青海省天峻县木里煤田煤层气有利区块的 多层次模糊数学评判

对影响煤层气勘探开发潜力的各种因素进行了综合研究,确定了煤层气勘探开发潜力评价的3个二级指标(生气潜力、储层物性和封盖性能)及对应的三级指标。采用模糊数学方法对各级因素指标赋予权重,建立了用于煤层气勘探开发潜力评价的多层次模糊数学评判模型。利用该模型,对青海木里煤田中低煤阶煤层气资源勘探开发潜力进行了评价,认为江仓矿区是木里煤层气勘探开发的最佳试验区。所建立的评价体系可以作为中低煤阶煤层气资源开发潜力评价的参考体系。     

煤层气采收率预测方法评述

综合评述了煤层气采收率预测方法。分别对类比法、解吸法、气含量降低估算法、等温吸附曲线法和气藏数值模拟法的原理、适用条件以及存在问题等进行了探讨,并对关键参数的确定方法进行了详细的介绍。文章指出:解吸法、气含量降低估算法和等温吸附曲线法虽然计算过程简单,但因其考虑因素少,确定的采收率可靠性差;类比法取决于研究者对研究区和类比区的研究程度以及自身的技术水平和经验;气藏数值模拟法确定的煤层气采收率比较准确,但适用的范围较窄,而且所需数据多,计算过程复杂。     

煤层气系统——一种非常规含油气系统

为了更加有效地预测煤层气分布,指出煤层气有利勘探区域,引入了含油气系统来研究煤层气。煤层气系统是由煤层和其中的煤层气及煤层气藏形成所必需的一切地质要素和作用所组成的天然系统,其中的地质要素包括煤层及其顶底板,作用是煤层气的生成、储集和保存等。煤层气系统的建立和研究,为煤层气的勘探和开发提供了一种新的思维方式和研究方法,以及一套煤层气勘探研究的程序和框架。     

波兰煤矿瓦斯高效抽放技术特点

目前,在波兰41对主要生产矿井中,有23对高瓦斯矿井进行了瓦斯抽放。2004年瓦斯平均抽放率为30%,平均利用率为39%。根据瓦斯地质条件、瓦斯涌出特点和采区通风方式,着重介绍了波兰煤矿强化煤层、围岩和采空区瓦斯抽放,提高矿井瓦斯抽放效率的工艺技术特点。在工作面的瓦斯排放中,注重开采、通风与瓦斯抽放一体化,通过优化抽放钻孔布置,取得钻孔瓦斯抽放的最佳效果,是波兰煤矿瓦斯治理的一项成功经验,成为煤矿持续安全高效生产的重要技术保障。     

郑庄区块煤层气赋存特征及控气地质因素

沁水盆地南部郑庄区块煤层气资源条件良好,勘探开发潜力大。通过对郑庄区块煤层气地质条件和储层条件的深入分析,认为本区煤层气赋存条件良好,含气量较高,储层吸附/解吸能力较好,但储层渗透率相对较低;郑庄区块煤层气藏主要受3类地质因素控制：构造对煤层气含量和赋存规律具有明显的控制作用;水文地质条件对煤层气具明显的水力封闭作用,该区地下水径流较弱,为典型的等势面扇状缓流型,有利于区块内煤层气的富集;燕山晚期岩浆活动和高异常地热场对煤层热演化和煤层气生成有显著的控制作用。     

新疆煤层气资源赋存特征及开发潜力分析

通过对新疆主要煤田的煤炭资源分布特征，煤变质特征及构造特征分析，探讨新疆的煤层气资源赋存特征，对新疆主要煤田煤层气资源的勘探开发潜力进行初步评价，新疆的煤层气基本属于少生中储型，虽然单位含气量较低，但煤炭资源非常丰富，且相对集中，煤气具有较大的勘探开发潜力。     

