靖边气田北部中奥陶统马家沟组五_4~1储层沉积微相组合与储层非均质性控制因素

中奥陶统马家沟组上部马五41储层是鄂尔多斯盆地靖边气田主力产气段,根据该层段的岩石学特征和沉积构造等,可划分为3个亚相以及9个微相组合。该储层的储集性能具有强烈的非均质性,微观上表现为低孔低渗,以微细喉、细喉为主;纵向上表现为反韵律、随机韵律、均质韵律3种韵律模式,平面上表现为平均岩心孔隙度、渗透率分布的非均一性。沉积微相及微相组合差异性是控制岩石孔隙发育的基础,成岩作用决定了孔隙发育的程度,古岩溶地貌类型对储层分布有着明显制约作用,最终导致该区储集性能在纵横向上的非均质性。     

RETRACTED ARTICLE: Enhancement of bio-sludge gravitational thickening with weak ultrasound

Gravitational thickening is the prevailing method to reduce bio-sludge volume though the process is slow and usually requires addition of polyelectrolyte(s). This paper investigated the potential benefits of sonication on enhancing the bio-sludge gravitational thickening with very low energy dose, thereby called ??weak ultrasound??. Results showed that weak sonication significantly changed the bio-sludge settleability and the main mechanism was release of the loosely bound extracellular polymeric substances. The changes were strongly influenced by power density and sonication duration. Low frequency was better but the difference was insignificant. Weak sonication (<680?kJ/kg?DS) improved the sludge gravitational thickening while high ultrasonic energy deteriorated the process. Considering both the sludge thickening efficiency and energy consumption, the optimum conditions were 0.15?W/ml, 7?s and 25?kHz. Under such conditions, the energy dose was only 155?kJ/kg?DS, much lower than literature reports and the sludge settling time shortened from the original 24 to 12?h. Weak sonication could substitute expensive polyelectrolyte coagulant for bio-sludge thickening. Combination of weak sonication and polyelectrolyte could further reduce the settling time to 6?h. The final water content of the thickened bio-sludge was not changed after sonication or polyelectrolyte addition.     

The origin and accumulation model of crude oils from oil reservoirs Chang 9 and Chang 10 in the Yanchang Formation of the Ordos Basin

In the lower parts of oil reservoirs Chang 9 and Chang 10 of the Yanchang Formation are oil-bearing layers newly found in oil exploration in the Ordos Basin.Based on GC,GC-MS analyses of saturated hydrocarbons from crude oils and source rocks,reservoir fluid inclusions and BasinMod,the origin of crude oils,accumulation period and accumulation models are discussed in combination with other petroleum geology data in this paper.The result shows that(1) there are two different types of crude oils in oil reservoir Chang 9 in the Longdong and Jiyuan regions:crude oils of typeⅠ(Well D86,Well A44,Well A75,Well B227,Well X62 and Well Z150) are mainly de-rived from the Chang 7 source rocks(including mudstones and shales) and distributed in the Jiyuan and Longdong regions;those of typeⅡ(Well Z14 and Well Y427),are distributed in the Longdong region,which are derived from the Chang 9 source rocks.Crude oils from oil reservoir Chang 10 in the Shanbei region are mainly derived from the Chang-9 source rocks;(2) there are two phases of hydrocarbon filling in oil reservoir Chang 9 in the Jiyuan and Longdong regions and oil reservoir Chang 10 in the Shanbei region:The first phase started at the early stage of J2z.The process of hydrocarbon filling was discontinuous in the Late Jurassic,because of the tectonic-thermal event in the Ordos Basin.The second phase was the main accumulation period,and hydrocarbons began to accumulate from the late stage of J2a to the middle-late of K1,mainly at the middle-late stage of K1;(3) there exist two types of accu-mulation models in oil reservoirs Chang 9 and Chang 10 of the Yanchang Formation:source rocks of the reservoirs in oil reservoir Chang 9 in the Jiyuan region and oil reservoir Chang 10 in the Shanbei region,the mixed type of reservoirs on the lateral side of source rocks and source rocks of the reservoirs in oil reservoir Chang 9 in the Long-dong region.     

Spatial analysis of a historical phenomenon: using GIS to demonstrate the strategic placement of Umayyad desert palaces

The Umayyad qusour (desert palaces) are monumental structures built during the reign of the first caliphate of Islam. Usually dismissed as “pleasure palaces” or “hunting lodges,” some scholars are beginning to argue that these prominent structures were strategic interventions in the landscape. Until now, historians have relied mainly on textual, architectural and art-historical analyses of the qusour in order to understand Umayyad state architecture. This research proposes the use of spatial analysis through GIS to lend a new dimension to the discussion. The results of the analysis show that Umayyad qusour are carefully situated at routes of transhumance and water sources. The distribution pattern of the Umayyad qusour is clustered at the outlet of Wadi Sarhan, and there is actually line-of-sight communication between Azraq, Amra, Haranah, Muwaqqar, Umm al Walid, Mushatta, and Qastal. There is also a positive association between Umayyad qusour and their water sources. These results support the argument that the Umayyad qusour were built strategically at perennial water sources in order to monitor routes of transhumance amongst the socio-political centers of the period.     

