High Effective Porosity Research Articles

Facies-Controlled Geostatistical Porosity Model for Estimation of the Groundwater Potential Area in Hongliu Coalmine, Ordos Basin, China.

Accurate and reliable evaluations of potential groundwater areas are of significance in the hydrogeological assessments of coalfields because water inrush disasters may be caused by unclear groundwater potential. A three-dimensional geological model of porosity based on deterministic modeling and a facies-controlled method are used to determine the groundwater potential of the coal measure aquifer. The modeling processes are as follows: based on the interlayer and discontinuity (faults) data extracted from boreholes and geological maps, an integrated sequence framework model is developed. Using the results of sedimentary microfacies identification and the method of deterministic modeling, a sedimentary microfacies model is successfully established. Finally, based on facies-controlled and sequential Gaussian methods, an effective porosity model is established that can predict the groundwater potential. The predicted results show that sandstones sedimented in channel, point bar, and batture environments possess high effective porosity and strong groundwater potential; however, the sandstones sedimented in interdistributary bays, flood plains, and sand sheets possess low effective porosity. Model validation was performed based on the hydrological pumping test data collected from observation boreholes, drainage water inflow data from dewatered boreholes in the tunnel around workface, and the mine water inflow in tunnels and the workfaces. The validation analysis results show that the effective porosity and sedimentary facies were correlated with the actual flux. The predicted results are consistent with the actual flux data, validating the predicted model.

Effect of hexagonal structure nanoparticles on the morphological performance of the ceramic scaffold using analytical oscillation response

Porous bony scaffolds are utilized to manage the growth and migration of cells from adjacent tissues to a defective position. In the current investigation, the effect of titanium oxide (TiO2) nanoparticles on mechanical and physical properties of porous bony implants made of polymeric polycaprolactone (PCL) is studied. The bio-nanocomposite scaffolds are prepared with composition of nanocrystalline hydroxyapatite (HA) and TiO2 powder using the freeze-drying technique for different weight fractions of TiO2 (0 wt%, 5 wt%, 10 wt%, and 15 wt%). In order to identify the microstructure and morphology of the fabricated porous bio-nanocomposites, the X-ray diffraction (XRD), atomic force microscope (AFM) and scanning electron microscopy (SEM) are employed. Also, the biocompatibility and biodegradability of the manufactured scaffolds are examined by placing them in a simulated body fluid (SBF) for 21 days, their weight and pH changes are measured. The rate of degradation of the PCL-HA scaffold can be controlled by varying the percentage of its constituent components. Due to an increasing growth and activity of bone cells and the apatite formation on the free surface of the fabricated bio-nanocomposite implants as well as their reasonable mechanical properties, they have the potential to be used as a bone substitute. Additionally, with the aid of the experimentally extracted mechanical properties of the scaffolds, the vibrational characteristics of a beam-type implant made of the proposed porous bio-nanocomposites are explored. The results obtained from SEM image indicate that the scaffolds produced by the employed method have high total porosity (70%–85%) and effective porosity. The pore size is obtained between 60 and 200 μm, which is desirable for the growth and propagation of bone cells. Also, it is revealed that the addition of TiO2 nanoparticles leads to reduce the rate of dissolution of the fabricated bio-nanocomposite scaffolds.

Geophysical appraisal for the sandy levels within Abu Roash C and E members in Abu Gharadig Field, Western Desert, Egypt

