Medium Sand Research Articles

Pertumbuhan Stek Pucuk Mangga (Mangifera indica L.) terhadap Respon Konsentrasi IBA (Indole Butyric Acid) dan Macam Media Tanam

Mango (Mangifera indica L.) is a fruit plant that has long been known and has become a commodity that has high economic value and is a trade commodity between countries. Vegetative propagation technique is an alternative to reproduce this type of plant. This study aims to: 1) Determine the concentration of IBA (Indole Butyric Acid) which affects the growth of mango shoot cuttings (Mangifera indica L.). 2) Knowing the planting media that affect the growth of mango shoot cuttings (Mangifera indica L.). 3) To determine the interaction between the concentration of IBA (Indole Butyric Acid) and the planting medium which influences the growth of mango shoot cuttings (Mangifera indica L.). The research was carried out using Factorial Randomized Block Design (RBD) with 2 factors. The first factor was the concentration of IBA (Indole Butyric Acid) (0 ppm, 500 ppm and 1000 ppm) and the second factor was the planting medium (sand, husk charcoal and sand + husk charcoal) with 3 replications. The results of this study were 1) There was an effect of IBA (Indole Butyric Acid) concentration treatment on the growth of mango shoot cuttings (Mangifera indica L.). The effect occurred on the percentage of growing cuttings, days of shoot break, shoot length, and number of leaves. 2) There is an effect of growing media treatment on the growth of mango shoot cuttings (Mangifera indica L.). The effect occurred on the percentage of growing cuttings, shoot length and number of leaves. 3) There was no interaction between the treatment of IBA (Indole Butyric Acid) concentrations and the growing media on the growth of mango shoot cuttings (Mangifera indica L.).

DISTRIBUTION OF BOTTOM SEDIMENT BEFORE AND AFTER RECLAMATION AT CENTER POINT OF INDONESIA (CPI) MAKASSAR CITY

Characteristics and distribution of bottom sediment is one of the important parameters in determining the management plan and land use in coastal areas. The purpose of this study was to determine the condition of the distribution of bottom sediments and to compare the changes that occurred in the distribution of bottom sediment before and after the reclamation of the Center Point of Indonesia (CPI) in Makassar City. Sediment sampling was carried out using a grab sampler at four stations, namely stastions on the island adjacent to the reclamation area and two other stations in the water around the reclamation area. The results showed that the bottom sediment in the waters around the reclamation area consisted of coarse sand and medium sand with an organic matter content of 14.92% in the sediment. On the islands adjacent to the reclamation area, the bottom sediments are move varied, consisting of coarse sand, medium sand and fine sand with lower organic matter content of 4.92% to 5.38%.

Influence of manufactured sand gradation and water cement ratios on compressive strength of engineered cementitious composites

In recent years, many researchers have successfully examined the characterization of Engineered cementitious composites (ECC) with different materials owing to their pseudo-strain-hardening behavior and superior mechanical and durability properties compared to fibre-based conventional concrete. Meanwhile, incorporating different materials, water cement (w/c) ratio, gradation of sand and types of sand influence the ECC's properties. This study examines the influence of manufactured sand (Msand) gradation with different w/c ratios on ECC's compressive strength at 3, 7 and 28 days. The flowability of ECC with different gradations of sand and w/c ratio is also discussed. The interaction between the compressive strength of the ECC with the w/c ratio and gradation of sand is also highlighted. The experimental results showed that the ECC flowability increased with increasing sand gradation and w/c ratio. Similarly, ECC with fine and medium sand exhibited a lower compressive strength than coarse sand. The maximum compressive strength of ECC with fine, medium and coarse sand were attained of about 46.3 MPa, 48.2 MPa and 58.1 MPa at 0.33, 0.34 and 0.37 w/c ratios, respectively.

