bluuebunny/crossref_metadata_2025_split huggingface dataset:
Effects of Formation Damage and High-Velocity Flow on the Productivity of Perforated Horizontal Wells
Authors: Tang Yula , Yildiz Turhan , Ozkan Erdal , Kelkar Mohan 
Published: April 2006

Summary
A comprehensive semianalytical model has been built to investigate the effects of drilling and perforating damage and highvelocity flow on the performance of perforated horizontal wells. The model incorporates the additional pressure drop caused by formation damage and high-velocity flow into a semianalytical coupled wellbore/reservoir model. The reservoir model considers the details of flow in the vicinity of the wellbore, including 3D convergent flow into individual perforations, flow through the damaged zone around the wellbore and the crushed zone around the perforation tunnels, and non-Darcy flow in the near-wellbore region. The wellbore flow model includes the effect of frictional pressure drop. Both oil and gas wells are considered.
The expressions provided in this paper for additional pressure losses caused by perforating damage, drilling damage, and highvelocity flow can be used to optimize perforating parameters and decompose the total skin into its components (perforation pseu-doskin, damage skin, and non-Darcy skin).
Pore Network Modeling of Heavy-Oil Depressurization: A Parametric Study of Factors Affecting Critical Gas Saturation and Three-Phase Relative Permeabilities
Authors: Bondino I. , McDougall S. R. , Hamon G. 
Published: April 2006

Summary
This study deals with the application of pore-scale network modeling techniques to depressurization in heavy-oil systems. A three-phase simulator has been developed to account for the fundamental steps of such a depressurization process, from the nucleation of embryonic bubbles, to their growth by solute diffusion and expansion, to the final stages of coalescence, migration, and production. The model is utilized to examine the impact of a variety of different physicochemical properties—including bubble density and gas-oil diffusion coefficient–and different depletion strategies upon critical gas saturation and three-phase relative permeability. Results pertaining to heavy oils are also compared to those from light-oil depressurization simulations, and a number of important differences are highlighted.
The first sensitivity analyzes heavy-oil depressurization under conditions of instantaneous and progressive nucleation (IN and PN). In the first scenario, the evolution of gas is characterized by embryonic bubbles that are nucleated randomly soon after the bubblepoint pressure is reached. In the case of PN, a stochastic algorithm has been developed from related experimental observations. This models the progressive nucleation of additional bubbles as a function of local supersaturation (characterized by pore-scale variations in dissolved gas concentration). It is shown here that IN and PN observations are not necessarily contradictory—the model reconciles the two phenomena and shows how each relates to the underlying experimental parameters.
The vast majority of depressurization studies reported in the literature to date have tended to focus upon light oils and binary systems. However, the rather different characteristics of heavy oils—high interfacial tension, low gas/oil ratio (GOR), and high oil density—suggest that such studies may not be particularly representative of heavy-oil depressurization. In order to investigate this issue, a second set of sensitivity analyses is performed, whereby the network model is used to compare critical gas saturations and relative permeabilities arising from the depressurization of light and heavy oils. It is found that substantial differences can arise in the two systems. As a consequence, improved recoveries (with higher critical gas saturations) are predicted for some heavy-oil systems.
History Matching of Object-Based Stochastic Reservoir Models
Authors: Hu Lin Y. , Jenni Sandra 
Published: April 2006

SummaryThis paper first reviews the basic concepts of the widely used object-based Boolean model for modeling heterogeneous reservoirs. Then, we present a methodology for calibrating Boolean simulations to dynamic production data. This methodology is based on a generalization of the gradual deformation method that was initially developed for calibrating pixel-based Gaussianrelated reservoir models to dynamic data. Finally, two examples are presented and the results show the validity of the previously mentioned methodology. In particular, this methodology is potentially applicable to history matching of faulted and fractured reservoir models.
Effects of Mandrel, Borehole, and Invasion for Tilt-Coil Antennas
Authors: Hagiwara Terry , Banning Erik J. , Ostermeier Richard M. , Haugland S. Mark 
Published: April 2006

Summary
Several recently published studies discuss the concept of inductive resistivity-logging devices with oblique transmitting and/or receiving coils. Both wireline induction and logging-while-drilling (LWD) propagation resistivity-tool concepts have been considered. Directional resistivity measurements and improved anisotropy measurements are among the benefits promised by this type of device. Analyses based on point-magnetic dipole antennas were used to illustrate these potential benefits. The effects of a metallic mandrel, borehole, and invasion were not considered because of the absence of a suitable forward model.
This paper characterizes mandrel, borehole, and invasion effects for a variety of candidate tilt-coil devices with antenna array parameters similar to those of the previous studies. The characterization is based on calculations from a new forward model that includes tilted transmitting and receiving coils of finite diameter embedded in a concentric cylindrical structure.
Important details of the forward model used in the calculations are also provided.
New Semianalytic Technique To Determine Horizontal Well Productivity Index in Fractured Reservoirs
Authors: Fokker Peter A. , Verga Francesca , Egberts Paul J. P. 
Published: April 2006

