Evaluating defect reporting in new residential buildings in New Zealand

The need for defect reporting is becoming increasingly difficult to ignore at handover of new residential buildings. A general review in defect studies has consistently shown that newly built properties can be found to have a significant number of defects. Very often the responsibility for rectifying these common defects is borne by the new homeowner even though house developers are liable. In the current study, survey data is obtained from 216 recent home purchasers/owners across New Zealand urban cities. The intent of the investigation is to show that opportunities exist for defect reporting that will act as a mechanism to measure performance and thus improve the quality of finished construction products in New Zealand. The study found that a significant number (81%) of the participants were involved in the construction of their homes and could influence quality performance if they were proactive enough. The results show that (64.7%) did not engage the service of independent building inspectors for defect reporting on their new homes. Seventy-four percent now agree that independent building inspection was important in hindsight. The study findings are in line with literature on defects and the poor use of defect reporting in new residential buildings. The current challenge for defect rectification by house developers after handover is real and this could increase the confidence that new home owners can have in their developers. Defect reporting could confer benefits to new residential building quality in New Zealand and should be embraced as part of a wider best practice

Reservoir Characterization, Modelling and Lateral Predictions Using Multivariate Analysis: A Case Study of Hems Field, Bohai Bay, Liaohe Field, China

Qualitative and quantitative predictions of reservoir properties and geometries beyond well control are vital to understanding the intrinsic characteristics of subsurface formations. Using well log data, 3D Seismic data, Geostatistical simulations, reservoir characterization, modeling via multivariate analysis was carried out for and lateral predictions on data set obtained from Liaohe field, western sag, Bohai Bay, Northern China. This sag is an intra-cratonic basin of Archean to Recent age. Stratigraphic analysis, structural analysis, geomodel building and geostatistical methods were used. Well logs methods include conventional interpretation by picking sand units based on Self potential log (SP) and Resistivity logs (LLD) in addition to computation of volume of shale and other petrophysical properties. Unavailable logs like Density and Neutron were predicted from a cored well whilst missing logs sections were predicted using neural networks and fuzzy logic. Clustering technique was employed to predict facies (electrofacies) occurrences based on various log types. Sand tops earlier picked from well logs were laterally traced on seismic sections after well to seismic tie. Structural interpretation was done to map the architectural pattern of the rock units. The post-stack seismic inversion was done and calibrated with logs from 12 wells producing acoustic impedance and elastic impedance volumes. Multi-attribute analysis was used to predict rock properties like porosity from inversion results and vintage seismic data. Modeling of variogram and structural elements was done, after which suitable geostatistical simulation algorithms were used to populate cells and realize multiple equiprobable rock properties for the zone of interest after upscaling all needed rock properties into the earlier built non-partitioned simulation case. These were achieved using standard software such as Petrel®2008, CGGVeritas™ Hampson Russell suite (2008), Interactive Petrophysics v3.5, Kingdom Suite (SMT) 2008, GeoGraphix® 2008 and Surfer 9 (Golden Software). Results show that clustering models converged to 2 classes namely sand and shale. Sand and shale sequences are fairly mixed and vertically inconsistent as a result of rapid deposition amidst unconsolidation on the toe of the sag structure. Petrophysical values viz hydrocarbon saturation is above 70%, porosity between 0.1 and 0.4, permeability between 0.6 and 3.0mD and volume of shale between 0.3 and 0.8. Structurally, 35 major and minor faults were mapped with 15 used for modeling. Prevailing fault orientation is northeast/southwest, dipping south-easterly and trending northwest-southeast direction. Bedforms are complex with gradual lateral changes in lithofacies. Sharp boundaries in horizontal direction define different depositional facies with a flexible non-partitioned model adopted. The lithofacies model result showed continuous lithological units with inconsistencies of stratigraphic and structural truncations which were also replicated on the rock properties model with clear heterogeneity seen in the observed values. Horizon cubes produced in regions of interest defined relationships that are clearly correlative with rock properties than with seismic attributes/properties. Majority, some of the properties predicted from multiattribute analysis of seismic data calibrated with computed logs correlated well with the simulated rock property volumes. In conclusion, successful prediction has been done for rock properties at inter-well points and locations beyond well control. The heavy hydrocarbon in reservoir units of the field can be recovered by steam injection method (SAGD). The methodology and interpretation approach adopted in this work can be implemented initially with very few wells for multiattribute volume prediction, seismic inversion and on a larger scale with more wells for geostatistical simulations and modeling

Sequence stratigraphy study within a chronostratigraphic framework of ‘Ningning field’, Niger Delta

