Clay Materials Research Articles

Investigation and modeling of physicochemical properties of bentonite-chitosan composites versus the concentration of chitosan added by intercalation

This study attempts to understand the relationship between structural and physicochemical changes of clay modified by a chitosan intercalation, and to valorize the clay-chitosan composites for wastewater treatment purpose. More precisely, the main aim was a characterization and modeling of the physicochemical properties of clay-polymer composites (especially bentonite-chitosan composites) versus the concentration of chitosan added by intercalation. We first developed a method for intercalating chitosan into the clay matrix, with different polymer concentrations (6g/L, 12g/L, 18g/L, 24g/L, 27g/L and 30g/L). Second, we carried out a characterization of the structural and physicochemical properties of clay-polymer composites based on X-Rays Diffraction (XRD), Fourier Transform Infrared (FTIR) and Scanning Electric Microscopy (SEM). In particular, the results of these analyses show that the measured pores within the composites with chitosan concentrations 6g/L and 30g/L are of nanometric order, while the composite at 12g/L is rather of microscopic order. Third, XRD measurements allow the determination of the clay interlayer space (basal distance) and particles size versus the polymer concentration. For basal distance, we have demonstrated the existence of five regimes depending on the value of the polymer concentration, namely (i) dilute regime, (ii) first semi-dilute regime, (iii) well-regime, (iv) second semi-dilute regime and (v) saturation regime. Finally, these bentonite-chitosan composites may be used as kinds of filtration membranes for wastewater, retaining, for example, a dye whose adsorption quantity was found to be improved by an amount of 76.92 %.

Enrichment mechanisms of Nb, Zr, and REY in the Late Permian coal-bearing strata in western Guizhou, SW China

Niobium, Zr, REE, and Y are widely enriched in the Upper Permian coal-bearing strata in southwestern China and are regarded as a substantial resource. To better understand the occurrence modes and enrichment mechanisms of these rare metals, comprehensive heavy-mineral separation, Micro-Raman spectroscopy, EPMA, and LA-ICP-MS analyses of primary and secondary metal minerals were conducted in the polymetallic beds in western Guizhou. In addition, the XRD, XRF, and ICP-MS analyses of bulk rocks were carried out. Our results suggest that Nb is primarily hosted in secondary TiO2 polymorphs which converted from primary Nb-rich rutile, and occurs as minor ilmenorutile and columbite-(Fe). The Zr is sequestered in both detrital zircon and secondary microcrystalline zircon. REE and Y (REY) are mainly incorporated into secondary florencite-(Ce), rhabdophane-(Ce), churchite-(Y), and zircon, also partially adsorbed by clay minerals. The assemblage of detrital zircon, Nb-rich rutile, and discrete Nb minerals reveals that rare metals are preconcentrated during the waning-stage Emeishan alkaline magmatisms. Complex zonings in rutile crystals may result from the diffusion of Nb5+ and Fe2+, and these grains are further overprinted by magmatic-hydrothermal and enveloped by ilmenorutile and columbite-(Fe). Furthermore, magmatic rutile is commonly converted into anatase, brookite, and leucoxene under supergene conditions, and then persisted as stable phases. Authigenic REY-rich (Al)-phosphates and zircon are sourced from the leaching, even decomposition of primary REY-phosphates and zircons. Their colloidal aggregates are precipitated from the acidic and oxidizing low-temperature fluids, which are superposed onto clay matrix. The mineralogical and geochemical features suggest that the polymetallic beds are enriched by both alkaline magmatic-hydrothermal processes in source rocks and supergene fluid alterations in sediments. This study gives new insights into the enrichment processes and conditions, and further extraction of critical metals in the coeval coal-bearing strata in southwestern China.

