Southeastern Niger Research Articles

Integrating Old and New Data-Evaluation Techniques for Effective Reservoir Characterization of Southeastern Niger Delta Reservoirs

Summary The value of data integration has been proved in assessing the thin-bedded H4 reservoir and the stratigraphically natured H5 reservoir in UKU Field, southeastern Niger Delta, toward planning effective development strategies for depletion. Reservoirs of these definitions pose problems during mapping from seismic for well planning and drilling activities, as well as at the production stage. Data for this work consist of a recently acquired full-stack, 3D ocean-bottom-cable (OBC), prestack-time-migrated (PSTM) seismic data; well logs from five vertical wells; core information; and modular-dynamic-test (MDT) data. Seismic-attribute maps and extracted geobodies revealed the reservoir extent within the limit of seismic resolution (≈27 ft), while petrophysical analysis indicates the reservoirs to be of excellent flow-and-storage quality. MDT data reveal the hydrocarbon fill to be of medium-to-heavy grade. While water production was decided not to be probable for H4 reservoir depletion, it is of certainty in H5 reservoir production. Mapping showed that the field is separated into two fault blocks (FB1 and FB2) on the basis of the difference in water-contact levels, with calculated oil volume of 4 million BO (FB1) and 12 million BO (FB2) in H4 reservoir and 12 million BO (FB1) and 2 million BO (FB2) in H5 reservoir. Gas reserves in H4 sand were calculated to be 480 MMcF in FB2.

Analysis of the Structure and Diversity of Prosopis africana (G. et Perr.) Taub. Tree Stands in the Southeastern Niger

All parts of <em>Prosopis africana</em> are used by rural people in Niger, and this exposes it to degradation and a regeneration problems. The objective of this study was to determine the structure and regeneration of <em>P. africana</em> stands in the southern regions of Maradi and Zinder, Niger. Data were collected in plots, following transects after stratified sampling. Trunk diameter of all woody species was recorded in 126 plots. The diversity was analyzed and diameter structure and regeneration rates were determined. <em>P. africana </em>was the predominant species in both Maradi and Zinder: frequency = 40.35% and 43.95% of all species, respectively in Maradi and Zinder; importance value index = 40.57% in Maradi and 48.60% in Zinder. The Shannon diversity index was 2.82 in Maradi and 2.40 in Zinder and the Sorensen similarity index between the two regions was 0.73. According to the diameter structure, the stands were degraded in Zinder but regenerating in Maradi. The density of <em>P. africana </em>per hectare for trees with trunk diameter <span style="text-decoration: underline;">></span> 5 cm and < 5 cm, respectively was 16 and 51 in Maradi, and 30 and 12 in Zinder. The regeneration rate of <em>P. africana</em> was low compared with the general woody population. These results show the need for reforestation operations, using appropriate techniques, to avoid local extinction of the species.

Local Practices and Knowledge Associated with Date Palm Cultivation in Southeastern Niger

The date palm (Phoenix dactylifera L.), a dioecious species, is of particular interest in the Sahel due to its phenological plasticity in relation to climate change and its double-flowering capacity. This article explores local practices and knowledge associated with date palm cultivation in the oasis basins of southeastern Niger, and provides an inventory of local seed propagated varieties, for more effectively guiding agricultural research and the breeding of this species. We carried out a survey of 30 date palm growers in 14 villages of the Manga region. The qualitative data of the survey were processed by a Multiple Correspondence Analysis. We inventoried 19 date palm varieties, for which the main distinctive criterion was fruit colour, but some other criteria such as biology or provenance were also used. The cultural practices and knowledge associated with the date palm in Manga have improved since the 1990s. They also depend on ethnic groups and the importance they assign to farming compared to livestock rearing and trading activities. The type of basin (high, intermediate, or low water table) influences growers’ practices and perceptions. Lastly, the date harvest in the wet season is abundant, but of mediocre quality, whereas it is the opposite for the dry season harvest. To conclude, sustainable development of date palm cultivation in the Sahel zone relies firstly on the selection of varieties that are early fruit producers or that can complete fruit maturation during the raining season and secondly on technical capacity building for producers.

