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1.
Permeability–porosity relationships for sediments from the northern Barbados, Costa Rica, Nankai, and Peru subduction zones were examined based on sediment type, grain size distribution, and general mechanical and chemical compaction history. Greater correlation was observed between permeability and porosity in siliciclastic sediments, diatom oozes, and nannofossil chalks than in nannofossil oozes. For siliciclastic sediments, grouping of sediments by percentage of clay-sized material yields relationships that are generally consistent with results from other marine settings and suggests decreasing permeability as percentage of clay-sized material increases. Correction of measured porosities for smectite content improved the correlation of permeability–porosity relationships for siliciclastic sediments and diatom oozes. The relationship between permeability and porosity for diatom oozes is very similar to the relationship in siliciclastic sediments, and permeabilities of both sediment types are related to the amount of clay-size particles. In contrast, nannofossil oozes have higher permeability values by 1.5 orders of magnitude than siliciclastic sediments of the same porosity and show poor correlation between permeability and porosity. More indurated calcareous sediments, nannofossil chalks, overlap siliciclastic permeabilities at the lower end of their measured permeability range, suggesting similar consolidation patterns at depth. Thus, the lack of correlation between permeability and porosity for nannofossil oozes is likely related to variations in mechanical and chemical compaction at shallow depths. This study provides the foundation for a much-needed global database with fundamental properties that relate to permeability in marine settings. Further progress in delineating controls on permeability requires additional carefully documented permeability measurements on well-characterized samples. 相似文献
2.
Permeability characterisation of low permeability, clay-rich gas sandstones is part of production forecasting and reservoir management. The physically based Kozeny (1927) equation linking permeability with porosity and pore size is derived for a porous medium with a homogeneous pore size, whereas the pore sizes in tight sandstones can range from nm to μm. Nuclear magnetic resonance (NMR) transverse relaxation was used to estimate a pore size distribution for 63 samples of Rotliegend sandstone. The surface relaxation parameter required to relate NMR to pore size is estimated by combination of NMR and mercury injection data. To estimate which pores control permeability to gas, gas permeability was calculated for each pore size increment by using the Kozeny equation. Permeability to brine is modelled by assuming a bound water layer on the mineral pore interface. The measured brine permeabilities are lower than predicted based on bound water alone for these illite rich samples. Based on the fibrous textures of illite as visible in electron microscopy we speculate that these may contribute to a lower brine permeability. 相似文献
3.
Gas production from shale resource plays has transformed the USA energy market. Despite the knowledge gained from the analysis of large amounts of shale core, appraisal of shale gas resource plays requires a large number of wells to be drilled and tested. Ideally, core analysis results would provide an indication of both the gas filled porosity and permeability of shale resource plays, which could then be used to reduce the number of wells needed during appraisal. A combination of laboratory experiments, numerical modelling and a round-robin test have been conducted to assess the validity of the crushed shale method (CSM), which has been widely used in industry to assess the porosity and permeability of shale. The results suggest that the CSM can provide reasonably precise estimates of porosity measured at ambient stress if a standard sample cleaning method is adopted; although a reliable method to correct these values to subsurface conditions needs to be developed. The CSM does not, however, appear to provide useful information on shale permeability. A round-robin test shows that differences of up to four orders of magnitude in permeability were provided by different laboratories when analysing the same sample. These huge differences seem to occur due to a combination of errors in calculating permeabilities from pressure transients, differences in the way that permeability is calculated as well as uncertainties regarding the effective size of crushed shale particles. However, even if standardized, the CSM may not be particularly useful for characterizing the flow capacity of shale because it is insensitive to the presence of high permeability zones that would control flow in the subsurface. 相似文献
4.
