Recognition of Milankovitch Cycles in the Natural Gamma—Ray Logging of Upper Cretaceous Terrestrial Strata in the Songliao Basin

Spectrogram analysis of seven natural gamma-ray logging of Member 1 of the Qingshankou Formation （K2qn^1） and Member 1 and 2 of the Nenjiang Formation （K2n^1-2） of Late Cretaceous age in the Songliao Basin reveals sedimentary cyclicities controlled by Milankovitch climate periodicities. The recognition of Milankovitch cycles allows estimation of an average accumulation rate of ～7.55- 8.62 cm/ka for the K2qn^1 sections, and ～6.69-10.16 cm/ka for the K2n^1-2 sections. Two marine transgression events occurred during the deposition of K2qn^1 and K2n^1-2 and their ages are at ～0.74- 1.10 Ma and ～2.38-4.84 Ma, respectively. Identification of Milankoviteh cycles from fine-grained deep lake sedimentary rocks in the Songliao Basin may provide great potential for high-resolution stratigraphic subdivisions and correlations.

Salvage logging versus natural regeneration post-fire practices in a forest: Soil chemical and microbial aspects

The increase in forest-wildfire events around the world has revived the old debate regarding the practice of salvage logging and its effectiveness in comparison to the unlogged, natural regeneration of burned forests. Since the logging of burned trees may have undesirable outcomes in soil systems, such as soil compaction and nutrient losses, these changes could further cause disturbances to soil microbial-community activity. The aim of this study was to examine chemical and biological changes in soil under two post-fire practices: salvage logging and unlogged, natural regeneration of burned areas, in the recently burned Byria Forest in Israel. Results indicated that salvage logging had a short- lived effect on soil chemical and biological properties that was confined mostly to the first year after logging. Soil moisture was greatly affected by salvage logging, and drier conditions were found in the logged compared to the unlogged burned areas. Moreover, logging had a negative effect on microbial biomass, with reduced biomass in the logged compared to unlogged areas, which was more evident during the first year after fire. These findings support the recommendations in the literature to postpone post-fire practices such as logging or, in turn, to combine the two practices in order to create a mosaic of burned-logged and burned-naturally regenerated areas.

Natural regeneration in logging gaps of different sizes in Subri River Forest Reserve(Ghana)

Subri River Forest Reserve(SR)is the most extensive forest area in Ghana with an accompanying rich floral species.Over the years,logging from both legally prescribed and illegal operations remain the predominant forest disturbance in SR.Gap creation following logging is crucial in determining tree species composition and diversity.Hence,the study evaluated the composition and diversity of naturally regenerated tree species in logging gaps of different sizes and,again examined the roles of these tree species in fulfilling the economic and ecological agenda of sustainable forest management after logging in SR.Twelve gaps were randomly selected:4 each were grouped into small size(≤200 m^(2)),medium size(201–300 m^(2)),and large size(≥300 m^(2)).Data were gathered from 1 m^(2) circular area at gap centres and repeatedly inside 1 m width strip along 20 m individual N-S-E-W transects.Species diversity differed significantly between gap sizes.Higher diversity indices were measured in large size gaps.Gap sizes shared similar species.There were significant differences among various height groupings of tree species across all three gap sizes.Pioneers preferred medium to large size gaps,while shadetolerant tree species preferred small size gaps for their abundance.Vulnerable and Lower Risk Near Threatened tree species under Conservation Status and,Premium and Commercial tree species under Utilisation Status preferred small size gaps for their proliferation and conservation.Therefore,we recommend the single tree-based selective logging for ensuring creations of small to medium size(200–300 m^(2))gaps through adjustments to the logging permit process,revision of Allocation Quota Permit,strict adherence to the 40-year polycyclic selection system,along with more dedicated enforcement and monitoring.Changes along these protocols would tremendously facilitate natural regeneration of different suites of timber species resulting in the improvement of the overall biodiversity conservation associated with the forest,more sustainable forest harvests and more income to those who receive permits.