Synergistic effects of Reflux Flotation Cell's downcomer and reverse fluidization bed in rejecting clay entrainment during particle separation

The Reflux Flotation Cell (RFC) technology is heralded as an innovative game-changer, promising significant advancements in particle separation, and offering generational benefits for the resources industry. This paper meticulously assessed the RFC's capabilities in tackling another critical industry challenge in resources processing— severe entrainment of waste clay particles during flotation separation and compared the performance with conventional mechanical flotation. Through flotation tests where kaolinite particles were separated from combustible materials, in-situ particle aggregation measurements and calculating air fractions in both flotation systems, this study identified the superior performance of the RFC in reducing kaolinite entrainment and producing a high product quality. This was attributed to a synergistic function between the RFC's downcomer for kaolinite dispersion and the RFC's fluidization bed for generating a low air fraction in reducing kaolinite entrainment. While kaolinite dispersion avoided the blocking of water drainage channels between air bubbles by aggregates, a low air fraction ensured a large gap between air bubbles to allow the displacement of entrained fine particles with fluidization water. Herein, the research findings will guide the resources industry to process low quality resources by successfully rejecting clay and other fine waste materials.

The role of compaction in the diagenetic evolution of Pre-Salt Aptian deposits of Santos Basin, Brazil

The discovery of huge oil accumulations in the South Atlantic Pre-Salt carbonate lacustrine deposits has attracted much exploration and research interest on these challenging reservoirs, but no work has focused on the compaction processes. A petrological and geochemical study was therefore performed on two cored wells in Santos Basin to identify the main syngenetic and diagenetic constituents, and to identify the compaction features that affected these deposits. They are mainly composed of Mg-clays, calcite spherulites and fascicular shrubs, which have undergone a heterogeneous diagenetic evolution. Mechanical compaction occurred during shallow burial, promoting a closer packing of the constituents, reorientation and fracturing of calcite spherulites and bioclasts, and deformation of the clay matrix. Pressure dissolution occurred under increasing pressure and temperature during burial, developing inter-aggregate sutured contacts, dissolution seams and stylolites, as consequence of overburden. Macrocrystalline quartz and calcite, drusy quartz, and saddle dolomite precipitated during burial diagenesis, related to basinal fluids and probably to pressure dissolution, as source for the late carbonate phases. Understanding the role of compaction is essential to evaluate trends of porosity destruction, thickness modification and mass transfer, which directly impacted the quality and the dynamic evolution of fluids in the deep Pre-Salt reservoirs.

Evaluation of shielding properties of a developed nanocomposite from intercalated attapulgite clay by Cd/Pb oxides nanoparticles

The study investigated new nanocomposites’ γ-ray and neutron shielding properties based on raw attapulgite, a clay matrix intercalated with different weight percentages of mixed nano metal oxides CdO and PbO. The various percentages were as follows: (100–2x)% Attapulgite + x%CdO + x%PbO, abbreviated as (AT100–2x CdxPb x ), where x = 5, 10, 15%. The nanocomposites were characterized using XRD, FTIR, and EDX, confirming their successful preparation. SEM images revealed that the mixed oxide nanoparticles were successfully intercalated into the layers of attapulgite clay, with an average particle size of approximately 31.46 nm. The bulk densities of the prepared nanocomposites were measured to be in the range of 2.034 to 2.555 g/cm3. GEANT4 simulations were employed to evaluate the nanocomposites’ γ-ray and neutron shielding performance in the photon energy range of 0.015 to 15 MeV. Phys-X code was used for verification. The simulation results showed a maximum difference of approximately 9.5% between GEANT4 and Phys-X predictions. To assess the γ-ray shielding performance, various shielding parameters were calculated at selected photon energies. The μ m values ranged from 4.589 to 0.020 cm2.g−1, 6.311 to 0.021 cm2.g−1, 8.350 to 0.022 cm2.g−1 and 10.804 to 0.023 cm2.g−1 for raw attapulgite, AT90Pb5Cd5, AT80Pb10Cd10, AT70Pb15Cd15 across the photon energy range. The AT70Pb15Cd15 nanocomposite exhibited the highest μ m , Z eff , Z eq , and the lowest T 1/2, T 1/10, and MFP values. Notably, it also demonstrated the highest FNRCS (approximately 0.1 cm−1). These findings suggest that clay-based nanocomposites represent a new class of low-cost, locally available advanced materials with potential applications in γ-ray and neutron shielding characteristics.