Analisis Karakteristik Dan Laju Angkutan Sedimen Total Saluran Rawasari Indah Kota Tarakan

Embung as one of the waterworks that serves as a reservoir for water, Embung Rawasari Indah is one of the 5 reservoirs in Tarakan yann city currently experiencing silting due to sedimentation process, which causes the water discharge flowing towards the reservoir to be not optimal. The purpose of this study was to determine the characteristics and discharge of total sediment transport in Rawasari indah Channel and obtain a comparison of three methods of calculating the total sediment transport in Rawasari Indah Channel. Based on the results of laboratory tests sediment classification is dominated by fine sand, very fine sand and medium sand. The results of the study obtained the average value of sediment transport discharge on Engelund and Hansen's method is 1.382998513 tons/year, the method is 15.88046241 tons/year, Laursen method is 2.000124533 tons / year. Based on the calculation results with the largest value, the method chosen as a benchmark in the calculation of sediment transport.

Sedimentology and Mineralogy of Sedimentary Sequences in Nanim Field in the Niger Delta basin, Nigeria.

A total of nineteen ditch cuttings from the sedimentary sequence of Nanim Field, were subjected to both sedimentological and mineralogical analysis with the aim of investigating the mineralogical composition of the studied section (1810 m - 2650m) in the study area. The shale samples were grinded, pulverized and sieved with less than 75μm and analyzed using X-ray diffraction techniques (XRD) for mineralogical composition. Results of the sedimentological analysis, suggests four lithofacies made up of sandstone, shaly sand, shale and sandy shale in he studied section. The studied section has been interpreted as a shallow marine environment  divided into two broad lithofacies sequences made up of beach sand (1810 m - 2290 m.) and upper shoreface (2300 m – 2650m) respectively. The beach sand sequences comprises thick sands, brownish, grey to black, fine to coarse grained, whereas the upper shoreface sequence is essentially a heterogeneous sequence of alternating sand medium to very fine grained sand and shale - grey. Results from the XRD analysis shows that the mineralogical composition of the basal part (upper shoreface) of the studied section is characterized by kaolinite a dominant in sediments of fluviatile environments and is known to concentrate in many near-shore sediments (shallow marine) with a decrease in abundance from the shoreline as other clay minerals increase basinward.

Riverbank erosion and char stability along the fluvial-to-tidal transition zone in the Lower Meghna River and Tentulia Channel in the Ganges-Brahmaputra-Meghna Delta, Bangladesh

The Ganges-Brahmaputra-Meghna (GBM) delta has been named one of the world's most vulnerable sinking deltas. It is also one of the most dynamic deltas, with the world's highest sediment discharge and third highest water discharge, with semi-diurnal mesoscale (2–4 m) tides. The high fluvial discharge and significant tidal velocities (1–2 m/s) create an expansive fluvial-to-tidal transition zone (FTTZ) along the entire Lower Meghna River (LMR). Within this FTTZ, tidally elongated channel bars, locally called ‘chars’, rapidly evolve due to the high sediment and water discharges. Chars along the LMR have a total population exceeding 5 million people; thus, evaluating the interactions of fluvial and tidal processes along the FTTZ is crucial to understanding vulnerability among char communities with respect to flooding and sea-level rise. Here, we utilize a multi-faceted approach to assess the geomorphology, sedimentology, and hydrology of three chars longitudinally spaced within the LMR and one of its distributaries – the Tentulia Channel. Decadal land change analyses revealed that the FTTZ along the upper LMR and Tentulia Channel has been gaining land at a rate of 4.7 km2/yr, with erosion being most prevalent upstream and most accretion occurring within 50 km of the coast. Almost all the stratigraphic profiles show fine and/or medium sands at depth (0.5–2 m), implying that the three chars are similarly susceptible to erosion by tidal currents and high river discharge. Thus, we attribute the increased stability of chars in the downstream direction to increased tidal influence rather than sedimentology. Land elevation and water level surveys reveal that elevation relative to sea level decreases as the distance to the mouth of the LMR decreases: from 4.05 m (130 km from the mouth), to 2.56 m (100 km from the mouth), and 1.85 m (70 km from the mouth). By incorporating local water level data with the elevation surveys, we conclude that fluvial, namely monsoonal, processes control the geomorphology of the chars near the confluence of the LMR and the head of Tentulia Channel. The shift between fluvial-dominated and tidal-dominated regions of the FTTZ occurs just downstream of Char 3 (∼70 km from the LMR mouth). Therefore, char communities near the LMR confluence are most vulnerable to riverbank erosion and flooding associated with the monsoon season, and chars proximal to the coast are most vulnerable to erosion and flooding related to storm surges and relative sea-level rise.

