贵州省合层开发煤层气井产层含气性特征研究

贵州省是中国煤层气开发的重点地区,以贵州省及其周边地区已开发的煤层气井为研究对象,结合钻井、测井、排采等现场资料,从贵州省煤层气井的含气量、气体组成、等温吸附特征和含气饱和度四个方面进行系统的分析。研究表明:贵州省煤层气产层的含气量主要集中在10～18 m³/t;500 m以深解吸CH₄的体积分数均超过90%;相比于周边地区,不同区块的兰氏体积、兰氏压力差异明显;含气饱和度主要为70%～90%,整体含气性较好,见套压时所对应的井底流压变化较大,在2.0～8.0 MPa范围。贵州省单一产层对比周边地区煤层气井产层没有优势,体现了多煤层开发工艺在贵州省资源开发中的重要地位,虽然其含气量、兰氏体积、兰氏压力差异明显,层间干扰严重,但是总体含气性较好,临界解析压力较高,认为贵州省煤层气产出的重心应该放在如何正确地优选适合合采的煤层,在不同井组乃至不同井之间,根据其储层物性的变化,制订专属的排采工艺及制度,从而实现煤层气井的高产。     

煤层气井邻井碰撞事故处理工艺

煤层气工业化平台开发模式中,钻井过程中易发生井碰事故.在山西沁水郑庄区块ZH-L12-1井钻井过程中井眼轨迹与ZH-L12井发生碰撞事故,导致ZH-L12井二开技术套管和三开生产套管同时被打穿.通过采用分级固井处理该事故,成功消除了井眼轨迹碰撞影响,避免了大的经济损失,同时也为煤层气井碰事故处理提供了思路.     

煤层气井水平段坍塌不规则井眼封固研究

为了提高煤层气的采收率,煤层气开发多采用L形水平井、U形水平对接井和多分支井设计方案。水平井钻井施工进入水平段后,常出现井眼坍塌的情况。针对煤层气井水平段的坍塌情况,结合不规则井眼的实际,对一系列难点和封固井中存在的问题和方法进行深入、细致的研究,以提高煤层气井水平段坍塌不规则井眼的封固质量。     

反循环钻进工艺在煤层气井中的应用

介绍反循环钻进工艺的工作原理、运用条件与施工要求。通过在某煤层气井中应用反循环钻进与常规正循环钻进2种钻进技术,对2种工艺的效果进行对比分析研究。研究结果显示:较之常规钻进工艺,反循环钻进工艺具有便捷捞砂、漏层钻井效率高、可减少或消除钻井液的漏失、保护储层、延长泥浆泵使用寿命、井控灵活等优点。     

煤层气井杆管偏磨治理对策

在煤层气排采的过程中,管杆磨损已经成为造成排采中断的主要影响因素,而排采中断势必会造成煤层气井产气量的下降,严重制约了对煤层气井的产能评价,通过对煤层气定向井的偏磨特征,根据煤层气井生产实际中杆管的偏磨情况分析,对杆管结构进行针对性优化,并优化了扶正器的类型和位置,形成了煤层气井防偏磨配套措施,达到了延长修井周期的目的.     

霍林河盆地煤层气地质特征研究

主要是从霍林河河组的地质条件及其煤层特征双角度出发,详细地阐述了霍林河盆地煤层气的基本地质特征,指出煤的镜质组反射率多在0.5%~0.6%之间,煤质含气量最高为7.7m3?t-1。煤质中煤层气含量以及煤层气中甲烷含量随深度加大而迅速增加。400m以下为甲烷带,400m以上为甲烷——氮气带。同时,预测了有利于煤层气形成和勘探的有利地段,9-73孔、21-11孔附近地区为最有利煤层气勘探区。     

煤层气勘探开发中常用试井测试技术探讨

试井测试是目前能够准确获取煤层参数的有效方法。从实际应用的角度,重点介绍煤层气井常用试井方法,并时各种试井测试方法的优缺点、适用范围进行研究评价。结合煤层渗透率及储层压力的特征,探计试井测试方法在煤层气勘探开发中的应用。     

