Simulation of Contaminants Transport in Groundwater From Nickel Mining Waste Dump Southeast Sulawesi

The irregularities of nickel resource mining in Indonesia cause many serious environmental problems. Piles of leftover rocks on nickel mining waste dumps have the potential to be a source of heavy metal seepage into the water. This study was conducted to assess the impact of nickel mining in the Langgikima Subdistrict of the North Konawe Regency of Southeast Sulawesi Province. The focus is to assess the migration of hexavalent chromium (Cr6+) and iron (Fe) using MT3DMS to model the transport of solutes. The study's goal was to identify cr6+ and Fe concentrations in waste dumps and predict the spread of contaminants over a 20-year period of time. XRF (X-Ray Fluorescence) is done to determine the content of elements and minerals in rocks. Toxicity Characteristics Leaching Procedure (TCLP) is performed to estimate the concentration of Cr6+ and Fe in waste dumps. AAS (Atomic Absorption Spectrophotometer) to find out the content of Cr6+ and Fe in surface water and land water samples. The results showed the highest concentrations of Cr6+ of 0.0462 mg/L and Feat 0.8709 mg/L. Simulations without compacted clay coatings, Cr6+ and Fe contaminants could be transported consecutively by 2.7 km and 2.42 km while simulations used compacted clay layers with a hydraulic conductivity of 1 × 10−9 m/s of Cr6+ and Fe contaminants could be transported consecutively by 0.412 km and 0.467 km. It can therefore be concluded that heavy metals in the remaining rock piles from the waste dump can be transported into groundwater, and the action of using a compacted layer of clay must be taken to prevent contaminant migration into groundwater.

Recharge mechanism and salinization processes in coastal aquifers in Nam Dinh province, Vietnam

In Nam Dinh province, in the Red River delta plain in Northern Vietnam, groundwater in the shallow Holocene aquifer shows elevated total dissolved solids up to 35 km from the coastline, indicating a saltwater intrusion from the Gulf of Tonkin. High groundwater salinities have been encountered below and adjacent to the Red River in the deep Pleistocene aquifer. Since 1996, large-scale groundwater abstraction was initiated from the deep aquifer, and the observed elevated salinities now raise concerns about whether the groundwater abstraction is undertaken sustainably. We have conducted a study to obtain a fundamental understanding of the recharge mechanisms and salinization processes in the Nam Dinh province. A holistic approach with multiple methods including transient electromagnetic sounding and borehole logging, exploratory drilling, sampling and analyzing primary ion and stable isotope compositions of water and pore water, groundwater head monitoring, hydraulic experiments laboratory of clay layers, and groundwater modeling by using the SEAWAT code. Results reveal that saline river water is leached from the Red River and its distributaries into the shallow aquifers. The distribution and occurrence of salty pore water in the Holocene aquitard clay shows that meteoric water has not been flowing through these low permeable clay layers. Marine pore water has, however, been leached out of the Pleistocene clay. When this layer is present, it offers protection of the lower aquifer against high salinity water from above. Salinity as high as 80 % of oceanic water is observed in interstitial pore water of the transgressive Holocene clay. Saltwater is transported into the Pleistocene aquifer, where the Holocene clay is directly overlying the aquifer.

Development of New Collagen/Clay Composite Biomaterials

The fabrication of collagen-based biomaterials for skin regeneration offers various challenges for tissue engineers. The purpose of this study was to obtain a novel series of composite biomaterials based on collagen and several types of clays. In order to investigate the influence of clay type on drug release behavior, the obtained collagen-based composite materials were further loaded with gentamicin. Physiochemical and biological analyses were performed to analyze the obtained nanocomposite materials after nanoclay embedding. Infrared spectra confirmed the inclusion of clay in the collagen polymeric matrix without any denaturation of triple helical conformation. All the composite samples revealed a slight change in the 2-theta values pointing toward a homogenous distribution of clay layers inside the collagen matrix with the obtaining of mainly intercalated collagen-clay structures, according X-ray diffraction analyses. The porosity of collagen/clay composite biomaterials varied depending on clay nanoparticles sort. Thermo-mechanical analyses indicated enhanced thermal and mechanical features for collagen composites as compared with neat type II collagen matrix. Biodegradation findings were supported by swelling studies, which indicated a more crosslinked structure due additional H bonding brought on by nanoclays. The biology tests demonstrated the influence of clay type on cellular viability but also on the antimicrobial behavior of composite scaffolds. All nanocomposite samples presented a delayed gentamicin release when compared with the collagen-gentamicin sample. The obtained results highlighted the importance of clay type selection as this affects the performances of the collagen-based composites as promising biomaterials for future applications in the biomedical field.

