The Late Quaternary tephrostratigraphy of annually laminated sediments from Meerfelder Maar, Germany

© 2015 Elsevier Ltd.The record of Late Quaternary environmental change within the sediments of Meerfelder Maar in the Eifel region of Germany is renowned for its high precision chronology, which is annually laminated throughout the Last Glacial to Interglacial transition (LGIT) and most of the Holocene. Two visible tephra layers are prominent within the floating varve chronology of Meerfelder Maar. An Early Holocene tephra layer, the Ulmener Maar Tephra (~11,000 varve years BP), provides a tie-line of the Meerfelder Maar record to the varved Holocene record of nearby Lake Holzmaar. The Laacher See Tephra provides another prominent time marker for the late Allerød, ~200 varve years before the transition into the Younger Dryas at 12,680 varve years BP. Further investigation has now shown that there are also 15 cryptotephra layers within the Meerfelder Maar LGIT-Holocene stratigraphy and these layers hold the potential to make direct comparisons between the Meerfelder Maar record and other palaeoenvironmental archives from across Europe and the North Atlantic. Most notable is the presence of the Vedde Ash, the most widespread Icelandic eruption known from the Late Quaternary, which occurred midway through the Younger Dryas. The Vedde Ash has also been found in the Greenland ice cores and can be used as an isochron around which the GICC05 and Meerfelder Maar annual chronologies can be compared. Near the base of the annual laminations in Meerfelder Maar a cryptotephra is found that correlates to the Neapolitan Yellow Tuff, erupted from Campi Flegrei in southern Italy, 1200km away. This is the furthest north that the Neapolitan Yellow Tuff has been found, highlighting its importance in the construction of a European-wide tephrostratigraphic framework. The co-location of cryptotephra layers from Italian, Icelandic and Eifel volcanic sources, within such a precise chronological record, makes Meerfelder Maar one of the most important tephrostratotype records for continental Europe during the Last Glacial to Interglacial transition

The Arctic predictability and prediction on seasonal-to-interannual timescales (APPOSITE) data set version 1

This is the final version of the article. Available from the publisher via the DOI in this record. Discussion paper (published on 15 Oct 2015)Recent decades have seen significant developments in seasonal-to-interannual timescale climate prediction capabilities. However, until recently the potential of such systems to predict Arctic climate had not been assessed. This paper describes a multi- 5 model predictability experiment which was run as part of the Arctic Predictability and Prediction On Seasonal to Inter-annual Timescales (APPOSITE) project. The main goal of APPOSITE was to quantify the timescales on which Arctic climate is predictable. In order to achieve this, a coordinated set of idealised initial-value predictability experiments, with seven general circulation models, was conducted. This was the first model 10 intercomparison project designed to quantify the predictability of Arctic climate on seasonal to inter-annual timescales. Here we present a description of the archived data set (which is available at the British Atmospheric Data Centre) and an update of the project's results. Although designed to address Arctic predictability, this data set could also be used to assess the predictability of other regions and modes of climate vari15 ability on these timescales, such as the El Niño Southern Oscillation.This work was supported by the Natural Environment Research Council (grant NE/I029447/1). Helge Goessling was supported by a fellowship of the German Research Foundation (DFG grant GO 2464/1-1). Data storage and processing capacity was kindly provided by the British Atmospheric Data Centre (BADC). Thanks to Yanjun Jiao (CCCma) for his assistance with the CanCM4 simulations and to Bill Merryfield for his comments on a draft of the pape

Gel placement in production wells

Summary. Straightforward applications of fractional-flow theory and material-balance calculations demonstrate that, if zones are not isolated during gel placement in production wells, gelant can penetrate significantly into all open zones, not just those with high water saturations. Unless oil saturations in the oil-productive zones are extremely high, oil productivity will be damaged even if the gel reduces water permeability without affecting oil permeability. Also, in field applications, capillary pressure will not prevent gelant penetration into oil-productive zones. An explanation is provided for the occurrence of successful applications of gels in fractured wells produced by bottomwater drive. With the right properties, gels could significantly increase the critical rate for water influx in fractured wells

SPE 116226 Next-Generation Perforating System Enhances the Testing and Treatment of Fracture Stimulated Wells in Canada