煤层气废弃井处置研究

中国煤层气井地面开发大部分集中在煤矿区,随着采煤的范围和区域逐年扩大,造成的煤层气井废弃数量逐渐增多。对于煤层气地面垂直井,通过分析总结煤层气废弃井的现状,研究了煤层气井套管对煤炭开采的影响,开展了对套管射孔、套管锻铣、套管封堵三种不同处理措施的试验及总结。通过介绍项目实际情况,找出消除煤层气废弃井不利影响的方法,并对煤层气废弃井处置进行研究,最终形成煤层气废弃井的处置方法和煤层气井改造方法。     

煤层气井排出水的水质研究

叙述了煤层气排出水的水质物理、化学性质以及水质分析情况,提出,要对排出水进行检测,并采取有效防护措施,以免对环境造成影响,尤其是对地下水的污染。     

低渗透煤层气井产能数值模拟研究

在煤层气开采过程中,设计合理的开采流程可减少开采过程造成的煤层损伤,这是提高煤层气井产量的关键。叙述了煤层气储层特征及运移产出机理,利用Comet3软件进行了低渗透煤层气井产能数值模拟。     

Compress effects on porosity,gas‐phase tortuosity,and gas permeability in a simulated PEM gas diffusion layer

Among the parameters to take into account in the design of a proton exchange membrane fuel cell (PEMFC), the energy conversion efficiency and material cost are very important. Understanding in deep the behavior and properties of functional layers at the microscale is helpful for improving the performance of the system and find alternative materials. The functional layers of the PEMFC, i.e., the gas diffusion layer (GDL) and catalyst layer, are typically porous materials. This characteristic allows the transport of fluids and charges, which is needed for the energy conversion process. Specifically, in the GDL, structural parameters such as porosity, tortuosity, and permeability should be optimized and predicted under certain conditions. These parameters have effects on the performance of PEMFCs, and they can be modified when the assembly compression is effected. In this paper, the porosity, gas‐phase tortuosity, and through‐plane permeability are calculated. These variables change when the digitally created GDL is under compression conditions. The compression effects on the variables are studied until the thickness is 66% of the initial value. Because of the feasibility to handle problems in the porous media, the fluid flow behavior is evaluated using the lattice Boltzmann method. Our results show that when the GDL is compressed, the porosity and through‐plane permeability decrease, while the gas‐phase tortuosity increases, i.e., increase the gas‐phase transport resistance. Copyright © 2015 John Wiley & Sons, Ltd.     

Controlling mechanism of coal chemical structure on biological gas production characteristics

To find the effect of coal chemical structure on biogas production, Lignite B was collected and extracted with nitrogen methylpyrrolidone (NMP), acetone and 0.60 mol/L NaOH. Simultaneously, methanogenic bacteria were enriched, and gas production experiments involving solvent extraction from residual coal and secondary gas production experiments involving coal were performed. The characteristics of biogas production, microcrystalline structure and coal chemical structure were analyzed. The results showed that the biogas production capacity of residual coal extracted by different solvents differed. The biogas production capacity of residual coal extracted by 0.60 mol/L NaOH was severely inhibited. The biogas production capacity of residual coal extracted by NMP and acetone was enhanced compared with that of raw coal. In contrast, primary residual coal still exhibits potential for methane production, but the methane production efficiency was reduced. Changes in the microcrystalline structure and functional groups of residual coal showed that solvent extraction increases the spacing and stacking height of the aromatic lamellae of coal, reduces the hydroxyl, methyl, methylene and aromatic hydrocarbon levels in coal, loosens the macromolecular network structure of coal, and enhances the connectivity of pores and fissures, thus allowing methane-producing bacteria to enter the coal mass and create favorable conditions for gas production through interactions between the two. X-ray photoelectron spectroscopy measurements showed that the secondary gas production increased the C content on the coal surface, decreased the O content and the O/C ratio, thus promoting the consumption of oxygen-containing functional groups on the coal surface to further produce gas.     