The present work concerns with the geophysical assessment for the sandstones of Abu Roash C and E members for being potential hydrocarbon reservoirs at Abu Gharadig Field, Western Desert, Egypt. The analysis of seismic data covers Abu Gharadig Field showing ENE–WSW anticline fragmented by NW–SE normal faults. The presence of these structures is due to the dextral wrench corridor that extensively deformed the north area of the Western Desert within Late Cretaceous episode. The examination of well-log data of Abu Gharadig-6 Well revealed that the favourable zone locates between depths 9665–9700 ft (zone I) within Abu Roash “C” Member. The second promising zone in Abu Gharadig-15 Well occurs between depths 9962–9973 ft (zone II) in Abu Roash “E” Member. The quantitative evaluation indicated that zone I has better reservoir quality than zone II since it is characterised by low shale volume (0.01), high effective porosity (0.22), low water saturation (0.14), low bulk volume of water (0.03), higher values of absolute permeability (113 mD), high relative permeability to oil and low water cut, whereas zone II has 0.13 shale volume, 0.16 effective porosity, 0.39 water saturation, 0.06 bulk volume of water, lower values of absolute permeability (27 mD), low relative permeability to oil and relatively high water cut. The obtained results recommended that the drilling efforts should be focused on the sandy levels within Abu Roash C Member (1st priority) and the sand levels within Abu Roash E Member (2nd priority) in Abu Gharadig Basin and its surroundings.

Petrophysical evaluation of lower Cenomanian Bahariya reservoir, Salam oil field, Shushan basin, north Western Desert, Egypt.

Petrophysical evaluation of the lower Bahariya sediments was performed based on comprehensive interpretation of complete wireline logs suite from two wells in Salam oil field, southwest Shushan basin in the north Western Desert, Egypt. Several petrophysical parameters such as shale volume (VSH), total and effective porosities (PHIT, PHIE), water saturation (SW) and hydrocarbon saturation (SH) were deduced and utilized in the petrophysical subdivision of the lower Bahariya sediments. Neutron versus density, matrix volumetric versus matrix grain density and M-N crossplots revealed that quartzose sandstone is the dominant matrix component within the lower Bahariya sediments. Additionally, the litho-saturation crossplots typified the presence of oil-bearing intervals often associated with the quartzose sandstones with minimal contents of silts and clays. Dispersed and laminated clays are detrimental to the reservoir quality by obstructing the pore spaces and thus reducing the hydrocarbon flow storage and flow capacities. The obtained petrophysical results reveal that the lower Bahariya sediments have a good reservoir quality with high effective porosity values exceeding 18% and low water saturation values ~ 35%. The upper part of the lower Bahariya sediments hosts the most promising reservoir intervals which should be considered during future exploration and development of the oil fields in the study area. Petrophysical evaluation of the lower Bahariya sediments was performed based on comprehensive interpretation of complete wireline logs suite from two wells in Salam oil field, southwest Shushan basin in the north Western Desert, Egypt. Several petrophysical parameters such as shale volume (VSH), total and effective porosities (PHIT, PHIE), water saturation (SW) and hydrocarbon saturation (SH) were deduced and utilized in the petrophysical subdivision of the lower Bahariya sediments. Neutron versus density, matrix volumetric versus matrix grain density and M-N crossplots revealed that quartzose sandstone is the dominant matrix component within the lower Bahariya sediments. Additionally, the litho-saturation crossplots typified the presence of oil-bearing intervals often associated with the quartzose sandstones with minimal contents of silts and clays. Dispersed and laminated clays are detrimental to the reservoir quality by obstructing the pore spaces and thus reducing the hydrocarbon flow storage and flow capacities. The obtained petrophysical results reveal that the lower Bahariya sediments have a good reservoir quality with high effective porosity values exceeding 18% and low water saturation values ~ 35%. The upper part of the lower Bahariya sediments hosts the most promising reservoir intervals which should be considered during future exploration and development of the oil fields in the study area.

