scholarly journals Geophysical evaluation of geohydrokinetic properties of aquifer units in parts of Enugu state, Nigeria

2021 ◽  
Author(s):  
Johnson Cletus Ibuot ◽  
Emmanuel Tochukwu Omeje ◽  
Daniel Nnemeka Obiora
Keyword(s):  
Mean Value ◽  
Northwestern Part ◽  
Flow Zone ◽  
Southwestern Part ◽  
Contour Maps ◽  
Flow Units ◽  
Electrical Sounding ◽  
Enugu State ◽  
Hydraulic Flow Units ◽  
Very High

Abstract Vertical electrical sounding employing schlumberger electrode configuration was carried out in thirty locations across some parts of Enugu state, to investigate the hydrokinetic properties of hydrogeologic units of the study area. The result shows that resistivity and thickness of aquifer ranges from 27.3 to 59,569.0 Ωm and 23.3 to 242.1 m respectively. Permeability and fractional porosity values range from 4,531.254 to 74,006.76 mD and 0.026 to 0.159. AQI having a mean value of 13.5451 μm range from 6.809 to 52.976 μm. FZI and HFU values range from 37.582 to 1,962.074 μm and 18 to 26 respectively. Contour maps were generated from the results to visualize the variations of the hydrokinetic properties across the study area. From the contour maps, southern part of the study area was identified to be characterized with high AQI, FZI and HFU with northwestern part and a small proportion along the southwestern part identified as areas with low AQI, FZI and HFU. HFU along the study area was observed to be fractionated into nine distinct properties (HFU 18, HFU 19, HFU 20, HFU 21, HFU 22, HFU 23, HFU 24, HFU 25, and HFU 26) with HFU 19 and HFU 20 dominating the area. The results from the nine hydraulic flow units based on flow zone indicator cut off values (Log FZI>0.25) shows that the reservoir quality is very high.

scholarly journals Investigation of Hydrokinetic Properties of Hydrogeologic Units of Sandy Lithofacies: A Case Study of Parts of Enugu State, Southeastern Nigeria

2020 ◽  
Author(s):  
Johnson Cletus Ibuot ◽  
Emmanuel T. Omeje ◽  
Daniel Nnemeka Obiora
Keyword(s):  
Mean Value ◽  
Northwestern Part ◽  
Southeastern Nigeria ◽  
Contour Maps ◽  
Flow Units ◽  
Electrical Sounding ◽  
Enugu State ◽  
Hydraulic Flow Units ◽  
Very High

Abstract Vertical electrical sounding employing schlumberger electrode configuration was carried out in thirty locations across some parts of Enugu state, to investigate the hydrokinetic properties of hydrogeologic units of the study area. The result shows that resistivity and thickness of aquifer ranges from 27.3 to 59569.0 Ωm and 23.3 to 242.1 m respectively. Permeability and fractional porosity values range from 4531.254 to 74006.76 mD and 0.026 to 0.159. AQI having a mean value of 13.5451 µm range from 6.809 to 52.976 µm. FZI and HFU values range from 37.582 to 1962.074 µm and 18 to 26 respectively. Contour maps were generated from the results to visualize the variations of the hydrokinetic properties across the study area. From the contour maps, southern part of the study area was identified to be characterized with high AQI, FZI and HFU with northwestern part and a small proportion along the southwestern part identified as areas with low AQI, FZI and HFU. HFU along the study area was observed to be fractionated into nine distinct properties (HFU 18, HFU 19, HFU 20, HFU 21, HFU 22, HFU 23, HFU 24, HFU 25, and HFU 26) with HFU 19 and HFU 20 dominating the area. The results from the nine hydraulic flow units based on flow zone indicator cut off values (Log FZI ˃ 0.25) shows that the reservoir quality is very high.

scholarly journals Predicting the flow zone indicator of carbonate reservoirs using NMR echo transforms, and routine open-hole log measurements: Insights from a field case study spanning extreme micro-structure properties