Sequence stratigraphy model developed for the Ningning field is based on the interpretation carried out on the different wells that penetrated the various subsurface lithologies. Basically three depositional sequences were delineated from the five wells studied. The Vail model used made out a third and forth order stratigraphic surfaces that all fall within the central swamp depobelt of the Basin. The five wells used show the presentation of the interpretation and the models. All the sequence tracts were appropriately represented starting from the Lowstand Transgressive and Highstand system tracts, except in well 005 where the Lowstand of the second sequence was missing. This is achieved by incorporating signature motifs from wireline logs coupled with biostratigraphy data and inferred paleobathymetry. This has revealed the field-wide reconstruction of a chronostratigraphically constrained biostratigraphy of subsurface lithological sequences with limited informatio

Seismic Stratigraphic Analysis Fordepositional Environment and Hydrocarbon Occurrence Appraisal using Attributes

Seismic stratigraphical interpretation of rock deposits has been done using migrated 3D seismic data in SEGY format. This has taken into consideration the analysis of both seismic sequences and seismic facies within the hydrocarbon reservoir of the Dongian oil block, North-east China. Methods adopted include that which identifies contacts of the upper and lower boundaries of the depositional sequences that were not absolutely correlatable. The style of the reflection patterns is discovered to be borne out of the very chaotic and dipping basement rocks. This is responsible for the arrangements of the overlying sequences which were continuous or truncated either on the basement or by the gently dipping listric fault amidst the middle portion of the sequences. In all two unconformities were observed. It was discovered that sequence 1 is the prolific reservoir and the overlying sequence 2 characterized by the sub-parallel to sigmoidal internal reflection pattern is a combination of reservoir and the seal that impedes hydrocarbon migration and makes the trapping system effectiv

Role of the African Council for Distance Education in Fostering Quality Assurance in Open and Distance Learning in Africa

The African Council for Distance Education (ACDE) was established to promote research, policy and quality in open and distance learning (ODL), so as to increase access to education and training in Africa. This paper discusses the role of the council in fostering establishment of a quality assurance and accreditation agency (QAAA) aimed at addressing concerns for quality in ODL on the continent, so that the society can have confidence in it. The paper discusses the context within which establishment of the council and development of the QAAA were necessitated as well as the policy framework within which the QAAA is being developed. The challenges being experienced in implementing the project are examined and recommendations towards their resolution, and ensuring the success and sustainability of the agency, are made.Keywords: Quality assurance; Open and distance learning; Accreditation; ACD

2- D Electrical Imaging And Its Application In Groundwater Exploration In Part Of Kubanni River Basin-Zaria, Nigeria

A modern field system, Terrameter (Signal Averaging System) SAS 4000/1000, was used to accomplish the task of exploring groundwater in Kubanni River Basin. 23 image lines were measured at different strategic locations of the study area based on the fractured map of the area and previous information obtained from the area. Four straight line profiles with a spread of 200 m per section were traversed during the course of this survey with three of them generally trending along a North-South direction while the fourth, trends approximately along the East- West direction. The four profiles have a total coverage distance of about 4.2 km. The data used for this survey was acquired by measuring a series of constant traverse along the same line but with the electrode spacing being increased with each successive traverse. Since increasing separation leads to greater depth penetration, the measured apparent resistivities was used to construct a vertical contoured section displaying the variation of resistivity both laterally and vertically over the section. Interpretation of the data acquired using this equipment revealed the suitability of the Southern part of the study area for location of boreholes, as the resistivity values of rock obtained around this zone reflects aquiferous materials. More layers of rock units around Area BZ and Tudun Sarki were revealed than what was reported by previous workers. Also observed were slight variation in depth to bed rock around area BZ and the Nigerian College of Aviation Technology as compared with observations made by previous workers. However, the observation of the increasing undulating bedrock geometry with depth towards the southern part of the study area was consistent with that of the previous workers

RESERVOIR CHARACTERISATION AND STRUCTURAL INTERPRETATION FOR PROSPECT EVALUATION- A CASE STUDY

This paper presents a case study dealing with reservoir delineation and characterisation of the Basecopia field, part of Niger Delta Nigeria. The data set utilized for this work incorporate 3D seismic data, well log suites containing gamma rays, resistivity and porosity logs (neutron and density). These logs were utilized to focus petro-physical properties in three (3) wells. 780 inlines and 496 crosslines of seismic information covering an area of about 234 km2 were utilized. Faults were picked and correlated. Horizons of hydrocarbon bearing sands were picked in view of the re-suit from seismic- to-well tie. These were utilized to produce time and depth maps for a horizon keeping in mind the end goal to recognize the different basic highlights inside the field. Petro-physical aftereffects of the study demonstrate the dominating liquid found in the three wells is light oil at True Vertical Depth Sub Surface (TVDSS) of -7109 to -7333 ft. in Well A, -6916 to -7044 ft. in Well B and -7694 to -7858 ft. in Well C. Thereafter, seismic attributes such as the instantaneous frequency and the dominant frequency indicated the presence of channel filled sand containing hydrocarbon in regions around the wells. Hence, the wells can be said to be properly situated within the reservoir hydrocarbon bearing sand with spatial facies evenly distributed. The study however concluded that Well A bears a considerable amount of reserves of about 209.52Mbbl

Evaluation of Shale Effect on Saturation Exponent from Well Logs in an Offshore Field, Niger Delta.