Geological model Construction for Yamama Formation at Faihaa Oil Field- South of Iraq

A construction of a 3D geological model of Yamama Formation to explain the distribution of petrophysical properties (shale volume, effective porosity and hydrocarbon saturation) by using Petrel software. Five wells were selected in order to build structural and petrophysical models based on interpretation of well logs and petrophysical properties. Yamama reservoir is divided into four main units (YA, YB, YC, and YD), YA is divided into five secondary reservoir units (YA1, YA2, YA3, YA4, and YA5), YB is divided into two secondary reservoir units (YB1 and YB2), YC is divided into two secondary reservoir units (YC1 and YC2) and YD is divided into three secondary reservoir units (YD1, YD2, and YD3). Structural model showed Faihaa oil field represented by anticlinal fold with double plunging. Petrophysical models (shale volume, effective porosity and hydrocarbon saturation) constructed for each subunit of Yamama reservoir using sequential Gaussian simulation executed with Petrel software. According to data analyzes and the results from modeling, the subunits for both YB and YB are good reservoir units regarding its good petrophysical properties (high effective porosity and high hydrocarbon saturation) and considered as the most important productive units in Yamama Formation

Hartha Formation divisions Based on Well Logs Analysis in Majnoon Oil Field, Southern Iraq

This study aims to evaluate reservoir characteristics of Hartha Formation in Majnoon oil field based on well logs data for three wells (Mj-1, Mj-3 and Mj-11). Log interpretation was carried out by using a full set of logs to calculate main petrophysical properties such as effective porosity and water saturation, as well as to find the volume of shale. The evaluation of the formation included computer processes interpretation (CPI) using Interactive Petrophysics (IP) software. Based on the results of CPI, Hartha Formation is divided into five reservoir units (A1, A2, A3, B1, B2), deposited in a ramp setting. Facies associations is added to well logs interpretation of Hartha Formation, and was inferred by a microfacies analysis of thin sections from core and cutting samples. The CPI shows that the A2 is the main oil- bearing unit, which is characterized by good reservoir properties, as indicated by high effective porosity, low water saturation, and low shale volume. Less important units include A1 and A3, because they have low petrophysical properties compared to the unit A2.

Depositional environment of E Oligocene sedimentary and prediction of sand distribution in Southeast area, Cuu Long basin

According to petrophysical and geophysical data, the depositional facies of E Oligocene are determined. Furthermore, the correlation lines between wells and the seismic line also created for confirming Oligocene E distribution in Cuu Long basin. Using appropriate methods such as petrophysical curves, geophysical characteristics, interpretation of gross depositional environment as well as mapping of seismic attributes for sub-sequence Oligocene E upper and E lower in Southeast area, results of prediction the sand distribution in Oligocene E upper and E lower sub-sequence, factors effect to porosity-permeability preservation of E sand reservoirs in Southeast area, Cuu Long basin and oil-gas industry flow-producing possibility in varied sedimentary facies were reported in this paper. The E Oligocene sedimentary distributes in a large area with hydrocarbon accumulations along the Southeast margin Cuu Long basin in relation with the existence of half-grabens along Con Son swell, in which formation rocks consist of varying grain size, mainly sandstone interbeds by siltstone and shale stone. A bitum shale layer of 20÷70 m thickness exits to play the role of a shield to maintain a much higher effective porosity of the reservoir section than usual (up to 18%). In the area, there are two sandstone reservoirs of excellent quality at 2,600÷2,700 mMD and 3,000÷3,400 mMD depths. In order to determine the oil and gas potential of the target, petroleum systems in exploration activities must carefully be evaluated, especially looking for stratigraphic traps, and the reservoir modeling should be modified accurately.

Potential formation mechanisms of early diagenetic displacive veins in the Permian Boda Claystone Formation

The Boda Claystone Formation is the most promising host rock for the disposal of high-level radioactive waste in Hungary. The formation has several properties obstructing the migration of radionuclides; however, structural heterogeneities may nonetheless act as migration pathways. Therefore, understanding the tectonic evolution of the formation is vital. Previous research has identified four different vein generations in the BAF–2 well. This study deals with the generation of veins that contain characteristic microstructures, such as curved wall rock inclusions in bands, trails and cone-in-cone arrangements. Based on optical, cathodoluminescence and electron microscopy, together with X-ray fluorescence and Raman microspectroscopy, these veins appear to have potentially formed during early diagenetic processes. Vein development was continuous and occurred along horizontal surfaces. The abovementioned structural elements were formed by growing crystals; however, primary crystal morphologies were presumably replaced during diagenetic and hydrothermal processes. A theoretical model is described, which could be responsible for the horizontal and continuous vein opening and simultaneous crystallisation in sediments with high (but easily degraded) effective porosity. According to this model, compaction, pressure solution, elevated pore fluid pressures, seepage forces and the force of crystallisation can all play important roles in the formation of these types of veins.

