定向水力压裂裂隙扩展动态特征分析及其应用

为减少煤矿井下水力压裂卸压盲区,扩大压裂影响范围,提高卸压增透效果,在分析水力压裂起裂机理和裂隙发展特征的基础上,提出定向水力压裂技术,分析定向水力压裂过程中煤体的裂隙发展分布规律,并利用RFPA2D-Flow软件模拟了压裂的起裂、扩展和延伸过程,对定向压裂与非定向压裂的效果进行了比较。最后将定向水力压裂技术在平煤集团十二矿己15-31010工作面进行了现场应用,得出在27 MPa的水压下,单孔压裂有效影响半径达6 m;单孔瓦斯抽放平均浓度较未压裂时提高80%,平均流量上升了382%,取得了显著的效果,具有良好的推广应用价值。     

Matrix diffusion coefficients in volcanic rocks at the Nevada test site: influence of matrix porosity, matrix permeability, and fracture coating minerals

Diffusion cell experiments were conducted to measure nonsorbing solute matrix diffusion coefficients in forty-seven different volcanic rock matrix samples from eight different locations (with multiple depth intervals represented at several locations) at the Nevada Test Site. The solutes used in the experiments included bromide, iodide, pentafluorobenzoate (PFBA), and tritiated water ((3)HHO). The porosity and saturated permeability of most of the diffusion cell samples were measured to evaluate the correlation of these two variables with tracer matrix diffusion coefficients divided by the free-water diffusion coefficient (D(m)/D*). To investigate the influence of fracture coating minerals on matrix diffusion, ten of the diffusion cells represented paired samples from the same depth interval in which one sample contained a fracture surface with mineral coatings and the other sample consisted of only pure matrix. The log of (D(m)/D*) was found to be positively correlated with both the matrix porosity and the log of matrix permeability. A multiple linear regression analysis indicated that both parameters contributed significantly to the regression at the 95% confidence level. However, the log of the matrix diffusion coefficient was more highly-correlated with the log of matrix permeability than with matrix porosity, which suggests that matrix diffusion coefficients, like matrix permeabilities, have a greater dependence on the interconnectedness of matrix porosity than on the matrix porosity itself. The regression equation for the volcanic rocks was found to provide satisfactory predictions of log(D(m)/D*) for other types of rocks with similar ranges of matrix porosity and permeability as the volcanic rocks, but it did a poorer job predicting log(D(m)/D*) for rocks with lower porosities and/or permeabilities. The presence of mineral coatings on fracture walls did not appear to have a significant effect on matrix diffusion in the ten paired diffusion cell experiments.     

木屑生物炭对填料土的氮磷吸附及雨水持留改良影响

现阶段生物滞留系统的填料土存在氮磷营养盐净化效果不稳定、雨水持留能力下降等问题.为评估木屑生物炭作为生物滞留系统填料土添加剂的改良效果,选用对照填料土和施用了木屑生物炭的改良填料土进行对比研究,通过理化性质测试、等温吸附实验、土柱实验和土水特征曲线测定,研究木屑生物炭对填料土的改良影响与优化机制.结果表明,木屑生物炭孔隙率大、比表面积大、饱和含水率高和CEC高,可优化填料土的结构,提升填料土的离子交换能力;木屑生物炭对填料土的氮磷吸附改良效果突出,对NH4+-N的最大吸附量提高了 2.80倍,去除率由31.30％提高至64.10％,对PO43--P的最大吸附量提高了 1.28倍,去除率由61.90％提高至90.00％;经木屑生物炭改良后,填料土的饱和含水率提高1.63倍,渗透系数提高2.43倍,在各含水率下的基质吸力明显增加.木屑生物炭的添加可优化生物滞留系统填料土的性能,加强对雨水径流中氮磷营养盐的吸附,提高系统的渗透性和雨水持留能力.     

Herbicide promotes the conjugative transfer of multi-resistance genes by facilitating cellular contact and plasmid transfer

The global dissemination of antibiotic resistance genes (ARGs), especially via plasmid-mediated horizontal transfer, is becoming a pervasive health threat. While our previous study found that herbicides can accelerate the horizontal gene transfer (HGT) of ARGs in soil bacteria, the underlying mechanisms by which herbicides promote the HGT of ARGs across and within bacterial genera are still unclear. Here, the underlying mechanism associated with herbicide-promoted HGT was analyzed by detecting intracellular reactive oxygen species (ROS) production, extracellular polymeric substance composition, cell membrane integrity and proton motive force combined with genome-wide RNA sequencing. Exposure to herbicides induced a series of the above bacterial responses to promote HGT except for the ROS response, including compact cell-to-cell contact by enhancing pilus-encoded gene expression and decreasing cell surface charge, increasing cell membrane permeability, and enhancing the proton motive force, providing additional power for DNA uptake. This study provides a mechanistic understanding of the risk of bacterial resistance spread promoted by herbicides, which elucidates a new perspective on nonantibiotic agrochemical acceleration of the HGT of ARGs.     

