Multiphase flow simulation through porous media with explicitly resolved fractures

Accurate simulation of multiphase flow in fractured porous media remains a challenge. An important problem is the representation of the discontinuous or near discontinuous behaviour of saturation in real geological formations. In the classical continuum approach, a refined mesh is required at the interface between fracture and porous media to capture the steep gradients in saturation and saturation‐dependent transport properties. This dramatically increases the computational load when large numbers of fractures are present in the numerical model. A discontinuous finite element method is reported here to model flow in fractured porous media. The governing multiphase porous media flow equations are solved in the adaptive mesh computational fluid dynamics code IC‐FERST on unstructured meshes. The method is based on a mixed control volume – discontinuous finite element formulation. This is combined with the P_N+1DG‐P_NDG element pair, which has discontinuous (order N+1) representation for velocity and discontinuous (order N) representation for pressure. A number of test cases are used to evaluate the method's ability to model fracture flow. The first is used to verify the performance of the element pair on structured and unstructured meshes of different resolution. Multiphase flow is then modelled in a range of idealised and simple fracture patterns. Solutions with sharp saturation fronts and computational economy in terms of mesh size are illustrated.     

Hydraulic and hydrochemical properties of deep sedimentary reservoirs of the Upper Rhine Graben,Europe

Hydraulic and hydrochemical data from several hundred wells mostly drilled by the oil and gas industry within the four deep carbonate and siliciclastic reservoirs of the Upper Rhine Graben area in France and Germany have been compiled, examined, validated and analysed with the aim to characterize fluids and reservoir properties. Due to enhanced temperatures in the subsurface of the Upper Rhine Graben, this study on hydraulic and hydrochemical properties has been motivated by an increasing interest in deep hydrogeothermal energy projects in the Rhine rift valley. The four examined geothermal reservoir formations are characterized by high hydraulic conductivity reflecting the active tectonic setting of the rift valley and its fractured and karstified reservoirs. The hydraulic conductivity decreases only marginally with depth in each of the reservoirs, because the Upper Rhine Graben is a young tectonically active structure. The generally high hydraulic conductivity of the reservoir rocks permits cross‐formation advective flow of thermal water. Water composition data reflect the origin and hydrochemical evolution of deep water. Shallow water to 500 m depth is, in general, weakly mineralized. The chemical signature of the water is controlled by fluid–rock geochemical interactions. With increasing depth, the total of dissolved solids (TDS) increases. In all reservoirs, the fluids evolve to a NaCl‐dominated brine. The high salinity of the reservoirs is partly derived from dissolution of halite in evaporitic Triassic and Cenozoic formations, and partly from the fluids residing in the crystalline basement. Water of all four reservoirs is saturated with respect to calcite and other minerals including quartz and barite.     

明初大运河南旺分水枢纽水工技术考

明朝初年,国脉皆仰东南,为解决南方粮财物的北运问题,宋礼和白英受命组织修建了大运河山东段南旺分水枢纽。该枢纽主要包括引汶济运、导泉补源、设立水柜和置闸节流四个组成部分。其中,引汶济运是工程之重点,包括戴村坝、小汶河、南旺分水以及配套工程等四个子系统。这些水利设施组成一个和谐的系统工程,保证了该段运河的水量稳定充足,从而实现了大运河500余年的正常通行。南旺分水枢纽代表了我国古代运河水工的最高科学技术成就,堪称世界水利史上的一大经典范例。     

Evidence of Stress Fracture in a Homo antecessor Metatarsal from Gran Dolina Site (Atapuerca,Spain)

We present the palaeopathological analysis of a right fourth metatarsal (ATD6‐124) recovered from the Atapuerca–Gran Dolina site (Spain). This fossil, ca. 1 Ma, belongs to Homo antecessor, the earliest known European hominin species. The metatarsal exhibits a proliferative lesion on its medial periosteal surface. Periosteal reaction can be the bone response to a wide number of injurious processes. We describe a lesion on the basis of macroscopic and microscopic analyses, including microtomography and scanning electron microscopy. Externally, the osteoblastic lesion presents a highly porotic and disorganised morphology. Internally, we observe a series of micro‐fractures on the compact bone that do not affect the medullary canal. We provide a differential diagnosis and suggest that the ATD6‐124 lesion could correspond to a pedal stress fracture, also known as fatigue or march fracture. Stress fractures have been related to a load increase and muscular fatigue. This type of fracture has been widely reported in the foot of soldiers and athletes, which are usually engaged in strenuous, excessive or prolonged locomotive activities. Despite its high frequency in these groups, stress fractures have not been reported as such in fossil collections, with the exception of a metatarsal belonging to the Sima de los Huesos site (Atapuerca). Copyright © 2013 John Wiley & Sons, Ltd.     

