As one of the distribution areas of the oldest organic shale in China, Yanshan area contained a Middle-Upper Proterozoic sedimentary succession, in which the exploration of shale oil and gas resources is of great significance. To investigate shale oil and gas accumulation conditions and resources potential of the Middle-Upper Proterozoic strata, here we carried out total organic carbon (TOC) analysis, equal vitrinite reflectance (Ro) measurement, Porosity and permeability, and isothermal adsorption experiments on shale samples collected from Xinglong-Kuancheng area. Organic shale-bearing strata in this area include Chuanlinggou, Hongshuizhuang, and Xiamaling Formations, of which Hongshuizhuang and Xiamaling Formations develop organic shales better. Due to favorable sedimentary environments, Honghongzhuang and Xiamaling Formations have large shale thickness values, with ranges of 20-140 m and 100-300 m, respectively. A large number of oil seepages in the field outcrop provide direct evidence for hydrocarbon generation in this set of strata. Organic shales with TOC greater than 2.0% are widely distributed and have high hydrocarbon generation ability. The thermal evolution degree of shale organic matter is from low maturity to over maturity and Ro generally ranges from 0.6% to 2.2%. Especially, the maturity of organic matter in Xiamaling Formation varies greatly with the distance from diabase dikes. Hongshuizhuang and Xiamaling Formation shales are characterized by ultra-low porosity and permeability, indicating a good development potential. From the perspective of shale oil and gas accumulation conditions, this study demonstrates the good resources potential of Hongshuizhuang and Xiamaling Formations. The North Hebei Depression is a favorable area for shale oil and gas exploration.
The Shaanbei Chang 7 shale oil members in the Ordos Basin develops vertically with multiple lithologic superimpositions. The interlayer stress of the sand-mud-shale thin interlayer is different, and the stress in the small layer is variable, resulting in high hydraulic pressure fractures and short extension distances. The effective retrofit volume did not meet expectations. According to the characteristics of 3 small reservoirs in Chang 7 Member in Xin’anbian area of Shaanbei, combined with the geological, structural, and sedimentary characteristics of the block, the in-situ stress distribution law of vertical multi-interbedded layers with different lithologies was obtained by finely interpreting the in-situ stress logging results of the single well, and the sand was simulated. A three-dimensional regional model of in-situ stress of mud-sheet multi-thin interbedded lithologic reservoirs. The calculation results show that the overall three-dimensional stress of the block is σ V > σ H > σ h (the σ V is vertical stress, the σ H is horizontal maximum stress, and the σ h is horizontal minimum ground stress), the stress value of sandstone in the lateral upper layer is greater than that of shale and that of mudstone, and the difference of horizontal stress in the vertical direction increases with the increase of depth. Combined with the hydraulic fracturing physical model experiment, the fracture initiation and vertical extension patterns of hydraulic fractures in shale oil reservoirs under different stress differences were analyzed. The experiment found that the perforation of the horizon with a large difference between the vertical stress and the minimum horizontal principal stress is preferred, which is beneficial to hydraulic pressure. The expansion of fractures through layers increases the volume of complex fractures and improves the effect of volume stimulation of shale oil reservoirs.
Climate change has a serious impact on the food crop ecosystem. Rice is not only an important food crop for human beings, but also one of the food crops sensitive to climate change. The research progress on the effects of climate change on rice in China is reviewed in this paper. Climate change significantly shifted the planting boundary of rice to the north, which shortened the growth and development period of rice, and then decreased the overall planting yield and quality of rice. The adverse effects of climate change can be dealt with through the adjustment of planting distribution, variety improvement, and technological improvement. In the future, climate change will further affect rice production. It is still necessary to strengthen the research on the impact mechanism of climate change and countermeasures to promote and ensure the sustainable development of rice. The purpose of this paper is to provide a reference for the assessment of the impact of climate change on rice and the sustainable development of rice.