Geneses of dolomites and dolomite reservoirs: Review, advances, and prospects

This study systematically reviews and summarizes the history and advances of research on the geneses of dolomites and dolomite reservoirs, and outlines the prospects for future research orientations. The study of dolomites has had a history of over 200 years, while research on dolomite reservoirs has been kicked off since the 1950s. Previous studies established dolomitization models under varying geological conditions represented by seepage reflux and burial-compaction, and explained the geneses of dolomites with varying characteristics and occurrences in nature. Accordingly, the dolomite pores may mainly result from dolomitization as concluded. Over the past decade, progress has been made by incorporating modern sedimentary observations and simulation experiments, and four genetic types of dolomites have been identified, that is, the low-temperature organic precipitation type, the low- and high-temperature metasomatism types, and the high-temperature inorganic precipitation type. Based on this, the plot for identifying the geological and geochemical characteristics of dolomites is developed. It has been revealed that the genesis of dolomites cannot be simply equated with that of dolomite reservoirs. The porosity in dolomite reservoirs is mainly inherited from original porosity followed by modification, featuring more significant facies control and inheritance rather than modification. Although some dolomite pores are the products of burial dissolution, early-stage dolomitization is favorable for pore preservation. Two dolomitization pathways, i.e., dolomitization with protolith texture preserved and burial-based limestone dolomitization, have been identified, with the former exhibiting the optimal reservoir-forming effects. The advancements in experimental techniques have deepened the understanding of the geneses of dolomites, while simulation experiments provide deep insights into the geneses of dolomite reservoirs. In response to hydrocarbon exploration and production, future research should intensify the fine characterization and modeling of dolomite reservoirs, as well as logging-based reservoir identification and seismics-based reservoir prediction using the geological models of reservoirs.