《Marine and Petroleum Geology》2013,39(1):53-72
Evaluation of the reservoir quality of the Triassic Halfway–Montney–Doig hybrid gas shale/tight gas reservoir in the Groundbirch field in northeastern British Colombia requires an integration of unconventional and conventional methodologies. Reservoir evaluation includes reservoir thickness and structure, total porosity, TOC content, organic maturity, pore size distribution (micro- to macro-pore size fractions), surface area, mineralogy and pulse-decay permeability. Quartz (10–74%), carbonate (13–73%) and feldspar (0–42%) dominate the mineralogy of all formations with illite (0–32%) being locally important. The Tmax values range between 443 and 478 °C placing the reservoirs beyond the oil window. Pore size distribution by low-pressure gas adsorption analysis identifies a large variation between the contributions from the micro-, meso- and macro-pore size fractions. Matrix permeabilities range between 1.0E-3 and 6.5E-7 mD at an effective stress between 2400 and 3300 PSI (16.5–22.8 MPa).Changes in depositional environments and diagenetic processes manifest as differences in lithology and mineralogy within the Montney and Doig reservoirs which subsequently affect the fabric, texture and pore size distribution. Fabric, texture and pore size distribution contribute to the variation in the permeability and the proportions of free to sorbed gas within the reservoir. Quartz-rich, coarser-grained intervals (upper portions of Doig C, B and Halfway Formation) have lower surface area, greater porosities and a higher volume of macropores compared to the carbonate- and clay-rich finer-grained intervals (Doig A). Permeabilities do not vary according to lithology with higher permeabilities found within both fine-grained (Doig A) and coarser-grained (Halfway Formation) units. Permeability is controlled by pore size distribution. Higher permeability samples contain a balanced ratio between micro-, meso- and macro-porosity. The finer-grained intervals have higher sorbed gas capacity due to higher surface areas because of the higher volumes of finer mesopores and micropores than the coarser-grained units. However, porosity and permeability are low in some parts of the Doig A and fracture stimulation is necessary to achieve economic flow rates. 相似文献
5.
观察中国对虾蜕皮间期皮肤与外骨骼的组织学构造。指出外骨骼分为表层和里层,表层由较薄的外表层和较厚的内表层组成。里层又分为外层和内层:外层由平行于表面的纤维小板组成(暗板带),平行的纤维小板之间有抛物线状纤维联系(明板带);内层纤维小板比外层小。内层与外层之间有一结晶钙薄层,是两层之间临界面。表皮为单层细胞,有基膜衬托。皮肤腺和色素细胞位于表皮层之下,分布全身。 相似文献
6.
Bentheimer sandstone outcrop samples are ideal for laboratory studies due to their lateral continuity and block scale homogeneous nature. Over the years they have been used to investigate reservoir topics ranging from passive and active properties of oil/gas/water/rock interaction and processes to flow and transport.This work shows an evaluation of Bentheimer sandstone properties and their characteristics to advance understanding on the mineral accessory and the physical and electrical transport properties. On the basis of the nature of depositional environments and diagenesis, we measure and characterize spatial attributes of the matrix, mainly by qualitative analysis, laboratory and stereological measurements and statistical 2D/3D reconstructions. The main contribution of this paper is the impact of mineral composition on the petrophysical quality and block scale homogeneity of the reservoir. With 3D techniques reconstructions of the new rock grain framework pore structures have been created.Based on measurements, a review of literature data and interpretation of variation between the outcrops and flow relevant parameters, we conclude that Bentheimer sandstone is a rock that shows constant mineralogy and is largely free of paramagnetic impurities. In accordance with the results of 3D reconstructions techniques and in line with the depositional settings, they show a well sorted grain framework and a pore network that can be used to calculate the permeability and resistivity without conducting any direct laboratory measurements of either parameter. It presents a porosity with a range of 0.21–0.27 and permeabilities varying between 0.52 and 3.02 Darcy. Based on our work and literature, it is found that high permeability together with similar distribution of pore throats and bodies make the sandstone an attractive and easy obtainable candidate for comparative experimental studies. Moreover, we state by comparing various techniques that the efficiency and resolution accuracy of the applied method must be taken into consideration when planning the measurements. 相似文献
7.
