Simulation of the impact of faults on CO2 injection into sandstone reservoirs

Numerical simulations of multiphase CO₂ behavior within faulted sandstone reservoirs examine the impact of fractures and faults on CO₂ migration in potential subsurface injection systems. In southeastern Utah, some natural CO₂ reservoirs are breached and CO₂‐charged water flows to the surface along permeable damage zones adjacent to faults; in other sites, faulted sandstones form barriers to flow and large CO₂‐filled reservoirs result. These end‐members serve as the guides for our modeling, both at sites where nature offers ‘successful’ storage and at sites where leakage has occurred. We consider two end‐member fault types: low‐permeability faults dominated by deformation‐band networks and high‐permeability faults dominated by fracture networks in damage zones adjacent to clay‐rich gouge. Equivalent permeability (k) values for the fault zones can range from <10^?14 m² for deformation‐band‐dominated faults to >10^?12 m² for fracture‐dominated faults regardless of the permeability of unfaulted sandstone. Water–CO₂ fluid‐flow simulations model the injection of CO₂ into high‐k sandstone (5 × 10^?13 m²) with low‐k (5 × 10^?17 m²) or high‐k (5 × 10^?12 m²) fault zones that correspond to deformation‐band‐ or fracture‐dominated faults, respectively. After 500 days, CO₂ rises to produce an inverted cone of free and dissolved CO₂ that spreads laterally away from the injection well. Free CO₂ fills no more than 41% of the pore space behind the advancing CO₂ front, where dissolved CO₂ is at or near geochemical saturation. The low‐k fault zone exerts the greatest impact on the shape of the advancing CO₂ front and restricts the bulk of the dissolved and free CO₂ to the region upstream of the fault barrier. In the high‐k aquifer, the high‐k fault zone exerts a small influence on the shape of the advancing CO₂ front. We also model stacked reservoir seal pairs, and the fracture‐dominated fault acts as a vertical bypass, allowing upward movement of CO₂ into overlying strata. High‐permeability fault zones are important pathways for CO₂ to bypass unfaulted sandstone, which leads to reduce sequestration efficiency. Aquifer compartmentalization by low‐permeability fault barriers leads to improved storativity because the barriers restrict lateral CO₂ migration and maximize the volume and pressure of CO₂ that might be emplaced in each fault‐bound compartment. As much as a 3.5‐MPa pressure increase may develop in the injected reservoir in this model domain, which under certain conditions may lead to pressures close to the fracture pressure of the top seal.     

Scotland's wartime airfields: Conflict and legacy

Prior to the outbreak of World War 2 there were very few active military airfields in Scotland but with the end of Appeasement in 1938 a major programme of expansion was underway. This paper traces the origins of the airfields used in World War 2 and discusses wartime roles and duties undertaken. Spatial distribution and socio‐economic effects are considered along with post‐war uses of this substantial legacy.     

典型硫酸盐环境中砖质文物的脱盐与加固材料

中国保存有众多砖质文物建筑,目前这些文物多处于户外环境中,面临严重盐害导致的掏蚀损毁问题。因而,研究兼具脱盐功能的加固材料成为砖质文物等保护的一种创新思路,加固材料的研制和工艺技术的开发是其重点和难点,具有重大的社会需求和急迫性。为此,本工作从可溶性盐的破坏机制出发,研究出一种双组分无机加固材料,加固方法是Ba(OH)_2甲醇溶液与H_2C_2O_4、H_3PO_4乙醇溶液交替滴加,并模拟可溶性盐(NaCl、KCl、Na_2SO_4)分布的典型环境,进行加固、除盐,借助X射线衍射仪(XRD)、X射线荧光光谱仪(XRF)和无线阻尼抗钻仪等现代科学仪器,追踪盐的流出与转化过程。结果表明,本材料不仅能够加固模拟样品,同时能对最具破坏性的盐Na_2SO_4实现不可逆转化,生成重晶石的主要成分BaSO_4,加固与脱盐一次完成,是一种具有实际应用潜力的新材料。     

3D Digital Documentation,Assessment, and Damage Quantifi cation of the Al-Deir Monument in the Ancient City of Petra,Jordan

Abstract

The rock-cut monuments in the ancient city of Petra in Jordan form an outstanding tangible heritage site. Unfortunately, this important part of the world's cultural heritage is gradually being diminished due to weathering and erosion problems. In this research, an approach combining in situ surveying and laboratory analysis is applied in order to provide sufficient and comprehensive data regarding the documentation and evaluation of the status of the Al-Deir monument in Petra. The purpose was not only to quantify the damage, but also to make a first step towards creating a 3D monitoring programme of the deterioration rate. The approach presents a correlation study between the environmental condition and the surface weathering damage, using 2D mapping of the weathering form and accurate 3D realistic modelling from laser scanning and digital photogrammetry. The 2D mapping provides detailed weathering damage information for the entire stone surface of the monument, whereas the 3D modelling provides information on the spatial distribution and texture of the damage. Additionally, the 3D digital model can provide reference data as an exact guide to the restoration needed. In order to support the visual presentation of 3D surface details, a hybrid approach combining data from laser scanning and digital imagery was developed.