Natural Radioactivity Assessment and Radiological Hazards in Soils from Qarun Lake and Wadi El Rayan in Faiyum, Egypt

The activity concentrations of naturally occurring 238U, 232Th and 40K in surface soils along Qarun Lake and Wadi El Rayan located in Faiyum, Egypt were determined. The measurements were carried out through gamma-ray spectrometry using a coaxial HPGe detector. The results were compared with those reported in the literature. The radiological hazard radium-equivalent activity index, external and internal indices, radioactivity level index, absorbed dose rate, annual effective dose rate and total absorbed dose rate associated with radioactivity in all samples were evaluated and compared with recommended values. Correlation studies between pairs of radionuclides were performed and discussed.

Soil Seed Bank Characteristics in Congolese Rainforests and Implications for Post-Logging Plots Reforestation

The soil seed bank is considered as an important mechanism for the natural regeneration, resilience and conservation of the forests after disturbances. This study evaluates the characteristics of the soil seed bank in two post-logging plots of Loundoungou-Toukoulaka Forest Management Unit: one plot exploited in 2008 and another exploited in 2021. In each study plot, 40 samples were collected per soil layer (0 - 5 cm, 5 - 10 cm, 10 - 15 cm, 15 - 20 cm and 20 - 25 cm depth). The species diversity and abundance of the soil seed bank were estimated after soil samples were brought to germination. The results demonstrated that 347 seedlings belonging to 37 species in the plot exploited in 2008 and 418 seedlings belonging to 27 species in that exploited in 2021 germinated during 20 weeks of monitoring. The total densities of the seedlings identified were respectively 1446 seedlings/m2 and 1742 seedlings/m2. The plot exploited in 2021 presented a higher proportion of herbaceous species (93.78%) compared to that exploited in 2008 (82.71%). Two pioneer species were recorded in the plot exploited in 2008. These are Macaranga barteri (0.29%) in the 0 - 5 cm layer and Musanga cecropioides (2.31%) up to 20 cm deep. On the other hand, in the plot exploited in 2021, Macaranga spinosa (0.96%) in the 0 - 5 cm layer and M. cecropioides (0.96%) up to 20 cm deep were identified. In the plot exploited in 2008, the 20 - 25 cm layer demonstrated important proportions in woody species (9%), these are in particular Rubiaceae sp.4 and Nauclea diderrichii. While that exploited in 2021, presented 19% of woody species, namely the species of Rubiaceae sp.4, Rubiaceae sp.5 and N. diderrichii, greatly exceeding the proportions obtained in the 15 - 20 cm layer of the two plots. Nonetheless, N. diderrichii was the only commercial species recorded with densities of 108 seedlings/m2 and 4 seedlings/m2, respectively in the plot exploited in 2008 and that exploited in 2021. Commercial tree species are poorly represented in the soil seed bank. Consequently, the study suggests that to improve the natural regeneration of the commercial species, silvicultural interventions based on planting techniques in the exploited plots should be more effective in order to sustainably manage these production forests.

Effect of Environmental Gradients on the Quantity and Quality of Fallen Logs in Tsuga longibracteata Forest in Tianbaoyan National Nature Reserve, Fujian Province,China

We investigated the quantity and quality of fallen logs in different Tsuga longibracteata forest communities in the Tianbaoyan National Nature Reserve. We used redundancy analysis to determine the spatial distribution of fallen logs in the different forest communities and to analyze the relationships among stand structure, topographic factors and human disturbance. The volume, covered area, mean log length and number of fallen logs differed significantly among forest types(P < 0.05), but mean diameter at breast height showed no significant difference(P > 0.05). The log volume and covered area in different forest types showed the following trend: T. longibracteata pure forest < T.longibracteata + Oligostachyum scabriflorur < T.longibracteata + hardwood < Rhododendron simiarum + T. longibracteata < T. longibracteata +Phyllostachys heterocycla pubescens. The spatial distribution patterns of logs quantity and quality indicated that log volume and covered area were strongly affected by environmental factors in the following order: human disturbance > elevation >slope position > bole height > tree height > slope aspect > density > basal area > slope gradient. The relative contribution of environmental variables on the total variance was topography(76%) >disturbance(42%) > stand structure(35%).Topography and disturbance combined explained83% of the variance. Fallen logs quantity and qualitywere negatively related to elevation and slope position,and positively associated to human disturbance. The log volume decreased from northern to southern slopes. Environmental factors had the highest impact on class I(slightly decayed), and lowest impact on class V(highly decayed).

