Reservoir quality analysis is aimed at characterizing and locating favorable pore systems in the subsurface. Over the past two decades, and especially in the major deep-water plays, typical siliciclastic exploration targets have evolved from quartzose sandstones found in shallow, cool burial environments to sandstones that contain abundant chemically unstable grains and occur in deeper, hotter, and older burial settings. Sandstones containing such reactive grains are subject to extensive chemical diagenesis during burial that includes grain dissolution and precipitation of a variety of mineral cements and grain replacements. The increasing complexity of plays provides new challenges to reservoir quality specialists when evaluating reservoir quality away from well control. Standard industry modeling tools were primarily designed to emulate physical compaction and quartz cementation on a genetic basis, and most of the remaining non-quartz cements in these models are evaluated by ad hoc, non-genetic methods. Prediction of clay, zeolite, and carbonate cements may be especially challenging in emerging exploration areas.