Studies of stone texture and spatial distribution of soluble salts were carried out at the monument in order to explain the mechanism of the weathering problem. Relative humidity, temperature, and wind are the main factors in the salt damage process. In order to study the effect of these conditions in the salt crystallization process a series of fieldwork investigations and laboratory work were undertaken. The results show that visible zoning of weathering damage is correlated to different salt concentrations.     

Building Pâris’ Beden Seyad: a replica of the Omani 19th‐century sewn fishing vessel

The beden seyad is a simple yet elegant Omani sewn fishing craft documented by the French naval officer François‐Edmond Pâris during his visit in Oman in 1838–1839. A 10m‐long scaled‐down replica of the vessel was built by a team of experts in a traditional boatyard in Qantab, the Sultanate of Oman, and is displayed in the Maritime History Gallery at the National Museum of Oman. This article describes different aspects of the building process of the vessel, from the material used to the method of construction. It compares the different versions of the beden drawing provided by Pâris and discusses the decision‐making and problem‐solving procedures carried out by the construction team.     

Blutkreislauf und Dreieinigkeit. Medizinischer Antitrinitarismus von Michael Servet (1511–1553) bis Giorgio Biandrata (1515–1588)

This paper centers on the relationship between renaissance medicine and antitrinitarianism forming an important part of the radical reformation in 16th century. Antitrinitarians denied the theological concept of the triune Christian God. Modern antitriniarianism was first formulated by Michael Servetus, a Spanish physician. The doctrine soon won disciples in northern Italy (Padua, Pisa, Rome) and in some countries of eastern central Europe (Poland, Moravia, Transylvania). Physicians who believed in or sympathized with antitrinitarianism revolutionized the theory of blood flow. They developed new concepts leading to Harvey's theory of the circulation of the blood. Parts of Servet's theory looked like Paracelsus's mystical idea of the eternal flesh of the body of Christ (Latin limbus aeternus), but later the medicine and natural philosophy of antitrinitarian physicians tended to be empiristic, rational and sometimes materialistic. They contributed heavily to the diffusion and physiological foundation of antitrinitarian concepts like unitarianism, tolerance and irenism.     

Republicans,Unionists and Jacobites: The 1st Marquess of Tweeddale and the Restoration of the British Parliament

Although John Hay, 1st marquess of Tweeddale, contributed significantly to both the ruthless overthrow of Charles I, and the establishment of the first British parliament in the 1650s, most of his political career was concerned with attempting to re-establish this parliament after it was dissolved at the restoration of Charles II. His first attempt ended in defeat at the hands of the king and the duke of Lauderdale in 1670, but following the overthrow of James VII and II in 1688, Tweeddale tried to persuade the prince of Orange to unite Scotland and England. The prince, however, showed much more interest in securing the crown of Scotland than uniting the two kingdoms. Tweeddale, as lord high commissioner to the Scottish parliament in 1695, responded by passing legislation designed to provoke the English parliament into accepting union. He was also engaged in a jacobite intrigue to restore King James. Tweeddale intended that the restored monarch would be little more than a puppet, who could be used to legitimise what was effectively a republican regime in all but name. By this means the restored parliament would avoid the unpopularity which brought down the first British parliament in 1660. Tweeddale's scheme came to nought, but the technique he employed to manipulate the English parliament, and exploit the jacobite threat, contributed to the restoration of the British parliament ten years after his death.     

Study of coal gas wettability for CO2 storage and CH4 recovery

To quantify and rank gas wettability of coal as a key parameter affecting the extent of CO₂ sequestration in coal and CH₄ recovery from coal, we developed a contact angle measuring system based on a captive gas bubble technique. We used this system to study the gas wetting properties of an Australian coal from the Sydney Basin. Gas bubbles were generated and captivated beneath a coal sample within a distilled water‐filled (pH 5.7) pressurised cell. Because of the use of distilled water, and the continuous dissolution and shrinkage of the gas bubble in water during measurement, the contact angles measured correspond to a ‘transient receding’ contact angle. To take into account the mixed‐gas nature (CO₂, CH₄, and to a lesser extent N₂) of coal seam gas in the basin, we evaluated the relative wettability of coal by CH₄, CO₂ and N₂ gases in the presence of water. Measurements were taken at various pressures of up to 15 MPa for CH₄ and N₂, and up to 6 MPa for CO₂ at a constant temperature of 22°C. Overall, our results show that CO₂ wets coal more extensively than CH₄, which in turn wets coal slightly more than N₂. Moreover, the contact angle reduces as the pressure increases, and becomes < 90° at various pressures depending on the gas type. In other words, all three gases wet coal better than water under sufficiently high pressure.     

Economic geography and the evolution of networks

An evolutionary perspective on economic geography requires adynamic understanding of change in networks. This article explorestheories of network evolution for their use in geography anddevelops the conceptual framework of geographical network trajectories.It specifically assesses how tie selection constitutes the evolutionaryprocess of retention and variation in network structure andhow geography affects these mechanisms. Finally, a typologyof regional network formations is used to discuss opportunitiesfor innovation in and across regions.