Pre-treatment of hydrolysable nuclear organic liquids prior to their waste management: Solid impregnation of vegetable oil on surfactant-grafted clay particles

In the context of advancing nuclear waste management techniques, this study delves into the novel use of surfactant-grafted clay particles for pre-treating hydrolysable nuclear organic liquids. Our research explores the potential of modified clay materials in immobilizing vegetable oil, a surrogate for complex nuclear waste. We investigate the adsorption capabilities of various clays, including metakaolin, diatomaceous earth and sepiolite, when grafted with cetyltrimethylammonium bromide (CTAB) as cationic surfactant, or decyl glucoside (DG) as non-ionic surfactant. This study employs characterization techniques to assess the physicochemical transformations in clays post surfactant-grafting. Grafting was initially highlighted by TGA, where the breakdown of surfactants can be observed. This is also evidenced by measurements of the ζ-potential, which demonstrate a reduction in surface charge upon the addition of the cationic surfactant, excepted for sepiolite for which the surface charge did not change. Additionally, Washburn measurements indicate that the grafting process converts hydrophilic particles into hydrophobic ones. The oil absorption tests indicated that the CTAB-grafted sepiolite demonstrated superior characteristics, notably exhibiting no oil rejection. Consequently, this specifically synthesized powder was utilized in a two-step process consisting in pre-impregnation of oil up to 20 %v of vegetable oil prior to its immobilization within a geopolymer matrix. Furthermore, the outcomes of the leaching tests revealed that the vegetable oil remained effectively confined within the immobilization matrix, ensuring its retention. The research contributes to the goal of enhancing hydrolysable nuclear waste management practices, ensuring long-term sustainability and environmental safety.

Investigation of the feasibility of alternative burnout material (maize cob) versus the traditional material (sawdust) for point-of-use ceramic water filter production

Ceramic water filters, are a promising household water treatment technology. Filters were produced using clay as the base material and two locally available burnout materials (sawdust and maize cob). The clay which was classified as an Inorganic clay of low to medium plasticity has a liquid limit of 41.1% and plasticity index of 37.4%. The sizes of the combustible materials are 5,10, 22 microns mixed in proportions of 1:1 and 1:2 by proportions of clay and burnout materials respectively, moulded and fired to a temperature of 1000℃. In the end, ten filters were produced from various particles sizes and proportions of the sawdust and maize cob. The bulk density of the filters ranged from 1.67 to 3.5 g/cm3 with a typical value of 2.63±0.57 g/cm3 . Apparent porosity ranged from 94.94 to 99.87% with a typical value of 99.10±1.13%; while water absorption varied from 28.6 to 59.71 % with a mean of 40.02±9.49 %. Flow rate ranged from very slow rate of 0.051 to 0.92 L/h with a typical value of 0.354±0.226 L/h. Based on type of burnout material, filters made with sawdust had higher flow rates (0.433 L/hr) than those made from maize cob (0.291 L/hr). The percent turbidity removal ranged from 9.1% - 43.7% on the first week to 30.6 – 70.4% on the fifth week of the test for filters made from maize cob; whereas the percent turbidity removal ranged from 5.7 – 35.3% on the first week to 44.9 – 75.6% on the fifth day for sawdust. Filters made from sawdust performed significantly better than those made from maize cob (p = 0.044) at 95% confidence level. In terms of particle size, there was an increase in efficiency of Coliform removal efficiency from 99.6 to 99.8% as the particle size of burnout materials increased from 5 μm to 22 μm. Filters made with lower proportion (1:1) of burnout materials exhibited higher Coliform removal (99.76%) than those made with higher (2:1) proportion (99.63%). However, the proportion of burnout materials within the range used in this study did not significantly affect percentage Coliform removal (p = 0.247). Filters made from sawdust generally performed better than those made from maize cob.