Reservoir Characterization with Acoustic Impedance Inversion and Multi attribute Method on “Essen” Field, Talang Akar Formation, Sub-Ciputat Basin, North West Java

Acoustic impedance and multi-attribute seismic inversion seismic are a number of seismic methods that can be used to map sandstone reservoir distribution. Using this method, we can separate the sandstone and shale in the Talang Akar Formation found on the “Essen” Field, Ciputat Sub-Basin. Both of these methods will be compared with each other in order to get more valid results in sandstone reservoir mapping. The inversion method used in this study is a model-based method. While the multi-attribute method used is the neural network in mapping gamma-ray volume, shale volume, and porosity. The inversion results are not able to image the sandstone distribution good enough because the range is too large and there is overlapping on the acoustic impedance values of sandstones with ranges (8000-12000) (m/s)*(g/cc). The results of the gamma-ray multi-attribute, shale volume and porosity, have been shown to consistently show the distribution of sandstones that have a trend in the distribution of NW-SE reservoir zones. From the results of the analysis there are several potential areas that have the potential to become the next development area, namely the distribution of sandstones in the northern part with high effective porosity, and good seals; In the south with a large volume of sandstones; as well as the distribution formed on the channel surrounding the fault.

Experimental and numerical study on catalyst layer of polymer electrolyte membrane fuel cell prepared with diverse drying methods

High manufacturing cost is a major challenge to commercialization of the polymer electrolyte membrane fuel cell (PEMFC) technology in high volume market. Catalyst layer (CL) of PEMFC should incorporate high effective porosity, electrochemically active surface-area, gas permeability, and favorable ionomer distribution. Drying of the CL is a very significant step of electrode fabrication, and determines most of the properties mentioned above, but is rarely a subject of investigation. From various possible drying processes of CL, freeze-drying shows some beneficial properties, such as higher porosity, better ionomer distribution, and reduces the mass transport resistance significantly by allowing more reactant gas into reactive interface. In this work, the influence of diverse drying techniques on the microstructure and performance is investigated. Complementarily, a transient 2D physical continuum-model is used to investigate the effect of the structural properties on cell performance of electrodes prepared with different drying methods. A sensitivity analysis has been also performed to determine the influence of individual parameters applied in the model. Both of the experimental and simulation results stress on the fact that the freeze-drying technique not only significantly enhances the oxygen transport properties through ionomer but also improves the porosity along with the tortuosity of the CL microstructure.

GEOLOGICAL MODEL OF HARTHA FORMATION IN MAJNOON OILFIELD, SOUTHERN IRAQ

This study aims to construct a 2D geological model for Hartha Formation in Majnoon oil field based on well logs data from eight wells (Mj-1, Mj-3, Mj-10, Mj-11, Mj-15, Mj-16, Mj-20 and Mj-33), core and cutting samples. Petrophysical properties (effective porosity and water saturation) are derived from CPI interpretation of well logs while facies associations are interpreted through the study of microfacies analysis of thin sections for core and cutting samples. By using RockWorks16 software, 2D facies and petrophysical model are built to estimate the vertical and lateral variation of these properties. The 2D facies models display the dominance of outer ramp facies in the lower part of Hartha Formation, whereas mid-ramp, shoal, and inner ramp facies associations occupy the upper part. The shoal facies has a wide and continuous extent, which is characterized by high effective porosity and low water saturation. Therefore, it represents the most important reservoir of Hartha Formation in Majnoon oilfield. Other facies have less reservoir quality due to low porosity and high water saturation. Besides, their occurrence in deeper structural depths. Based on the output of the 2D effective porosity model, the porosity increased upward the succession of Hartha Formation as a result of the transition from outer ramp to shoal or inner ramp facies. Accordingly, the water saturation model shows low values at upper parts of the anticline structure of Majnoon oil field, which indicates high hydrocarbon saturation at the upper parts of Hartha Formation.