Engineering Assessment of South-Eastern Niger Delta Soils Utilized for Highway Pavement

Engineering properties of soils recovered along a road alignment route (right-of-way) and borrow pits of a 30 km road in the South-Eastern Niger Delta area, Nigeria were assessed for utilization as highway pavement earth materials. Laboratory soil tests conducted included the natural moisture content, grain size distribution analysis, consistency limits, standard proctor compaction and California bearing ratio (CBR). About thirty-five (35) soil samples were retrieved from the fifteen (15) boreholes and examined. Results show that all identified and examined soil samples from the borings along the road route and the borrow pits classified as A- 3, A-2-4 and A-2-6 are excellent sub-grade, good fill and sub-base materials. However, none of the soil types meet the engineering requirements for use as base course. Earth materials comprising overburden of clayey sands, silty sands and sandfills (previously used as sub-grades) along the Ahoada-Upatabo-Oyigba-Ebiriba-Ombor 30 km. road in South-eastern Niger Delta were evaluated for highway pavement construction. The results are presented in this paper. The objective of the study was to examine the appropriateness of these soils for the purpose of pavement design and construction as sub-grades, sub-base and base course materials. Previous related studies in the area include works by (1-5).

Comparative analysis of sonic and neutron-density logs for porosity determination in the South-eastern Niger Delta Basin, Nigeria

A comparative analysis of porosity values computed from sonic and neutron-density logs obtained from the same well is here presented. The aim is to identify the more reliable logging tool between sonic and neutron-density in the estimation of porosity values in a formation. Two wells from different parts of Niger Delta were logged for Transit times, bulk density and hydrogen index of the formation as a function of depth. The analysis of sonic, density and neutron porosity values shows a conventional trend of decrease in porosity with depth. Sonic porosity values of well A, and well B varies from 1 to 17%, and 27 to 60% respectively while Neutron-Density Porosity values of well A, and well B varies from 24 to 45%, and 21 to 37% respectively. The Coefficient of Variation for sonic porosity data are 56%, and 23%of well A, and well B respectively , similarly the Coefficient of Variation for Neutron-Density porosity data are 15%, and 14% of well A, and well B respectively. Coefficient of variation of Neutron-density log derived porosities is less than sonic log derived porosities; therefore Neutron-density log derived porosity is more reliable tool for porosity data estimation than sonic log derived porosity. Neutron and density logging tool is here recommended for determination of a reliable porosity value of a formation.

Biomarkers in surface sediments from the Cross River and estuary system, SE Nigeria: Assessment of organic matter sources of natural and anthropogenic origins

Herein, lipid biomarker analysis is applied to surface sediments from the southeastern Niger Delta region for the quantitative determination of aliphatic lipids, steroids and triterpenoids in order to differentiate between natural (autochthonous vs. allochthonous) and anthropogenic organic matter (OM) inputs to this deltaic environment. This ecosystem, composed of the Cross, Great Kwa and Calabar Rivers, is receiving new attention due to increased human and industrial development activities and the potential effects of these activities impacting its environmental health. While the presence of low molecular weight n-alkanes (<C22) and the fossil biomarkers pristane and phytane in all samples, are indicative of a minor petroleum related input, the total extractable organic component of the surface sediments of these rivers remains predominantly of a natural origin as characterized by the variety and predominance of lipid classes that are mainly derived from the epicuticular waxes of vascular plants and include n-alkanes, n-alkanols, n-alkan-2-ones, n-alkanoic acids, steroids and triterpenoids. In addition, recent OM inputs from microorganisms are indicated by the presence of lower molecular weight n-alkanoic acids (Cmax=16), while the major triterpenoids of the sediments, taraxerol and friedelin, and the major sterol, sitosterol, indicate recent OM inputs from vascular plants. Plankton-derived sterols, such as fucosterol and dinosterol, are also found in sediments from the Cross and Great Kwa Rivers and likely originate from autochthonous primary productivity. Furthermore, the coprosterols coprostanol and 24-ethylcoprostanol are present in most samples and indicate measurable anthropogenic contributions from domestic untreated sewage inputs and agricultural run-off, respectively. Of the three rivers studied, the Cross River system was excessively influenced by human and industrial development activities, including drivers such as urbanization and population center growth, land-use change to support agricultural production and animal husbandry, and petroleum exploration and production. These influences were found to be regionally specific as controlled by point sources of pollution based on the relative distributions measured and on the fact that the molecular characteristics of sedimentary OM were not distributed smoothly along a gradient.

