In Press Articles
Upper Ordovician‒Lower Silurian Wufeng-Longmaxi Formation is the most developed strata of shale gas in southern China. Due to the complex sedimentary environment adjacent to the Kangdian Uplift, the favorable area for organic-rich shale development is still undetermined. The authors, therefore, focus on the mechanism of accumulation of organic matter and the characterization of the sedimentary environment of the Wufeng-Longmaxi Shales to have a more complete understanding and new discovering of organic matter enrichment and favorable area in the marginal region around Sichuan Basin. Multiple methods were applied in this study, including thin section identification, scanning electron microscopy (SEM) observations and X-ray diffraction (XRD), and elemental analysis on outcrop samples. Five lithofacies have been defined according to the mineralogical and petrological analyses, including mudstone, bioclastic limestone, silty shale, dolomitic shale, and carbonaceous siliceous shale. The paleo-environments have been reconstructed and the organic enrichment mechanism has been identified as a reduced environment and high productivity. The Wufeng period is generally a suboxic environment and the early Longmaxi period is a reducing environment based on geochemical characterization. High dolomite content in the study area is accompanied by high TOC, which may potentially indicate the restricted anoxic environment formed by biological flourishing in shallower water. And for the area close to the Kangdian Uplift, the shale gas generation capability is comparatively favorable. The geochemical parameters implied that new favorable areas for shale gas exploration could be targeted, and more shale gas resources in the mountain-basin transitional zone might be identified in the future.
based on the data of geology, well drilling, well logging, well test, this paper systematically analyzed the Geological characteristics of tight oil in Gao3 and Gao4 layers of the Qijia area. It shows that there are three kinds of hydrocarbon source rocks, which have excellent I and II type parent types of organic matter and have high organic matter abundance mostly in the mature stage. The reservoir is generally composed of intercalations between thin-bedded mudstone, siltstone and sandstone, with a poor porosity and a poor air permeability. The main reservoir space primarily includes intergranular pores, secondary soluble pores and intergranular soluble pores. Three types of orifice throats were identified, namely fine throat, extra-fine throat and micro-fine throat. The siltstone is generally oil-bearing, the reservoirs with slime and calcium become worse oil-bearing.The brittleness indices of the sandstone range from 40% to 60%, and the mudstone range from 40% to 45%. Based on the study of a typical core hole data, this paper gives a comprehensive evaluation of properties of the tight oil, and establishes a tight oil single well Composite bar chart. This study has theoretical guiding significance and practical application value for tight oil exploration and evaluationt in Qijia area
Elemental analysis, 13C nuclear magnetic resonance (NMR) spectroscopy, X-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectroscopy (FTIR), combined with Grand Canonical ensemble Monte Carlo (GCMC) simulations and energy minimizations were used to establish the molecular structure model of middle-high coal rank accurately. The three-dimensional molecular structure models of middle-high coal rank (from the No. 6 Mine of Pingdingshan (PDS) Mining Area and the No. 4 Mine of Hebi (HB) Mining Area in Henan Province, Xiegou (XG) Mine, Changping (CP) Mine, and Sihe (SH) Mine in Shanxi Province, China) were optimized and constructed. The results showed that the structural arrangement is more orderly and compact with the increase of coal rank. The established molecular formulae for PDS, HB, XG, CP, and SH are respectively C69H43NO3, C166H93N3O8, C191H125N3O7, C169H105N3O7, and C221H123N3O7.
It is still controversial in the existence, scale and affinity of the basement of the Bainaimiao Arc Belt (BAB). We report a new discovery of Neoarchaean zircon ages from the diabase in the Ar Horqin Banner area of the north edge of the BAB. All of the zircons analyzed are subhedral, show fine-scale oscillatory growth zoning in CL images and have high Th/U ratios of 0.3—1.0, implying their magmatic origin. As a result of the LA-ICP-MS U-Pb zircon dating from the diabase, high proportional captured zircons (16 data of the total 22 zircons) have a weighted mean 207Pb/206Pb ages of 2526±19 Ma (MSWD=1.5) and an upper intercept age of 2559±20 Ma (MSWD=0.42), which clearly suggests the presence of Neoarchaean geological body on the northern edge of the BAB, reflecting the existence of the Neoarchaean crystalline basement.
The continuous enrichment of heavy metals in soils poses a potential hazard to groundwater. Previous research lacked a method to quantitatively evaluate the hazard degree of soil heavy metals to groundwater. This paper combined the groundwater cycle and solid-liquid equilibrium theory to construct a simple and easy-to-use flux model of soil heavy metals into groundwater, and proposed an innovative method for evaluating the hazard of soil heavy metals to groundwater on the basis of evaluating the environmental capacity of groundwater.The results show that the fluxes of soil heavy metals into groundwater in the study area are Zn, Cu, As, Pb, Cd, Ni and Hg in descending order, and that the heavy metals in groundwater (As, Hg, Cu, Pb, Zn, Ni and Cd) in most areas do not reach the environmental capacity threshold within 10 years, and the hazard level of soil heavy metals to groundwater in the majority of townships is at the moderate level or below. This evaluation method can quantify the flux of soil heavy metals into groundwater in a simple and quick way, determine the remaining capacity of groundwater for heavy metals, evaluate the hazardous status of soil heavy metals to groundwater, provide support for relevant departments to carry out environmental protection of soil and groundwater, and provide reference for related scholars to carry out similar studies.
Groundwater is an important source of drinking water. Groundwater pollution severely endangers drinking water safety and sustainable social development. In the case of groundwater pollution, the top priority is to identify pollution sources, and accurate information on pollution sources is the premise of efficient remediation. Then, an appropriate pollution remediation scheme should be developed according to information on pollution sources, site conditions, and economic costs. The methods for identifying pollution sources mainly include geophysical exploration, geochemistry, isotopic tracing, and numerical modeling. Among these identification methods, only the numerical modeling can recognize various information on pollution sources, while other methods can only identify a certain aspect of pollution sources. The remediation technologies of groundwater can be divided into in-situ and ex-situ remediation technologies according to the remediation location. The in-situ remediation technologies enjoy low costs and a wide remediation range, but their remediation performance is prone to be affected by environmental conditions and cause secondary pollution. The ex-situ remediation technologies boast high remediation efficiency, high processing capacity, and high treatment concentration but suffer high costs. Different methods for pollution source identification and remediation technologies are applicable to different conditions. To achieve the expected identification and remediation results, it is feasible to combine several methods and technologies according to the actual hydrogeological conditions of contaminated sites and the nature of pollutants. Additionally, detailed knowledge about the hydrogeological conditions and stratigraphic structure of the contaminated site is the basis of all work regardless of the adopted identification methods or remediation technologies.