3-D static modelling of lateral heterogeneity using geostatistics and artificial neural network in reservoir characterisation of “P” field, Niger Delta

ABSTRACT The anisotropic and heterogeneous nature of the subsurface units at offset wells gets more complex at locations outside well control. However, qualitative and quantitative predictions of reservoir properties and geometries beyond well control are vital to understanding the intrinsic characteristics of subsurface formations. Supervised Multi-layer Perceptron neural network and conditional sequential Gaussian simulation were applied to a suite of well logs data set and three dimensional (3-D) seismic dataset acquired from P-field, Niger Delta to predict lateral continuity of hydrocarbon reservoir properties. Multilayer perceptron neural network was used to model effective porosity (Eϕ) at the root-mean-square error of 0.00531 with an estimated average effective porosity of 0.2952. Furthermore, MLPNN modelling of hydrocarbon saturation (Sh) at root mean square error of 0.02821 yielded an estimated average of 69.73%. The volume of shale (Vsh) was also modelled at the root mean square error of 0.0282, with an estimated Vsh average of 9% for the study area. It was discovered that a comparatively higher net-to-gross (N-T-G), relatively higher effective porosity, high hydrocarbon saturation, very low volume of shale, and high permeability were observed in the areas of interest in the study area. A geostatistical approach was also used to model petrophysical properties. The parametric semivariogram model shows the range of 94–5230 m, nugget effect of 0.062, and sills of 0.075, 0.093, and 0.0121. Realisations were generated and ranked using the SGS algorithm suggest that any one of the realisations can independently represent the real picture of the subsurface geology within the study area. The integration of these different prediction tools and analyses of the outcomes from the research has improved our understanding of delineated reservoirs and improved lateral variation prediction of its properties. These prediction tools served better as a complementary tool to each other rather than as a comparison tool.

Reservoir units of Mishrif Formation in Majnoon Oil field, Southern Iraq

The reservoir units of Mishrif Formation in Majnoon oil field were studied by using available wireline logs (gamma ray, porosity and resistivity) and facies that derived from core and cutting samples for three wells including Mj-1, Mj-15, and Mj-20. The reservoir properties were determined and interpreted by using IP software. The results showed that unit D have the best reservoir properties due to high effective porosity, low water saturation and very low volume of shale. Furthermore, a large part of this unit was deposited in shoal environment. The other reservoir units are then graded in reservoir properties including units B, A, F & E respectively, except unit C, which is considered as a cap unit, because it consists of restricted marine facies so that; it has high volume of shale and water saturation and very low effective porosity.

Radon and its progenies variation in the urban polluted atmosphere of the Mediterranean city of Thessaloniki, Greece.

Radon and Rn progenies' concentrations were determined in the urban polluted atmosphere of Thessaloniki's city center using two experimental procedures: (i) filter with 0.8-μm porosity measured using α-counting technique determining the radon equilibrium equivalent concentration (CEER), which varies from 2.6 to 8.9 Bq m-3, and (ii) filter with 0.3-μm porosity measured in the laboratory using γ-spectrometry determining 214Pb activity concentration 1.3-7.5 Bq m-3 and 214Bi activity 3.1-11.5 Bq m-3. Strong daily correlation with the relative humidity is presented, in association to an inverse correlation with the temperature gradient. Radon and its daughter's concentration correlate well smoke particles' content because radon is trapped inside them due to their high effective porosity, and so the Rn daughter collection in the filter increases. Gas pollutants have similar daily distribution with the radon activity, while SO2 levels are correlated the best with 214Pb and 214Bi concentrations, as Pb is more chemically associated to sulfuric complex ions than nitric formation in presence of vapors. The lower 214Pb/ 214Bi activity ratio appeared during the highest temperature gradient and amount of vapors, smoke, and gases giving rise to high formation of ultrafine aerosol particles. The ultrafine aerosol creation boosts 214Pb recoil effect taken place during 218Po α-decay, so 214Pb nuclei become free starting the clustering process yet again having ingrowth coefficient ~ 0.1 nm2 s-1 regarding accumulation mode aerosols.