A method of monitoring gas saturation in carbon dioxide injection heavy oil reservoirs by pulsed neutron logging technology

A method is proposed to characterize the fast neutron scattering cross-section ( s f) quantitatively by the combina-tion of inelastic gamma rays and captured gamma rays, so as to realize the gas saturation evaluation of CO_(2)-injected heavy oilreservoirs based on the three-de tector pulsed neutron logging technology. Factors influencing of the evaluation effect of thismethod are analyzed and the effectiveness of this method is verified by a simulation example. By using the Monte Carlo simu-lation method and the physical model of bulk-volume rock, the relationship between s f and CO_(2) saturation is studied, and thesaturation interpretation model is established. The influences of formation temperature and pressure, heavy oil density, bore-hole fluid and reservoir methane content on the evaluation results of CO_(2) saturation are analyzed. The results show that thecharacterization of s f by the combination of secondary gamma information can eliminate the influence of formation lithology,borehole fluid and methane content are the main factors affecting the quantitative monitoring of CO_(2) saturation, and the ef-fects of formation temperature and pressure and heavy oil density are negligible. The simulation example verified the feasibilityof the method for evaluating the CO_(2) saturation of CO_(2)-injected heavy oil reservoirs.

Assessment of Natural Radioactivity in Rivers Sediment and Soil from the Copper Belt Artisanal Mining Region, Democratic Republic of the Congo

The concentrations and distribution of naturally occurring radionuclides (238U, 235U, 234U, 230Th, 226Ra, 210Pb, 232Th, 228Ra, and 40K) were determined by alpha and gamma spectrometry in soil and sediments collected from Luilu and Dilala rivers located in the mining district of Kolwezi (Lualaba Province) of the Democratic Republic of the Congo. The average concentrations of 238U and 226Ra in the analyzed samples were 5 - 10 times higher than the world average values for soil provided by the United Nations Scientific Committee on the Effects of Atomic Radiation. However, the average concentrations of 232Th were found similar to the world average. In both river basins, artisanal mining activities and mineral washing sites displayed the higher concentration values of radionuclides. The mean values of health risk indices calculated for those sites were found significantly higher compared to world average levels. Radiation protection measures seem needed to ensure the radiation safety of local populations. Graphical Abstract

Photosynthetic Characteristics of Clerodendrum trichotomum Thumb. Responses to Drought, Salt and Water-logging Stresses

In order to reveal the photosynthetic characteristics of C. trichotomum responses to drought, salt and water-logging stresses, one-year-old potted seedlings were taken as materials, and the several stresses including natural drought, submergence stress, water-logging and different salt treatments （0.2%, 0.4%, 0.6% and 0.8% NaCl） were carried out on August 15, 2012. The morphological and photosynthetic characteristics were observed and determined. The results showed that adverse enviromental stress had a significant effect on the morphological changes and photosynthetic characteristics of C. trichotomum. On the 14th day after natural drought, the leaves wilted and could not recovery at night, and 60% of the seedlings could recover after re-watering. From the 7th day to the 10th day after submergence stress treatment, the 2nd and the 3rd leaves at the base of 60% seedling turned yellow and the lenticels were observed. At the early stage of water-logging stress, white lenticels appeared at the base of seedlings, and the leaves wilted, chlorina and fallen off on the 8th day. A large number of leaves fallen off under 0.6% NaCl or more salt stress, and even the whole plant died. The chlorophyll content, net photosynthetic rate （Pn） and transpiration rate （Tr） decreased gradually with the stress process, such as 8 days after natural drought, less than 0.4% salt stress and water-logging stress, but the changes were not significant compared with those of the control. With the increase of the stress intensity and the prolonged time, the changes of photosynthetic index were significant. All the results indicated that C. trichotomum had a certain degree of tolerance to drought, water and salt, but it was not suitable for living, in water-logging condition for a long time.