2021 ◽  
Author(s):  
Mabkhout Al-Dousari ◽  
◽  
Salah Almudhhi ◽  
Ali A. Garrouch ◽  
◽  
...  
Keyword(s):  
Relative Error ◽  
Carbonate Reservoir ◽  
Micro Structure ◽  
Flow Zone ◽  
Hydraulic Flow ◽  
Absolute Relative Error ◽  
Flow Units ◽  
Average Absolute Relative Error ◽  
Open Hole ◽  
Hydraulic Flow Units

Predicting the flow zone indicator is essential for identifying the hydraulic flow units of hydrocarbon reservoirs. Delineation of hydraulic flow units is crucial for mapping petrophysical and rock mechanical properties. Precise prediction of the flow zone indicator (FZI) of carbonate rocks using well log measurements in un-cored intervals is still a daunting challenge for petrophysicists. This study presents a data mining methodology for predicting the rock FZI using NMR echo transforms, and conventional open-hole log measurements. The methodology is applied on a carbonate reservoir with extreme microstructure properties, from an oil “M” field characterized by a relatively high-permeability with a median of approximately 167 mD, and a maximum of 3480 mD. The reservoir from the M field features detritic, or vuggy structure, covering a wide range of rock fabrics varying from microcrystalline mudstones to coarse-grained grainstones. Porosity has a median of approximately 22%. Dimensional analysis and regression analysis are applied for the derivation of four transforms that appear to capture approximately 80% of the FZI variance. These four transforms are formulated using the geometric mean of the transverse NMR relaxation time (T2lm), the ratio of the free fluid index (FFI) to the bulk volume irreducible (BVI), the bulk density, the sonic compressional travel time, the true resistivity, the photo-electric absorption, and the effective porosity. Non-linear regression models have been developed for predicting the FZI using the derived transforms, for the carbonate reservoir from the M field. The average relative error for the estimated FZI values is approximately 52%. The same transforms are used as input for training a developed general regression neural network (GRNN), built for the purpose of predicting rock FZI. The constructed GRNN predicts FZI with a notable precision. The average absolute relative error on FZI for the training set is approximately 3.1%. The average absolute relative error on FZI for the blind testing set is approximately 22.0 %. The data mining approach presented in this study appears to suggest that (i) the relationship between the flow zone indicator and open-hole log attributes is highly non-linear, (ii) the FZI is highly affected by parameters that reflect rock texture, rock micro-structure geometry, and diagenetic alterations, and (iii) the derived transforms provide a means for further enhancement of the flow zone indicator prediction in carbonate reservoirs.

scholarly journals Halogenated Volatile Organic Compounds in Water Samples and Inorganic Elements Levels in Ores for Characterizing a High Anthropogenic Polluted Area in the Northern Latium Region (Italy)

2021 ◽  
Vol 18 (4) ◽  
pp. 1628
Author(s):  
Mario Vincenzo Russo ◽  
Ivan Notardonato ◽  
Alberto Rosada ◽  
Giuseppe Ianiri ◽  
Pasquale Avino
Keyword(s):  
Organic Compounds ◽  
Mean Value ◽  
Greenhouse Crops ◽  
River Waters ◽  
Liquid Liquid Extraction ◽  
Volatile Organic ◽  
High Concentrations ◽  
Very High ◽  
Inorganic Fraction

This paper shows a characterization of the organic and inorganic fraction of river waters (Tiber and Marta) and ores/soil samples collected in the Northern Latium region of Italy for evaluating the anthropogenic/natural source contribution to the environmental pollution of this area. For organic compounds, organochloride volatile compounds in Tiber and Marta rivers were analyzed by two different clean-up methods (i.e., liquid–liquid extraction and static headspace) followed by gas chromatography–electron capture detector (GC-ECD) analysis. The results show very high concentrations of bromoform (up to 1.82 and 3.2 µg L−1 in Tiber and Marta rivers, respectively), due to the presence of greenhouse crops, and of chloroform and tetrachloroethene, due to the presence of handicrafts installations. For the qualitative and quantitative assessment of the inorganic fraction, it is highlighted the use of a nuclear analytical method, instrumental neutron activation analysis, which allows having more information as possible from the sample without performing any chemical-physical pretreatment. The results have evidenced high levels of mercury (mean value 88.6 µg g−1), antimony (77.7 µg g−1), strontium (12,039 µg g−1) and zinc (103 µg g−1), whereas rare earth elements show levels similar to the literature data. Particular consideration is drawn for arsenic (414 µg g−1): the levels found in this paper (ranging between 1 and 5100 µg g−1) explain the high content of such element (as arsenates) in the aquifer, a big issue in this area.