Evaluation of Nubia sandstone reservoir as inferred from well logging data interpretation for Rabeh East-25 well, Southwest Gulf of suez, Egypt

The present study interprets well log responses obtained from the Nubia sandstone in the Rabeh East-25 Well, Southwest Gulf of Suez in Egypt. The reservoir characterization of the Nubia sandstone reservoir demonstrates that it has excellent potential for hydrocarbon production. Based on the qualitative interpretation of available well log data, the examined well through the Nubia sandstone succession has been subdivided into four zones. The hydrocarbon-bearing zones include zone II, a shaly reservoir occurs between depths of 5610 and 5631 ft, and zone IV, characterized by a clean sandstone reservoir is located between depths of 5656 and 5685 ft. When both zones are combined, the net pay thickness of the Nubia sandstone reservoir in the studied well reaches 60 ft. The petrophysical parameters of the oil-bearing zones were calculated to determine their reservoir properties, including their fluid saturation, shale volume, porosity, bulk volume of water and permeability values. The shaly sandstones in zone II have low water saturation (17–47%), low shale volume (0–50%), high total porosity (18–23%) and high effective porosity (8–23%) values. However, the clean sandstones in zone IV display lower water saturation (8–38%), high total porosity (17–22%) and high effective porosity (14–22%) values. Both zones exhibit high permeability values (usually above 50 MD), and their values of the Movable Oil Index are lower than 0.7reflecting the movability of the preserved oil. The constructed Buckles plots for the two zones indicate that the points which follow 0.04 and 0.05 BVW hyperbolas in zone II and points track 0.02, 0.03 and 0.035 BVW hyperbolas in zone IV will produce oil without water. The relative permeability to oil is usually less than 1.0, and the relative permeability to water is less than 0.01. Additionally, the water contents accompanying production are relatively low, i.e., they vary between 0 and 20%, thus reflecting the good reservoir quality of both zones.

Petrophysical parameters estimation and reservoir characterisation based on well log data in the Joya Mair Oil Field, Minwal X-01 Well, Potwar Sub-Basin and Upper Indus Basin of Pakistan

The aim of this study is to assess the reservoir potential of the Eocene age Chorgali and Sakesar formations encountered in Minwal X-01 Well Potwar Sub-Basin.The current study is concerned with the reservoir potential evaluation using petrophysical approach of Minwal X-01 located in Potwar basin. Minwal X-01 is selected for research, where the prevailing assessment involves identifying, marking, analysing and interpreting the reservoir zones from well logs and computational analysis through different formulas. Several well logs were used comprising sonic log, gamma ray log, density log, neutron log, and resistivity logs. The petrophysical parameters such as the shale volume (Vsh), total porosity (PHT), effective porosity (PHE), water saturation (Sw), hydrocarbon saturation (Sh), and pay zone were assessed from wireline logs. The best possible reservoirs in the study area are Chorgali and Sakesar formations in Minwal X-01. These reservoirs have good net pay zones thicknesses (20-52 feet). Based on well log data, these reservoirs are classified as excellent reservoirs owing to their high effective porosity and hydrocarbon saturation.