Evaluation and application of Moroccan clay materials in ceramic tiles: Composition and technological behavior

This paper aims to assess the suitability of various Moroccan clay materials for application in ceramic tile production. Six clay samples (S1–S6) sourced from cities including Fez-Meknes, Safi, Berrechid, and Benslimane were collected and subjected to comprehensive characterization to elucidate their chemical and mineralogical composition, as well as their morphological and thermal behavior. The impact of sintering temperatures ranging from 900 to 1100 °C on parameters such as bulk density, porosity, water absorption, shrinkage, flexural strength, and chemical resistance was investigated. Results revealed elevated levels of Fe2O3 (>3 %), indicative of dark firing clays across all samples. Additionally, the samples exhibited a composition comprising clay minerals, quartz, feldspars, and carbonates. Based on the findings, it was determined that these clay materials are suitable for the production of cottoforte and majolica falling within the BIIb and BIII ceramic classes (ISO 13006). The study underscores the potential of these materials for utilization in industrial ceramic products, given their demonstrated characteristics.

Variation and correlation between water retention capacity and gas permeability of compacted loess overburden during wetting-drying cycles

Landfill gases can have numerous detrimental effects on the global climate and urban ecological environment. The protective efficacy of the final cover layer against landfill gases, following exposure to periodic natural meteorological changes during long-term service, remains unclear. This study conducted centrifuge tests and gas permeability tests on compacted loess. The experiments examined the impact and relationship of wetting-drying cycles and dry density on the soil water characteristic curve (SWCC) and gas permeability of compacted loess. Research findings reveal that during the dehumidification process of compacted loess, the gas permeability increases non-linearly, varying the gas permeability of soil with different densities to different extents under wetting-drying cycles. Two models were introduced to describe the impact of wetting-drying cycles on gas permeability of loess with various dry densities, where fitting parameters increased with the number of wetting-drying cycles. Sensitivity analysis of the parameters in the Parker-Van Genuchten-Mualem (P-VG-M) model suggests that parameter γ′s accuracy should be ensured in practical applications. Finally, from a microstructural perspective, wetting-drying cycles cause dispersed clay and other binding materials coalesce to fill minuscule pores, leading to an increase in the effective pores responsible for the gas permeability of the soil. These research results offer valuable guidance for designing water retention and gas permeability in compacted loess cover layers under wetting-drying cycles.

Efficient Quantification of Soluble and Insoluble Oxalates in Clay Mineral Mixtures

ABSTRACT Quantification of oxalate salts in soil clay minerals is necessary to study oxalate biogeochemistry, but existing analytical techniques are expensive and time-consuming. We aim to develop an efficient attenuated total reflectance mid-infrared (MIR) spectroscopic technique to quantify oxalate salts in a clay mineral matrix. We calibrated MIR models for analysis of oxalate anion concentrations in standard solutions (0–0.01 M) by using a partial least-squares regression algorithm. MIR models were also developed for analysis of sodium oxalate (NaOx) and calcium oxalate (CaOx) content in clay mineral mixtures with composition like soils of a semi-arid region and with contrasting concentrations (0–1.0 g g−1 for both oxalate salts) to test sensitivity of analyses. Validation plots (true vs predicted values) showed excellent model fit (R2 ≥ 0.96) and accuracy (normalized root mean squared error of prediction ≤ 0.06) for CaOx, NaOx and oxalic acid components. Once predictive models are stored in analytical software, MIR spectroscopic analyses of samples are much more efficient than chemical techniques. Our MIR spectral-based models are suitable for direct quantification of oxalate salts in clay mineral mixtures for samples like those used for model calibration.

