基于土地利用和RWEQ模型的内蒙古防风固沙服务评价（英文）

内蒙古是我国北方重要的生态屏障区,在区域生态系统防风固沙中发挥了重要的作用。本研究基于RWEQ模型模拟了内蒙古2010年和2015年生态系统防风固沙物质量,通过恢复成本法估算了其价值量,分析了内蒙古各盟市以及各生态系统防风固沙物质量和价值量变化的空间格局。结果表明2015年内蒙古防风固沙物质量和价值量总量分别为73.87亿t和738.66亿元,相比于2010年共减少了4.61亿t和46.16亿元。在各盟市中,锡林郭勒盟防风固沙总量最高,2015年达18.65亿t,乌海市最少,呼伦贝尔市防风固沙总量增长幅度最大,达4.37亿t;在各生态系统中草地生态系统防风固沙总量最高,占比在55%以上,但总量降低了1.05亿t,森林生态系统防风固沙增长量最高,达0.19亿t。结合生态系统变化及造林实施情况分析,发现造林等工程的投入实施通过增加森林面积、提升森林质量等有效增加了防风固沙物质量,但不合理的土地利用导致沙漠化土地的增加造成了内蒙古防风固沙量的显著降低。     

Evaluation of 40Ar/39Ar Geochronology of Authigenic Illites in Determining Hydrocarbon Charge Timing: A Case Study from the Silurian Bituminous Sandstone Reservoirs,Tarim Basin,China

The Silurian bituminous sandstones(SBS) in the Tarim Basin, China are important basinwide reservoirs with an estimated area of approximately 249000 km2. We investigated the ages of authigenic illites in the SBS reservoirs and constrained their formation timing by using the ~(40)Ar/~(39)Ar step wise heating method. The age spectra, ~(39)Ar recoil loss and their controlling factors were investigated systematically. The ~(40)Ar/~(39)Ar ages were compared with the conventional K/Ar ages of identical clay fractions. The clay in the SBS reservoirs is dominated by orderly mixed-layer illite/smectite(I/S) with 5%–30% smectite layers. The I/S minerals morphology comprises primarily honeycomb, short filamentous and curved-lath particles, characteristic of authigenic illites. The unencapsulated ~(40)Ar/~(39)Ar total gas ages(UTGA) of the authigenic illites range from 188.56 ± 6.20 Ma to 491.86 ± 27.68 Ma, which are 7% to 103% older than the corresponding K/Ar ages of 124.87 ± 1.11 Ma to 383.45 ± 2.80 Ma, respectively. The K-Ar ages indicate multistage accumulations with distinct distribution patterns in the Tarim Basin: older(late Caledonian-early Hercynian) around the basin margin, younger(late Hercynian) in the basin centre, and the youngest(middle to late Yanshanian) in the Ha-6 well-block, central area of the North Uplift. The age difference is believed to have been caused by the ~(39)Ar recoil loss during the irradiation process. Compared with the K/Ar ages, the estimated ~(39)Ar recoil losses in this study are in the range from 7% to 51%. The ~(39)Ar recoil loss appears to increase not only with the decreasing particle sizes of the I/S, but also with increasing percentage of smectite layers(IR) of the I/S, and smectite layer content(SLC) of the samples. We conclude that due to significant ~(39)Ar recoil losses, UTGA may not offer any meaningful geological ages of the authigenic illite formation in the SBS and thus can not be used to represent the hydrocarbon charge timing. ~(39)Ar recoil losses during ~(40)Ar/~(39)Ar dating can not be neglected when dating fine authigenic illite, especially when the ordered mixed-layer I/S containing small amount of smectite layers(IR30%) in the reservoir formations. Compared with the unencapsulated Ar-Ar method, the conventional K-Ar method is less complicated, more accurate and reliable in dating authigenic illites in petroleum reservoirs.     

Diagenesis of the Paleogene Sandstones in the DN2 Gas Field,Kuqa Foreland Basin and its Link to Tectonics

We investigated diagenesis of the sandstones from the DN2 Gas Field of the Kuqa Foreland Basin(KFB),in order to infer the timing of fluid migration and discuss the linkage between fluids and tectonics.The textures and chemical composition of authigenic minerals,fluid evidence from fluid inclusions and formation water measurements were all used to fulfill this aim.Eodiagenesis occurred with the participation of meteoric water and connate water.Mesodiagenesis is related to high salinity fluids,whi...     