Investigation of Mortars and Plasters of a Byzantine Church in Southwest Anatolia with Emphasis on Possible Pozzolan Use

Characterization of mortars and plasters used in historical structures is crucial before conservation interventions in order to propose proper repair materials and avoid any damage caused by material incompatibility. In the present study, mortars and plasters of a Byzantine Church in the ancient city of Stratonikeia dated back to 5th – 7th centuries were examined in terms of physical/physico-mechanical characteristics and raw materials used by various analytical techniques. Possible use of pozzolanic materials in mortar and plaster samples were investigated by pozzolanic activity tests performed on the aggregates (< 125 µm) and examining the reaction products formed after immersion of these aggregates in a saturated solution of Ca(OH)2. Investigated mortar and plaster samples were found to have relatively low bulk density and high effective porosity. Compressive strength values of mortar samples were found to be in the range of 3.92 – 4.47 MPa. Binder used in the mortar and plaster samples were assessed to be fat lime. Aggregates of the samples smaller than 125 µm were found to have good pozzolanicity. Formation of pozzolanic reaction products by the reaction of the finer aggregates with Ca(OH)2 were confirmed by the results of SEM-EDX and FTIR analyses.DOI: http://dx.doi.org/10.5755/j01.ms.24.3.18590

Geohydrodynamic Parameters and Their Implications on the Coastal Conservation: A Case Study of Abak Local Government Area (LGA), Akwa Ibom State, Southern Nigeria

A total of 14 vertical electrical soundings using Schlumberger electrode configuration and the complementary laboratory analysis of aquifer samples were carried out in the Abak Local Government Area of Akwa Ibom State, the coastal region of Nigeria. The study focused on the estimation of geohydrodynamic parameters of the frequently exploited aquifers and the implication of hydrodynamic parameters on the lithostratigraphy and the anticipated exposure of the assessed geologic formation at the shorelines. These parameters were porosity (ϕ), tortuosity (τ), formation factor (F), aquifer water formation resistivity (Rw) and coefficient of permeability/hydraulic conductivity (K). Computation of the effective porosities from the aquifer cuttings was carried out using wet weight–dry weight technique and petrophysical techniques. The F values were computed using the aquifer formation bulk resistivity measured from field 1-D resistivity data analysis, whose interpretation was constrained by nearby borehole information. The formation pore water resistivities were estimated from the laboratory using electrical resistivity metre. The Win RESIST software program was used in interpreting the field data electronically. The results of interpretation gave the primary parameters of saturated and unsaturated units of the coastal regions used in this work. The area generally shows seemingly high porosity with high coefficient of permeability. The primary and secondary parameters have been contoured to model their distributions. Besides, some functional relations have been realized through regression analyses. The contour distribution of the geohydrodynamic parameters indicates the vulnerability of the water repositories to contaminations as well as the vulnerability of the shoreline to waterborne erosion. The seemingly high effective porosity in the compliant laboratory and calculated values indicate that the coastal region is neither lithified nor compacted/consolidated. This signals the possibility of the formation to be easily eroded, weathered or flooded where these units are exposed to water current. With these revelations, the shorelines could be properly managed and conserved by geotechnically reinforcing with hard and water-resistant concrete that can protect the vulnerable and erosion-prone porous sediments.

Analytical study of impact of the wick’s fractal parameters on the heat transfer capacity of a novel micro-channel loop heat pipe

This paper presents an analytical study of the impact of a wick’s fractal geometrical parameters on the heat transfer capacity of a novel micro-channel loop heat pipe (MCLHP) which is applicable to solar heating system. By treating the wick of the micro-channel evaporator of the MCLHP as a thin porous layer, i.e. a combination of random/tortuous pores and water-containing skeletons, the impact of the fractal geometrical parameters of the wick on the heat transport capacity of the MCLHP was investigated. Based on the classical heat transfer limits and fractal equations, a dedicated computerised analytical model was developed by using the Newton-Raphson method; this model was then applied to analyze a few macro parameters of the wick (i.e., effective thermal conductivity and permeability) and heat transfer limits of the MCLHP, including capillary, viscous, entrainment, sonic and boiling ones. Comparison among these five limits was made using the minimum value searching approach, leading to the determination of the final heat transfer constraint of the MCLHP, which is identified as the capillary limit. A higher effective porosity and a larger pore diameter lead to an increased wick fractal dimension and thus a higher capillary limit. An increased height difference between the evaporator and the condenser also increases the heat transfer (i.e. capillary) limit of the MCLHP. Decreased effective porosity (ε), pores portion, and increased tortuosity of capillaries help enhance the heat transfer (boiling) limit of the MCLHP. Overall, fractal theory is thought to be an ideal method to address the impact of an irregular porous wick on the heat transfer performance of a MCLHP.