Utilization of Quicklime and Limboto Lake Sediment as Basic Materials for Brick Walls

This study is based on knowing the compressive strength of bricks. The objectives that can be achieved are to analyze the characteristics of brick walls using lime, sedimentary soil and clay as well as conventional bricks and evaluate the comparative cost of making conventional bricks and lime-mixed bricks plus sedimentary soil. In this study, Data obtained from testing and analyzed quantitatively using appropriate statistical methods. This analysis will help in understanding the relationship between the composition of the mixture, the manufacturing process, and the characteristics of the resulting bricks. From the results of the analysis, the water absorption of bricks mixed with sedimentary materials, clay and lime. variation of sample 1, where the sample mixture (75% / 20% / 5%) water absorption is (29.72%) variation of sample 2, where the sample mixture (50% / 45% / 5%) water absorption is (9.45%) and Sample 3, (25% / 70% / 5%) water absorption is (9.22%). and clay bricks or without a mixture (100%) is (8.25%). This shows that the absorption capacity of mixed bricks of sediment, clay and lime materials which only have two variations 2 and 3. Meet the requirements of SNI 15-2094-2000 which requires a maximum water absorption capacity of 20% of bricks. While the average compressive strength comparison value of mixed bricks of sediment, clay and lime materials. sample variation 1, which sample mixture (75%/20%/5%) compressive strength value (13.6 kg/cm2) sample variation 2, (50%/45%/5%) which compressive strength value (19.8 kg/cm2) and sample 3, (25%/70%/5%) which compressive strength value (7.4 kg/cm2). and clay bricks without a mixture (100%) namely (36.4 kg/cm2). The compressive strength value of mixed bricks of sediment, clay and lime materials. Does not meet the minimum compressive strength requirements for building earthquake-safe houses (≥30).

Review on Investigating Soil Stabilized Mud Blocks with Combined C&D Waste

Buildings built by ancient civilizations like the Mesopotamians and Egyptians were made of clay and other materials, and the use of stabilized soil for construction dates to those times. On the other hand, the scientific underpinnings of soil stabilization were not established until the early 1900s. In comparison to conventional building materials, the use of stabilized soil-based construction materials, such as soil stabilized mud blocks, can offer several advantages, such as improved strength and durability, less of an adverse effect on the environment, and lower costs. The world is facing an issue that calls for the disposal of inorganic solid waste to be addressed right away. This solid waste that is produced when old buildings are demolished is frequently classified as industrial waste or C&D waste. In India alone, enormous amounts of waste are produced, very little of which is recycled. When modifying the properties of stabilized soil, this C&D waste can be used in place of soil or quarry sand. This work explores the use of a stabilizing agent in conjunction with combined C&D waste for soil sampling. The studies use combined C&D waste and soil stabilized mud blocks to test the hollow blocks' water absorption capacity and strength for various replacements. The materials needed for the study came from nearby structures that had been demolished. Using mortar, cylindrical samples for 32 different ratios of mixed construction and demolition waste with a 9% cement content were cast for various compositions. To determine whether the stabilized samples were suitable for use in construction, tests were conducted on their compressive strength and water absorption properties. Based on the least compressive values found in cylindrical samples, the C&D waste was used in ratios ranging from 0% to 100% in place of soil. Mud blocks stabilized by soil were poured and examined for durability, strength, and mechanical qualities. In this study, an effort was made to use C&D waste—that is, brick and concrete waste—in varying amounts to create cylindrical samples that could be used to create concrete and stabilized mud blocks. In order to create cylindrical samples, different ratios of brick waste, concrete waste, and brick-concrete waste were used for 23 mix proportions. Cylindrical samples were manufactured using a cement content of 9 and 12%. These samples' mechanical and physical characteristics, such as their compressive strength, water absorption capacity, and initial rate of absorption, were investigated.

Low Capacity Brick Factories

The article outlines the concept of construction of seasonal plants of small and medium capacity with proposals to complete them exclusively with domestic equipment and economic justification of profitability of such enterprises. It should be noted that, contrary to popular opinion, the idea of building small and medium capacity plants, including seasonal operation, has proven to be quite viable and reasonable for a number of southern and central regions of Russia and, in the future, for the new regions of Novorossiya, where agriculture is the main type of activity. This is due to climate, population density, building traditions and many other factors. In the foreign press, small factories are mentioned not only in terms of special products, but also as branches of large enterprises for the development of small deposits of unique clay raw materials, on the basis of which the production of facade building ceramics is organized.

