To address evaluation challenges of A Oilfield's D oil layer shale reservoirs (high clay 40% ~ 45%, low maturity Ro < 0.75%, strong vertical porosity heterogeneity 5% ~ 10%), this study developed a logging-core coupled technical system. Integrating multi-well data, a “data-model-verification” loop achieved high-precision parameter calculation: mineral composition error < 5% (traditional > 12%), porosity error < 8% (industry standard < 10%), oil saturation error 4.8%, in-situ stress error 2.0 MPa. Significant “four properties” differences were revealed: D1 with high TOC (2.8%), porosity (9.8%), oil saturation (62.3%) shows strong resource potential; D2 with high brittleness (44.6%) and low fracture pressure (37.8 MPa) exhibits excellent recoverability. This system overcomes traditional logging limitations in micro-nano pore (<1μm) and dispersed clay characterization, providing reliable support for lacustrine shale oil sweet spot prediction and serving as a promotable paradigm for similar high-clay low-maturity reservoirs, with significant value for unconventional oil and gas development.