Laminae characteristics of lacustrine shales from the Paleogene Kongdian Formation in the Cangdong Sag, Bohai Bay Basin, China: Why do laminated shales have better reservoir physical properties?

Differences between Laminated and Massive Shales in the Permian Lucaogou Formation: Insights into the Paleoenvironment, Petrology, Organic Matter, and Microstructure

“…Xin et al compared laminated and massive shale samples in the Kongdian Formation (Fm.) and concluded that laminated shale presents better physical properties than massive samples . These studies show that the petroleum accumulation difference caused by paleoenvironment discrepancy should be emphasized.…”

“…The content of anhydrite is least in massive shale samples, and the massive source rock has higher pyrite content than fine and thick laminated shale (Table ). According to the ternary graph based on carbonate, clay, and felsic mineral contents, the laminated shale mainly belongs to mixed shale and calcareous shale, and the massive samples are mainly scattered in the calcareous shale, argillaceous shale, and siliceous shale (Figure ).…”

“…In recent years, benefiting from a breakthrough in horizontal drilling and hydraulic fracture techniques, oil production from fine-grained sediment reservoirs has become notable. Among the fine-grained rocks, the mineral compositions in laminated and massive shales might be similar; however, their physical properties are different . In addition, the orderly arrangement of mineral and organic matter (OM) makes the pore structure of laminated and massive shales vary at the multiscale. , Combined with fine scattered silt grains, the laminated, organic-rich shale is considered the ideal source rock for shale oil .…”

“…Among the fine-grained rocks, the mineral compositions in laminated and massive shales might be similar; however, their physical properties are different . In addition, the orderly arrangement of mineral and organic matter (OM) makes the pore structure of laminated and massive shales vary at the multiscale. , Combined with fine scattered silt grains, the laminated, organic-rich shale is considered the ideal source rock for shale oil . The research on laminated and massive shales has become a hot topic and is important for accurately evaluating petroleum energy resources. − …”

Pore types, genesis, and evolution model of lacustrine oil-prone shale: a case study of the Cretaceous Qingshankou Formation, Songliao Basin, NE China

“…Although studies have emplofyed low-pressure gas adsorption analysis to clarify the occurrence of intragranular and dissolution pores in the lacustrine Qingshankou shales of the Gulong sag 16 , the unreliability of low-pressure gas adsorption data for describing of shale pore types 18 necessitates further investigations using sample imaging techniques such as FE-SEM. Furthermore, the relevance of using XRD and FE-SEM without combing with experimental fluid penetration techniques, such as mercury injection capillary pressure (MICP) and low-pressure gas adsorption, to evaluate the pore structure and composition in lacustrine shales was recently proposed in an investigation of pore structure in the Kongdian Formation 19 . The types and composition of pores within the lacustrine shale samples observed through FE-SEM are discussed in this section.…”