We combine nuclear magnetic resonance (NMR) transverse relaxation time data and gamma ray data to estimate lithology-dependent permeability in silt- and clay-rich sediments. This approach extends the utility of the Schlumberger-Doll Research (SDR) permeability equation from reservoirs to aquicludes and seals, and thus improves the value and robustness of NMR data. Data from Keathley Canyon, northern Gulf of Mexico show that NMR data can be used to define permeability from 10−18 to 10−14 m2 (0.001–10 millidarcies) as calibrated and tested by direct measurements on core samples. We performed uniaxial, constant rate-of-strain consolidation experiments on sediments from Keathley Canyon to determine core-scale permeability. Permeabilities from these experiments were compared to permeabilities calculated from logging-while-drilling data. A better fit between log-derived permeability and laboratory-measured permeability was obtained using the SDR equation with a variable coefficient A, rather than a constant A as is typically used. We show how A is a function of lithology and can be modeled from gamma ray data. The relationship between A and gamma ray values suggests that variations in A are caused by platy clay minerals and the effect they have on the pore system. Our results provide improved means for permeability estimation for application in basin flow modeling, hydrocarbon migration modeling, and well completion design. 相似文献
8.
Fundamental response of pore-water pressure to microfabric and permeability characteristics: Eckernförde Bay 总被引：1，自引：0，他引：1
R. H. Bennett M. H. Hulbert M. M. Meyer D. M. Lavoie K. B. Briggs D. L. Lavoie R. J. Baerwald W. A. Chiou 《Geo-Marine Letters》1996,16(3):182-188
Ambient and dynamic in situ pore pressures were measured, and microfabric was examined in finegrained, shallow-water sediment in Eckernförde Bay, Germany. In situ permeabilities were calculated from piezometer data. Pore-water pressure decay times in sediments 0.5–1.0 m subbottom are indicative of clayey materials. Shallower sediments, although of similar classical grain size as the deeper sediments, have quicker decay times typical of silty marine sediment. Pore pressure response is a function of the microfabric, porometry, and sediment permeability. Aggregates (composed of fine-grained material, biota, and extracellular polymers) produce large pores and complex microstructure, resulting in effective permeabilities characteristic of silts. 相似文献
9.
西沙海槽区作为气水合物的可能聚集地越来越受到关注。浅析地震相分析方法,通过地震相标志的识别,归纳出自中中新世以来,西沙海槽发育有8种地震相：S形前积地震相、斜交前积地震相、下超型前积地震相、丘状地震相、杂乱地震相、空白地震相、透镜状地震相和席状地震相。较细致地描述了各种地震相的反射特征,并结合研究区的沉积背景,对不同地震相的沉积学特征做出了合理解释。 相似文献
10.
MS2000激光粒度仪测量第四纪沉积物粒度的定量进样研究 总被引：1，自引：0，他引：1
粒度是第四纪古气候与古环境重建的常用替代指标,目前通常采用Mastersizer2000激光粒度仪进行分析,该测试仪器优点是速度快、精度高、重复性好,缺点是进样过程未实现定量化,对部分沉积样品的分析结果出现一定的随机性和不确定性,分析结果易产生人为误差。为探究样品量和进样方法对测试结果可能造成的影响,本研究选取6类代表性第四纪松散沉积物,预处理后分别采用倾倒法、吸管法及定量进样法进行多次重复实验。结果显示:粒度组分越单一,不同进样方法造成的结果误差越小;如果沉积物含有多个粒度组分,而预处理样品量过多,倾倒法容易造成粒度结果偏细,吸管法往往造成实验结果偏粗,定量进样法实验结果居于前两者之间。采用烧失量法计算沉积物中碳酸盐、有机质含量,结合马尔文激光粒度仪测试原理及多次定量重复实验结果,计算了一次实验所需样品量,发现其与中值粒径和碳酸盐、有机质(合称杂质)含量呈线性正相关。根据该线性关系式,在分析第四纪沉积物中值粒径范围及杂质含量的前提下,可计算一次测试所需样品量,将全部预处理后样品倒入测试烧杯中,可有效避免样品量和进样方法对样品粒度实验结果造成的误差。 相似文献
11.