Multiple-Point Statistics for Modeling Facies Heterogeneities in a Porous Medium: The Komadugu-Yobe Alluvium, Lake Chad Basin

Multiple-point statistics are used to model facies heterogeneities in the vadose zone of the Komadugu-Yobe River valley (southeastern Niger) which is presently submitted to an undergoing intensive agricultural development; therefore, increasing quantitative and qualitative pressures are exerted on groundwater resources. The sand–clay heterogeneities are analyzed by means of a Landsat image acquired during a high flow period over a 160 km stretch in the downstream part of the valley and a set of 50 boreholes drilled near the town of Diffa (4 km×4 km area). The horizontal variograms of heterogeneities are characterized by a noticeably constant length scale of 380 m and clayey objects are shown to be randomly distributed in space according to a Poisson process. A set of two-dimensional vertical images is built based on a Boolean procedure and the Snesim algorithm is used to simulate synthetic three-dimensional media. When the vertical correlation length is fitted, the three-dimensional model satisfactorily reproduces the second order statistics of heterogeneities and the specific facies patterns.

Abdim’s Stork Ciconia abdimii Exploitation of Senegalese Grasshopper Oedaleus senegalensis in South-eastern Niger

Abstract Abdim’s Storks Ciconia abdimii were studied in a post-breeding staging area dominated by Sahelian grasslands in southeastern Niger. In late September 2003, a total of 5,763 birds was recorded on systematic transect counts. The estimated density was 5.66 per km2, equivalent to a total of c. 17,000 Abdim’s Stork within the utilized area of 3,000 km2. A high percentage of juveniles in the flocks in late August, when the Nigerien breeding population is still at their nests, indicate a southern origin of the birds. The storks probably make northward post-breeding movements into the Sahel to feed on locally abundant food supplies, first of all Senegalese Grasshopper Oedaleus senegalensis, the dominant grasshopper species in the area. The mean density of Oedaleus in late September 2003 was 11.2 per m2 (6.7 g fresh weight/m2). Storks feeding on grasshoppers made on average 5.6 successful pecks per min during their first h of daily feeding, enabling them to fulfil 95% of their daily energy requirements wi...

Environmental Knowledge and Pastoral Migration among the Wod Aabe of South-Eastern Niger

Introduction The present paper describes and analyses environmental knowledge among Wodaabe cattle raisers of West Africa with respect to their organisation of herd management. The Wodaabe pastoral system focuses mainly on raising Zebu cattle (na'i bodeeji) and has two primary aims: first, to guarantee and increase herd reproduction; second, to bring the herd with minimal loss in weight and size through the dry season when fodder is in short supply. For the Wodaabe, herd growth is not so much the outcome of a naturally given fecundity, but rather of proper animal nutrition. Of all measures that a cattle raiser may take to further his herd's prosperity, Wodaabe consider the good nourishment of the animals as the most important. To be taken seriously as a herder, a man has to regularly provide for the best seasonally available fodder, to avoid all influences that could reduce an animal's food intake, and to look out for anything that could stimulate its grazing activity. This orientation of pastoral labour is due to the Wodaabe's economic specialisation: whereas other groups of pastoral Fulani reduce their economic dependency on herds and the need to sell animals--for example by cultivating staples (Bierschenk 1997: 209)--Wodaabe herders concentrate on improving the physical condition of their cattle in order to optimise herd reproduction. By doing this the Wodaabe can sell more animals to obtain money for buying their staple food: millet. It is through high spatial mobility of herd and household together that Wodaabe herders translate their evaluation of the cattle's nutritional needs into practice. They move to combine a whole set of ecological conditions optimally, such as soil quality, relief and species composition; thereby they obtain fodder of the highest nutritional value at any point in the seasonal cycle. Pastoral mobility, therefore, is a means of organising the exploitation of seasonally variable fodder resources to reach the goal of optimising herd reproduction. When making decisions on where and how to feed the animals, though, herders have not only to respond to the cyclic fluctuations of resource availability in the Sahel, they have also to consider their animals' current and anticipated physical condition, which varies seasonally between well nourished and seriously emaciated. After a brief overview of Wodaabe categories of pastoral migration and their meanings in the local context of south-eastern Niger, I shall try to demonstrate the interrelations between: --Wodaabe environmental knowledge --the perceived potential of natural resources with respect to the pastoral aims of conserving and increasing herd fertility --the fact that natural resources as well as the physical condition of the herds are subject to high seasonal variation --herd movement as the principal instrument through which Wodaabe herders control the availability of eagerly sought after resources Data presented here concern a group of herders of the Siiganko'en lineage (taarde) of the Suudu Suka'el clan (lenyol) of the Wodaabe people (sg. Bodaado) (2) living in south-eastern Niger. Ecological knowledge, pastoral practice and use of mobility are not the same among all Wodaabe, and surely some parts of this description will be peculiar to Wodaabe living in the plains of the Lake Chad basin. Nevertheless, this paper is meant as a contribution to a general understanding of Wodaabe culture. Moreover, it seems reasonable to assume that a good deal of Siiganko'en knowledge and practice is understood and even shared by other Wodaabe groups (see Bonfiglioli 1981, 1990, 1991, Bonfiglioli et al. 1984, Dupire 1957, 1996, Stenning 1957, 1959). Hence, the use of the term `Wodaabe' is considered appropriate here. Clearly, even among the Siiganko'en, knowledge is not uniform, stable or uniformly distributed. However, questions of distribution, generation and communication of knowledge go beyond the scope of this paper. …