Diagenetic stages of oil-saturated sandstones of the pashyisky horizon at the Romashkinskoye oil field

It was identified three stages of reservoir rock formation of the Pashyisky horizon of the Frasnian stage of the Upper Devonian at the Romashkinskoye field, based on optical microscopic studies. The first stage, associated with clastic deposits sedimentation and marked by clastic grains dense structural packing formation, close to cubic. The second diagenetic stage of quartz sandstones is associated with the subsidence stage of sediments into the burial zone. During this period were actively proceeding the processes of grains mechanical deformation, blastesis of quartz clasts, the formation of siderite fragments, and fibrous chalcedony, partially metasomatic replacing clay layers in sandstones. The third diagenetic stage in quartz sandstones is associated with the migration of underground gas-water solutions. Analysis of the transformation degree of the Pashyisky horizon quartz sandstones at different areas of the Romashkinskoye field revealed the relationship between the intensity of secondary diagenetic processes and the degree of rocks oil saturation. Keywords: pashyisky horizon; oil; sandstone; reservoir; diagenesis.

Study of migration of radioactive elements in clay layers during the burial of radioactive waste

In 2015, Kazakhstan and the International Atomic Energy Agency (IAEA) signed an agreement to host a low-enriched uranium bank in Ust-Kamenogorsk. In 2019, several batches of enriched uranium were delivered to Kazakhstan and the bank began operations at the Ulba Metallurgical Plant. When transporting and disposing of radioactive elements, there is a need to reduce this possibility by limiting the transfer of uranium from underground storage to underground water. Therefore, in this article, a study was conducted on the migration of radioactive elements in clay layers during the disposal of radioactive uranium waste. There are now many underground repositories (for some types of radioactive waste). These systems are based on different underground container structures for different geological formations. For underground repositories located in geological environments where enriched uranium can migrate, other system components must reduce this possibility by preventing or limiting uranium mobility. This work investigates the process of convective transport of radioactive elements, in a moist soil layer through the installation of an additional natural clay barrier layer, the migration of radioactive elements during safe disposal, the effect of diffusion and convection through the solid waste layer.

An exceptional surface occurrence: the middle to upper Miocene succession of Pécs-Danitzpuszta (SW Hungary)

The Pécs-Danitzpuszta sand pit is the most important outcrop of the oldest Pannonian (upper Miocene, Tortonian) deposits in southern Hungary. A trench excavated in 2018 exposed Lake Pannon deposits and underlying Paratethys strata down to the upper Badenian (Serravallian), and together with the sand pit they make up a continuous sedimentary succession with a true thickness of ~220 metres. Due to tectonic deformation, middle Miocene deposits and carbonates in the lowermost Pannonian are overturned. Layers become vertical close to the marl-sand boundary, then the dip changes to normal, with continuously decreasing dip angles. The exposed succession starts with 5 m of upper Badenian (13.8-12.6 Ma old) calcareous marls and sandy limestones with sublittoral, then littoral molluscs, which were deposited in the normal salinity seawaters of the Central Paratethys. The overlying 8 m of sand, silt, sandy breccia and conglomerate are fossil-free,; only the lowermost silt layer contains reworked Badenian microfauna. This unit probably accumulated from gravity-driven flows in a fan-like, probably terrestrial depositional setting. The next 7.5 m of frequently alternating thin-bedded limestones, marls and clays with sublittoral biota represent rapid transgression. Foraminifers, ostracods, molluscs and calcareous nannoplankton indicate late Sarmatian, then Pannonian age for this interval. However, the locations of the boundaries indicated by the various groups are not are not consistent, making the position of the Sarmatian/Pannonian boundary uncertain. The Sarmatian beds with marine fossils still accumulated in the Paratethys, between ~12.1–11.6 Ma, under varying salinities due among others to temporary freshwater input. The Pannonian strata already represent sediments of the brackish Lake Pannon. Above these beds, uniform calcareous marl becomes dominant with some clay layers and graded or structureless conglomerate to sandstone interbeds. The deposition of the overall 64- m- thick Pannonian calcareous marl section took place in the open, probably few -hundred -metres -deep water of the lake between ~11.62 and 10.5–10.2 Ma. It may represent a rare, well-exposed surface occurrence of the Endrőd Formation which is known from thousands of wells in the Pannonian Basin. Above this section, a 6-7 -m- thick transitional interval of silty marls and sands is followed by ~140 m of limonitic, pebbly sands. They have poor to moderate sorting and rounding, metre -thick beds with transitional boundaries and abundant fossils and clasts reworked from older Miocene units. Their accumulation took place between 10.2-10.5 and 9.6 Ma by gravity flows connected to deep-water portions of fan deltas.