An artificial neural network model for flood simulation using GIS: Johor River Basin, Malaysia

Flooding is one of the most destructive natural hazards that cause damage to both life and property every year, and therefore the development of flood model to determine inundation area in watersheds is important for decision makers. In recent years, data mining approaches such as artificial neural network (ANN) techniques are being increasingly used for flood modeling. Previously, this ANN method was frequently used for hydrological and flood modeling by taking rainfall as input and runoff data as output, usually without taking into consideration of other flood causative factors. The specific objective of this study is to develop a flood model using various flood causative factors using ANN techniques and geographic information system (GIS) to modeling and simulate flood-prone areas in the southern part of Peninsular Malaysia. The ANN model for this study was developed in MATLAB using seven flood causative factors. Relevant thematic layers (including rainfall, slope, elevation, flow accumulation, soil, land use, and geology) are generated using GIS, remote sensing data, and field surveys. In the context of objective weight assignments, the ANN is used to directly produce water levels and then the flood map is constructed in GIS. To measure the performance of the model, four criteria performances, including a coefficient of determination (R ²), the sum squared error, the mean square error, and the root mean square error are used. The verification results showed satisfactory agreement between the predicted and the real hydrological records. The results of this study could be used to help local and national government plan for the future and develop appropriate (to the local environmental conditions) new infrastructure to protect the lives and property of the people of Johor.     

Resilient and plastic strain behavior of freezing–thawing mucky clay under subway loading in Shanghai

Depending on artificial freezing method applied in subway tunnel construction, a series of stress-controlled cyclic triaxial tests were conducted on freezing–thawing mucky clay to investigate their resilient and plastic strain behavior. In terms of practical engineering, this study focuses on three significant influencing factors which are artificial freezing temperatures, dynamic stress amplitude and loading frequency. This study demonstrates how these influence factors effect on the resilient strain or dynamic elastic modulus and accumulated plastic strain which are crucial to better understanding the strain behavior of freezing–thawing soil. The results indicate that the value of freezing temperature has slight influence on dynamic elastic modulus, but the freeze–thaw action can truly decrease the dynamic elastic modulus of soil, and soil with higher freezing temperature possesses larger accumulated axial strain. Besides, the dynamic elastic modulus decreases remarkably with the increasing of the cyclic stress amplitude, while the accumulated plastic strain behaves adversely. In addition, loading frequency has the least effect compared with other two factors, but lower frequency can generate larger accumulated plastic strain.     

创业者区位选择的家乡偏好及其驱动机制

作为家乡认同感浓厚且出现大规模流动人口的转型中国家,中国的创业者在区位选择上究竟偏好家乡还是异地亟待回答,这关乎地方创业政策的方向性布局。基于2014年中国劳动力动态调查数据,从微观个体层面实证检验了创业者在区位选择上是否存在家乡偏好,并探究了其驱动机制。研究发现：创业者在区位选择上的确存在家乡偏好,且这种偏好在生存型和机会型的创业者中均普遍存在;在剔除可能造成家乡偏好高估的样本后,上述发现依然成立。进一步的机制分析发现,创业者偏好在家乡创业是为了借助熟悉的社会网络拓展营销渠道并照顾子女和父母。上述发现为制定创业人才政策提供了科学依据。     

“一体化成井技术”在施工降水中的应用研究

北京西部卵石地层常采用冲击钻进工艺成井,机械体积大、成孔时间长、洗井质量差、对地面交通影响大,成井过程中产生的泥浆对环境影响较大.“一体化成井技术”采用风动潜孔锤成孔,跟进钢制井管一次成井.该工法具有成孔效率高、不用制备泥浆、不用专门洗井,施工占地较小、灵活等特点,尤其在改善环境及交通方面优势明显.介绍了该工艺在北京地铁降水工程中的应用,探讨了一套完备的一体化成井技术,经近两年多的施工实践,充分表明对类似工程具有很好的参考价值.     

Fine-Scale Detection of Estuarine Water Quality with Managed Freshwater Releases

Freshwater pulses to subtropical estuaries often occur on time scales less than 1 week. In particular, introduction of low-level pulses are potentially important during the dry season (November–April) when freshwater is scarce. Determining potential ecological benefits of pulses requires an innovative method of data acquisition at the appropriate spatial and temporal scales. The South Florida Water Management District conducted a pilot study to assess changes in water column attributes with pulse releases to the Caloosahatchee River Estuary (CRE) from January to April 2012. An average inflow of 450 cfs was targeted for a series of freshwater pulses. This study utilized an onboard, flow-through system to record surface water temperature, salinity (S), pH, dissolved oxygen, turbidity, and in situ chlorophyll a (in situ CHL) at 5 s intervals along the 42-km length of the estuary. On each of seven research cruises, the vessel stopped at multiple stations to conduct vertical water column profiles. Salinity increased throughout the CRE as inflow decreased during the study period. Simple correlation and partial least squares regression were used to determine that the downstream locations of the S?=?10 isohaline and the maximum CHL concentration (in situ CHL_max) were positively related to inflow. While the in situ CHL_max was located 12–20 km downstream on five of the cruises, it was only a few kilometer from the estuary head on the first (1/12) and last (4/11) dates. It is possible that two circumstances related to freshwater inflow accounted for this pattern. First, water column stratification before January could have stimulated remineralization and primary production. Second, inflow ceased as water temperature increased to 26.0 °C by April to promote algal growth. Further study of the relationships among inflow, water level, flushing time, and CHL is warranted. Future efforts will examine the range of wet season discharge by incorporating a sensor for colored dissolved organic matter to fully connect inflow, salinity, submarine light, and phytoplankton attributes in the CRE.