Assessment of turf quality in Paspalum vaginatum Sw. accessions of Sumatra, Java, and Bali (Indonesia) with clay and amended sand growing media

Abstract. Rahayu, Ariyanto DP, Usrotin AH, Hatami FR, Mo YG. 2023. Assessment of turf quality in Paspalum vaginatum Sw. accessions of Sumatra, Java, and Bali (Indonesia) with clay and amended sand growing media. Biodiversitas 24: 1650-1658. Seashore paspalum (Paspalum vaginatum Sw.) is a selected turfgrass species in the FIFA football world cup Qatar 2022. The choice considers its turf quality, growth habit, quick recovery from damage, tolerance in warm conditions, and low water consumption. Since the breeding program of seashore paspalum worldwide still needs to be improved and is yet to start in Indonesia, we suppose that in the future, seashore paspalum will become a favorite turfgrass industry. Previous studies showed that Indonesia has many accessions to the germplasm of seashore paspalum. This study aimed to find superior mother lines of Indonesian germplasm accession by select of visual and functional quality using clay soil of vertisol and vertisol-amended sand as growing media for quality evaluation. This study was a wild-type collection followed by a plot experiment using Randomized Complete Block Design. In this experiment, the control was using a commercialized cultivar. Seashore paspalum accessions were collected from Java, Bali, and Sumatra Indonesian islands. Observation of variables were visual qualities, i.e., tiller density, color, leaf texture, uniformity, and functional quality, i.e., surface covering, recoverability, clippings dry weight, root length, root dry weight. The National Turfgrass Evaluation Program (NTEP) rated those qualities by scoring. The quality index of turfgrass used a rating score formulated from a visual and functional quality score. The data were analyzed using DMRT and T-test. Results showed that growing paspalum in clay-amended sand media showed a better recovery rate than the accessions grown in vertisol media. Mowing the grass can reduce plant height and leaf texture, and increases the clipping dry weight. Sand amendment to vertisol soil can improve the seashore paspalum visual qualities, i.e., leaf texture, tiller density, color score, and functional quality, such as root length. Seashore paspalum accessions vary in quality, i.e., visual and functional. Native accessions have a better recovery rate, higher tiller density, and uniformity than the control but a higher clipping yield. Bogor accession had faster soil surface coverage, Siak accession had a high recovery rate. Rumbei accession was the highest clipping dry weight, fast land cover, and high root dry weight. The accessions of Siak and Rumbei have higher quality index than the control after mowing. Siak accession performed better in vertisol, whereas Rumbei accession performed better in vertisol-amended sand. The performance of Rumbai and Siak accessions showed that seashore paspalum from Sumatra has better characteristics than Java and Bali and is promising for further cultivar development.

Use of Various Filtaritaion Media in Lowering the Level of Water Hardness

Hard water is common in areas with thick topsoil and limestone formations. Because the topography of Kupang City is in the form of limestone, in the rainy season rainwater passes through the limestone soil layer so that the raw water becomes hard or very hard. Identification and analysis of field parameters and levels of raw water hardness before and after treatment to calculate the effectiveness of decreasing hardness of various types of filter media. This research is an experimental study. The object of inspection is raw water from Oenesu springs that have undergone filter media treatment. The filter media consists of activated carbon, silica sand, quartz sand, and zeolite with a residence time of 60 minutes. The results of laboratory tests are displayed in the form of tables and graphs and analyzed. The field parameters tested are smell, taste, color, temperature, turbidity, TDS and pH to meet water quality standards. The level of hardness before and after treatment obtained raw water hardness of 365.33 mg/L, activated carbon media 362.85 mg/L, silica sand media 236.53 mg/L, quartz sand media 239.01 mg/L and zeolite media 296.59 mg/L. The field parameters tested meet water quality standards according to Permenkes 32 of 2017. The level of water hardness treated by the filtration process with quartz sand media is more effective in reducing the level of raw water hardness, with a decrease efficiency of 35.26%.

