Controlling Factors of Meteoric Diagenesis in Karst Reservoirs: An Example from the Majiagou Formation, Ordos Basin, China

Karst reservoirs have always been a key field of oil and gas exploration. However, quantifying the process meteoric transformation remains persistent challenge that limits accuracy reservoir quality prediction. To explore controlling factors cementation on karst reservoirs, Majiagou Formation Ordos Basin in China was selected as an example. The petrology; carbon, oxygen, strontium isotopes; situ major, trace, rare earth elements were used, types origins calcite cements analyzed detail. results revealed five (Cal-1~Cal-5), four cathodoluminescence (CL) intensities (dull, dull red, deep bright red luminescence), six element patterns (Pattern-1~Pattern-6). These developed three periods. Cal-1 (transition CL) Cal-2 (dull precipitated during Early Pennsylvanian period, freshwater clean; Cal-3 Cal-4 (bright at end Late Carboniferous fluids had strong dissolution ability polluted by terrigenous debris; Cal-5 deposited burial fluid pure pore water or groundwater. control cement period much weaker than cements. Therefore, explorations should be focused weak epigenetic period.