Complex Approach to Green Fields Development and Fracturing Strategy by the Example of Pilot on the Field by Name of Alexandra Zhagrina

The article describes an approach to creating, in conditions of limited input information, a strategy for performing the first hydraulic fracturing operations on deviated and horizontal wells in the A. Zhagrin field. The field is in the active phase of exploration, the planned count is mainly composed of horizontal wells with multi-stage hydraulic fracturing. Approaches to the design of pilot works with control of the height of hydraulic fractures, which have proved their effectiveness by well logging studies and the obtained oil productivity, they have been successfully introduced into the technology of multistage hydraulic fracturing in horizontal wells. Due to the minimum number of reference wells, a significant area of the field (100 km2), the uncertainty of the distribution of water-saturated zones in the target and adjacent formations, the spread in the thickness of clay layers from 10 to 30 m, there is a risk of unwanted introduction of these interlayers by hydraulic fractures. The project team was able to assess the risks in terms of hydraulic fracturing, depending on the geological and physical characteristics (thickness of the target formation and clay layers, saturation) and in joint cross-functional work (with geological, geomechanical and hydrodynamic support) to implement hydraulic fracturing technologies that have confirmed their efficiency in oil production. To test hypotheses at the initial stage, various scenario conditions with a probabilistic assessment of uncertainties were selected at the deviated wells, as a result, the matrix of technological solutions was developed. In directional wells, the capabilities of technologies selected for pilot testing were confirmed using methods for diagnosing the height of hydraulic fracturing. The performed correction of stress profiles in a modern corporate hydraulic fracturing simulator increased the correctness of the 3D geomechanical model, which made it possible to optimize fracture geometry and horizontal wellbore drilling direction. Due to a thorough study of the conditions for the applicability of the considered hydraulic fracturing technologies, it was excluded the inclusion of water-saturated horizons without losing the effective half-length of hydraulic fractures. The workflow, during the implementation of which a matrix of solutions for successful well development was created, will ensure the achievement of planned oil production rates in the future for a field without rich field practice in hydraulic fracturing.

Preparation of PP/PP-g-MAH/C15A Nanocomposite by Melt Extrusion Process and Comparative Study of its Mechanical and Non-Isothermal Crystallization Behaviour

Nanocomposite films have been prepared by melt blending method with the help of twin screw extruder using polymer polypropylene(PP)nucleating agent like organically modified nanoclay at optimum loading condition. Compatibilizers such as polypropylene grafted maleic anhydride (PP-g-MAH) were used for better compatibility between polymer matrix and filler. The effect of organoclay on nucleation effect and subsequent incremental values in mechanical and thermal behavior of different nanocomposite films has been investigated and explained with justifications. The tensile properties have shown to be improved in presence of clay nanoparticles due to resistance exerted by clay layers against plastic deformation of the polymer. Thermal properties measured by differential scanning calorimeter shows increased crystallization temperature of the nanocomposites in presence of clay particles and compatibilizer of optimum concentration.

A New Cationic Shale Inhibitor and Water Blocking Agent for Water-Based Drilling Fluid

Drilling a shale formation is one of the challenges faced by the petroleum industry. Designing the drilling fluid, that reduces the interaction with shale, is important for safe and efficient drilling. This study investigates the new cationic surfactant as a shale inhibitor for the drilling fluid. The main objective of this study is to block the water penetration into the clay layers using the new shale inhibitor and evaluate its performance with commercial shale inhibitors. To assess the performance of new cationic surfactant two reliable clay sources were considered. The first source is from unconventional Qusiba (Kaolinite) formation in Saudi Arabia and the second is a commercial Bentonite. The effect of new cationic formulation on preventing clay swelling were tested using API dynamic swelling meter at reservoir condition. Further, X-ray diffraction and SEM analysis were performed to ensure clay stability before exposing it to WBM and after exposure for cation exchange phenomenon, shape and size of the particle and efficacy of water penetration blockage. The results were also compared with commercial shale inhibitor. The results show that the new cationic surfactant can act as a shale inhibitor as well as water blocking agent. It also showed acceptable performance compare with common shale inhibitors used in the industry, the performance can be further improved by optimizing the percentage of surfactant addition to the drilling fluid. This study provides the new cationic surfactant and proved to have good feature for oilfield applications and the cationity which is helping to reduce the water shale interactions.