The Significance of Traditional Culture for Agricultural Biodiversity—Experiences from GIAHS

Agricultural biodiversity has a high importance in social-cultural, economic, and environmental aspects, and can help in adapting to and withstanding climate change. Conserving the GIAHS sites and the important components within them can help conserve the agricultural biodiversity and traditional agricultural culture of the whole country. This study considered Ifugao Rice Terraces, Dong’s Rice-Fish-Duck System, and Hani Rice Terraces System as three examples which show that traditional culture can be used to protect agricultural biodiversity, while as a carrier of traditional culture, agricultural biodiversity also conveys and protects the traditional culture of the nation. According to the analyses, through several years of efforts, the status of agricultural biodiversity and traditional culture in them has improved. Then, to further promote agricultural biodiversity conservation and traditional culture protection, several suggestions are made, such as establishing community seed banks; documenting and preserving traditional farming methods, techniques, and tools and developing participatory activities which encourage more farmers to participate in the protection work.     

Quantitative estimate of residual or palaeo-oil column height

A method to quantitatively estimate residual or palaeo-oil column heights is proposed using criteria based on the presence or absence of oil shows in a single heterogeneous reservoir rock sample. The residual or palaeo-oil column height below the sample is constrained through the determination of the displacement pressure of regions in the sample containing oil shows (P_d-o) and the displacement pressure for regions that are devoid of any evidence of oil shows (P_d-w). The height of the residual or palaeo-oil column below the sampling depth can then be estimated to be greater than the equivalent height corresponding to P_d-o, but less than the height corresponding to P_d-w. Three examples from two basins in China were investigated using the method to determine their residual and palaeo-oil column heights.     

A unified model for the formation and distribution of both conventional and unconventional hydrocarbon reservoirs

The discovery and large-scale exploration of unconventional oil/gas resources since 1980s have been considered as the most important advancement in the history of petroleum geology;that has not only changed the balance of supply and demand in the global energy market,but also improved our understanding of the formation mechanisms and distribution characteristics of oil/gas reservoirs.However,what is the difference of conventional and unconventional resources and why they always related to each other in petroliferous basins is not clear.As the differences and correlations between unconventional and conventional resources are complex challenging issues and very critical for resources assessment and hydrocarbon exploration,this paper focused on studying the relationship of formations and distributions among different oil/gas reservoirs.Drilling results of 12,237 exploratory wells in 6 representative petroliferous basins of China and distribution characteristics for 52,926 oil/gas accumulations over the world were applied to clarify the formation conditions and genetic relations of different oil/gas reservoirs in a petroliferous basin,and then to establish a unified model to address the differences and correlations of conventional and unconventional reservoirs.In this model,conventional reservoirs formed in free hydrocarbon dynamic field with high porosity and permeability located above the boundary of hydrocarbon buoyancy-driven accumulation depth limit.Unconventional tight reservoirs formed in confined hydrocarbon dynamic field with low porosity and permeability located between hydrocarbon buoyancy-driven accumulation depth limit and hydrocarbon accumulation depth limit.Shale oil/gas reservoirs formed in the bound hydrocarbon dynamic field with low porosity and ultra-low permeability within the source rock layers.More than 75%of proved reserves around the world are discovered in the free hydrocarbon dynamic field,which is estimated to contain only 10%of originally generated hydrocarbons.Most of undiscovered resources distributed in the confined hydrocarbon dynamic field and the bound hydrocarbon dynamic field,which contains 90%of original generated hydrocarbons,implying a reasonable and promising area for future hydrocarbon explorations.The buried depths of hydrocarbon dynamic fields become shallow with the increase of heat flow,and the remaining oil/gas resources mainly exist in the deep area of“cold basin”with low geothermal gradient.Lithology changing in the hydrocarbon dynamic field causes local anomalies in the oil/gas dynamic mechanism,leading to the local formation of unconventional hydrocarbon reservoirs in the free hydrocarbon dynamic field or the occurrence of oil/gas enrichment sweet points with high porosity and permeability in the confined hydrocarbon dynamic field.The tectonic movements destroy the medium conditions and oil/gas components,which leads to the transformation of conventional oil/gas reservoirs formed in free hydrocarbon dynamic field to unconventional ones or unconventional ones formed in confined and bound hydrocarbon dynamic fields to conventional ones.     

