The intrusive rock buried-hill reservoir is one of the main targets for oil and gas exploration in the offshore sedimentary basins of China. In order to discover the reservoir as early as possible for decision-making to save costs, reservoir interpretation with mud-logging data needs to be studied. Previous studies have showed that the homogeneity rocks reservoir can be well interpreted with mud-logging data u the K_b (mechanical specific energy ratio) method and the W_L (tangential power)-W_H (vertical power) intersection method. However, reservoir interpretation with mud-logging data for intrusive rock buried-hill has not been reported. The key steps or parameters of these two kinds of methods used for reservoir interpretation need to be modified for the vertical variation of intrusive rock buried-hill. Furthermore, confirming the interpretation of these two kinds of methods has not been reported. Taking the Y area in the Qiongdongnan Basin of the South China Sea as an example, the intrusive rock buried-hill can be divided into four zones based on its characteristics and genesis in descending order: the sand–gravel weathering zone, the weathering fracture zone, the inner fracture zone, and the base rock zone. The reservoir can be well interpreted when taking the M_SE (mechanical specific energy) geometrical mean of the base rock zone as a basic value to calculate K_b. The reservoir will also be well interpreted when W_H ranges from 0 to 4.5 MPa and W_L ranges from 0 to 99 MPa in the column while intersecting. The layers of the reservoir can be interpreted as K_b < 1 in the sand–gravel weathering zone and the weathering fracture zone. The K_b < 1 and effective intersection of W_L-W_H layers at the same time could be interpreted as a reservoir in the inner fracture zone and the base rock zone. After combining the K_b method with the W_L-W_H intersection method, the reservoir of intrusive rock buried-hill can be well interpreted. The total thickness of the uninterpretable reservoir ratio is less than 20% compared to reservoir interpretation with well-logging for each well.

Through detailed drill-core description, petrography, cathodoluminescence imaging, and geochemistry analysis, sedimentary deposits with a high content of volcanogenic components (27.6%) were discovered in the Shanxi Formation of the Daniudi Gas Field, Ordos Basin. The volcanogenic components include volcanogenic quartz, lava fragments (dominated by rhyolite fragments), tuff fragments, and tuffaceous matrix. In addition, at least two volcanic ash layers were discovered. Although the metamorphic rocks of the Precambrian succession in the ancient land of Yin Mountain are usually considered the primary source of the Shanxi formation, it is most likely that the volcanogenic components were derived from intermediate-acid volcanic materials that accumulated in the Daqingshan area during the Late Carboniferous to Early Permian. Those volcanogenic components are mainly transported by flowing water rather than by air from origin to basin. In addition, the accumulation of volcanic materials in the Daqingshan area was controlled by volcanic eruptions occurring solely in this area, rather than by the Inner Mongolia Orogenic Belt. Those volcanic eruptions were related to the southward subduction of the Paleo-Asian Ocean Plate beneath the northern margin of the North China Plate in the Late Carboniferous to Early Permian. The active continental margin related to the subduction of the Paleo-Asian Ocean Plate lasted at least until the Early Permian, and the closure of the Paleo-Asian Ocean must have occurred later than the Early Permian.

The detrital compositions in sandstone are important recorders of sedimentary provenance and transport, both of which have significant implications for the lithology, age and tectonic evolution of provenance. Through detailed identification and analysis, a high content of volcanogenic compositions (27.6%) was discovered in Shanxi formation of Daniudi Gas Field, Ordos Basin, which is much higher than that of the previous study. The volcanogenic compositions include volcanogenic quartz, lava fragments (dominated by various kinds of rhyolite fragments), tuff fragments, and tuffaceous matrix. In addition, at least 2 volcanic ash layers were discovered. Although the metamorphic rocks of the Precambrian succession in the ancient land of Yin Mountain are usually considered the primary source of the Shanxi formation, it is most likely that the volcanogenic compositions were derived from intermediate-acidic volcanic materials that accumulated in the Daqingshan area during the Late Carboniferous to Early Permian. Those volcanogenic compositions are mainly transported by flowing water rather than by air from provenance to basin. And the accumulation of volcanic materials in the Daqingshan area was controlled by volcanic eruptions occurring solely in this area, rather than by the Inner Mongolia Orogenic Belt. Those volcanic eruptions related to the southward subduction of the Paleo-Asian Ocean Plate beneath the northern margin of the North China Plate in Late Carboniferous to Early Permian. The active continental margin related to the subduction of the Paleo-Asian Ocean Plate lasted until at least the Early Permian, and the closure of the Paleo-Asian Ocean must have occurred later than the Early Permian.

火石岭组是松辽盆地早期断陷充填的第一套序列,也是国际大陆科学钻探松科2井的主要目的层之一。松科2井2018年完钻后是否钻遇火石岭组一直存在争议。地质-地球物理资料综合分析表明,松科2井钻遇了火石岭组,井深5613.41~5959.84m,厚346.43m,以高含量的火山物质为特征,顶部以凝灰岩层与上覆沙河子组为界;GR和RRD曲线呈现较大的起伏和不稳定的特征;地震上表现为同相轴连续性好、振幅强、频率较高的特征;沉积-充填速率显著小于沙河子组。将火石岭组定义为不整合于基底之上,与上覆沙河子组(局部与营城组、登娄库组或泉头组)呈整合/不整合接触的第一套火山-沉积充填序列,代表了断陷早期火山活动较为强烈的一个阶段。松辽盆地断陷期充填演化,北部和西部受控于北部蒙古-鄂霍茨克构造体系,中部和东南部受控于东部环太平洋构造体系。控陷构造体系差异、板块俯冲的距离效应以及岩浆中心的迁移等,是各断陷发育时间、发育规模、火山-沉积充填时间和规模等时空差异的根本原因。松辽盆地断陷期总体经历了火石岭组和营城组火山-沉积建造夹沙河子组火山平静期陆源碎屑沉积的过程,但不同部位断陷启动时间、各组充填时间和充填序列又存在显著差异: 断陷启动时间和沙河子组开始沉积时间具有北部早、南部次之、中部最晚的特点;火石岭组火山-沉积建造在盆内广泛分布,而营城组火山-沉积建造主要分布于盆地中部。松辽盆地断陷期相同组段可能不具有统一的同位素年龄,直到营城组之后(约103~104Ma),盆地断陷演化阶段结束,整个盆地同时坳陷沉降,各个组段形成统一的时间格架。