The permeability of faults within siliciclastic petroleum reservoirs of the North Sea and Norwegian Continental Shelf 总被引：1，自引：0，他引：1
Faulting in Middle Jurassic reservoirs occurred at shallow depth during regional extension. Clean sandstones (<15% clay) deformed without significant grain fracturing and permeability reduction. Faults in impure sandstones (15–40% clay) experienced significant syn-deformation compaction and permeability reduction. Enhanced compaction during deeper burial reduced their permeabilities further from an average of 0.05 mD at <2.5 km to 0.001 mD at >4 km. Clay-rich sediments (>40% clay) deformed to produce clay smears with very low permeabilities (<0.001 mD). Faulting in the Rotliegendes occurred at greater depth during both basin extension and inversion. Extensional faulting produced cataclasites with permeability reductions of <10–>106; their permeabilities range from 0.2 to 0.0001 mD and are inversely related to their maximum burial depth. Faults formed or reactivated during inversion experienced permeability increase. These results can be extrapolated to other hydrocarbon reservoirs if differences in stress and temperature history are taken into account.The permeability of most (>80%) faults is not sufficiently low, compared to their wallrock, to retard single-phase fluid flow on a km-scale. Nevertheless, most faults could retard the flow of a non-wetting phase if present at low saturations. It may be necessary to incorporate the two-phase fluid flow properties of fault rocks into reservoir simulators using upscaling or pseudoisation techniques. Fault property data should be calibrated against production data before it can be used confidently. 相似文献
12.
Bennett R.H. Hulbert M.H. Curry C. Johnson H.P. Hutnak M. Curry K.J. 《Oceanic Engineering, IEEE Journal of》2002,27(3):571-580
An in situ permeameter probe was deployed off Fort Walton Beach, Florida in shallow-water coastal sandy sediment. Stations were occupied in a 600 m /spl times/ 600 m area. Intrinsic permeability in sand at 17 stations varied from 0.3 to 6.1 /spl times/ 10/sup -11/ m/sup 2/ to subbottom depths of 50 cm. Permeability decreased with increasing subbottom depth and minimal compaction. The sediment is a well-sorted, medium quartz sand with a mean grain size of approximately 0.34-0.52 mm and with 5%-8% carbonate shells and shell fragments. The probe was tested in a slightly finer-grained sediment near the main study area and revealed permeabilities of 0.1-3.2 /spl times/ 10/sup -11/ m/sup 2/. The permeabilities measured are reasonable for the observed sandy and slightly finer-grained sediments. 相似文献
13.
选择长江口盐沼典型高程部位(高潮滩上部、中潮滩下部、光滩)柱状样,采用小间隔(1 cm)取样,通过粒度、颗粒有机碳(POC)含量与碳稳定同位素组成(δ13C)分析,研究盐沼滩面发育的沉积和地球化学特征,结果表明,盐沼沉积物的粒度参数、POC含量与δ13C值随深度变化明显;在盐沼典型高程部位沉积物的颗粒组成与地球化学特征差异显著,有明显的滩面趋势,这与滩面的规律性演化密切相关.柱样有限深度内有明显的相对淤积期与冲刷作用相对较强时期的交替,表明长江口盐沼滩面发育过程并不是线性的.盐沼沉积物黏粒含量对POC含量和δ13C值的垂向变化及滩面趋势影响显著,表明流域来水来沙明显制约河口盐沼的发育.对于沉积动力环境复杂、冲淤过程频繁、厚度为毫米级的砂质纹层和泥质纹层发育的河口盐沼,在沉积和地球化学研究中采用小间隔取样的效果明显,有助于揭示盐沼发育过程的更多信息,为年际滩面冲淤演变研究提供新途径. 相似文献
14.
15.
Sampling effort required to recover the main gradients in marine benthic species composition 
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下载免费PDF全文 Marine benthic surveys and monitoring programs may have several goals. When the aim of such studies is to reveal and describe gradients in species composition, the gain in ecological insight achieved by the study depends on how well the spatial variability of species’ occurrence and abundance within the study area is covered by the sampling design. The common practice in such programs is to collect four or five grab samples from each visited site to capture the site's species composition. The rationale for this practice is based on the aim of capturing a large proportion of species at a specific site (i.e. point). We argue that this practice has been established without taking Iterative approaches into account, such as decreasing the sampling effort at each site and instead increase the number of sites visited. The collection and processing of data from marine sediment ecosystems are time‐consuming and, thus, expensive. Therefore, finding the optimal trade‐off between the number of sites visited and the number of samples per site is important. We examined this trade‐off by exploring how reduction of sampling effort per site affects the stability and recovery of gradients in species composition of marine benthic macrofauna. Our full data set consisted of four grab samples from each of 28 sites from the inner part of the Oslofjord, SE Norway. Procrustes analysis and calculation of Kendall's rank correlation coefficients showed that the main gradient in species composition extracted by detrended correspondence analysis of data sets with reduced per‐site sampling effort closely resembled the main gradient extracted for the full data set. Our results therefore suggest that marine benthic surveys that aim to identify the main gradient structure of species composition and relate this structure to main environmental complex gradients are likely to benefit from reducing the sampling effort at each site and, instead, increasing the number of visited sites. We argue that coverage of both the variation in species composition and the environment in the study area will then be improved. Monitoring programs with other aims than to identify the main gradients in species composition may also benefit from the adoption of a many‐sites, one‐sample sampling strategy. This may be particularly true if additional sampled sites are based on a stratified sampling strategy that ensures that the spatial variability in the study area is accounted for. 相似文献
16.
