and 164 down-regulated genes. This preliminary result provides new clues for further study on the molecular mechanism of root differentiation of rice calli.