Estimation de la recharge de la nappe quaternaire dans le Nord-Ouest du bassin du lac Tchad (Niger oriental) à partir de mesures isotopiques

The Quaternary water table is present over almost the whole Lake Chad basin. In its Niger part, where annual rainfall varies from 0 to 350 mm, radioactive isotopes ( 3 H and 14 C) are interpreted in terms of renewal rate; medians are 0.10 and 0.05 %, respectively, which means a recharge of about 2 or 3 mm.yr –1 . This very weak infiltration is compatible with the stable isotope contents ( 2 H and 18 O) in groundwater, which show a mixing of old and recent waters, infiltrated during the last humid period and the present drier times. La nappe contenue dans les sédiments quaternaires couvre la quasi-totalité du bassin du lac Tchad. Dans sa partie nigérienne, où les précipitations annuelles sont comprises entre 0 et 350 mm, l'interprétation des teneurs en isotopes radioactifs ( 3 H et 14 C) aboutit à des taux de renouvellement annuels médians de 0,10 et 0,05 % respectivement, soit environ 2 ou 3 mm.an –1 . Ces chiffres très faibles sont compatibles avec les teneurs en isotopes stables ( 2 H et 18 O) de la nappe, qui suggèrent un mélange d'eaux anciennes, infiltrées durant la dernière période humide, et d'eaux récentes, infiltrées sous un climat plus sec.

Abstract: Slope deformation controls on trap and reservoir development in turbidite systems, southeastern Niger delta, offshore Nigeria

Abstract: Slope deformation controls on trap and reservoir development in turbidite systems, southeastern Niger delta, offshore Nigeria

No space for participation: pastoralist narratives and the etiology of park-herder conflict in southeastern Niger

State-sponsored programs for protecting natural areas in Africa have increasingly adopted ‘participatory’ approaches. While a welcome change from the more coercive approaches of the past, a major impediment to the effectiveness of such programs is how conservationists conceptualize the logics, constraints, and spatial scales associated with the production practices of rural inhabitants that may cross protected perimeters. This paper examines the growing conflict between Fulße herders and managers of National Park ‘W’ in southeastern Niger. Rationales for conservationist reactions to herder incursions in the coercive past and ‘participatory’ present are supported by ‘development narratives’ that surround Fulße livestock husbandry in West Africa. It will be shown that these narratives are constructed by sequentially conflating linguistic group, ethnic identity, production practice, production logic, and environmental trajectories in an ahistorical fashion. The Fulße people of West Africa are often characterized by the development/conservation community as ‘pastoralists’ and as such are viewed as being highly mobile, tradition-bound, politically unorganized, and managers of an unsustainable (ecological or social) form of livestock husbandry. Oral histories and the examination of historical documents demonstrate that herd management by the Say Fulße has historically been governed by a two-tiered political structure and displayed highly circumscribed patterns of mobility with close integration with agricultural production. Increased incursions of herders into the park are traced, not to a rigid adherence to livestock mobility, but to the growing shortage of pastures in the home territory near Say. Both draconian enforcements by park guards and ‘participatory’ programs to educate local herders about the merits of sedentary livestock husbandry provide little space for herder-park constructive engagement and in fact have reduced its potential by eroding indigenous political control over livestock movements. Copyright © 1999 John Wiley & Sons, Ltd.

