Formation of chlorite rims and the impact of pore-lining chlorite on reservoir quality: a case study from Shiqianfeng sandstones in upper Permian of Dongpu Depression, Bohai Bay Basin, eastern China

The formation mechanism of authigenic chlorite in tight sandstone and its effect on tight oil adsorption during hydrocarbon filling

“…Authigenic chlorite is produced during diagenesis, with a generally relatively complete crystal shape is generally relatively complete, with sharp edges and corners and clear edges (Zhang et al, 2012;Ma et al, 2017aMa et al, , 2017bWorden et al, 2020). Chlorite is a layered silicate mineral that forms in an iron-rich, alkaline-reduction environment (Anjos et al, 1999;Huang et al, 2004;Huggett et al, 2015; Worden et al, 2020).…”

“…Therefore, it is necessary to discuss the impact that chlorite has on the quality of the reservoir. Many studies have investigated the effects of authigenic chlorite on reservoir quality (Baker et al, 2000;Berger et al, 2009;Chen et al, 2011;Ding et al, 2010;Ehrenberg, 1993;Huang et al, 2004;Liu et al, 2009;Liu and Li, 1996;Ma et al, 2017aMa et al, , 2017bPittman, 1992;Salman et al, 2002;Yao et al, 2011). However, the protection mechanism of authigenic chlorite on the quality of the reservoir has been inconclusive.…”

“…This indicates that the initial physical properties are mainly determined by the petrological characteristics of sand bodies that are deposited under strong hydrodynamic conditions (Berger et al, 2009;Worden et al, 2020). However, the development of authigenic chlorite does not preserve the primary pores; in contrast, it destroys them, particularly during the reconstruction of throats (Zhang et al, 2012;Ma et al, 2017aMa et al, , 2017b.…”

“…The paleo-climatic environment during deposition, the fluid nature of the burial diagenesis stage, the weathering of terrigenous volcanic rocks, and the dissolution of lithic debris are all considered to be important factors that control the formation of chlorite.The supply of iron-magnesium-rich materials and the geochemical conditions of the fluid control the growth of authigenic chlorite, which is predominantly precipitated in diagenetic fluids with a high pH (alkali-rich environment) that are rich in Fe 2+ and Mg 2+ (Zhang et al, 2012;Worden et al, 2020). Sufficient volcanic material supply is considered to be one of the most important conditions surrounding the formation of large amounts of authigenic chlorite; this is particularly true of volcanic events, which may have had a significant impact on the precipitation of chlorite during the Mesozoic-Cenozoic periods in the Ordos Basin (Zhang et al, 2012;Ma et al, 2017aMa et al, , 2017b. The wide distribution of the Mesozoic-Cenozoic lacustrine sandstone reservoirs means that these features can provide important information on the fluid evolution, chemical composition changes, and diagenetic evolutionary processes that occurred in reservoirs.…”

“…Chlorite has been of interest to petroleum geologists for well over 50 years, ever since its association with deeplyburied sandstones became apparent (Heald and Anderegg, 1960;Pittman and Lumsden, 1968;Zhang et al, 2012;Ma et al, 2017aMa et al, , 2017bWorden et al, 2020). However, some texts and primary sources of geological and mineralogical information neglect the effect that chlorite is an essential constituent of many sedimentary and diagenetic systems (King, 2019), and that it can affect the reservoir fluid environment of a reservoir during hydrocarbon filling.…”