Abstract Ineffective perforation can adversely affect the completion of fracture stimulated wells in several ways. If the interval is to be tested prior to fracturing, a clean connection to the formation is required to facilitate meaningful data acquisition. Excessive perforation damage can mask true formation potential and lead to incorrect diagnosis and decision making. Inadequate perforations can result in significant fracture tortuosity, increasing formation breakdown pressure -occasionally beyond the capacity of surface equipment or design rating of the well. Finally, limited entry perforation -a common technique for diverting a treatment across multiple fracture initiation points -demands that as many perforations as possible are open and can accept treatment fluids. Low perforating efficiency and variations in perforation cleanup associated with heterogeneous formations can cause uneven treatment distribution and suboptimal completion. Traditional methods for achieving clean perforations depend on creating a pressure gradient between formation and wellbore to induce flow and remove debris from the perforation tunnels -this can be difficult to accomplish, especially in low-pressure reservoirs. Underbalance cleanup favors intervals with higher flow potential -typically those with greater permeability -and may result in low perforation efficiency in poor or variable quality zones. Operators of wells requiring fracture stimulation are therefore faced with a significant challenge to find reliable, cost-effective perforating methods. A new class of reactive shaped charges has recently been introduced that generates a powerful secondary effect within each perforation tunnel immediately after it is formed. The reaction supercharges each tunnel, causing a surge of flow into the wellbore that removes all compacted debris and the near-tunnel crushed zone that would otherwise impair flow performance. Since this effect is independent of rock properties and wellbore conditions, a very high percentage of clean tunnels can be obtained across the entire interval without necessarily perforating in an underbalanced condition. This paper describes the new charge technology in greater detail and reports on its successful deployment in more than a dozen wells for different operators in Canada. Specific examples are used to illustrate how the system facilitates pre-frac evaluation, fracture initiation and limited entry fracture stimulation. Introduction Shaped charge perforators are the dominant method used to create a flow path between formations of interest and the wellbore in a cased and perforated completion. The vast majority of perforated completions depend on the use of shaped charges because of the relative speed and simplicity of their deployment compared to alternatives, such as mechanical penetrators or hydro-abrasive jetting tools. However, despite these advantages shaped charges provide an imperfect solution. Shaped charges are formed by compressing high explosive powder within a metal case using a conical or parabolic metal liner, as depicted i

First discovery of Holocene cryptotephra in Amazonia

The use of volcanic ash layers for dating and correlation (tephrochronology) is widely applied in the study of past environmental changes. We describe the first cryptotephra (non-visible volcanic ash horizon) to be identified in the Amazon basin, which is tentatively attributed to a source in the Ecuadorian Eastern Cordillera (0–1°S, 78-79°W), some 500-600 km away from our field site in the Peruvian Amazon. Our discovery 1) indicates that the Amazon basin has been subject to volcanic ash fallout during the recent past; 2) highlights the opportunities for using cryptotephras to date palaeoenvironmental records in the Amazon basin and 3) indicates that cryptotephra layers are preserved in a dynamic Amazonian peatland, suggesting that similar layers are likely to be present in other peat sequences that are important for palaeoenvironmental reconstruction. The discovery of cryptotephra in an Amazonian peatland provides a baseline for further investigation of Amazonian tephrochronology and the potential impacts of volcanism on vegetation

SPE 73758 The optimization of the productivity index and the fracture geometry of a stimulated well with fracture face and choke skins

Abstract The post-treatment performance of hydraulically fractured wells has been a recurring theme in the petroleum literature, covering the spectrum of understanding the physics of flow to the optimization of design. Optimization itself has taken different hues meaning comprehensive economic, or just the reduction of execution costs, or the maximization of the production or injection rates. Irrespective of the ultimate criterion, the magnitude of the reservoir permeability has been central to the fracture morphology. Long fractures are warranted for lowpermeability reservoirs; wide but short fractures are indicated for high-permeability formations. For a given reservoir of known permeability and dimensions the mass of proppant injected to the pay describes a unique and constant proppant number for which a maximum well productivity index can be achieved at the optimum dimensionless fracture conductivity. The proppant number and the optimum dimensionless fracture conductivity determine exclusively the optimum fracture dimensions. However, damaged hydraulic fracture performance deviates substantially from that of undamaged fractures. Two types of damage are considered, fracture face, often caused by fluid leakoff into the reservoir and choke fracture, which is caused by proppant flow-back, over-displacement or polymer damage. These damages, described by skin effects cause a departure, at times substantial, from the indicated undamaged optimum fracture geometry. In this work, the performance of a fractured well is calculated using a direct boundary element method. The method calculates the dimensionless productivity index and the model allows for the presence of the two different skin effects. The fracture face skin effect was found to have a significant detrimental effect on the dimensionless productivity index, especially for high-permeability reservoirs

