Surface hydration‐induced damage in tight oil‐bearing sandy conglomerate reservoirs

Abstract This study focuses on the surface hydration‐induced damage in the tight oil‐bearing sandy conglomerate reservoirs of the Mahu oilfield. Through experiments on core samples, a distinct two‐stage surface hydration process is identified. In the first 0–100 min, the hydration rate is high, with diverse sample reactions, while from 100 to 540 min, the rate is lower and sample reactions are more uniform. Mineralogically, smectite promotes hydration, particularly in the later stage, while chlorite may inhibit it. Plagioclase shows a promoting effect, but the impact of potassium feldspar on hydration remains ambiguous. Elementally, carbon facilitates hydration, while silicon hinders it. Magnesium does not enhance hydration and may be linked to reduced oil content and increased porosity, and calcium oxide may promote hydration and porosity increase. Infrared thermal imaging indicates that hydration causes fragmentation of sandy conglomerates, attributed to smectite's water‐absorption expansion, mineral dissolution/precipitation, and hydrolysis. These findings not only contribute to a deeper understanding of the hydration mechanism in the tight oil‐bearing sandy conglomerate reservoirs of the Mahu oilfield but also provide crucial references for the development of sandstone and conglomerate reservoirs with similar geological conditions worldwide. By grasping the influence laws of minerals and elements on hydration, petroleum engineers can more accurately formulate extraction strategies, effectively improve reservoir recovery rates, and promote the efficient development and utilization of unconventional oil and gas resources.