Dynamic Field Division of Hydrocarbon Migration,Accumulation and Hydrocarbon Enrichment Rules in Sedimentary Basins

Hydrocarbon distribution rules in the deep and shallow parts of sedimentary basins are considerably different, particularly in the following four aspects. First, the critical porosity for hydrocarbon migration is much lower in the deep parts of basins: at a depth of 7000 m, hydrocarbons can accumulate only in rocks with porosity less than 5%. However, in the shallow parts of basins (i.e., depths of around 1000 m), hydrocarbon can accumulate in rocks only when porosity is over 20%. Second, hydrocarbon reservoirs tend to exhibit negative pressures after hydrocarbon accumulation at depth, with a pressure coefficient less than 0.7. However, hydrocarbon reservoirs at shallow depths tend to exhibit high pressure after hydrocarbon accumulation. Third, deep reservoirs tend to exhibit characteristics of oil (–gas)–water inversion, indicating that the oil (gas) accumulated under the water. However, the oil (gas) tends to accumulate over water in shallow reservoirs. Fourth, continuous unconventional tight hydrocarbon reservoirs are distributed widely in deep reservoirs, where the buoyancy force is not the primary dynamic force and the caprock is not involved during the process of hydrocarbon accumulation. Conversely, the majority of hydrocarbons in shallow regions accumulate in traps with complex structures. The results of this study indicate that two dynamic boundary conditions are primarily responsible for the above phenomena: a lower limit to the buoyancy force and the lower limit of hydrocarbon accumulation overall, corresponding to about 10%–12% porosity and irreducible water saturation of 100%, respectively.     

径流还原计算中淤地坝拦蓄水量还原计算方法

黄土高原地区淤地坝分布密集,对天然产汇流过程扰动较大,给径流还原或水资源评价带来了极大的影响。因此,研究淤地坝影响下的径流还原计算方法对区域水资源评价或径流设计有重要意义。以黑木头川流域为研究对象,分别采用还原系数法和径流系数法计算了殿市水文站控制产汇流区的淤地坝逐年拦蓄水量,并将两种方法的结果进行对比,论证了还原系数法的适用性。还原系数法的计算结果表明:1971~2007年殿市水文站产流区内的淤地坝平均年拦蓄水量为86.21×104m3,与径流系数法计算所得到的拦蓄水量基本一致,相对误差仅为1.36%。同时,研究发现单位控制面积分摊后的拦蓄水量在年际变化上并不显著,基本维持在某一区间内。研究结果表明还原系数法不仅可用于洪水还原,也可较为准确地计算淤地坝影响区的淤地坝拦蓄变量。作为河川径流还原计算方法或淤地坝影响的黄土高原地区水资源评价研究的计算方法之一,可与径流系数法进行交叉验证,进而获得比较准确的淤地坝拦蓄水量。且由于淤地坝年拦水量空间分摊后,单位控制面积的拦水量基本稳定,故在淤地坝上游无明显人类活动的情况下,可据此初估已知或近似区域淤地坝控制流域面积条件下的淤地坝年拦蓄水量,为黄土高原地区今后开展水资源评价和径流预报提供一条简单的途径。     

陕北地区河川基流的时空演变规律

The interaction between groundwater and surface water in northern Shaanxi is quite complicated and frequent under the influence of regional hydrogeological condition and human intervention. These performances bring serious challenges to regional water resources assessment and utilization. The river baseflow process at Gaojiabu Station in windy desert region, Gaoshiya and Caoping Station in loess region were taken as research objects, and their variation trends and change points in the river baseflow series were analyzed in this paper. In addition, to explore the cause of the baseflow change, this research compared their correlations with precipitations in the same area respectively from two aspects of flow variation and multi timescale characteristics. The results show that: ①groundwater recharges for river flow in windy desert region significantly exceed those in loess region; ②baseflows of all the rivers in the study area reducing significantly are mainly determined by human intervention such as the extensive pumping of groundwater; ③periodic changes of baseflow in each station response closely to precipitation change on meso-scale and small-scales; ④precipitation-runoff relationships in windy desert regions are much more complicated and unstable than loess region, which is mainly because of its more significant impact from groundwater storage and the lateral recharge change. Under the changing environment, the water cycle in windy desert regions would be in complexity and variability. Therefore, it is recommended that, groundwater changes need to be considered in regional water resources assessment.     

兰州台倾斜固体潮初步观测结果

1.台址及仪器状况兰州台是甘肃省唯一的(Ⅰ类)形变综合观测台,架设有国家地震局地震研究所研制的目前国内最先进的FSQ型自记水管倾斜仪。该台位于(L=103°.7520,λ=36°.0980,H=1550米)兰州市安宁区人防山洞内,洞体进深145米,岩层直立,覆盖层厚29—88米。为了