SummarySimplified analytical relations derived for homogeneous formations are usually applied to the determination of the productivity of horizontal wells, regardless of the presence of heterogeneities in the reservoir. Furthermore, complex well architectures and the wealth of completion options currently available cannot be taken into account properly because the well trajectory can only be schematized as a single horizontal wellbore. However, the use of numerical reservoir simulators to reliably forecast the productivity of horizontal wells draining heterogeneous reservoirs may be time-prohibitive or not feasible because of a lack of sufficiently detailed information, especially during the appraisal phase or the early stages of production.A new semianalytic technique is proposed in this paper to solve the inflow equations in an approximate yet reliable manner. A solution to 3D problems of single-phase flow into a horizontal well, taking into account friction in the wellbore, is provided for both single-layer reservoirs and reservoirs comprising two interfering layers. The method also has been extended to describe the fluid flow when the well intercepts one or more fractures. The presented technique allows very fast calculation of the well productivity in oil and gas reservoirs, offering great flexibility in the placement and architecture of the wells.The method has been applied to two field cases for which the well productivity under pseudosteady-state conditions was measured. One of these is a 200-m-long horizontal well draining an isotropic carbonatic reservoir and intersected by a natural low-conductivity fracture. The other is a similar well, intercepting a natural high-conductivity fault, but the oil-bearing formation is anisotropic. Good correspondence was found between the actual productivity and the predictions obtained by application of the proposed semianalytic technique.
Kinship, language and production: a conjectural history of Khoisan social structure
Authors: Barnard Alan 
Published: April 2006

Opening ParagraphIn earlier articles I have argued the merits of the method of controlled comparison, both for the study of hunter-gatherer social organisation and for the study of Khoisan kinship across the forager/non-forager divide. In this article I put these two interests together to examine specifically the relationbetweenkinship, production and culture contact among the Khoisan, and particularly the Khoe-speaking, peoples. Certain kinship structures and practices are dependent upon the means and methods of subsistence, while others are not. The latter are products of Khoisan history and in general reflect linguistic relationships between economically diverse Khoisan peoples.
Wear ‘n’ tear and repair: the colour coding of mystical mending in Zulu Zionist Churches
Authors: Kiernan J. P. 
Published: April 2006

AbstractOne of the most conspicuous aspects of religious experience in Zulu Zionist Churches is the bright colours that are worn and otherwise employed. Surprisingly, this highly visible feature has attracted only passing attention from those who have studied these Churches; certainly no serious effort has been made to uncover the ritual significance of their colour symbolism. Against the background of anthropological studies of the therapeutic deployment of colour symbols in Africa and in the light of my own research among Zulu Zionists, this article sets out to show that the colours selected by Zionists from among those of salience to Africans express how they situate themselves within their social universe and plot the process of their response to it in ritual healing.
Vulnerability to impoverishment in South African rural areas: the erosion of kinship and neighbourhood as social resources
Authors: Sharp John S. , Spiegel Andrew D. 
Published: April 2006

Opening ParagraphSince 1960 several million Africans have been relocated in South Africa, mainly from the common (or ‘white’) area to the so-called ‘homelands’. This process of relocation is still under way, and precise enumeration of the numbers of people who have been and will be affected is impossible. Estimates vary according to the definition of ‘relocation’: it is apparent, for instance, that official sources define the process as narrowly as possible in order to minimize the numbers involved. There is abundant evidence, however, that relocation has taken place on a vast scale, and that the process has generally resulted in increased poverty and misery for its victims (Surplus People Project, 1983). Kane-Berman has recently argued that the South African Bantustans are, at present, not so much reservoirs of a reserve army of labour as dumping grounds ‘for people who have little chance of obtaining employment anywhere’ (1981: 29). From having been sub-subsistence dormitory areas for labour migrants, they are rapidly becoming places to which the structurally unemployed are being permanently consigned.
Women's work role and fertility in Liberia
Authors: Kollehlon Konia T. 
Published: April 2006

