Dynamic Control of Multimineral Diagenetic Processes on the Evolution of Pore-Throat Structures and Hydrocarbon Accumulation Windows in Tight Sandstone Reservoirs

The evolution of pore and throat structures in tight sandstone reservoirs plays a critical role in determining reservoir quality and hydrocarbon accumulation efficiency. Despite growing attention to the impact of diagenesis on reservoir heterogeneity, the synergistic effects of multiple authigenic minerals and their dynamic control on hydrocarbon accumulation windows remain poorly understood. This study investigates typical tight sandstone reservoirs, including the Yanchang Formation in the Ordos Basin, the Wutonggou Formation in the Junggar Basin, and the Messinian salt crisis deposits in the Nile Delta Basin. Using advanced techniques such as scanning electron microscopy (SEM), cathodoluminescence (CL), synchrotron radiation analysis, thermodynamic modeling, and 3D pore-throat network reconstruction, we systematically analyze the interplay between zeolite and clay minerals during diagenetic evolution and their implications for reservoir quality.

The results demonstrate that early-stage zeolite dissolution significantly enhances pore structures, with an increase in porosity of 10%-18%, forming secondary pore-dominated "pore reconstruction zones." Subsequently, the progressive precipitation and cementation of clay minerals, such as smectite-illite mixed layers, lead to substantial pore-throat blockage, reducing permeability by 30%-45%. Chlorite coatings initially protect grain surfaces by delaying compaction, but excessive chlorite precipitation in later stages exacerbates pore-throat clogging and permeability degradation. Based on time-sequential analysis and thermodynamic modeling, we introduce the innovative concept of the "dissolution-accumulation window" and quantitatively define the critical reservoir properties for efficient hydrocarbon charging (porosity >8% and permeability >0.01 mD).

Regional comparative analysis highlights distinct diagenetic pathways under varying depositional and diagenetic environments. In the Ordos Basin, feldspar dissolution and kaolinite precipitation significantly improve reservoir quality, while intense zeolite cementation in volcanic lithic sandstones of the Junggar Basin accelerates reservoir densification. In the Messinian deposits of the Nile Delta, deep burial clay mineral transformations dominate reservoir heterogeneity and permeability reduction. This study develops a "dissolution-fill-reconstruction" multi-stage diagenetic evolution model, providing novel insights into the dynamic control of multimineral diagenesis on pore-throat structures and hydrocarbon accumulation. The findings offer a theoretical framework for predicting high-quality reservoirs across basins and guiding effective hydrocarbon exploration and development.

Keywords
Tight sandstone, Diagenesis, Pore-throat structure, Zeolite minerals, Clay minerals, Hydrocarbon accumulation window