A Study of Chemical, Mineral Compositions (of Some Metals) and Natural Radioactivity in Porcelain and Ceramic Dinner Ware

Fifteen Porcelain and Ceramic Dinner Wares samples (collected from local commercial suppliers—Jeddah Saudi Arabia) were studied applying X-Ray Diffraction and Atomic Absorption techniques were used to study the Chemical, Mineral, Compositions Concentrations (of Some Metals). In addition, the Natural Radioactivity measurements of 226Ra, 232Th and 40K, was used by a high-purity germanium (HPGe) detector. X-ray diffraction results showed that the major mineral constituents of 15 samples were quartz (SiO2) (except one), minor and trace elements vary from sample to sample. Atomic absorption spectroscopy results of the concentrations for (Al, Pb, Bi, U, Th and K) in (ppm) showed that Al2O average was 10.3 (ppm) (10%) less than the acceptable value. PbO, its average was 1.65 ppm which was slightly greater than the allowed value 1.35 ppm. Bi concentrations for all samples were lower than (DL < 10). For most samples U, concentrations were lower than (DL < 5) except samples C9 and C11. Th concentrations ranged from LDL (<1 to 52.88) and were much greater than the acceptable value 7.24 ppm except samples P1, P2, P4. The potassium concentration average was greater than the acceptable value. The average concentrations of 238U, 232Th and 40 K were (83.83, 91.05 and 751.07) Bq/kg dry. The radium equivalent activity concentration Raeq (Bq/kg) (302.61) was less than recommended value (370), gamma dose rate D (nGy/h) average (140.15) was much higher than the recommended value (60) (UNSCEER). Deff (mSv/year) and Hix were below the published admissible limit ≤ 1 and the risk is negligible. This study offers needed information for consumers at exposure risk and is useful to be found in terms of radiation protection.

Measurement of Natural Radioactivity in Sand Samples Collected from Ad-Dahna Desert in Saudi Arabia

Natural radioactivity is a source of continuous exposure to human beings. The natural radioactivity due to the presence of 226Ra, 232Th and 40K in sand samples collected from Ad-Dahna was measured by means of HPGe. The measured activity concentrations of radionuclides were compared with the worldwide reported data. Mean measured activity concentrations of 226Ra, 232Th and 40K varied between 16.2 - 30.6, 15.8 - 36.7 and 285.3 - 533.2 Bq·kg–1 respectively with a mean value of 23.4 ± 4.3 Bq·kg–1, 29.7 ± 5.9 Bq·kg–1 and 380 ± 65 Bq·kg–1 respectively. Mean values of radium equivalent activity, absorbed dose rate and external radiation hazard index were 106 ± 8 Bq·kg–1, 51.4 nGy·h–1 and 0.29 respectively. The annual effective radiation dose was calculated to be 0.32 mSv·y–1. The Raeq values of sand samples are lower than the limit of 370 Bq·kg–1, equivalent to a gamma dose of 1.5 mSv·yr–1.This study shows that the measured sand samples do not pose any significant source of radiation hazard and are safe for use in building materials.

Study and Simulated the Natural Radioactivity (NORM) U-238, Th-232 and K-40 of Igneous and Sedimentary Rocks of Al-Atawilah (Al-Baha) in Saudi Arabia

In this work, gamma-ray spectroscopy based on semiconductor hyper pure germanium (HPGe) detector was used to evaluate the activity concentrations of the natural radionuclides (U-238 (Ra-226), Th-232 and K-40) and the fallout nuclide (Cs-137) for thirty samples of igneous and sedimentary rocks of Al-Atawilah (Al-Baha). The mean values of the activity concentrations of U-238 (Ra-226), Th-232, K-40 and Cs-137 in the igneous samples are found as (11.0, 11.50, 1172.71, 1.47) Bq/Kg respectively. In the sedimentary rocks, the mean values of the activity concentrations of the natural radionuclides (U-238 (Ra-226), Th-232 and K-40) and the fallout nuclide (Cs-137) equal to (12.04, 13.18, 1131.36, 1.60) Bq/Kg respectively. The averages of radiological hazards (Raeq, Hex and Iγ) were calculated and found to be within the UNSCEAR permissible limit values (370 Bq/kg for Raeq, and 1 for Hex and Iγ), except for a slight increase of average value of Iγ in the igneous rock samples (1.36). The results indicate that the dose rate values depend on the kind of rocks (high in some igneous rock samples, and most of sedimentary rock samples have low dose rate). The activities of naturalnuclides were predicted and simulated in T time using a written MATLAB R2020a script based on the average activity concentrations and respective half-lives of U-238 and Th-232 series, and K-40, this is to evaluate the future effects of natural radionuclides on the population and estimate the human inputs in the future.