USE of Thermal Power Engineering Waste to Reduce the Average Density of Ceramic Wall Materials with a Matrix Structure

It has been presented the results of studies on reducing the average density of ceramic wall materials through the use of ash granules. The chemical, granulometric, and mineral compositions of clay raw materials and fly ash are given. It has been considered the compositions of ceramic charges with different contents of thermal power waste and sample preparation techniques. In the first case, mechanical mixing of the charge components was used, in the second case, granulation of the components and creation of a shell on the surface of the granules was used. The physical and mechanical properties of ceramic samples produced by both methods are presented. It has been established that an increase in the fly ash content in the charge leads to a decrease in the average density and compressive strength of ceramic samples. The use of the developed method for producing ceramic materials increases the strength characteristics of the samples, which makes it possible to increase the content of the ash component to 70–80 wt. % in the composition of the charge. It has been shown that the content of fly ash in the charge is more than 60 wt. % leads to an increase in water absorption of more than 20%, which practically indicates the absence of sintering processes in ash granules. Prospects and main directions for further research are formulated.

Use of Industrial Waste to Improve the Performance Properties of Ceramic

Industrial waste, with an in-depth study of its resource capacity, physico-chemical and technological properties, is a valuable raw material for construction ceramics. The possibility of replacing high-quality clays in technologies for producing clarified ceramic bricks and effective wall ceramics using high-calcium waste generated during water purification by liming in thermal power engineering, chemical and other enterprises has been established. The obtained physicochemical patterns of formation on their basis of the structure and properties of a ceramic composite provide a scientific basis for the use of typical waste, in these studies, dust from electric precipitators of cement production. The role of aluminum-containing waste generated during the electrolysis of molten aluminum in regulating the technological properties of the masses and firing properties of clinker bricks has been revealed, which allows the use of low-grade clays for its production. Scientific research and recommendations on the use of various industrial wastes not only for the purpose of recycling, but also for the use of their valuable properties associated with the chemical composition, behavior in heat treatment, reactivity, the possibility of strengthening due to the formation of a controlled structure of the material, help slow down the process of decline reserves of high-quality clay raw materials.

Clinker High-Hollow Ceramic Stones: Prospects for Technology and Application

A substantiation is given for the prospects of using clinker large-format ceramic stones of increased hollowness with a water absorption of less than 3% in construction. It has been shown that due to the high strength of the ceramic material itself (more than 100–150 MPa), ceram-ic stones will have the necessary strength – more than 10–15 MPa in terms of compressive strength. Due to the increased void content with as many rows of voids as possible per 100 mm length of the ceramic stone and a smaller thickness of the internal walls, the stones will have reduced thermal conductivity. Due to the low porosity of clinker ceram-ics as a material and the use of appropriate masonry mortars, masonry made of clinker stones will be guaranteed not to be vapor permeable, which will significantly increase the service life of buildings. When us-ing certain technological techniques, namely the application of cham-fers, relief, engobes on the front faces, large-format high-hollow clinker stones can also play the role of facing products, which will significantly increase their consumer attractiveness. With an increase in the hollow-ness of stones, the costs of mass preparation, drying and firing of products are proportionally reduced, which significantly reduces their cost. It has been shown that the “ideal” raw material for producing clinker large-format ceramic stones can be stone-like clay raw materials – argillite-like clays, argillites, shales and their transitional varieties. When grinding them and preparing molding masses, due to the for-mation of a certain grain composition and the introduction of corrective microadditives, it is possible to obtain molding masses with optimal pre-firing technological properties and a clinker shard with water ab-sorption of up to 3% and a compressive strength of up to 200 using one raw material. MPa, bending strength up to 50 MPa.