No space for participation: pastoralist narratives and the etiology of park‐herder conflict in southeastern Niger

No space for participation: pastoralist narratives and the etiology of park‐herder conflict in southeastern Niger

No space for participation: pastoralist narratives and the etiology of park‐herder conflict in southeastern Niger

No space for participation: pastoralist narratives and the etiology of park‐herder conflict in southeastern Niger

Abstract: Geochemical Characterization of the Hydrocarbons in the Petroleum System of the Southeastern Niger Delta

Abstract: Geochemical Characterization of the Hydrocarbons in the Petroleum System of the Southeastern Niger Delta

Sequence stratigraphy based on microfacies analysis: Mfamosing Limestone, Calabar Flank, Nigeria

Field observations and petrographic analysis allow a sequence-stratigraphic interpretation of the intensely karstified Albian Mfamosing Limestone Formation in the Calabar Flank of the south-eastern Niger Delta. Main criteria for this interpretation are the presence of siliciclastic intercalations, of prominent hardgrounds, of characteristic microfacies including stromatolites and of phreatic and vadose diagenetic patterns. These criteria enable the recognition, from bottom to top in the type section of the Mfamosing Limestone, of a late phase in the formation of a highstand systems tract and of a flooding surface followed by a lowstand systems tract in which erosional features have been developed locally. The succession is topped by a transgressive systems tract. Some of these units and key sequence-stratigraphic boundaries have been traced into other outcrops in the area. In their identification within the heavily karstified outcrops, petrography overprints and vertical sequence patterns play a significant role. A sedimentation model explains the areal differences in development. Siliciclastic shedding influenced the carbonate system. Time-equivalent carbonate bodies occur on either side of the opening South Atlantic Ocean.

Aspects of the Petroleum Systems in the Southeastern Niger Delta, Nigeria: ABSTRACT

Aspects of the Petroleum Systems in the Southeastern Niger Delta, Nigeria: ABSTRACT

Transitions Between Cultivation and Pastoralism in Sub-Saharan Africa [and Comments and Reply

This paper presents a dynamic optimality model of herding and farming as long-term survival strategies. The model can be used to predict which modes of subsistence will be associated with different ecological and economic conditions and therefore to examine under what circumstances people might change from one mode of subsistence to another. It predicts that the shift into pastoralism is associated, principally, with increasing wealth, and examples from recent history support his. It also explains such counter-intuitive b haviour as pastoralists' taking up cultivation in an area although farmers are moving out.

Food diversity and drought survival. The Hausa example

Two Hausa villages in the Sahel of south-eastern Niger were surveyed for food procurement practices, with special focus on dietary use of wild plants. Activities and behaviours during years of adequate rainfall were compared to practices during drought. A diversified food base was maintained through hunting, gathering, agriculture, horticulture, and animal husbandry. Members of households surveyed (n = 112) foraged for edible wild plants located in bushlands adjacent to villages, within household compounds, or within agricultural fields. Dominant agricultural crops were beans, millet, peanuts, and sorghum; prominent household garden species were melon, okra, and squash. At the time of the survey most households experienced marginal crop yields. Edible wild plants were prominent in local diet during both drought and during years of adequate rainfall; more than 80 species were commonly consumed. Protein values of several wild plants exceeded 20%, including Amaranthus hybridus, Cassia occidentalis, Cenchrus ...

The Afam Clay Member: a Lower Miocene incised channel in the south-eastern Niger Delta

This paper describes a Lower Miocene incised channel system and its lithic fill within the Niger Delta sedimentary succession. Stratigraphic cross-sections, which clearly show the base to be generally asymmetric, and very sharp with erosive characteristics in places, suggest a channel configuration for the base of the Afam Clay. The geometry of the channel and its lithic fill supports this interpretation. The channel was cut by fluvial processes into pre-existing unconsolidated Eocene-Miocene sediments of the Benin and Agbada Formations during a period of low sea level. The Imo River proto-channel is thought to have aided the channelling. The channel was subsequently enlarged by marine processes associated with a Middle Miocene rise in sea level. The lithic fill of the Afam channel is dominated by clay beds with localized development of sand bodies in time and space. Analysis of the spatial distribution of the sand units and their SP shapes supports the hypothesis of sand input from the north, east-central and west-central flanks of the channel. These are interpreted to reflect sand contributions from tributaries that fed the main channel. The faunal, lithological and textural characteristics of the Afam sediments suggest a predominance of marine conditions in the south, paralic conditions in the central area and fluvial processes in the north. In addition, the southern flanks of the channel may constitute truncation stratigraphic traps for hydrocarbons and it is proposed that these flanks should be fully explored.