Sedimentology and Sequence Stratigraphy of Automated Hydraulic Flow Units – the Permian Upper Dalan Formation, Persian Gulf

2021 ◽  
Author(s):  
Umid Kakemem ◽  
Mohammadfarid Ghasemi ◽  
Arman Jafarian ◽  
Ayoub Mahmoudi ◽  
Kresten Anderskouv
Keyword(s):  
Sequence Stratigraphy ◽  
Persian Gulf ◽  
Hydraulic Flow ◽  
Flow Units ◽  
Hydraulic Flow Units

scholarly journals Analysis of the coefficient of variation in shear and tensile bond strength tests

2005 ◽  
Vol 13 (3) ◽  
pp. 243-246 ◽  
Author(s):  
Fábio Lourenço Romano ◽  
Gláucia Maria Bovi Ambrosano ◽  
Maria Beatriz Borges de Araújo Magnani ◽  
Darcy Flávio Nouer
Keyword(s):  
Coefficient Of Variation ◽  
Mean Value ◽  
Scientific Article ◽  
A Value ◽  
Statistical Analysis System ◽  
Strength Tests ◽  
Analysis System ◽  
Very High

The coefficient of variation is a dispersion measurement that does not depend on the unit scales, thus allowing the comparison of experimental results involving different variables. Its calculation is crucial for the adhesive experiments performed in laboratories because both precision and reliability can be verified. The aim of this study was to evaluate and to suggest a classification of the coefficient variation (CV) for in vitro experiments on shear and tensile strengths. The experiments were performed in laboratory by fifty international and national studies on adhesion materials. Statistical data allowing the estimation of the coefficient of variation was gathered from each scientific article since none of them had such a measurement previously calculated. Excel worksheet was used for organizing the data while the sample normality was tested by using Shapiro Wilk tests (alpha = 0.05) and the Statistical Analysis System software (SAS). A mean value of 6.11 (SD = 1.83) for the coefficient of variation was found by the data analysis and the data had a normal distribution (p>0.05). A range classification was proposed for the coefficient of variation from such data, that is, it should be considered low for a value lesser than 2.44; intermediate for a value between 2.44 and 7.94, high for a value between 7.94 and 9.78, and finally, very high for a value greater than 9.78. Such classification can be used as a guide for experiments on adhesion materials, thus making the planning easier as well as revealing precision and validity concerning the data.

scholarly journals New Reservoir Grading Method for Tight Gas Reservoir – One Case Study in Kekeya Block, Tuha Basin, China

2015 ◽  
Vol 8 (1) ◽  
pp. 167-171
Author(s):  
Fangfang Wu ◽  
Jinchuan Zhang ◽  
Liuzhong Li ◽  
Jinlong Wu
Keyword(s):  
Flow Unit ◽  
Reservoir Evaluation ◽  
Flow Units ◽  
Core Dataset ◽  
Tight Gas Reservoir ◽  
Set Up ◽  
Productivity Prediction ◽  
Hydraulic Flow Units ◽  
New Reservoir

Tight sand reservoir is usually characterized by high heterogeneity and complex pore structure, which makes the permeability calculation a big challenge and leads to difficulties in reservoir classification and productivity evaluation. First, five different Hydraulic Flow Units and respective Porosity-permeability relations were built based on core dataset from Kekeya block, Tuha Basin; and then with BP Neutron Network method, flow unit was classified for un-cored intervals using normalized logging data, and permeability was calculated accordingly. This improved the accuracy of permeability calculation and helped a lot on un-cored reservoir evaluation. In addition, based on porosity, permeability and flow unit type, a new reservoir grading chart was set up by incorporating the testing or production data, which provides important guidance for productivity prediction and reservoir development.