Friction Characteristics Between Marine Clay and Construction Materials

Friction Characteristics Between Marine Clay and Construction Materials

Assessment and Characteristics of Molding Masses Based on Loam during Production Soft Molded Ceramic Brick

опThe article discusses the issues of assessing the properties of loams and selecting the composition of molding compounds based on them for the production of ceramic bricks using the soft molding method. It is noted that for soft molding technology, to date, no recommendations have been developed for the evaluation of raw materials with the establishment of relationships between the composition, technological properties, molding features and aesthetic features of the front edges of products. According to technological features, the method of soft molding of ceramic bricks is conventionally divided into 4 methods: manual molding, accelerated molding, pressing method and vibration molding method. The results of our work made it possible to identify the main indicators when assessing clay raw materials and to develop the basic principles for selecting the composition of molding masses. Thus, the critical compression stress and the degree of deformation of the workpieces should be on average 0.2–0.8 kg/cm2 and 3–5 units, respectively. In this case, the molding masses should have the minimum possible water content and stickiness, have minimal air shrinkage (less than 6–7%), and be slightly or moderately sensitive to drying. An algorithm has been developed for selecting molding compounds, including determination, in addition to generally accepted indicators, such as the degree of deformation and critical compressive stress at different water contents, specific penetration resistance, determination of the optimal electrolyte content, and stickiness. For typical loams, the dependences of the degree of deformation of the samples and the critical compressive stress on the water content of the molding masses are shown, as well as the influence of electrolytes on the water content. It has been shown that the introduction of electrolytes can significantly reduce the water content of molding masses. It is noted that the genesis of loams, their variable composition and the frequent presence of undesirable harmful impurities predetermined the situation that high-quality loams that meet the necessary requirements are quite rare and the only alternative can be the selection of compositions of molding compounds based on correct scientific and methodological

Diffusion of Radioactive Waste Elements from Underground Water and Leachates of Phosphate Waste Forms in Pore Solution of Clay Materials

Diffusion of Radioactive Waste Elements from Underground Water and Leachates of Phosphate Waste Forms in Pore Solution of Clay Materials

Diagenetic Impact on High-Pressure High-Temperature Reservoirs in Deep-Water Submarine Fan Sandstone of Qiongdongnan Basin, South China Sea

The diagenetic evolution of sandstone is very complicated under the conditions of high temperatures and pressures in deep-water, deep-buried regimes, which have great influence on reservoir quality. This study investigates the typical reservoir target of Neogene deep-water, submarine-fan sandstones under high-temperature, high-pressure regimes in the Qiongdongnan Basin, South China Sea. Utilizing a thin section, scanning electron microscope (SEM), mineral geochemistry combined with burial history evolution, complex diagenetic events, and main controlling factors of the sandstone in the Neogene Meishan Formation were determined. The results show that the evolution of sandstone reservoirs is initially controlled by depositional framework compositions and subsequently modified by eogenetic and mesogenetic alterations during progressive burial. Eogenetic alterations mainly include the following: (1) mechanical compaction; (2) dissolution of feldspar; (3) low-Fe calcite cementation. Mesogenetic events were identified as the following: (1) dissolution of feldspar; (2) ferroan calcite and ankerite formation; (3) precipitation of quartz and clay mineral. Mechanical compaction is greatly influenced by the original depositional framework composition, and sandstone samples enriched in high contents of detrital clay matrix always experienced extensive mechanical compaction. Different phases of carbonate cement during different diagenetic regimes lead to continuous destruction on reservoir porosity. The dissolution of unstable feldspar minerals during eogenetic and mesogenetic environments leads to the development of secondary porosities and would enhance the quality of the reservoir. Overpressure formation is pervasively developed owing to early disequilibrium compaction and subsequent natural gas charging. Only well-sorted sandstones with low contents of detrital clay matrix could resist early mechanical compaction, lead to ample residual original porosities, and then undergo extensive mineral dissolution to generate sufficient secondary porosities. Subsequently, these porosities would be effectively protected by overpressure formation. Poor-sorted sandstones with high contents of detrital clay matrix would experience strong mechanical compaction and extensive destruction of original porosities. Thus, these sandstones are difficult to have significant dissolution and are unable to be effectively protected by overpressure formation. Therefore, the interplay between the original framework composition and the corresponding diagenetic pathways coupled with overpressure formation would result in strong reservoir heterogeneity for the deep-buried sandstones during progressive burial.