Advancing tephrochronology as a global dating tool: Applications in volcanology, archaeology, and palaeoclimatic research

Layers of far-travelled volcanic ash (tephra) from explosive volcanic eruptions provide stratigraphic and numerical dating horizons in sedimentary and volcanic sequences. Such tephra layers may be dispersed over tens to thousands of kilometres from source, reaching far beyond individual volcanic regions. Tephrochronology is consequently a truly global dating tool, with applications increasingly widespread across a range of Quaternary and geoscience disciplines. This special issue of the International Focus Group on Tephrochronology and Volcanism (INTAV) showcases some of the many recent advances in tephrochronology, from methodological developments to diverse applications across volcanological, archaeological, and palaeoclimatological research

On the Link between the Subseasonal Evolution of the North Atlantic Oscillation and East Asian Climate

We analyse the impact of the North Atlantic Oscillation (NAO) on the climate of East Asia at subseasonal time scales during both winter and summer. These teleconections have mainly been investigated at seasonal and longer time scales, while higher-frequency links are largely unexplored. The NAO is defined using extended empirical orthogonal functions on pentad-mean observations, which allows to elucidate the oscillation’s spatial and temporal evolution and clearly separate the development and decay phases. The downstream dynamical imprint and associated temperature and precipitation anomalies are quantified by means of a linear regression analysis. It is shown that the NAO generates a significant climate response over East Asia during both the dry and wet seasons, whose spatial pattern is highly dependent on the phase of the NAO’s life cycle. Temperature and precipitation anomalies develop concurrently with the NAO mature phase, and reach maximum amplitude 5–10 days later. These are shown to be systematically related to mid and high-latitude teleconnections across the Eurasian continent via eastward-propagating quasi-stationary Rossby waves instigated over the Atlantic and terminating in the northeastern Pacific. These findings underscore the importance of rapidly evolving dynamical processes in governing the NAO’s downstream impacts and teleconnections with East Asia.</p

PROSEDUR PEMBIAYAAN KPR SUBSIDI PADA PT. BANK BRI SYARIAH KANTOR CABANG JAMBI

Laporan magang ini berjudul Prosedur Pembiayaan KPR Subsidi pada PT Bank BRISyariah Kantor Cabang Jambi. Dalam penulisan laporan magang ini penulis menggunakan teknik pengumpulan data yaitu observasi,wawancara, dan studi pustaka. Sedangkan metode analisis data yang digunakan dalam tugas akhir ini adalah metode analisis deskriptif. Tujuan dari pembuatan laporan magang ini adalah untuk mengetahui Prosedur pembiayaan KPR Subsidi pada PT. Bank BRISyariah khususnya Kantor Cabang Jambi.Kesimpulan yang dapat di ambil dari laporan magang ini adalah mahasiswa, PKL/Magang mengetahui bagaimana Prosedur KPR Subsidi pada PT Bank BRISyariah Kantor Cabang Jambi. Pembiayaan Kepemilikan Rumah (KPR) merupakan produk pembiayaan perumahan dengan dukungan bantuan dana Fasilitas Likuiditas Pembiayaan Perumahan (FLPP) atau subsidi kepada masyarakat berpenghasilan rendah (MBR) dalam rangka kepemilikan rumah sejahtera yang dibeli dari pengembang (Developer

the 1999 SPE Annual Technical Con-ference and Exhibition

Abstract We have developed methods of conditioning non-stationary Levy-stable geostatistical models 1,2 to 3D seismic data. The technique involves adapting the sequential Levy simulation method such that the convolutional response of the realisations acceptably &apos;matches&apos; the seismic amplitude map. A rejection scheme is used, which requires fast repetitive simulation of gridblock columns and generation of convolutional responses. The non-stationarity of the model means that this cannot be achieved using the conventional large kriging system. We use a different, but comparably rapid method, based on storing the relevant parts of a sequential simulation calculation for the column. Working directly with the amplitude traces also has the advantage of avoiding the ambiguities and non-uniqueness involved in inverting the traces to acoustic impedance. The most difficult part of the problem is estimation of the seismic wavelet, and this is often done non-optimally. We describe a sophisticated method of estimating the wavelet, and show that this can yield better than expected results. Suitable rejection criteria are proposed, based on reasonable probabilistic models. The application of the technique is demonstrated with a field example