Hydrocarbon filling and chemical diagenesis evolution of the clastic reservoir of the Paleogene in Dongying Sag

The micro characterstics of minerals in clastic reservoir, their assemblage features and the distribution features of clastic grains from different formations, cements and clay minerals in sedimentary profile in Eocene from Dongying Sag, Jingyan Depression are presented. The primary diagenesis of clastic reservoir and its geochemical process, and discusses the geological/geochemical factors controlling diagenesis of clastic rocks are analyzed. This study shows that the geological/geochemical factors controlling diagenesis of the reservoir rocks, including lithologic features of parent rocks, reservoir petrofacies, changes of pore water character in formation, filling of early stage calcites and hydrocarbon in pore. The most important factor is the alteration of geochemical conditions of pore water. The early stage precipitation of calcites, corrasion of feldspars and calcites, the geological/geochemical condictions for the formation and conversion of clay minerals, and the controlling roles that petroleum inflow plays in the evolution of reservoir diagenesis are presented.