scholarly journals GEOELECTRIC STUDY OF GROUNDWATER REPOSITORY IN PARTS OF AKWA IBOM STATE, SOUTHERN NIGERIA

2020 ◽  
Vol 4 (2) ◽  
pp. 99-102
Author(s):  
Johnson C. Ibuot ◽  
Moses M. M. Ekpa ◽  
Doris O. Okoroh ◽  
Aniefiok S. Akpan Emmanuel T. Omeje
Keyword(s):  
Hydraulic Conductivity ◽  
Groundwater Potential ◽  
Vertical Electrical Sounding ◽  
Protective Capacity ◽  
Longitudinal Conductance ◽  
Contour Maps ◽  
Transverse Resistance ◽  
Southern Nigeria ◽  
Electrical Sounding ◽  
Dar Zarrouk Parameters

Geoelectric survey employing Vertical Electrical Sounding (VES) was carried out in order to assess the groundwater repositories. A total of seven soundings were obtained with their layer resistivity, thickness and depth within the maximum electrode separation. The geoelectric parameters obtained were used to estimate the Dar-Zarrouk parameters (longitudinal conductance and transverse resistance), hydraulic conductivity and transmissivity. The result shows the aquifer resistivity ranging from 77.14 to 784.76 Ωm, with thickness ranging from 28.78 to 80.04 m. The longitudinal conductance have values ranging from 0.071 to 0.825 Ω-1 while the values of hydraulic conductivity and transmissivity range from 1.087 to 5.881 m/day and 60.180 to 374.031 𝑚2/day respectively. The contour maps generated show the variation of these parameters across the subsurface, and areas with poor protective capacity were delineated. The results also delineate the groundwater potential of the study area as moderate, while the corrosivity rating indicates non-corrosive and slightly corrosive.

Hydrogeophysical investigation for the aquifers in part of Ilorin, Central Nigeria: Implication on groundwater prospect

2021 ◽  
Vol 47 (2) ◽  
pp. 520-534
Author(s):  
Ayodele Kehinde Olawuyi
Keyword(s):  
Groundwater Resources ◽  
Groundwater Potential ◽  
Mean Value ◽  
Groundwater Prospect ◽  
Basement Complex ◽  
Type Curves ◽  
Lateritic Clay ◽  
Overburden Thickness ◽  
Weathered Layer ◽  
Electrical Sounding

Hydrogeophysical study involving the use of Vertical Electrical Sounding (VES) was carried out in part of the basement complex rocks of Ilorin, central Nigeria, with the aim of determining its geoelectric parameters and groundwater potential. A total of thirty (30) VES were carried out using Schlumberger electrode configuration, with half electrode separation (AB/2) varying from 1m to 100m. Information on the subsurface lithologies, overburden thickness and aquiferous layers were obtained from the different VES locations in the study area. From the quantitative interpretations of the data collected, using the method of curve matching with the Orellana-Mooney master curves and 1-D forward modeling with WinResist 1.0 version software, three to five lithologic units were identified in the study. These include: the topsoil, sandy/lateritic clay/laterite, the weathered basement, the fractured basement and the fresh bedrock which are predominantly of the ‘KH’ curve type (30%), followed by ‘H’ type (26.7%), other type curves include ‘QH’ (16.7%), ‘HKH’, ‘HA’ and ‘A’ (6.7% each) and KQ and KQH (3.3% each). The weathered layer and the fractured basement constitute the main aquifer units. The aquifers are of generally low resistivity values (mostly below 100 Ω-m). The depths to dry bedrock at the chosen VES locations vary from 2.7 to 62.7 m with a mean value of 13.02 m in the study area. The geoelectrical interpretations of data obtained in these areas have permitted the delineation of the study area into low and moderate groundwater potential zones. This study is expected to assist in future planning for groundwater resources. Keywords: Hydrogeophysical, Basement Complex, Groundwater, Electrical Soundings, Weathered, Fractured

Sign in / Sign up

Export Citation Format

Share Document