Graptolite-rich shale is the main layer of shale gas resources in the southern marine sedimentary basin. Recently, shale gas resources were discovered in the Ordovician marine graptolite-rich strata in the Ordos Basin. The graptolite shale in the study area is different from the marine graptolite shale in the Yangtze plate in southern China, and further exploration is needed. This paper presents core samples of the graptolite-rich shale of the Pingliang Formation in the southwest Ordos Basin as research objects. The graptolite genus and graptolite shale characteristics were studied using core observation, electron microscopy, scanning electron microscopy, and geochemical analysis. We determined the role of the sedimentary environment and thermal maturation of graptolite shale in hydrocarbon formation and explored the possibility of hydrocarbon generation. Many graptolite epidermises provide buried organic matter. The quiet sea and low-energy marine environment create favorable conditions for preserving organic matter. The tectonic process resulted in the evolution stage in the oil generation window. Different types of pores formed the spaces of hydrocarbons. Therefore, the shale of the Pingliang Formation has shale oil exploration potential, which complements the shale gas in the northwestern margin of the basin, and provides new venues for shale oil and gas exploration in northern China.

Different tectonic settings affect organic matter enrichment by influencing sedimentary environments. The formation, preservation, and enrichment patterns of organic matter in the Wulalike Formation are still unclear. The influence of the ancient tectonic pattern and sedimentary environment of the Wulalike Formation are summarized to provide insights into the organic matter enrichment through analysis methods such as tectonics, petrology, mineralogy, and geochemistry. The abundance of organic matter is low and heterogeneous vertically in the bulk of the Wulalike Formation. The Wulalike Formation was formed during a tectonic transformation, during which it transitioned from an active continental margin to a passive continental margin. It was at high sedimentation rates that the organic matter content was diluted by the input of clastic sediments. The terrestrial inputs increased through time. The preservation conditions of organic matter were disrupted by the increasing oxygen content with the increase of terrestrial inputs. The level of ancient productivity is gradually decreasing, and the hydrocarbon-generating organisms are a combination of floating algae and benthic algae. The enrichment pattern of organic matter in the Wulalike Formation is controlled by regional structures, dominated by sedimentation rate, terrestrial input, and preservation conditions, supplemented by primary productivity levels. The organic matter accumulation model proposed in this study will provide theoretical support for the exploration of shale gas in northern China.