Quantifyting research on the protection effect of a desert‒oasis ecotone in Dunhuang, Northwest China

A desert‒oasis ecotone is an important barrier for an oasis, although few studies have attempted to investigate and quantify the protection that it offers. In this paper, a portable wind-monitoring system, fixed automatic weather-monitoring instrument, and eight-directional sand-collecting instrument were used to study the protection benefits offered by a desert‒oasis ecotone in Dunhuang, Northwest China. The data showed that a desert–oasis ecotone can effectively reduce regional wind speed, sand-driving wind speed, drift potential, and wind-blown sand activity, while also increasing the aerodynamic roughness length in order to prevent erosion driven by surface winds. When passing through the ecotone, the percentage of sand-driving wind reduced from 21.0% to 2.98%, and the resultant drift potential was reduced from 135.67 to 14.94 VU. In the study area, the resultant sand-driving wind mainly traveled southwards, and the frequency of sand-driving winds decreased commensurately with increases in vegetation cover and desert–oasis ecotone width. In 2015, the total wind-blown sand fluxes were 3.90 kg m−1 d−1 in the desert environment, 1.09 kg m−1 d−1 in the desert‒oasis ecotone, and 1.08 kg m−1 d−1 in the oasis. The wind-blown material's grain size in the desert region was dominated by medium sand, which comprised 47–60% of the total; by contrast, wind-blown materials in the desert‒oasis ecotone and oasis were dominated by fine sand, with proportions of 51–63% and 52–70%, respectively. The protection offered by a desert‒oasis ecotone is related to aerodynamic roughness length, distance of airflow across the ecotone, and wind speed. Among them, aerodynamic roughness length and distance of airflow across the ecotone were positively correlated with the level of protection offered, while wind speed showed a negative correlation. We also present a mathematical relationships between these variables that can provide a scientific basis for determining the optimum width to develop desert–oasis ecotones in arid regions.

Mobilization pilot test of PCE sources in the transition zone to aquitards by combining mZVI and biostimulation with lactic acid

The potential toxic and carcinogenic effects of chlorinated solvents in groundwater on human health and aquatic ecosystems require very effective remediation strategies of contaminated groundwater to achieve the low legal cleanup targets required. The transition zones between aquifers and bottom aquitards occur mainly in prograding alluvial fan geological contexts. Hence, they are very frequent from a hydrogeological point of view. The transition zone consists of numerous thin layers of fine to coarse-grained clastic fragments (e.g., medium sands and gravels), which alternate with fine-grained materials (clays and silts). When the transition zones are affected by DNAPL spills, free-phase pools accumulate on the less conductive layers. Owing to the low overall conductivity of this zone, the pools are very recalcitrant. Little field research has been done on transition zone remediation techniques. Injection of iron microparticles has the disadvantage of the limited accessibility of this reagent to reach the entire source of contamination. Biostimulation of indigenous microorganisms in the medium has the disadvantage that few of the microorganisms are capable of complete biodegradation to total mineralization of the parent contaminant and metabolites. A field pilot test was conducted at a site where a transition zone existed in which DNAPL pools of PCE had accumulated. In particular, the interface with the bottom aquitard was where PCE concentrations were the highest. In this pilot test, a combined strategy using ZVI in microparticles and biostimulation with lactate in the form of lactic acid was conducted. Throughout the test it was found that the interdependence of the coupled biotic and abiotic processes generated synergies between these processes. This resulted in a greater degradation of the PCE and its transformation products. With the combination of the two techniques, the mobilization of the contaminant source of PCE was extremely effective.