IntroductionThere is a general recognition, supported to a large extent by research findings, that in most of the Western industrialized world, women's participation in the salaried work force has a depressing effect on fertility (Kupinsky, 1977; Stycos and Weller, 1967). But research findings on this topic in the less developed world have been largely inconsistent. While a number of these studies find the fertility of women who work for wages to be lower than that of other women (Miro and Rath, 1965; Jaffe and Azumi, 1960; World Fertility Survey, 1980; and Lightbourneet al., 1982), the findings of other studies suggest very little or no differences in the fertility of wage working and nonwage working women (Stycos, 1965; Stycos and Weller, 1965; Okediji, 1976; and Mott, 1974). Furthermore, the findings of other studies suggest that it may not be the assumed role incompatibility between wage employment and familial roleper sethat leads to reductions in fertility, but rather the degree of approval/disapproval of domestic roles for women (Hass, 1972), normative conflicts (Mason and Pelan, 1981), or the degree of work commitment (Safilios-Rothschild, 1972).
People and animals: constru(ct)ing the Asante experience
Authors: McCaskie T. C. 
Published: April 2006

AbstractThe Asante (Ashanti) are a forest-dwelling people of West Africa, now located in the Republic of Ghana. This article deals with the Asante perception of forest animals within a broad cultural and historical context. Such animals were ubiquitous in Asante life and thought, and the article offers an analysis of the readings—phenomenological and ontological—placed upon them. The article also explores the ways in which the constructions placed upon animals were linked to Asante understandings of selfhood and the person, and to readings of myth and history.
The rise of the north-western Tswana kingdoms: on the dynamics of interaction between internal relations and external forces
Authors: Gulbrandsen Ørnulf 
Published: April 2006

AbstractWhile southern African polities are often considered as essentially fissionary in nature, this article gives emphasis to the equally important fusionary processes. Examining the rise of the north-western kingdoms, it is focused upon the accumulation of material and symbolic capital in the royal centres. Particular attention is paid to how the rulers exploited this capital in their efforts to amalgamate the power structures surrounding their offices. The accumulation of the royal capital is related to the kingdoms' interaction with the larger world, and it is argued that the rise of the north-western Tswana kingdoms—located on the edge of the Kalahari—might profitably be seen as localised culminations of regional processes, propelled by regional and global forces. Thus the present historical approach helps to demonstrate how these kingdoms gained strength by translating ever newer types of external forces into the constructive underpinnings of a central authority: the initial conquest and incorporation of local groups gave these polities demographic strength. By virtue of virgin pastures, copper production and the natural resources of the Kalahari the centre grew in wealth and strength, attracting foreign groups and incorporating them politically through clientisation. These regional economic and ecological processes underpinned the growth of royal pastoral wealth and diversified the composition of the population, allowing the king to use particular cultural institutions to strengthen his internal control and military capacity. In particular, through several decades of military success from the later eighteenth century onwards, the resources and authority commanded by the king were institutionalised through a politico-administrative ward system.It is argued that the progressive strength of these polities involved two types of dialectical transformation: first, a socio-political dialectic at work in the interaction between internal relations and external forces, by which the king translated cattle and people into political controls; and, secondly, the reproduction and strengthening of the symbolic capital vested in the royal ancestorhood, upon which the king's legitimacy rested, was effected by the transformation of any successful ruler from being king to becoming a royal ancestor. Although the transformative operations of the rulers are thus emphasised, their successful agency in translating external forces into royal capital is attributed primarily not to their personal capacity but to the advantageous structural conditions under which they operated as the historical con-text evolved.
Preliminary notes on audiences in Africa
Authors: Barber Karin 
Published: April 2006

AbstractThere have been audiences, presumably, as long as there has been performance. The perception that what creates an audience is the listeners' intentional orientation towards the speaker is the starting point of a far-reaching development in performance and media studies which focuses on the activity and creativity of the audience. If the audience has an active role in constituting the performance, cultural historians seeking to uncover histories of consciousness in African popular genres cannot afford to ignore it. But audiences are not all the same. Just as much as performances, they are a historical product. There are different ways of convening and of experiencing reception, whether collectively or in dispersal, which are deeply connected with the nature of the social life of the age and place. How people come together; how they relate to each other and to the spectacle or utterance they are attending to; what they consider themselves to be part of in doing so; how the spectacle/utterance addresses them—all these are historically and culturally specific and need to be empirically investigated. Specific African audiences have distinctive, conventional modes and styles of making meaning, just as performers/speakers have. We need to ask how audiences do their work of interpretation.
The new development rhetoric and Lake Malawi
Authors: Ferguson Anne E. , Derman Bill , Mkandawire Richard M. 
Published: April 2006

