Determination of the Lower Limit of Physical Properties of Tight Oil Reservoirs: A Case Study of the Lower Es(3) in the Jiangjiadian Area, Linnan Sag

[Image: see text] The tight oil reservoir in Linnan Sag has great potential, a wide distribution range, and large total predicted resources. The rapid accumulation and burial of sediments in multiple source directions have resulted in the characteristics of low porosity and low permeability of the Lower Es(3) in the Jiangjiadian area, Linnan Sag. Based on conventional core analysis data, mercury injection data, and oil testing data, this paper comprehensively determines the lower limit of effective physical properties of reservoirs in the Jiangjiadian area of Linnan Sag and studies its main influencing factors. The results show that (1) the lower Es(3) reservoir in the Jiangjiadian area of Linnan Sag mainly develops feldspar sandstone and lithic feldspar sandstone. The porosity is mainly distributed at about 12%, and the permeability is mainly distributed at 0.3 mD; (2) based on the study of reservoir characteristics, the empirical statistical method based on core analysis data and the pore–permeability intersection method, the mercury injection parameter method based on test data, and the oil test verification method are used to comprehensively determine the lower limit of physical properties in the study area. The lower limit of porosity is 7.87%, and the lower limit of permeability is 0.16 mD; (3) sedimentation mainly affects the lower limit of physical properties by controlling reservoir lithology and pore structure. The existence of compaction and cementation in diagenesis will reduce the reservoir porosity and affect the lower limit of effective physical properties. The secondary dissolution pores formed by dissolution have a certain improvement effect on the effective physical properties of the reservoir.