A Research on Preparation and Performance of Volcanogenic Sand Concrete from the Philippines

The river sand in the Santo Tomas River area of the Philippines is a kind of volcanogenic sand. The sand is fine sand with a fineness modulus of 2.2, an apparent density of 2380 kg/m3, a bulk density of 1320 kg/m3, a mud content of 6.7%, a methylene blue value of 1.2, a soluble chloride ion content of 0.00071%, and a light-matter content of up to 12.2%, which does not meet the requirements of the three-zone grading. Based on a series of experiments, this paper systematically studies and compares the workability, mechanical properties, and durability of two kinds of concrete with the river sand in the Santo Tomas River area and natural river sand in Beijing, China as fine aggregates, respectively. In addition, volcanogenic sand in the Philippines is technically optimized for the purpose of in-depth study. After optimization, such sand reaches the standard of Zone II-graded medium sand and is comprehensively improved in performance, which is evidenced by a fineness modulus of 2.4, an apparent density of 2570 kg/m3, a bulk density of 1550 kg/m3, a light-matter content of 6.0%, and a mud content of 6.7%. Study results show that in terms of mechanical properties, the concrete made of the optimized river sand in the Santo Tomas River area is superior to that made from the natural river sand in the Beijing area. In addition, separated light matter can be used as a natural light aggregate, which has a bulk density of 960 kg/m3, a cylindrical compressive strength of 2.5 MPa, and a 1 h water absorption of 8.2%, respectively.

Effect of high temperature on residual splitting strength of desert sand concrete

AbstractThe ordinary medium sand can no longer meet the increasing demands of engineering projects. Construction costs can be reduced and the natural environment can be protected by rational use of the local desert sand. To evaluate the spalling and fire resistance of the concrete, the desert sand concrete (DSC) is heated to 100–800°C and then cooled for splitting tensile strength test. The test results indicate that with the increment of desert sand replacement rate (DSRR), the compressive strength of DSC increases first and then decreases. The maximum value is reached when DSRR is up to 40%. The presence of fly ash slows down the loss of splitting strength of concrete with the temperature increasing. The regression model is established to predict the functional relationship between the concrete splitting strength and temperatures under heating and air cooling conditions. The result shows that the predictions calculated by the formula are consistent with the experimental results. The formula can be employed as a constitutive relation of the computer model to evaluate the spalling and fire resistance of the DSC structure.

Sand filtration for greywater treatment: long-term performance evaluation and optimization by response surface methodology

ABSTRACT Greywater treatment and reuse is getting increasing attention all over the world, and sand filters are one of the on-site greywater treatment alternatives. Effects of media size, media depth and flow rates on the performance of the continuously operated saturated sand filters treating greywater were evaluated in this study. River sand of three different media sizes 0.30-0.60 (fine), 0.60-0.85 (medium), and 0.85-1.18 (coarse) mm was used and sand filters with the same media size were constructed and operated at flow rates of 10 (320 L/m2/day), 20 and 30 L/d. Fine sand media filter operated at a hydraulic loading rate of 320 L/m2/day gave the best performance with 99, 94 and 95% removal of turbidity, BOD and COD, respectively. NH4-N, PO4-P and FC were reduced by 84, 99% and 1.65 log, respectively. An optimization study showed an optimum sand size of 0.68 mm and a hydraulic loading rate of 470 L/m2/day.

ВЗАИМОСВЯЗЬ ГРАНУЛОМЕТРИЧЕСКОГО СОСТАВА ПОЧВ С ИХ НАИМЕНЬШЕЙ ВЛАГОЁМКОСТЬЮ В ЯБЛОНЕВЫХ САДАХ ООО «ТИМИРЯЗЕВСКИЙ» ЛИПЕЦКОЙ ОБЛАСТИ

