Research on the principal reservoir architecture of lacustrine delta-front: A case from the second member 7-8 sand groups of Shahejie formation (Es₂ ⁷-Es₂ ⁸) in Liang 60 fault block

This paper employs techniques for reservoir architecture characterization, focusing on the Liang 60 fault block in the central uplift of the Dongying Sag. It meticulously characterizes the internal structure of the principal reservoir in the lacustrine delta-front subfacies and establishes a reservoir architecture model. The results demonstrate that the study area was divided into 19 periods of a 4th-order reservoir architectural unit in the vertical direction, with the principal reservoir and mouth bar microfacies further subdivided into 70 periods of a 3rd-order reservoir architectural unit. Single mouth bar (4th-order reservoir architectural unit) exhibits three vertical combination patterns: separation, superimposition, and cutting superposition. Three types of planar combination-separation, lapping, and cutting are developed for single mouth bar. Filling modes of inner accretion layering of the mouth bar (3rd-order reservoir architectural unit) included progradation along the source direction and lateral accretion. The established reservoir architecture model accurately reflects the geological development of the target layer in this study area.