Microscopic Characteristics And Tight Reservoir Mechanism Of Lucaogou Group In Santanghu Basin

Based on the micro characterization of the tight reservoir of Lucaogou Formation, combined with the consideration of the effect of reservoir property by diagenesis and diagenetic stage, we figure out the reserve mechanism of target reservoir. These researches will contribute to the study of the petroleum accumulation of Lucaogou Formation, Malang Depression, Santanghu Basin, as well as the chosen of further exploration target. According to the data, the tight reservoir of Lucaogou Formation has fine grains and poor sizing, high clay content and high matrix content. Nano-pores and nano-throat are the majority in this area, so the super-low permeability and anisotropy are. We found good permeability in the reservoir developed in the early diagenetic stage; the sharply increase of impermeable reservoir damage the reservoir a lot. In diagenetic stage A1 sub-period, ultra-low permeability reservoirs with the permeability ≥1mD are found; but in the diagenetic stage A21-A22 micro-period, the majority is the unconventional reservoirs with permeability < 0.1mD. With the secondary pore widely found, we conclude that the tight reservoir of Lucaogou Formation is a typical tight diagenesis reservoir; the major factor to be tight is sediment factor, with the help of diagenesis factor.