Regulation of the NADH supply by nuoE deletion and pncB overexpression to enhance hydrogen production in Enterobacter aerogenes

In this study, seven mutants from E. aerogenes IAM1183 wildtype were constructed via different strategies including deletion of lactate dehydrogenase, disruption of NADH dehydrogenase gene nuoE, overexpression of pncB and a combination of both to regulate of the NADH supply to enhance hydrogen production. Compared with the parental strain, the hydrogen yields of the strains IAM1183-E, IAM1183-L and IAM1183-EL increased by 23.3, 81.7 and 97.9%, respectively. When the pncB gene was overexpressed, the hydrogen yield of IAM1183/P, IAM1183-E/P, IAM1183-L/P and IAM1183-EL/P increased by 39.0, 6.5, 5.9, and 5.1% compared with the respective original knockout strains. Among them, the total hydrogen yield of strain IAM1183-EL/P with highest production efficiency was 58% higher than IAM1183. Further metabolite analysis indicated that the knockout of nuoE and ldhA, combined with the overexpression of pncB, resulted in a redistribution of the metabolic fluxes in E. aerogenes, which led to an improvement of the hydrogen yield.     

Cladophora sp. as a sustainable feedstock for dark fermentative biohydrogen production

Macroalgae are rich in carbohydrates which can be used as a promising substrate for fermentative biohydrogen production. In this study, Cladophora sp. biomass was fermented for biohydrogen production at various inoculum/substrate (I/S) ratios against a control of inoculum without substrate in laboratory-scale batch reactors. The biohydrogen production yield ranged from 40.8 to 54.7 ml H₂/g-VS, with the I/S ratio ranging from 0.0625 to 4. The results indicated that low I/S ratios caused the overloaded accumulation of metabolic products and a significant pH decrease, which negatively affected hydrogen production bacteria's metabolic activity, thus leading to the decrease of hydrogen fermentation efficiency. The overall results demonstrated that Cladophora sp. biomass is an efficient fermentation feedstock for biohydrogen production.     

压裂水平井产能预测方法研究进展

水平井压裂技术在低渗透及非常规储层中得到了广泛应用,压裂后水平井的产能预测关系到油田开发方案的制定,因此,国内外学者对压后渗流模型的建立和求解方法做出了不懈的努力。本文详细回顾了国内外学者所建压裂水平井产能预测模型及求解方法,指出了不同模型和求解方法的优缺点,并展望了压裂水平井产能模型的发展方向。     

Comparative evaluation of the mesophilic and thermophilic biohydrogen production at optimized conditions using tequila vinasses as substrate

The objective of this work was to comparatively evaluate the production of biohydrogen (bio-H₂) from tequila vinasses at optimized mesophilic and thermophilic conditions and to elucidate the main metabolic routes involved. Optimal temperatures of 35 °C and 55 °C, and pH of 5.5 maximized the bio-H₂ production rates, 25.5 ± 0.01 NmL h⁻¹ and 169.9 ± 8.9 NmL h⁻¹ in the mesophilic and thermophilic regimens, respectively. During the operation of anaerobic sequencing batch reactors, the thermophilic process allowed a volumetric bio-H₂ production rate of 519 ± 13 NmL-H₂ L⁻¹ d⁻¹ equivalent to 750 ± 19 NmL-H₂ L_vinasse⁻¹, while the mesophilic one 448 ± 23 NmL-H₂ L⁻¹ d⁻¹ and 647 ± 33 NmL-H₂ L_vinasse⁻¹, respectively. Furthermore, the gas produced under thermophilic conditions showed high hydrogen content (86.5%). Finally, formate degradation and glucose fermentation to acetic and butyric acids were the main metabolic routes involved in bio-H₂ production under thermophilic conditions, while at mesophilic conditions, the lactate and formate degradation pathways governed.     

大牛地气田异常修正等时试井资料求取产能方法

大牛地气田为低渗-致密气田,因存在启动压力梯度等因素,修正等时试井曲线按常规方法处理出现异常,无法准确获取气井的产能方程.采用LIT法和异常曲线校正法对气田异常试井资料进行了重新处理,最终获得气井产能方程,为同类气藏产能试井可能出现的异常资料处理解释探索了新的途径.     

川东气藏直井完井方法的产能预测研究

在分析研究目前国内外油气井完井产能计算经验公式的基础上，针对四川气田东部浅层气藏常用的几种完井方式，建立了该地区完井产能预测的数学模型。通过实例计算，表明了其数学模型的准确可行性，并为出砂井和非出砂井的完井方式提供了选择依据：对于出砂井，砾石裸眼充填完井方式是最理想的完井方式；对于非出砂井，实际裸眼完井的产能最大。得出的结论对该地区直井完井方式的选择，完井参数优化设计以及产能预测具有一定的指导作用。     

重复压裂气井产能模拟研究

由于重复压裂气井原有裂缝的失效程度难以评价。导致重复压裂气井的产能预测常常有很大的误差。为此，根据重复压裂气井的压前产量和舍水率，拟合了原有裂缝的有效率，在考虑新裂缝和原有裂缝共同作用的情况下，建立了气、水两相平面二维的裂缝-油藏数学模型，通过对模型的数值求解，对重复压裂气井进行了产能评价。研究表明，在考虑新、老裂缝共同作用下的产能评价方法，能更为准确地预测重复压裂后的生产动态情况，对压裂时机的确定、压后经济效益的预测都具有重要的指导意义。     

选矿工艺流程的计算

选矿工艺流程计算很繁琐 ,试通过对磁选工艺流程的分析计算举例 ,展示较为简单适用的计算方法。     

预测油气田产量的β模型

通过对油气田产量变化规律进行系统研究，推导建立了预测油气田产量的β模型。该模型不但可以预测油气田产量、累积产量随生产时间的变化，而且可以预测可采储量、最高年产量及其发生的时间。实例检验该模型是可信的。     

建立气井产能方程及计算地层压力的新方法

气井产量取决于井底流动压力，所以气井产能方程应该能够直接描述流压与产量的关系。文中基于气井二项式产能方程，提出了可以直接反映流压与产量之间关系的二元回归形式的产能方程模型。介绍了该模型的基本原理并进行了实例分析。该模型可以预测地层压力。