Supercritical CO 2 breakthrough and flow mechanisms in shale have been investigated in laboratory experiments using a high pressure flow cell and cylindrical samples of shale from the Draupne formation in the North Sea. The main objective is to study the basic mechanisms involved in the breakthrough process and define the controlling parameters for supercritical CO 2 flow in a low permeable shale.Experimental testing provides new insight into the CO 2 breakthrough process through simultaneous measurements of deformation and ultrasonic velocities in the sample. A marked sample dilation associated with the CO 2 breakthrough is identified accompanied with a pronounced drop in ultrasonic velocities. X-ray images of the sample using a high resolution 3D computer tomography (CT) scanner provide information on macroscopic fracture distribution inside the sample before and after testing.The CO 2 breakthrough pressure for the Draupne material seems to depend on confining pressure and effective pressure rather than pore pressure difference across the sample. After breakthrough the effective CO 2 permeability was found to follow a simple model for permeability in fractured rock. The drop in ultrasonic velocity was associated with mechanical changes and possible micro fracturing inside the sample. Based on our observations we conclude that pressure-induced opening of micro-fractures during the breakthrough process is an important mechanism for flow in addition to capillary displacement. Our findings may have important consequences for later testing and estimation of CO 2 breakthrough pressure and flow in shale.

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This paper evaluated the water use efficiency in 12 Chinese western provinces from 2005 to 2015. Based on data availability and the index selection rationality and the slacks-based measure (SBM)-undesirable Window analysis model and the Malmquist productivity index, the water resource inputs and outputs were measured to analyze water use efficiency. Total investment in fixed assets for the whole society and total water, made up of total agricultural water, total industrial water, and total domestic water, were used as the input indexes, and regional GDP and waste water discharge were the output indexes, with the waste water discharge being regarded as an undesirable output. The data from different years and different provinces in the same period, and data from the same year and the same provinces in different periods were compared in order to derive the water resource efficiency and technical changes over time and space. It was found that the total water resource factor productivity in the 12 provinces grew slowly in the study period, that water resource technical progress positively affected water use efficiency, and that a lack of technical efficiency restricted water use efficiency growth. Several suggestions are given to optimize water use efficiency in the 12 provinces. The research findings and suggestions provide valuable reference for studies in related fields.

China has accelerated the pace of shale gas development from 2010. A series of policies were issued by the Chinese government to motivate and regulate shale gas exploration and exploitation. In order to investigate the effectiveness of these policies and provide reference to the policymakers, the most relevant policies from 2010 to 2016 were collected and analyzed. Our study summarized that, in total, eight government agencies issued 25 related policies, which cover all the main problems that impede China’s shale gas industry. With the aid of these policies, the approved research and development (R&D) funds exceed 350 million Chinese yuan (CNY) ($55 million), and over 80 domestic companies participated in exploration rights bidding and nine foreign companies initiated thirteen international cooperation projects. In 2016, China’s shale gas production reached 7.88 × 109 m3, ranking third in the world. However, these policies still have some shortcomings, such as low environmental concerns, weak financial stimulus, and inefficient implementation. Therefore, we suggest that future policy should put particular emphasis on (1) formulating special environmental regulations and determining development scale based on water resource; (2) providing detailed implementation plans and maintaining stable subsidy; (3) enhancing communication and supervision; and (4) establishing a public big data platform.

The distribution of mineral resources in China is mainly concentrated in minority areas. However, the technology of mineral resources development in minority areas is relatively backward and the utilization rate isn't high. Unreasonable exploitation for mineral resources has caused tremendous damage of mining environment, which restricts the sustainable, healthy and stable development of mining areas. Therefore, how to construct the ecological industrial chain of mineral resources in minority areas has become an important issue of mining sustainable development. In this paper, a SD model with the characteristic of minority areas is established by constructing the dynamical system flowchart that takes mineral resources-environment-economy-society (MEES system) as the main research object based on system dynamics simulation, combination determining weights, and fuzzy sets, etc. In addition, taking Tibetan minority areas for an example, this paper predicts the tendency of the MEES system in the region. Meanwhile, this paper designs four different development modes to provide the operable choice and reference for exploiting the mineral resources in minority areas.