基于改进ΔlogR方法估算低阻海相页岩储层总有机碳含量——以桂中坳陷A地区B组为例

总有机碳含量(total organic carbon,TOC)是确定烃源岩质量的最重要参数。为解决传统ΔlogR方法应用于沉积环境较复杂的海相页岩气储层精度低的问题,以桂中坳陷A区B组海相页岩气储层为研究对象,在分析研究区低阻原因的基础上,对测井曲线按照扩径范围进行井径校正,并利用自然伽马能谱测井中Th/K数据,与ΔlogR建立多元拟合关系,提出基于井径校正和自然伽马能谱测井的改进ΔlogR方法。结果表明:声波时差曲线经过校正后,降低了井径扩径带来的测井数据失真的影响,同时结合自然伽马能谱测井,能够适应研究区复杂的地质背景和较强的非均质性,大大提高总有机碳质量分数的预测精度,具有较好的推广性和适用性。该方法可以为桂中坳陷A区B组海相页岩气储层评价提供参考。

烃源岩测井识别与评价方法研究进展

烃源岩测井识别与定量评价对油气资源潜力勘查、储量评估及非常规油气勘探开发至关重要。烃源岩自身岩性和成熟度等差异、测井序列对烃源岩响应灵敏程度不同以及不同方法适用性区别等导致烃源岩测井评价工作仍受到限制。目前亟需进一步挖掘地球物理测井资料中蕴含的烃源岩信息,搭建烃源岩品质与测井信息之间桥梁,并实现以自生自储为特性的非常规油气烃源岩品质测井精细表征。笔者等首先阐明烃源岩分类及其地质表征参数,并分析不同类别烃源岩在常规测井序列及成像和核磁共振等新技术测井序列上响应特征。烃源岩通常表现为“四高一低”(高GR、高AC、高CNL、高RT和低DEN)测井响应特征。除单因素分析外,可优选交会图及构建敏感参数等实现烃源岩定性识别。而烃源岩有机碳含量(TOC)等参数测井定量预测方面则可采用ΔlgR法、修正ΔlgR法(变基线和变系数)、自然伽马能谱测井法、多元回归法、Litho Scanner测井资料法以及人工智能方法实现。在分别评述不同TOC含量测井计算方法的优缺点和适用条件的基础上,指出通过TOC结合生烃潜量等参数计算可实现烃源岩品质测井综合评价。最后解析烃源岩测井识别与评价工作中存在的问题与发展趋势,以期为油气资源评价及非常规油气勘探开发提供理论指导与技术支撑。

井中激发的瞬态、稳态响应与测井方法集成

研究井中激发的瞬态响应时需结合井内、外瞬态物理场的传播、扩散过程和探头的综合响应。发射探头能同时激发声、电、磁3种瞬态物理场,采用多种探头同时接收可获得地层的多个物理参数,实现测井方法集成。压电管和压电片激发瞬态振动瞬间同时激发同频谱的瞬变电磁场;带磁芯的线圈在其电流导通、关断瞬间激发瞬变电磁场时,磁芯磁致伸缩变形同时激发振动,振动和瞬变电磁在井和地层中分别根据声和电磁的规律传播、扩散。在井中对瞬态电磁场和声场同时测量可实现电阻率和声波测井。利用圆柱形井壁对径向传播声波的无数次反射形成的固有频率,采用共振响应的方式进行大功率激发,使能量有效地穿过井壁进入地层,可实现远距离探测。进一步加大激发功率,瞬态强磁场激发砂岩孔隙流体的核磁共振,强振动激发震电效应,在井中用高灵敏度探头接收可实现核磁和震电测量。采用稳态大功率超声激发高通量中子可实现中子、密度测井,再利用其导通和关断瞬间激发的瞬态响应进行声波和电阻率测井,最后实现测井原理集成的终极目标——声电磁核组合,这种集成方法可应用于裸眼井和套管井测井。