Characteristics of paleo-fluid of coal-bearing strata and its influence on the properties of CBM reservoirs in the Western Guizhou Province,China

The differential characteristics of paleo-fluids and their influence on the properties of coal reservoirs in Panxian and Zhijin areas were investigated by use of the data from experiments and drill wells. The results show that two generations of fluid activity related to hydrocarbon generation can be identified in these areas. The type of paleo-formation water indicates that the coal-bearing formation in Zhjin area is more favorable for hydrocarbon preservation than that of Panxian area. Under the influence of the paleo-fluid, the coal reservoirs in Zhijin area have poor pores connectivity, which are unfavorable to the output of coalbed methane.     

Implications of non-uniform porosity distribution in gas diffusion layer on the performance of a high temperature PEM fuel cell

The present study discusses a detailed investigation on the implications of non-uniform porosity distribution in the gas diffusion layer (GDL) on the performance of proton exchange membrane fuel cell (PEMFC). A three-dimensional, single-phase, isothermal model of high-temperature PEMFC is employed to study the effect of non-uniform porosity distribution in GDL. The different porosity configurations with stepwise, sinusoidal, and logarithmic variation in porosity along the streamwise direction of GDL are considered. The numerical experiments are performed, keeping average porosity as constant in the GDL. The electrochemical characteristics such as the oxygen molar concentration, power density, current density, total power dissipation density, average diffusion coefficient, vorticity magnitude, and overpotential are studied for a range of porosity distributions. Furthermore, the variations of oxygen concentration, average diffusion coefficient, and vorticity magnitude are also discussed to showcase the influence of non-uniform porosity distribution. Our study reveals that the PEM fuel cell performance is the best when the porosity of the GDL decreases logarithmically in the streamwise direction. On the contrary, the performance deteriorates when the GDL porosity decreases sinusoidally. Also, it has been observed that the effects of non-uniform porosity distribution are more pronounced, especially at higher current densities. The outcomes of present investigation have potential utility in GDL fabrication and membrane assembly's sintering process for manufacturing high valued PEMFC products.     

全方位加速油气生产

近期中国油气界针对不同类油气的发展孰先孰后、孰重孰轻出现了一些争论。从主体技术(水平井和压裂)和环保措施上看,致密(砂岩)油气、页岩油气、煤层气等都是基本相同的。我国致密油气成功实现规模生产,已掌握的致密油气成套技术为煤层气和页岩油气的发展奠定了相当雄厚的技术基础,不但水平井和压裂各自形成了完整的技术链,而且配套构成了庞大的技术系列,如果再加上改革和监管体系的重大进展,将使以致密油气、页岩油气、煤层气为主体的非常规油气具备良好的发展前景。据估算,目前我国致密油、致密气的产量至少分别占全国油、气产量的1/4和2/5左右。但即使如此,我国由常规油和致密油、重油构成的石油产量增长缓慢,天然气产量增长远不能满足能源构成调整和城镇化发展的需要,这就迫使我们要拓宽油气供应的思路。就国内生产而言,要确立常规和非常规并举,非常规油气中大力促进后起的页岩油气和煤层气的开拓,关注油页岩、煤制油(气)、生物质制油(气)等的发展,这就构成油气广义多元化发展的战略思维,进而因地因时制宜地全方位加速油气生产。     

羊粪沼气发酵过程中的纤维素酶酶活力与沼气产气量的关系研究

试验研究了在羊粪沼气发酵过程中纤维素酶酶活力与沼气产气量的变化关系.结果表明:在羊粪沼气发酵过程中,纤维素酶酶活力的大小与沼气产气量随时间表征出一致的变化趋势,但产气量的变化在时间上要落后于纤维素酶酶活力的变化,即在纤维素酶达到一峰值的下一时刻,产气量达到一峰值.     

