Predicting rock mechanical properties of carbonates from wireline logs (A case study: Arab-D reservoir,Ghawar field,Saudi Arabia)

Four hundred plug samples from the Arab-D carbonate reservoir, Ghawar field, were tested for acoustic and mechanical properties at increasing triaxial stress. The results show that the rock mechanical parameters are primarily functions of porosity and, to a lesser degree, of mineralogy, texture and pore fabric (in order of degree of impact from higher to lower). The rock mechanical parameters of the intact matrix rock show no significant changes with stress under reservoir condition.     

Investigation on influence factors of dual laterologs curve form

In order to investigate the influences of caliper, formation thickness and invaded zone on the form of dual laterologs, forward modeling technique were applied to calculate the dual laterologs for different cases. The result shows that the resistivity logs become smoother and lower as the borehole diameter increases, the increase of the contrast between mud resistivity and formation resistivity induce the logs to be more pointed. When the formation thickness is less than 1m, the two-peak on the logs for resistive invasion vanished, and for thickness between 1 m and 4 m, the form of logs does not vary significantly. If the formation thickness is greater than 4 m, a platform appears on the logs at the middle of the formation. The thinner the invaded zone is, the more obvious the invasion feature on the laterologs is. For thick invaded zone the form of logs tend to be that of an uninvaded resistive formation. The form and amplitude of logs depend on the resistivity contrast between invaded zone, uninvaded formation and adjacentlayers.     

冻土未冻水含量的低场核磁共振试验研究

采用低场核磁共振技术测试了冻融循环过程中不同土质、不同NaCl离子浓度饱和试样的未冻水含量,结合T2分布曲线从微细观角度分析了冻融过程中未冻水在孔隙赋存分布情况。试验结果表明：冻结过程可分为过冷度段、快速下降段、稳定段3个阶段,而融化过程仅存在稳定段、快速融化段,并不存在与过冷现象对应的过热现象。冻结时大孔隙的水首先冻结,而融化时孔隙水的增加却是从小孔隙开始的,这是由水分热动力学势能的差异导致孔隙水冻结和融化在时间上的有序性。并且分析了冻融循环中土质类型、离子浓度对未冻水含量的影响,以及探讨了冻融过程出现的滞后现象的原因。     

测井沉积学研究综述

在总结大量国内外有关测井沉积学研究资料的基础上,结合作者的工作体会,系统总结了测井地质学领域的一门新的学科——测井沉积学的概念、研究方法及内容以及计算机技术和数学方法在测井沉积学解释中的应用等问题。测井沉积学研究采用正演和反演的方法,关键是建立沉积学特征与测井地质信息之间的解释模型,尽量使沉积学特征定量化以便于处理和预测,因此先进的数学方法和计算机技术在测井沉积学研究中发挥了重要的作用。最后,概括总结了测井沉积学的发展方向及动态。     

二维轴对称介质中电磁波测井的响应函数

单发双收电磁波测井测的是两接收线圈的感应电动势之间的相位差和幅度比及测井响应与地层介电常数和电导率两者有关的一般情况,对此本文推导出其在二维轴对称介质中响应函数公式,给出它的快速算法.通过建立二维非均质反演Jacobi矩阵与响应函数的关系,开辟了Jacobi矩阵快速算法构造的有效途径.从理论上得到了在均匀介质中相位差和幅度比对地层的介电常数和电导率的空间分布探测特性具有交叉互补性的结果,即相位差对电导率（介电常数）的空间分布敏感区域和幅度比对介电常数（电导率）的空间分布敏感区域是相同的.     

磷灰石的核磁共振研究——(Ⅰ)19F的NMR谱学特征

对固相反应合成的氟羟磷灰石固溶体系列进行了19FMAs NMR分析,结果表明:当F含量较低时,只出现一个化学位移δ为-105.5的NMR峰,而当F相对含量超过(OH)的相对含量时,在δ为-103附近出现一个新的微弱肩状共振峰.随F含量增大,该峰相对强度逐渐增大,说明在高F含量的FHap结构中出现了两种化学环境下的F核.根据上述19F NMR峰的数量和位置,可以推断磷灰石中F-OH的相对含量和成键状态.     

核磁共振测井时域分析法数值模拟及影响因素分析

核磁共振测井时域分析法已广泛用于评价油气层,并获得了很多成功应用实例.然而,由于储层结构的复杂性以及孔隙流体性质的多变,也常常见到应用失败的实例,影响了时域分析法的应用效果.本文通过数值模拟研究时域分析法在不同储层条件下识别流体的效果,并分别从孔隙流体类型、地层孔径变化、信噪比以及采集参数等方面,分析影响时域分析法应用...     