The research was carried out in 2018-2021 in the old fruit-bearing, but not yet uprooted apple orchards of Timiryazevo LLC in the Lipetsk region. The lowest moisture capacity was determined by the method of gypsum casts, the granulometric composition was determined by the pyrophosphate method. The most moisture - intensive genetic horizons of soils were the following: in leached chernozem – A1+A1B (0-170 cm), in podzolized chernozem – A1 (0-42 cm), B (140-167 cm) and B +C (178-230 cm), in chernozem-meadow podzolized soil – B (110-160 cm). All types of soils in apple orchards differed significantly in the lowest moisture capacity of all genetic horizons located deeper than humus. The moisture capacity of hu-mus horizons (A) of all four soils is the same. In the profile of leached chernozem, the predominant frac-tion is silt and coarse dust, in the profile of podzolized chernozem – fine sand, coarse dust and silt, in the profile of podzolized slightly glued chernozem – medium and fine dust and silt, in the profile of cherno-zem meadow podzolized soil - fine sand, coarse dust and silt. The highest content of physical clay was ob-served in the humus horizon and the parent rock of the slightly frozen podzolized chernozem, as well as in the leached chernozem parent rock and the illuvial horizon of the podzolized chernozem. The lowest mois-ture capacity of soils increases as the silt content in the soil increases (r= 0.61-0.9), as the percentage of fi-ne dust in them decreases (r= -0.59...-0.97), medium dust (r= -0.67), fine sand (r= -0.61), medium sand (r= -0.75...-0.8) and coarse sand (r= -0.67...-0.92). The relatively low moisture capacity of transitional horizons (A1B) in podzolized chernozems is due to the presence in these layers of a large amount of dust and sand, but a small amount of silt.

Direct Shear Characteristics of Enzymatically Cemented Sands

A laboratory study was conducted to investigate the shear strength of bio cemented sands using enzyme-induced carbonate precipitation (EICP) via the direct shear test. Several specimens were prepared using four different application methods of EICP solution, namely spraying, mix-&-compact, percolation, and injection. Potential use of EICP for improving the sand-concrete interaction strength was also studied. Results indicated that the adopted application method of introducing the EICP solution to the soil affects the distribution pattern of CaCO3 precipitation in the soil matrix, thereby shear strength. Each method yielded a different response when sheared compared to untreated sand. The injection method was found to achieve higher shear strength and interparticle cementation under controlled rate and distribution followed by percolation. The spraying and mix-&-compact methods produced specimens with weaker particles' bond and lower shear strength measurement but still showed relatively better performance than the untreated sands. Better cementation of soil grains was achieved in medium sand and when fine and organic materials were removed. Sands response to EICP-treatment was inferred to vary depending on the geotechnical characteristic of the soils. Moreover, the interfacial strength between sand and concrete was found to be enhanced after applying the EICP treatment as it coarsened soil particles.

Granulometric calibration of the Erosion Potential Method (EPM) model: Estimation of sediment production that affects a coastal area

The beach sediment at the Ofanto river mouth (Apulia, Southern Italy) is very well sorted, and is mainly represented by medium sand. The granulometric analysis within the Ofanto basin shows a more heterogeneous distribution with coarser sediment prevailing upstream, and medium-fine sands more abundant in the other sectors. The occurrence of placers of volcanic minerals both in the river and in the beach sands allowed us to use them as geo-markers to estimate the grain size reduction from the river’s source to its mouth. The percentage of river sediment producing medium sand at the mouth was calculated for each sector of the Ofanto basin. It was, used as a reduction factor to correct the total budget of sediment production obtained by PyQGIS YES plug-in. In this way it was possible to calibrate the model and identify the areas of the feeding basin mainly contributing to the production of beach sediment at the river’s mouth.

Radioactive parameter analysis in soil samples at the Cauvery river

Cauvery, one among the major rivers, passing through three states, namely Karnataka, Tamil Nadu and Kerala. This river is crucial for drinking water, irrigation and electricity. In India, river sand is a key component of building construction. Through a gamma ray spectrometer with a NaI doped with thallium detector, the natural radioactive elements such as uranium, thorium and potassium (238U, 232Th, 40K) are explored and analysed. This analysis was already published. As per the report of United States Department of Agriculture (USDA) sediment and sand grain size is divided into several types, which include gravel medium sand (250–500µm), fine sand (100–250 µm), very fine sand (50–100µm), silty sand (2–50µm) and clay (<2µm). The range of gravel medium sand to fine sand (>125 µm) and non-magnetic grains were separated with the help of American Society for Testing Materials standard sieve and strong electromagnet. Those two samples for each site were subjected to Gamma ray spectroscopy and analysed. Related parameters like Absorbed-Dose (Din & Dout), Annual effective dose equivalent (AEin & AEout) is computed and correlated. By comparing the results of this investigation to the global average, it can be seen that practically all radioactive parameters are under control. However, the Cauvery River, with the exception of site no 31, does not present a radioactive hazard.