Caprock has the most important role in the long term safety of formation gas storage. The caprocks trap fluid accumulated beneath, contribute to lateral migration of this fluid and impede its upward migration. The rapid upward passage of invasive plumes due to buoyancy pressure is prevented by capillary pressure within these seal rocks. In the present study, two main seal rocks, from the Zagros basin in the southwest of Iran, a shale core sample of Asmari formation and an anhydrite core sample of Gachsaran formation, were provided. Absolute permeabilities of shale and anhydrite cores, considering the Klinkenberg effect, were measured as 6.09 × 10−18 and 0.89 × 10−18 m2, respectively. Capillary sealing efficiency of the cores was investigated using gas breakthrough experiments. To do so, two distinct techniques including step by step and residual capillary pressure approaches were performed, using carbon dioxide, nitrogen and methane gases at temperatures of 70 and 90 °C, under confining pressures in the range 24.13–37.92 MPa. In the first technique, it was found that capillary breakthrough pressure of the cores varies in the range from 2.76 to 34.34 MPa. Moreover, the measurements indicated that after capillary breakthrough, gas effective permeabilities lie in range 1.85 × 10−21 – 1.66 × 10−19 m2. In the second technique, the minimum capillary displacement pressure of shale varied from 0.66 to 1.45 MPa with the maximum effective permeability around 7.76 × 10−21 – 6.69 × 10−20 m2. The results indicate that anhydrite caprock of the Gachsaran formation provides proper capillary sealing efficacy, suitable for long term storage of the injected CO2 plumes, due to its higher capillary breakthrough pressure and lower gas effective permeability. 相似文献
17.
《Marine Geology》2005,214(4):411-430
The Atchafalaya River in Louisiana shares the third largest drainage basin in the world with the Mississippi River. Sediment cores and seismic profiles were used to examine the development and impact on land accretion of an early-stage subaqueous delta accumulating on the shallow (<25 m water depth) continental shelf seaward of the Atchafalaya River mouths in the period (∼100 years) since the Atchafalaya has captured a significant fraction of the overall Mississippi discharge. The subaqueous clinoform is muddy (70–100% finer than 63 μm) and extends approximately 21–26 km seaward of the shell reef (to 8 m water depth) across the mouth of the Atchafalaya Bay, with a discontinuous, and, in places, mobile modern mud layer <20 cm thick covering a relict deltaic shoal area further seaward. The sigmoidal clinoform has a topset surface that steepens from east to west (1:2500 to 1:1600), a foreset with maximum slopes of about 1:550, and a limited bottomset region (<0.5 km wide). 210Pb and 137Cs geochronology show maximum sediment accumulation rates (>3 cm/year) correspond to the foreset and bottomset region, with rates decreasing to as low as 0.9 cm/year on the shelf topset region and its extension inside Atchafalaya Bay. Seven sedimentary facies are observed in the subaqueous delta, with differences created by degree of biological destruction of physical stratification, which is inversely related to sediment accumulation rate, and by the proximity of an area to the riverine sand source. There is a marked alongshore sediment dispersal pattern observed by the progressive winnowing of sand and coarse silt to the west. There is also a significant increase in shell content in Atchafalaya Bay relative to shelf facies. The resulting sigmoidal clinoform deposit (<3 m thick) more closely resembles strata geometries of subaqueous mud deltas associated with energetic systems (e.g., Amazon, Ganges–Brahmaputra, Fly), than it does the mature Mississippi delta 180 km to the east, albeit on a smaller scale and in shallow water. 相似文献
18.