Metabolomic Study on the Halophyte Suaeda salsa in the Yellow River Delta

Plant metabolomics has been well established and applied across multiple fields including medicine, biotechnology, and environmental sciences in the post‐genomic era. The Chenopodiaceae C₃ halophyte Suaeda salsa is the most important plant species in the vegetation of saline soil and even intertidal zone in the Yellow River Delta, which is economically consumed as food, widely used as a bioindicator of environmental stresses (salinity, drought, and pollution) and typically applied for the phyto‐remediation of degraded wetland. However, no global studies have been focused on the metabolic profile of this halophyte which is widely applied in environment related research areas. In metabolomics, the first crucial step is the preparation of plant samples. In this work, several strategies of metabolite extraction from this C₃ halophytes S. salsa were evaluated and the metabolic profile was characterized by NMR‐based metabolomics. Multiple replicates of plant tissues (approx. 250 mg whole fresh weight of leaves and stems) were homogenized by a high throughput automated Precellys 24 bead‐based homogenizer and then extracted using the following solvent systems of varying polarities: methanol, water, methanol/water, methanol/chloroform/water, and acetonitrile. The hydrophilic metabolites were analyzed using one‐dimensional proton NMR spectroscopy, and the subsequent NMR spectra were evaluated by principal components analysis (PCA). Each extraction protocol revealed unique metabolic profile from S. salsa. Overall, the quality of each extraction protocol was assessed based on the yield, reproducibility, ease, and speed, and we concluded that the solvent of methanol/water was preferable for the metabolite extraction due to its highest reproducibility, ease, and speed, and considerably high yield. Validation of methanol/water (1:1) solvent also showed a high degree of reproducibility with technical variation being considerably lower than biological variation in S. salsa samples. This demonstrated the quality and robustness of the methanol/water extraction method for NMR‐based metabolomics studies.     

In-situ gas hydrate hydrate saturation estimated from various well logs at the Mount Elbert Gas Hydrate Stratigraphic Test Well, Alaska North Slope

In 2006, the U.S. Geological Survey (USGS) completed detailed analysis and interpretation of available 2-D and 3-D seismic data and proposed a viable method for identifying sub-permafrost gas hydrate prospects within the gas hydrate stability zone in the Milne Point area of northern Alaska. To validate the predictions of the USGS and to acquire critical reservoir data needed to develop a long-term production testing program, a well was drilled at the Mount Elbert prospect in February, 2007. Numerous well log data and cores were acquired to estimate in-situ gas hydrate saturations and reservoir properties.Gas hydrate saturations were estimated from various well logs such as nuclear magnetic resonance (NMR), P- and S-wave velocity, and electrical resistivity logs along with pore-water salinity. Gas hydrate saturations from the NMR log agree well with those estimated from P- and S-wave velocity data. Because of the low salinity of the connate water and the low formation temperature, the resistivity of connate water is comparable to that of shale. Therefore, the effect of clay should be accounted for to accurately estimate gas hydrate saturations from the resistivity data. Two highly gas hydrate-saturated intervals are identified - an upper ∼43 ft zone with an average gas hydrate saturation of 54% and a lower ∼53 ft zone with an average gas hydrate saturation of 50%; both zones reach a maximum of about 75% saturation.     

C and N NMR analysis of some fungal melanins in comparison with soil organic matter

A variety of fungal melanins with natural ¹⁵N abundance are characterized by solid-state ¹³C and ¹⁵N NMR spectroscopy and are compared to solid-state ¹³C and ¹⁵N NMR spectra of organic matter from representative soils. In all solid-state ¹⁵N NMR spectra the peptide/amide region (−220 to −285 ppm) dominates with more than 70% of the total intensity. The region between −285 and −375 ppm, assigned to amino and ammonium groups, always contains more than half of the remaining intensity. The area in the region from −30 to −220 ppm, where aromatic heterocycles would show signals, makes up less than 10% of the total intensity. These findings call into question common structural models for melanins. The solid-state ¹³C NMR spectra, on the other hand, reveal large differences when the melanins are compared to each other, and to composts and soils. The concentration of the aromatic carbon varies from 5 to 40% in the melanin series. The ratio C_aro/N_tot and C_ali/N_tot were calculated, and confirm that nitrogen in these samples is bound in C_a-groups rather than in aromatic heterocyclic structures.