A pre-Paleogene unconformity surface of the Sikeshu Sag, Junggar Basin: Lithological, geophysical and geochemical implications for the transportation of hydrocarbons

The unconformity surface at the bottom of the Paleogene is one of the most important migration pathways in the Sikeshu Sag of the Junggar Basin,which consists of three layers：upper coarse clastic rock,lower weathering crust and leached zone.The upper coarse clastic rock is characterized by higher density and lower SDT and gamma-ray logging parameters,while the lower weathering crust displays opposite features.The transport coefficient of the unconformity surface is controlled by its position in respect to the basal sandstone; it is higher in the ramp region but lower in the adjacent uplifted and sag areas.The content of saturated hydrocarbons increases with the decrease of the content of nonhydrocarbons and asphaltenes.The content of benzo[c] carbazole decreases as the content of benzo[a]carbazole and [alkyl carbazole]/[alkyl ＋ benzo carbazole] increases.This suggests that the unconformity surface is an efficient medium for the transportation of hydrocarbons.

Implementation of the direct demodulation method for natural gamma ray spectral logging

Spectrum analysis of natural gamma ray spectral logging （SGR） data is a critical part of surface informa- tion processing systems. Due to the low resolution, which is an inherent weakness of SGR, and the low signal-to-noise ratio problem of logging measurements, SGR is usually treated with a low confidence level. The Direct Demodulation （DD） method is an advanced technique to solve modulation equations interactively under physical constraints. It has higher sensitivity and spatial resolution than the traditional methods and can effectively suppress the logging noise. Based on standard count rate spectral data obtained from the China Offshore Oil Logging Company SGR Calibration Facility, this paper presents the application of the DD method to gamma-ray logging. The results are compared with four traditional algorithmic methods, showing that the DD method is a credible choice, with higher sensitivity and higher spatial resolution in gamma-ray log interpretation. The Point-Spread-Function of the Shengli Oil Logging Company＇s natural gamma ray spectroscopy instrument is obtained for the first time. The quantities of various radionuclides in their calibration pits are also obtained. The DD method was applied successfully to gamma-ray logging, offering a new option for SGR logging algorithm selection.

基于Logistic统计的模糊判别法在储层流体识别中的应用

在测井储层评价中准确识别储层流体性质是其关键。但当储层测井响应特征并不特别明显时,只采用常规测井识别方法不易准确区分气、水层。为此,综合常规测井和试油资料,选取反映气、水层特点的特征参数建立划分气层、气水同层及水层的模糊综合判别因素,利用Logistic统计法确定隶属函数曲线,即以Logistic函数为激活函数,利用模糊统计法确定隶属函数曲线;然后结合权重集建立了模糊综合判别模型对流体的性质进行模糊判别,经检验该方法能较准确地判别出水层、气水同层和气层。

优化储能容量配置的ln基底型VSG自适应控制策略

针对虚拟同步发电机VSG(virtual synchronous generator)自适应控制大范围调节参数导致需要较大储能容量配置的问题,设计ln基底型自适应控制策略以优化储能容量配置。通过对基于速度反馈控制的虚拟同步发电机VF-VSG(velocity feedback control based VSG)进行数学建模,建立VSG在输入功率扰动时与所需储能容量之间的关系,据此分析速度反馈系数、VSG转动惯量和阻尼系数对储能容量的影响,以此设计ln基底型自适应控制策略,避免参数大范围调节,优化储能容量配置。通过仿真实验可知:所提控制策略在暂态性能优良的前提下,降低了9.8%储能容量的配置,验证了所提策略的有效性。

拟声波测井曲线在砂岩型铀矿反演中的研究与应用

砂岩型铀矿往往赋存于“泥—砂—泥”、“煤—砂—泥”等互层结构的砂体之中,且埋藏深度较浅,般在300~800 m之间,这就易造成其上覆砂泥岩受地层压实作用力小,导致相邻地层之间声波时差(AC)与密度差异值小,即波阻抗差异小;再加之受测井资料品质及地下构造等综合因素的影响,对研究区地震资料使用声波密度曲线开展叠后波阻抗反演工作时往往只能对剖面上的大套砂体及含砾砂体进行区分.