Research and development in ocean engineering, particularly in the areas of deep ocean drilling and platform construction, have progressed remarkably in the past few decades. By and large, instrumentation for biological ocean research, in comparison, remains simplistic. A brief review of marine biological sampling devices is provided, indicating the relative inadequacies of marine bio-instrumentation. Equipment for plankton, benthos, and nekton sampling has been improved in recent years compared to that available for nannoplankton. Nevertheless, there are limitations even in the best of these devices, and improvements in sampling gear would benefit ocean biology significantly. Precise sample collection of surface slicks, water column, and ocean sediment is mandatory for biological assessment of environmental impact. The necessary sampling gear is either not available or under development and, in cases where the instrumentation is available, it is, in general, either limited in application or not entirely reliable. As an example, increasingly, the ocean serves as the receptor of discharge from sewage outfalls, deep water disposal, and ocean dumping. Thus assessment of biological impact is required, particularly in light of the increasing frequency of reports of survival of bacteria and viruses pathogenic for man in those regions of the world oceans significantly affected by these activities. Improved instrumentation for aseptic sample collection and retrieval of water, sediment, and biota for quantitative, as well as qualitative, microbiological analyses are needed. Developments in baromicrobiology have been rapid, but improved instrumentation is needed. Even though aseptic collection of deep ocean water samples is possible, sediment sample collection for microbiology is still accomplished by coring or grab devices, with no instrument yet available for quantitative undisturbed sample collection without contamination from water column microorganisms. 相似文献
19.
在异质性潮间带湿地中通过野外采样估算大型底栖动物物种丰富度，面临的挑战是统计上精确性的要求与实际采样难度之间的矛盾。为了解决这个问题，本研究通过对采样策略整个过程的三个主要部分进行优化设计（优化采样方法、确定最少采样效力、探索最佳的采样间距），以期在中国长江河口典型的潮间带湿地中获得一个优化、有效和实用的大型底栖动物采样策略。本研究选取了横断面采样方法，并根据典型栖息地类型（潮滩、潮沟、盐沼植被）进行分层优化采样，这种类型的采样也称为横断面分层抽样。最少采样效力和最佳的采样间距由两个数学方法确定：蒙特·卡洛模拟和物种累积曲线。结果表明，根据典型栖息地类型优化的横断面分层采样，在大为减少采样效力和劳动力的情况下，还能采集样地81%物种，优化效果明显。同时，还分别确定了三类栖息地的最佳采样间隔和最小采样效力：在盐沼植被中，采样效力需要超过1.8 m2，最佳采样间隔为10 m；在潮滩中，最小采样效力2 m2，最佳采样间隔为10 m；在潮沟中，采样效力为3 m2，间隔为1 m。不同栖息地类型之间最小采样效力和最佳采样间隔的差异可能受到优势物种的迁移范围和栖息地的物理差异（例如潮汐水文、底泥、植被覆盖）的影响。本研究所采用的优化采样策略在平衡采样效力的情况下，为大型底栖动物丰富度估算提供良好的精度。此外，在河口湿地进行大型底栖动物调查之时，本研究的结论能提供采样策略参考。本研究所采用的采样策略设计注重采样的三个关键部分，具有良好的采样效果，可作为栖息地管理或生态系统评估的野外实地采样指南。 相似文献
20.
潮汐沉积率与沉积间断 总被引：16，自引：3，他引：16
在浙北奥陶系文昌组和长江三角洲开敞型淤泥质海岸非潮道潮汐纹层研究的基础上,得出与国外同类研究相近的沉积率。现代海岸进积速度和潮坪沉积的观察及测试证明,上述沉积率是难以置信的。现代潮坪观测表明,潮汐纹层在形成过程中即包含着改造,所保留的纹层占应形成数的不到１０％,其余９０％以上被侵蚀。小型层序是风暴和平静天气的产物,为风暴层序,与大小潮周期无关。其地层中保留的数量不到应生成数的１０％,其余９０％被改造。小型层序被侵蚀,其中的纹层随之消失。致使潮坪层序中保存的纹层数仅为应形成数的０．２％。被改造的纹层和单层留下的仅是侵蚀面,即小间断。在进行潮汐沉积高分辨率的研究时应充分重视沉积间断的作用 相似文献