Application of multilayer perceptron neural network and seismic multiattribute transforms in reservoir characterization of Pennay field, Niger Delta

Supervised multilayer perceptron neural network and seismic multiattribute transforms were applied to three-dimensional (3D) seismic and a suite of borehole log data set obtained from Pennay field, offshore Niger Delta with a view to predicting lateral continuity of hydrocarbon reservoir properties beyond well control. Four (4) hydrocarbon-bearing sands, namely, Pennay 1, 2, 3, and 4, were delineated from borehole log data. Four (4) horizons corresponding to near top of mapped hydrocarbon-bearing sands were used to produce time maps and then depth structural maps using appropriate checkshot data. Petrophysical analysis of the mapped reservoirs revealed that the area is characterized with hydrocarbon saturation ranging from 56 to 72%, water saturations between 27 and 44%, volume of shale between 7 and 20%, and porosity between 25 and 31%. Three major structure building faults (F2, F3, and F5 which are normal, listric concave in nature), two antithetic (F1 and F4), were identified. Structural closures identified as roll-over anticlines and displayed on the time and depth structure maps suggest probable hydrocarbon accumulation at the upthrown side of the fault F4. Seismic attribute results reveal two main characteristic patterns of high and low amplitude and frequency areas. There is an intermediate zone between the low and high amplitude and frequency that may be regarded as transition zone. Multilayer Perceptron Neural Networks (MLPNN) revealed how permeability, net-to-gross, porosity, volume of shale, and hydrocarbon saturation vary away from well control across the entire field. The supervised MLPNN-simulated volumes for petrophysical properties of interest have their uncertainties quantified and measure of accuracy in prediction and the predictive power in terms of root-mean-square error (RMSE). RMSE is the standard deviation of residual which is difference between the predicted values and observed values, i.e., input and output of the network. RSME ranges between 0 and 1 and values closer to zero (0) indicate a fit that is more useful for prediction and also very high confidence level for the resulting output. Permeability modelled at RMSE of 0.030 revealed some thief zones (channel with high absolute permeability) within and outside the areas with well concentration with average permeability of 635md. MLPNN-modelled map of net-to-gross (NTG) at RMSE of 0.0290 revealed that 72% of the reservoirs have a very high NTG (ratio of the volume of the sand in the reservoir to the total volume of the reservoir) with average NTG of 0.7184. Effective porosity was modelled at RMS error of 0.0053 with resulting average effective porosity of 0.295. The effective porosity slice on top of reservoirs revealed the lateral variation of effective porosity across the field with very high effective porosity areas coincide with the delineated regions of interests. Moreover, hydrocarbon saturation was also modelled at RMSE of 0.0282 with an average of 69.7% and volume of shale was modelled at RMSE of 0.028 and average volume of shale of 9%. A comparison of MLPNN slices of petrophysical properties on the mapped horizons revealed that a relatively higher NTG, low volume of shale, high hydrocarbon saturation, high permeability, and high effective porosity were observed in the regions of interest in the field. In conclusion, successful MLPNN prediction has been done for petrophysical properties at inter-well points and locations beyond well control. MLPNN-modelled maps revealed some bypassed sand channels and some thief zones within and outside the areas with well concentration that are not evident on the structural maps and attribute slices. The integration of the different analyses and results from the study has improved our understanding of mapped reservoirs and enhanced lateral prediction of its properties.