Bioarchaeological Analysis of a Royal Burial from the Oldest Maya Tomb in Palenque,Mexico

In 1957, a new discovery inside Temple XVIII‐A was made in Palenque, the Mayan archaeological site in Chiapas Mexico, a royal tomb of an original design which proved to be the oldest at the site. Two skeletons were found, the principal (PAL‐44) was at the centre showing red pigmentation on the surface of some bones, personal adornments and offerings, which indicate that he was an early ruler of Palenque. The second (PAL‐45), deposited at the entrance, not in a special mortuary position, without offerings, suggests it was of a lower social status. This research presents a new bioarchaeological analysis with the following results: (i) The result of a direct radiocarbon dating of PAL‐44 by accelerator mass spectrometry is 250–420 cal AD (LTL12759A:1696 ± 30 BP). This means that the personage was buried long before the first designated ruler of Palenque, who, according to the epigraphic record was enthroned in ad 431. (ii) With X‐Ray Fluorescence, the red pigment was identified as cinnabar (HgS). (iii) PAL‐44 is a young adult male with a severe idiopathic scoliosis with a double curvature that affected the ribcage and lower limbs. Such a three‐dimensional deformity resulted in changes to his body mechanics and induced motion asymmetry. Consequently, his health and mobility must have been significantly affected by such a severe condition. (iv) PAL‐45 is an adult female with signs of nutritional problems in childhood and entheseal changes probably related to her activity. Three ante‐mortem traumas are registered: rib fracture, frontal depressed circular fracture and a nasal septal deviation. This traumatic event took place two weeks, approximately, prior to PAL‐45's death. Copyright © 2013 John Wiley & Sons, Ltd.     

Legalized trauma

In the past, criminals were executed by a variety of means, including beheading or hanging, and both these methods may leave signs on the skeleton. It is not difficult to recognize individuals who have been beheaded because one or other of the cervical vertebrae will show evidence of the fatal blow, and there may also be cut marks on the base of the skull or the back of the mandible. Death from hanging, however, often leaves no marks on the skeleton, especially when carried out with a running noose and no drop. With a drop, dislocation of the sutures at the base of the skull may be noted and the classic ‘hangman's fracture’, which is a fracture dislocation of the second cervical vertebra, may be present. When there is no evidence of trauma, death from hanging may have to be inferred in skeletons which are found with the hands tied or with other signs that are discussed here.     

Applying forensic techniques to interpret cranial fracture patterns in an archaeological specimen

This paper presents some of the basic principles of bone fracture physics and outlines characteristics used by forensic anthropologists to distinguish gunshot trauma from blunt trauma. The fracture pattern of a cranium from a historic cemetery in Memphis, Tennessee provides an example of how the mechanism of trauma could be misinterpreted. The pattern of the perimortem fractures is indicative of gunshot trauma with a bullet entering one side of the vault and impacting the opposite side. Identification of radiating fractures, concentric heaving fractures, and observation of the direction of bevel on the fractured surfaces are essential for interpretation of the mechanism that produced the injury.     

The Role of Engineer-in-Chief and the Introduction of Foreign Hydraulic Dredging Technology and River Conservancy into China, 1890s–1930s

This paper discusses studies of the development of river conservancy in modern China, and the role of engineers-in-chief in river improvement planning on rivers such as the Hai-ho (Haihe) and the Whangpoo (Huangpu). It discusses the introduction of foreign hydraulic dredging technology and management into two major Chinese ports. It then analyses the process by which two agencies of the Chinese government absorbed and adjusted this technology to suit local circumstances in the treaty ports of Tianjin and Shanghai beginning in the 1890s. Without prior experience in river conservancy, the conservancy boards adopted a range of foreign technologies. This allowed them to develop into major institutions that facilitated increasing trade flows between China and the rest of the world. Of particular significance in this process of technological change was the role of the expatriate engineers-in-chief who were employed as chief executive officers of both agencies. They were responsible for establishing the operations of the agencies, accommodating an increasing range of responsibilities such as financial and human resource management, and training Chinese engineers and managers for senior positions until they were ready to replace the expatriate engineers-in-chief after the 1930s.     

Polyphasic hydrothermal and meteoric fluid regimes during the growth of a segmented fault involving crystalline and carbonate rocks (Barcelona Plain,NE Spain)

A polyphasic tectonic‐fluid system of a fault that involves crystalline and carbonate rocks (Hospital fault, Barcelona Plain) has been inferred from regional to thin section scale observations combined with geochemical analyses. Cathodoluminescence, microprobe analyses and stable isotopy in fracture‐related cements record the circulation of successive alternations of hydrothermal and low‐temperature meteoric fluids linked with three main regional tectonic events. The first event corresponds to the Mesozoic extension, which had two rifting stages, and it is characterized by the independent tectonic activity of two fault segments, namely southern and northern Hospital fault segments. During the Late Permian‐Middle Jurassic rifting, these segments controlled the thickness and distribution of the Triassic sediments. Also, dolomitization was produced in an early stage by Triassic seawater at shallow conditions. During increasing burial, formation of fractures and their dolomite‐related cements took place. Fault activity during the Middle Jurassic–Late Cretaceous rifting was localized in the southern segment, and it was characterized by hydrothermal brines, with temperatures over 180°C, which ascended through this fault segment precipitating quartz, chlorite, and calcite. The second event corresponds to the Paleogene compression (Chattian), which produced exhumation, folding and erosion, favouring the percolation of low‐temperature meteoric fluids which produced the calcitization of the dolostones and of the dolomite cements. The third event is linked with the Neogene extension, where three stages have been identified. During the syn‐rift stage, the southern segment of the Hospital fault grew by tip propagation. In the relay zone, hydrothermal brines with temperature around 140°C upflowed. During the late postrift, the Hospital fault acted as a unique segment and deformation occurred at shallow conditions and under a low‐temperature meteoric regime. Finally, and possibly during the Messinian compression, NW‐SE strike‐slip faults offset the Hospital fault to its current configuration.