煤层气开采过程中渗透率模型比较研究

为了得到煤层气开采过程中渗透率的准确预测模型，分析了不同泊松比和孔隙压力下的储层孔隙率变化规律，通过理论分析对4种经典渗透率模型进行了比较研究。研究结果表明: P&M模型和C&B模型对泊松比敏感度较小，改进P&M模型和S&D模型对泊松比敏感度较大；改进P&M模型能有效反映渗透率变化趋势，在p＜1.4 MPa和p＞4.1 MPa时k/k0数值拟合度较高；P&M模型和S&D模型不能准确描述p＜1.4 MPa时k/k0变化情况，而在p＞1.4MPa时k/k0数值拟合度较高；煤层渗透率随孔隙压力增大表现为“U”型趋势，包含低孔隙压力骤减区、中孔隙压力稳定区和高孔隙压力稳步升高区3个阶段，改进P&M和S&D模型更能表现煤层气渗透率随孔隙压力变化趋势。     

高瓦斯低透气性煤层深孔预裂爆破增透技术研究及应用*

为解决高瓦斯矿井开采过程中煤体透气性差、瓦斯预抽周期长、抽采效果不佳的难题，提出利用深孔预裂爆破技术提高煤体裂隙发育度，增加煤体透气性，从而提高瓦斯抽采率的方法。通过现场调研、理论分析、数值模拟及工业性试验等方法，分析深孔预裂爆破卸压增透内在机理，确定爆破影响半径为4.5~5.3 m，并在A110605工作面进行现场应用，同时考察煤层增透效果。研究结果表明:煤层爆破致裂后，平均瓦斯抽采浓度提高了2.17倍，平均瓦斯抽采纯量提高了2.02倍，煤层透气性系数提高了近5.3倍，煤层卸压增透效果显著，很大程度上消除了煤与瓦斯突出危险性，为实现工作面的安全开采及正常接替提供了保障。     

微波作用下煤层渗透性变化规律实验研究

为了深入研究微波辐射条件下功率、辐射时间、渗透率、有效应力之间的关系，采用自行设计的微波辐射含瓦斯煤渗流实验系统，进行了不同微波功率、不同辐射时间条件下的煤样渗透率测量实验。研究结果表明:微波辐射条件下，渗透率与有效应力之间遵循负指数函数关系,拟合结果R2均大于0.98；渗透率随微波功率和辐射时间的增加单调递增，并且在低有效应力区数据增长的线性拟合斜率大于高有效应力区；煤样在微波作用下，相同的能量输入，微波功率越高，煤样渗透率越大；研究结果为微波辐射技术在煤层气开采领域的应用提供理论参考。     

采空区多孔介质空隙率与渗透特性三维空间动态分布模型*

为揭示采空区垮落后堆积体及上覆岩层空隙率与渗透率三维空间的动态分布规律，基于开采空间守恒理论，构建采空区的空隙率与渗透率三维空间动态分布模型。利用该模型，得出不同空间位置与不同开采结束时间下空隙率和渗透率分布图。结果表明:采空区垮落岩体的空隙率和渗透率在水平方向呈“凹”状分布，采空区两侧巷道附近空隙率和渗透率较大，中部较小；在垂直方向随着与底板距离的增大，空隙率和渗透率大幅度减小。该模型描述了采空区多孔介质空隙率与渗透特性三维空间分布随时间逐步压密实的过程，可为煤矿瓦斯预测与防治提供一定的借鉴和参考。     

a-亚麻酸对赤潮异弯藻生长的抑制作用

探讨了a-亚麻酸对赤潮异弯藻(Heterosigma akashiwo)生长的抑制作用,并从细胞膜渗透性、抗氧化酶系和光合放氧量等方面研究了其抑制机理.结果表明,a-亚麻酸对赤潮异弯藻有明显的抑制作用,其第7d的IC50为2.4μL/L.在a-亚麻酸作用下,细胞内Na+、K+、Mg2+和Ca2+浓度随着实验的进行受到不同程度的影响,在36h后都出现明显的下降;藻细胞内可溶性蛋白质含量下降,超氧化物歧化酶(SOD)活性、过氧化物酶(POD)活性、过氧化氢酶(CAT).在8h时明显高于对照组,之后逐渐下降,到36h时低于对照组;丙二醛含量(MDA)表征了脂质过氧化强度和膜系统受损程度,其在12h时明显高于对照组,之后慢慢下降;藻细胞的光合放氧量呈逐渐下降趋势.结果表明,a-亚麻酸通过改变细胞膜透性和自由基反应,从而破坏藻细胞的结构,进而达到抑藻的效果.     

Research and practice on fluctuation water injection technology at low permeability coal seam

In order to solve the problem of poor affusion effect on low permeability coal seam, the paper analyzes the micro process of the coal seam water infusion in wetting coal and determines the main factors affecting coal seam water infusion. The permeability of the NO.3 coal seam in east working face of Xingcun coal mine by MTS815.03 servo-controlled rock mechanical test system has been tested. Results show that when the peak stress in coal sample specimens reaches 48.53 MPa, permeability ranges from 0.5158 to 2.9576 × 10⁻⁸ Darcy, and it means that the coal seam is low in permeability and difficult in water injection. Based on the characteristics of low permeability and geostress situation, efficient fluctuation water injection technology with permeable agent and relevant process parameters have been designed. The surface tension of the permeable agent developed here is 31.18 m N/m when mass concentration reaches 0.05%. The permeable agent can permeate into 2 cm thick coal layer completely in 10 s, thus improving the wettability of water effectively and the water injection pressure fluctuates between 7 MPa and 25 MPa. The application of the technique in the 3rd coal seam in east working face of Xingcun coal mine shows not only single-arch injection experienced a significant increase on average, from no more than 10 m³ to 63.3886 m³, but also the effect of dust fall, cooling and rock burst prevention is remarkable.