Quantitative characterization of middle-high ranked coal reservoirs in the Hancheng Block,eastern margin,Ordos Basin,China: implications for permeability evolution with the coal macrolithotypes

Macrolithotypes control the pore-fracture distribution heterogeneity in coal impacting the coalbed methane (CBM) production from the reservoir. However, few studies have focused on the characteristics of macrolithotypes. Here, the macrolithotype samples from the three continuous seams (No. 3, 5 and 11) in the Hancheng Block, Ordos Basin, China were quantitatively characterized by multiple length scales. The results indicate that the bright coal has the best development of micro-fracture than those of the other macrolithotypes, which with good openness and connectivity under the optical microscopy; N₂ adsorption/desorption results reflect that the adsorption pores of the semi-dull and dull coal are more developed than the bright coal and semi-bright coal, and are dominated by plate-like and ink-bottle pores. The characteristics of the mercury intrusion/extrusion curves were determined by the mercury injection (MIP). From bright to dull coal the pore connectivity being worse, and the uniformity of pore and throats distribution becomes lower. The pore type that divided by NMR are recovered to be seepage type (the bright), comprehensive type (the semi-bright and semi-dull), and the type of adsorption (the dull). The behavioral differences would impact the porosity and permeability in coal. Thus, by the well logging evaluation approach, the relationship between coal macrolithotypes and select logging parameters were determined for coal macrolithotype identification, and with the petrel software included, the porosity-permeability models were built to investigate the permeability evolution with the coal macrolithotypes. Macrolithotypes are closely related to the permeability of coal reservoirs in this area. The greater contribution of permeability is typically from of the bright and semi-bright coal, and followed by semi-dull and dull coal, the better development of bright coal, the better permeability of the reservoir and vice versa.     

贵州省近50年降水量时空分布及变化特征

基于贵州省19个站点1960~2009年月降水资料,运用降水集度、气候趋势系数、Mann-kendall突变检验法、滑动T检验及小波分析等方法,分析了贵州省降水在不同时间尺度下的时空规律。结果表明,贵州省年降水量空间分布不均,整体呈东多西少的分布趋势,并形成了三多三少的降水集中区;近50年降水量呈下降趋势,年内降水呈季节性变化,春、秋季降水量有显著下降趋势,夏、冬季降水量呈上升趋势但不显著;贵州省年降水量存在22年左右的周期变化,在1984、1991、2001年发生突变,各季节周期变化和突变位置有所差异,这均增强了极端气候事件发生的概率,加剧了农业旱灾发生的风险。     

基于相对湿润度指数的贵州省近十年干旱特征分析

为分析贵州省干旱分布特征,基于贵州省均匀分布的30个气象站点2010～2019年的逐日气象数据,以相对湿润度指数为干旱监测指标,利用反距离权重插值分析及相关分析研究贵州省近10年的干旱特征.结果 表明,贵州省不同月份的干旱强度和干旱发生范围有所不同,且总体上呈干旱等级越高,干旱范围越小的态势.不同时间尺度的干旱强度和干...     

贵州省岩溶地区年径流系数受下垫面影响的分析

为研究岩溶地区年径流系数受特殊地貌、地质条件的影响程度,利用贵州省境内23个岩溶流域1961~2000年的径流资料和气象资料,采用Budyko方程拟合表征流域下垫面特征的参数值,并通过Mann-Kendall方法与相关分析,分析年径流系数变化趋势及其与流域下垫面特征的关系。结果表明,贵州省多年平均径流系数的空间分布与流域坡度呈正相关,与碳酸盐岩所占比例呈负相关;1961~2000年年径流系数呈增大趋势,与下垫面特征参数变化趋势一致,可见相对于气候变化,下垫面变化是影响贵州省年径流系数变化的主要因素。