Comparative evaluation of the material of the artificial levees

Artificial levees have major importance in protecting human lives and infrastructure as they are essential elements of the flood protection measures. Nevertheless, the lack of the necessary information about their structure and internal composition might cause high risks. To monitor their stability, integrated surveys are needed, including geophysical and geotechnical methods. Levees along the rivers in Hungary were constructed more than 150 years ago, and they were heightened several times; therefore, investigations are required to assure their performance in flood risk mitigation. Our investigation aimed to utilise non-invasive geophysical techniques, primarily electrical resistivity imaging, with the validation of geotechnical investigations to map and compare the compositional and structural variations of two very different levee sections along River Tisza and River Maros. Integrating the analysed drilling data with ERT profiles showed that the main composition of the investigated Tisza levee section is fine and medium silt with an average resistivity 30 Ωm, however, the investigated section of Maros levee was built of not only of fine and medium silt but also of medium and coarse sand exhibiting higher resistivity values reaching up to 2200 Ωm. Several physical parameters were measured to study the nature of constituting levee materials like moisture content, grain-size, porosity, bulk-density, saturated hydraulic conductivity, and resistivity. It was found that most of them show a connection with resistivity, but the hydraulic conductivity did not show a direct connection, however the latter could exhibit the aquitard nature of Tisza levee materials and the non-aquitard nature of Maros levee materials.

Sand control screen erosion-failure prediction method in weakly consolidated sandstone reservoir

Sand production is one of the most common problems encountered in oil and gas field development, particularly in weakly consolidated sandstone reservoirs. Mechanical sand control screens are widely used to mitigate sand production. However, sand containing production fluid can lead to screen mesh erosion wear and sand screen prematurely failure. In this study, an experimental device was developed to simulate the local “hot spot” screen erosion damage considering the actual downhole radial sand carrying flow. The experimental results show that the erosion mass loss of the screen is positively correlated with the sand fluid velocity, sand concentration, median sand particle size and erosion time. A comprehensive sand screen erosion prediction model is established, which presents the correlations between erosion mass loss and various parameters, such as sand median particle size D50, sand concentration, fluid erosion velocity and erosion time. Compared with the field data, the predicted results accuracy of the effective life of the screen is more than 80%. The new sand screen erosion prediction model proposed in this paper can effectively predict the screen's erosion rate and service life in the field.

Infiltration behaviour and microstructure of filter cake from sand-modified bentonite slurry

This study uses a setup involving a scanning electron microscopy (SEM) to examine the infiltration behaviour and mechanism of the formation of filter cake from sand-modified bentonite slurry. We began by determining whether a filter cake can be formed by using water–bentonite slurry in samples of the fine, medium, and coarse sand (Series 1). Water–bentonite–sand slurries with different mass ratios of bentonite and fine sand (B:S) were subsequently tested using the medium and coarse sand (Series 2). The results show that for Series 1, a thin filter cake (<0.1 mm after drying) with extremely low permeability (∼10−8 m/s) was formed only when the fine sand was used. The filter cake consisted of layers of dense bentonite platelets arranged perpendicular to the infiltration direction. Similar results were obtained for Series 2 between the medium and coarse sand. Within the range of 1:1.5 ≤ B:S ≤ 1:0.5, the low permeable filter cake was formed on the deposited layer of fine sand and bentonite platelet. Contrary to expectations, adding more sand (B:S = 1:2) did not complete the formation of filter cake, and instead led to continuous deposition of fine sand and bentonite platelet, which may cause inadequate effective face support during slurry shield tunneling.