Progress of normal-pressure shale gas engineering technology in southeast Chongqing and the research direction of next steps

The normal-pressure shale gas block in southeast Chongqing is located in the transitional zone of the basin margin and the extrabasinal fold area, which has the geological characteristics of complex structure, large stress difference and low pressure coefficient, which brings great challenges to improve the efficiency and production of engineering technology. Shallow surface fractures and caverns are developed in this area, with many thief zones, and long drilling and completion period. The structural stress changes quickly and the difference coefficient is large, so it is difficult to form complex fracture network. The lack of formation energy and low drainage efficiency affect the continuous and stable production of gas wells. Therefore, with the goal of "increasing quality, speed, efficiency and yield", key technologies are innovated and implemented, and the benefits of engineering processes are created constantly. With the aim to "speed up, improve efficiency and reduce cost" in drilling projects, the normal-pressure shale gas drilling and completion technology is formed, which focuses on well structure optimization and drilling with optimized parameters, and integrates equipment and tools. The mechanical drilling rate increases by 14.90% per year, the drilling and completion period decreases by 10.67%, and the drilling cost decreases by 7.64%, setting multiple new records in the same period. Focusing on increasing efficiency and reducing cost of fracturing projects, fracture complexity is improved through "moderately close cutting + temporary plugging and turning", effective multi-scale support of fracture network is promoted by "high-strength sand injection + sand-ceramic particle size combination", low-cost fracturing materials and cost-reduced equipment and tools are integrated and applied, forming the characteristic fracturing process and supporting facilities of "complex fracture network + economic materials + intelligent fracturing equipment". The final EUR of one kilometer per well was increased from 34 to 45 million cubic meters, and the cost decreased by 34.6%. With the goal of "fine management of the whole life cycle, delay of decline, and efficiency improvement by tapping the potential", the full-life cycle drainage and gas production technology system of mechanical drainage such as early selection of pipe string, mid-stage foam drainage + compressor depressurized mining, late-stage single pipe jet pump and heavy-duty pump + liner pipe has been established, and precise policies have been implemented in different areas, classification and stages, and the annual decline rate of old wells has been reduced by 2.1%. The production time rate of the whole field increased from 95.9% to 98.7%. Through the research on the whole process of engineering technology, it strongly supports the efficient development of normal-pressure shale gas in southeast Chongqing, and provides beneficial reference for the efficient exploitation of other normal-pressure shale gas

High-resolution maps of intensive and extensive livestock production in China

Reliable and detailed information on livestock distribution is essential for studies of food security, environmental change, and even sustainable development. However, insufficient accuracy and inadequate validation currently remain in high-resolution livestock distribution datasets primarily resulting from using spatially-continuous models and deficient data. This study presents, for the first time to our knowledge, a spatially detailed dataset on intensive (point) and extensive (30”× 30” grid) livestock production in China (HIEL-China) in 2017 based on an improved model and multi-scale data. Technical validation shows high accuracy in spatial distribution and farm-size simulation. Based on the more reliable depiction of livestock farms, we addressed the obvious underestimation of livestock density in previous datasets, and found different structures of livestock production systems in urban, peri-urban and rural areas. This study accordingly contributes to an essential data basis for livestock-associated analyses targeting at sustainable development of food systems, especially for the largest contributor to global livestock production

Heterogeneous Reactions of Acetic Acid with Oxide Surfaces: Effects of Mineralogy and Relative Humidity

We have investigated the heterogeneous uptake of gaseous acetic acid on different oxides including γ-Al₂O₃, SiO₂, and CaO under a range of relative humidity conditions. Under dry conditions, the uptake of acetic acid leads to the formation of both acetate and molecularly adsorbed acetic acid on γ-Al₂O₃ and CaO and only molecularly adsorbed acetic acid on SiO₂. More importantly, under the conditions of this study, dimers are the major form for molecularly adsorbed acetic acid on all three particle surfaces investigated, even at low acetic acid pressures under which monomers are the dominant species in the gas phase. We have also determined saturation surface coverages for acetic acid adsorption on these three oxides under dry conditions as well as Langmuir adsorption constants in some cases. Kinetic analysis shows that the reaction rate of acetic acid increases by a factor of 3–5 for γ-Al₂O₃ when relative humidity increases from 0% to 15%, whereas for SiO₂ particles, acetic acid and water are found to compete for surface adsorption sites

Choroidal and Retinal Thickness in Children With Different Refractive Status Measured by Swept-Source Optical Coherence Tomography

To investigate the choroidal and retinal thickness in myopic, emmetropic, and hyperopic Chinese children by swept-source longer-wavelength optical coherence tomography. Cross-sectional study. Two-hundred and seventy-six schoolchildren aged 7-13 years underwent comprehensive ophthalmic examinations, including cycloplegic refraction, and swept-source optical coherence tomography measurements. The thickness of the choroid, retina, ganglion cell layer, and nerve fiber layer were compared among children of different refractive status. The topographic variation and factors related to the thickness of the choroid and retinal layers were analyzed. Compared to emmetropic subjects, those with myopia had a significantly thinner choroid in all regions (P .05). The axial length and refractive diopters were independently related to central foveal choroidal thickness (R(2) = 0.17, P .05). Choroidal thickness, but not retinal thickness, correlated closely with axial length and refractive diopters in Chinese children. Choroid thinning occurs before retina thinning early in myopic progression