Hydrocarbon recovery is subject to various elements set to validate not only the availability of the type of fluid present at the subsurface, but also how saturated is the host rock with the fluid. A study on saturation was carried out on the hydrocarbon locked in reservoirs of the N-1 and D-1 wells. The water saturations were determined using various saturation equations by various authors from literatures. This evaluation led to the determination of the permeability of the reservoirs through the Timur equation and the values were within the range 222.8mD-2518.5mD in well N-1 and 434.4mD-2534.3mD in well D-1. The 7 pay zones of both wells showed a high correlation based on the petrophysical parameters which could be the basis of a conclusion of lateral continuity across the reservoir although the formations interpreted are characterized by clay fingering. An analysis carried out for the determination of the permissible range of the saturation exponent ‘n’ used and assumed as 2 which agrees with that in the basic Archie equation, but for the BOD-1b zone of D-1 with both values 1 and 2 perfectly matching

Reservoir characterization and modeling of lateral heterogeneity using multivariate analysis

Reservoir characterization deals with the description of the reservoir in detail for rock and fluid properties within a zone of interest. The scope of this study is to model lateral continuity of lithofacies and characterize reservoir rock properties using geostatistical approach on multiple data sets obtained from a structural depression in the bight of Bohai basin, China. Analytical methods used include basic log analysis with normalization. Alternating deflections observed on spontaneous potential (SP) log and resistivity log served as the basis for delineating reservoir sand units and later tied to seismic data. Computation of variogram was done on the generated petrophysical logs prior to adopting suitable simulation algorithms for the data types. Sequential indicator simulation (SIS) was used for facies modeling while sequential gaussian simulation (SGS) was adopted for the continuous logs. The geomodel built with faults and stratigraphical attitude gave unique result for the depositional environment studied. Heterogeneity was observed within the zone both in the faulted and unfaulted area. Reservoir rock properties observed follows the interfingering pattern of rock units and is either truncated by structural discontinuities or naturally pinches out. Petrophysical property models successfully accounted for lithofacies distribution. Porosity volume computed against SP volume resulted in Net to gross volume while Impedance volume results gave credibility to the earlier defined locations of lithofacies (sand and shale) characterized by porosity and permeability. Use of multiple variables in modeling lithofacies and characterizing reservoir units for rock properties has been revisited with success using hydrocarbon exploration data. An integrated approach to subsurface lithological units and hydrocarbon potential assessment has been given priority using stochastic means of laterally populating rock column with properties. This method finds application in production assessment and predicting rock properties with scale disparity during hydrocarbon exploration

Tailoring consent to context: designing an appropriate consent process for a biomedical study in a low income setting

Background Currently there is increasing recognition of the need for research in developing countries where disease burden is high. Understanding the role of local factors is important for undertaking ethical research in developing countries. We explored factors relating to information and communication during the process of informed consent, and the approach that should be followed for gaining consent. The study was conducted prior to a family-based genetic study among people with podoconiosis (non-filarial elephantiasis) in southern Ethiopia. Methodology/Principal Findings We adapted a method of rapid assessment validated in The Gambia. The methodology was entirely qualitative, involving focus-group discussions and in-depth interviews. Discussions were conducted with podoconiosis patients and non-patients in the community, fieldworkers, researchers, staff of the local non-governmental organisation (NGO) working on prevention and treatment of podoconiosis, and community leaders. We found that the extent of use of everyday language, the degree to which expectations of potential participants were addressed, and the techniques of presentation of information had considerable impact on comprehension of information provided about research. Approaching podoconiosis patients via locally trusted individuals and preceding individual consent with community sensitization were considered the optimal means of communication. Prevailing poverty among podoconiosis patients, the absence of alternative treatment facilities, and participants' trust in the local NGO were identified as potential barriers for obtaining genuine informed consent. Conclusions Researchers should evaluate the effectiveness of consent processes in providing appropriate information in a comprehensible manner and in supporting voluntary decision-making on a study-by-study basis