AbstractDespite the new development rhetoric emphasising sustainability, preservationof biodiversity, natural resource management, income generation and participatory research, the new World Bank Malawi Fisheries Development Project represents a continuation of past practices. This article examines the underlying conceptual framework and implications of this World Bank project in the light of research among fishing communities on Lake Malawi. The Bank, it is argued, is mistakenly promoting assistance to the large-scale commercial fishing sector rather than attempting to implement more innovative and collaborative project initiatives with small-scale fishers, processors and traders who comprise the vast majority of lake users.
Disguising chiefs and God as history: questions on the acephalousness of LoDagaa politics and religion
Authors: Hawkins Sean 
Published: April 2006

AbstractThis article examines two periods in the historiography and ethnography of the LoDagaa of northern Ghana and analyses the similarities between them. In the late 1920s the institution of chieftaincy was written into LoDagaa history by colonial administrators, only two decades after they themselves had created that institution in a society they had once considered bereft of political authority. By the early 1930s colonial administrators had created a historical fiction, namely that chiefs had always existed among the LoDagaa, despite the view of a generation of earlier officers that there had been no chiefs prior to the arrival of the British. Administrators needed to finesse the past, not to convince the LoDagaa of the legitimacy of the chiefs, but in order to continue ruling through chiefs once indirect rule had been introduced. Colonial political engineering had to be indigenised in order to survive under the terms of indirect rule. This finessing of the past has bequeathed ambiguities and contradictions evident in contemporary attitudes toward the position of chiefs among the LoDagaa.Similarly, in the 1970s and 1980s the indigenous clergy among the LoDagaa, who had taken over from the missionaries in the 1960s, began to reassess the nature of god in indigenous religious thought in order to narrow the distance between LoDagaa culture and Catholicism. The idea of inculturation, which grew after the Second Vatican Council, was the specific impetus for such enquiries. LoDagaa priests reexamined indigenous religion and discovered the existence of belief in and worship of a single, absolute deity which had been neglected by earlier missionaries and ethnographers. The latter had argued that there was only a diffuse or otiose notion of an absolute god in LoDagaa culture and thought. The once otiose god was repatriated, as if it had been exiled by earlier observers, in ways and circumstances similar to the invention of chieftaincy as an indigenous pre-colonial reality. While earlier political revisions were finessed by colonial officers, with the acquiescence of colonial chiefs, bent on changing LoDagaa culture and history for administrative convenience, the latter revisionists were seemingly concerned with defending and preserving indigenous culture rather than changing it. However, the notion of the pre-missionary worship of god is as much a historical fiction as the idea of the existence of chiefs in the pre-colonial period.
Impurity and power: women in Aladura churches
Authors: Crumbley Deidre Helen 
Published: April 2006

AbstractWhat is there about being female which elicits religious rituals of control? More specifically, what is there about menstrual blood which elicits a language of ritual impurity? What is the relationship between exclusion from the sacred and exclusion from power? This article, based on fieldwork among the Aladura or ‘praying’ churches of Nigeria (1982 to 1986), explores these questions in three Aladura denominations. While these three ‘spiritual’ churches share similar features in being indigenous, healing and prophesying churches, the status and roles of women in their respective organisational structures vary remarkably. The ways in which an ideology of impurity impacts or fails to impact upon gender and power relationships is investigated, and an explanatory framework for assessing such variations is suggested.
Rural people as conservationists: querying neo-Malthusian assumptions about biodiversity in Sierra Leone
Authors: Kandeh H. B. S. , Richards Paul 
Published: April 2006

AbstractContrary to neo-Malthusian assumptions population increase may not necessarily mean less biodiversity. More people may mean more care of the environment. Much depends on the circumstances through which local populations develop an awareness of, and practical involvement in, biodiversity management. This article considers two instances. In the first, an apparently pristine rain forest turns out on closer inspection to be heavy with the marks of past human occupance. This may have been quite good for some classes of biodiversity—the birds, for instance. In a second case, attention is paid to crop genetic resources in a densely populated agrarian landscape. Here genetic biodiversity may have been conserved through the activities of farmers selecting planting materials adapted to harsh physical conditions. Case-study material of this kind provides a basis for conservationists and community groups to develop mutual understanding.
The Pollen Evidence for the Environment of Early Man and Extinct Mammals at the Lehner Mammoth Site, Southeastern Arizona
Authors: Mehringer Peter J. , Haynes C. Vance 
Published: April 2006

AbstractFossil pollen is directly associated with a radiocarbon date, mammoth bones, and the same stratigraphic units in which mammoth, bison, tapir, and horse bones and Clovis artifacts were recovered at the Lehner site. The pollen evidence indicates that desert grassland occupied the San Pedro Valley of southeastern Arizona about 9000 B.C.