基于干扰试井技术的煤层气储层参数测定

为弥补传统注入压降试井测试结果以点代面的问题,提出基于煤层气干扰试井的储层参数测试方法,阐述了其基本原理、测试方法和数据分析依据。以沁水盆地南部1口激动井和4口检测井组成的井组为例,结合该井组前期注入压降法、历史拟合法测试结果,并与干扰试井测试结果进行对比分析。结果表明,煤层气干扰试井法各井测点渗透率接近利用排采数据的历史拟合值,且高于注入压降测值,但3种方法获得数据处于同一数量级之内;煤层气干扰试井技术方法可以反映试验5口井的区域渗透率分布特征,其区域东南方向渗透率较大,即为主裂隙发育方向。结合3种方法测得的参数值对比可知,煤层气干扰试井法既可获得离散点的参数值,又可以获得区域井组的连通性和优势渗流方向,结果有助于认识区域储层参数,为进一步的井网和排采井的布置提供比较直接的数据依据。     

Application of AVO Analysis to Seismic Data for Detection of Gas below Methane Hydrate Stability Zone in Nankai Trough Area

Abstract. For the purpose of development of methane hydrate, occurring in the deep marine subsurface, as a resource, the most important issue is to understand the methane hydrate system (generation, migration and accumulation) as well as to delineate the methane hydrate reservoir properties. We have applied the Amplitude Versus Offset (AVO) analysis to the seismic data acquired in the Nankai Trough, offshore Japan, in order to confirm the occurrence of gas just below the methane hydrate-bearing zone, assuming that gas will show a so-called Class-3 AVO response. Knowledge of the amount and occurrence of gas in the sediment below methane hydrate-bearing zone is one of the keys to understand the methane hydrate system.
We have utilized the qualitative analysis of AVO methodology to delineate how gas is located below the BSR, which is thought to be the reflection event from the interface between the methane hydrate-bearing zone and the underlying gas-bearing zone. In the region of MITI Nankai Trough Well PSW-3, we observe two BSRs separated by 25 ms. After AVO modeling using well data, we applied AVO attribute analysis and attribute crossplot analysis to the seismic data. Finally we applied an offset-amplitude analysis to CMP gather data at specific locations to confirm the results of AVO attribute analysis. The AVO analysis shows that there is very little gas located in the underlying sediment below methane hydrate-bearing zone. This result supports the fact that we could not obtain any clear evidence of gas occurrence just below the methane hydrate-bearing zone in the Nankai Trough well drilling.     

陕西渭河盆地固市凹陷渭热2井组 甲烷气成因及其意义

渭河盆地固市凹陷渭热2井组甲烷气的成功点火,再一次引起人们对渭河盆地油气资源前景的关注。渭热2井组及邻区7口井天然气组分、甲烷C同位素等分析指标显示,该区甲烷气具有2种成因类型,浅部气层为新近系张家坡组生物成因气,中深部天然气来自前新生界煤型热解-裂解气;伴生CO2气为有机成因。地质分析认为,渭河盆地固市凹陷具有良好的新生界生物气资源前景,前新生界煤系地层也是渭河盆地重要的潜在烃源岩,表明渭河盆地具有开展进一步油气调查的资源基础。     

Methane exchange between coal-bearing basins and the atmosphere: the Ruhr Basin and the Lower Rhine Embayment, Germany

A precise knowledge of methane exchange processes is required to fully understand the recent rise of atmospheric methane concentration. Three of these processes take place at the lithosphere/atmosphere boundary: bacterial consumption of methane and emission of bacterial or thermogenic methane. This study was initiated to quantify these processes on a regional scale in the Ruhr Basin and the Lower Rhine Embayment. Since these areas are subject to bituminous coal and lignite mining, natural and anthropogenically-induced methane exchange processes could be studied. The methane emission and consumption rates and their carbon isotope signal were measured at the lithosphere/atmosphere boundary using flux chambers. On most of the soils studied, methane consumption by bacteria was identified. Thermogenic methane was released only at some of the natural faults examined. In active and abandoned bituminous coal mining areas methane emissions were restricted to small areas, where high emission rates were measured. The carbon isotope composition of methane at natural faults and in mining subsidence troughs was typical of thermogenic methane (−45 to −32 ‰ δ¹³C). Methane exchange balancing revealed that natural methane emissions from these two basins represent no source of atmospheric importance. However, methane release by upcast mining shafts dominates the methane exchange processes and is by about two orders of magnitude greater than methane consumption by bacterial oxidation in the soils.