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Rare-earth orthoferrites are receiving ever-increasing attention for their potential applications in magneto-optical switching, multiferroics, and novel physics originating from complicated interactions between magnetic rare-earth and iron ions. In this work, a Dy0.5Pr0.5FeO3single crystal was studied in comparison with DyFeO3and PrFeO3single crystals to ascertain the effects of interactions between rare-earth spins in Dy0.5Pr0.5FeO3on its magnetic properties. Dy3+and Pr3+spins do not behave as separate entities in Dy0.5Pr0.5FeO3. The interaction between them was found to be the strongest below their antiferromagnetic ordering temperature. However, this interaction still persists to substantially higher temperatures. While the ordering temperature of Dy3+spins is field-independent for DyFeO3, it becomes strongly field-dependent for Dy0.5Pr0.5FeO3. External field produces field polarization of nonordered rare-earth spins below ∼25 K for all three systems. High-field-induced spin transition of rare-earth spins was observed for Dy0.5Pr0.5FeO3when a large field H≥ 3.5 T is oriented along the crystalline a-axis at temperatures below and above the ordering temperature of the rare-earth spins, while the Fe3+spin structure was not affected. This is different from the field-induced spin reorientation of the Dy3+spin structure in DyFeO3, which occurs only when Dy3+spins are ordered. The complicated behavior of rare earths uncovered in this work further deepens the understanding of such a complex material system.

La-Sa-Xing oilfield is the maximum continental multi-layered sandstone reservoir in China, which has already entered the ultra-high water-cut development stage. Three major contradictions are more prominent and residual oil is highly scattered, the traditional qualitative reservoir evaluation method is hard to meet the demand of current reservoir production and development. According to the requirement of production situation and technology development at ultra-high water-cut stage, combining fine reservoir geological characteristics and development efficiency, a new reservoir evaluation method is established by using multi-parameter product method, multi-parameter bound analysis, etc. The method proposed is set up with storage-permeate assessment parameter and dominant sand-body distribution degree as assessment parameters. It establishes the relationship between static geology and dynamic production and reveals a certain oil-layer potential. The introduction of dominant sand-body distribution degree emphasizes the reservoir plane heterogeneous characters, it can quantitatively characterize the matching relationship between reservoir and well pattern; the reservoir classification based on the above two aspects providing reliable basis for designing water flood, polymer flood and ASP flood development plan.