Nanoscale pore structure characteristics and their main controlling factors are key elements affecting the gas storage capacity, permeability, and the accumulation mechanism of shale. A multidisciplinary analytical program was applied to quantify the pore structure of all sizes of Xiamaling shale from Zhangjiakou, Hebei. The result implies that Mercury injection porosimetry (MIP) and low-pressure N₂ curves of the samples can be divided into three and four types, respectively, reflecting different connectivity performances. The maximum CO₂ adsorbing capacity increases with increasing total organic carbon (TOC) content, pore volume (PV), and surface area (SA) of the micropores are distributed in a three-peak type. The full-scale pore structure distribution characteristics reveal the coexistence of multiple peaks with multiple dominant scales and bi-peak forms with mesopores and micropores. The porosity positively correlates with the TOC and quartz content, but negatively correlates with clay mineral content. Organic matter (OM) is the main contributor to micropore and mesopore development. Smectite and illite/smectite (I/S) assist the development of the PV and SA of pores with different size. Illite promotes the development of the nanoscale PV, but is detrimental to the development of the SA. Thermal maturity controls the evolution of pores with different size, and the evolution model for the TOC-normalized PVs of different diameter scales is established. Residual hydrocarbon is mainly accumulated in micropores sized 0.3 to 1.0 nm and mesopores sized 40 nm, 2 nm and less than 10 nm. Since the samples were extracted, the pore space occupied by residual hydrocarbon was released, resulting in a remarkable increase in PV and SA.

Geothermal resources as a type of renewable clean energy are highly contributive to sustainable development. In this study, the geothermal resources in some sedimentary basins of China were characterized, and sedimentary basins from different eras and of different types were discussed. On this basis, the major influence factors on the geothermal resources of different regions were elaborated. The geothermal resource potentials in major sedimentary basins of China were evaluated. The geothermal resources in the sedimentary basins of China are extensively distributed and diverse, which are geologically different from East to West China. The target strata of faulted basins in East China, superimposed basins in Central China, and cratonic basins in West China are mainly Cenozoic strata, Mesozoic strata, and Paleozoic strata, respectively. These target strata experienced different types of thermal events in geological historical periods. The Cenozoic faulted basins in East China are mostly heat basins. The Cenozoic sediments are superthick and largely differ in thickness among regions. The effects of Cenozoic geothermal events and the major controlling factors both differed among regions, and the causes of differences included thermal subsidence activities and magmatic activities. These basins are major potential zones for exploitation of hot dry rocks in China. The Mesozoic superimposed basins in Central China are mostly temperate basins, and the ground temperatures nowadays are mainly controlled by thermal subsidence. The potential target zones of hot dry rocks in these basins are the Paleozoic strata in the southwest of basins, which can develop into medium-temperature geothermal resources. In the Paleozoic cratonic basins in West China, the Paleozoic marine sedimentary strata are the major target strata of hot dry rocks. The Paleozoic volcanic events little affected the formation of hot dry rocks, and the formation of major hot dry rocks relied on superthick sedimentary strata, where middle- to low-temperature geothermal resources developed.