Acta Petrologica et Mineralogica

Recently, the bauxite gas reservoir of Taiyuan Formation has become a hot spot of exploration in Longdong area of Ordos Basin. In order to systematically explore the distribution of bauxite rock and the main controlling factors of reservoir formation, based on the latest drilling cores, rock slices, three-dimensional seismic, logging, scanning electron microscopy, model forward modeling and other methods, the distribution characteristics of bauxite rock in Taiyuan Formation were studied in detail, and then the main controlling factors of bauxite rock reservoir formation were expounded. The results show that the aluminiferous rock series has a typical five-stage type in the longitudinal direction, in which the C section is the main reservoir section of the bauxite rock, and the content of diaspore is more than 80%. The longitudinal lithologic association of the aluminiferous rock series is mainly controlled by the karst paleogeomorphology unit. The distribution characteristics of bauxite in karst highland, karst slope and karst depression are punctate, banded and flaky, respectively. The bauxite reservoir in the karst slope area is the most developed. The enrichment of natural gas in bauxite rock is mainly controlled by high-quality reservoirs, faults, fractures and structural positions. Reservoirs are the premise of natural gas enrichment and high yield. Early faults show construction effect, and late faults show destruction effect. Fractures can improve reservoir physical properties. Low-amplitude structures or nose-like traps in high structural parts are more likely to accumulate. Karst slope area is the most favorable paleogeomorphologic unit for natural gas accumulation in bauxite rock.

Ordos Basin; karst paleogeomorphology; aluminiferous rock series; distribution characteristics; natural gas enrichment