Rock Surface Research Articles

ADHESIVE ABILITY OF GYPSUM-CONTAINING PLASTER COMPOSITIONS

The traditional material for the construction of buildings in the Northern Black Sea region is a cheap local stone ‒ limestone-shell rock. Most of the buildings in the central part of the city of Odesa, which are of historical and architectural value, are constructed of this material. With proper care and maintenance, these structures can perform their functions for hundreds of years, but as a result of shell rock moisture due to negligent operation and a number of other reasons, the supporting structures are damaged, followed by the collapse of the building. In many cases, the direct cause of the destruction of load-bearing walls is the damage or absence of the outer plaster layer. Repairing walls with cement compounds exacerbates the problem. The article discusses some aspects of the possible use of gypsum-based composite materials for repairing damaged walls of limestone-shell rock buildings. The requirements for the repair composition are formulated. The expediency of using gypsum as a binder for the repair plaster mixture for exterior repairs is substantiated. An ash-gypsum-cement composition was used to increase the water resistance of the plaster. Sufficient water resistance and vapor permeability of the proposed composition were confirmed. This paper presents the results of studying the adhesive strength of the contact of the developed composition with the surface of various materials. Methods and measuring equipment developed at the ODABA were used. The adhesion strength of the proposed mixture with the surface of shell rock is close to the standard strength. The use of the adhesive additive Ceresit CC 81 increases the adhesive strength of the joint of the proposed composition with shell rock by 1.5 ‒ 2 times. The optimal amount of the adhesive additive to be introduced will be determined by the results of a multifactorial experiment to study the effect of a complex of chemical additives of different functional purposes on the properties of the proposed repair composition.

Review of Reservoir Damage Mechanisms Induced by Working Fluids and the Design Principles of Reservoir Protection Fluids: From Oil–Gas Reservoirs to Geothermal Reservoirs

Various working fluids are applied during geothermal reservoir development, and geothermal reservoir damage induced by contacts between working fluids and reservoir formations are inevitable. Reservoir damage mechanisms, including solid and colloidal plugging, fluid sensitivity, stress sensitivity, and water locking, provide guidance for designing reservoir protection working fluids. In this paper, based on the design principles of reservoir protection working fluids applied in oil–gas reservoirs, four design principles of reservoir protection working fluids are proposed to eliminate potential geothermal reservoir damage for geothermal reservoirs, containing solid-free, facilitated flowback, temporary plugging, and inhibition. Solid-free is achieved by replacing solids with polymers in working fluids. Surfactant and materials with low affinity towards rock surfaces are applied for the facilitated flowback of working fluids from reservoir formations. Temporary plugging is achieved by using temporary plugging materials, some of which are polymers that also apply to solid-free working fluids. Besides, some of the temporary plugging materials, such as surfactant, are applicable for both the facilitated flowback and inhibition of working fluids. The inhibition of working fluids include the inhibition of clay minerals, which can be attributed to clay mineral inhibitors or activity regulators in working fluids, as well as the inhibition of mineral precipitations. This review aims to provide insights for geothermal reservoir protection working fluids, contributing to achieving an efficient development of geothermal resources.

Microscale insights into enzyme-induced carbonate precipitation in rock-based microfluidic chips

Biomineralisation technology shows promise for sealing subsurface fractures, but understanding its microscale mechanisms in real rock fractures remains incomplete. In this study, a microfluidic chip incorporating real rock slices was utilised to conduct enzymatically induced carbonate precipitation (EICP) experiments using a one-phase continuous injection strategy. Real-time observations revealed grey flocs forming and clustering into aggregates susceptible to transport by flow. Calcium carbonate (CaCO3) crystals that formed on rock and polydimethylsiloxane surfaces effectively filled and bridged fractures, leading to a significant pressure drop. Rough surfaces can provide additional sites for solute attachment and heterogeneous nucleation of calcium carbonate. High velocities and small apertures generally promoted floc formation and reduced crystal growth. Precipitation content gradually increased with a decreasing rate. Lower estimated precipitation efficiency was obtained in smaller, high-flow fractures. Precipitates on rock interfaces induced eddies and significant pressure drops within narrow pore throats. Crystal growth displayed a two-stage development: an initial increase followed by a decrease, varying across different facets (the surfaces or orientations of the growing crystals). Growth competition will occur when two or more neighbouring crystals come into contact with diverse grain orientations. The findings provide valuable microscale insights into microscale processes governing EICP within real rock fractures, contributing to evaluation of its efficacy in subsurface fracture sealing applications.

Features and processes of rock weathering in central Dronning Maud Land, Antarctica

In this study, we have investigated rock weathering phenomena in the central part of Dronning Maud Land, Antarctica. The area is characterized by low mean annual temperatures (−18 °C), strong katabatic winds, and minimal liquid water at the surface. Weathering features, including ventifacts, tafoni, and grus accumulations, are characterized through field observations, rock surface temperature measurements, and microscopic analysis. Abrasion by sand and ice particles transported by strong winds has locally resulted in ridge-shaped ventifacts and rock surfaces with elongated pits, furrows, and grooves. The abrasion-caused features, such as polished facets, keels, and grooves, indicate a northeast-facing wind direction, aligning with the present-day wind regime. The dominant weathering processes in coarse-grained intrusive rocks are oxidation and granular disintegration. Fe-oxidation induces cracking, increasing the porosity and enhancing susceptibility to further weathering. Additionally, temperature fluctuations on rock surfaces caused by solar radiation create thermal stress, which can lead to the formation of microcracks. These microcracks, formed due to thermal expansion, are likely to propagate through subcritical cracking, which is a slow, long-term process. Together, Fe-oxidation, thermal expansion, and subcritical cracking are important mechanisms contributing to long-term weathering and rock decay. Salt weathering, facilitated by snow and ice meltwater, particularly within tafoni, leads to flaking and disintegration of the parent rock. These findings shed light on the complex interactions shaping the geomorphology of central Dronning Maud Land and provide insights into long-term weathering processes operating in Antarctica's extreme environment.

Luminescence dating of rock surfaces in challenging environments: The case of MIS5e gravelly transgressive lag deposit (Southern Sardinia, West Mediterranean Sea)

Determining the age of precise sea level markers such as marine terraces is often difficult because of the inherent limitation of traditional dating methods. A novel method based on Optical Stimulated Luminescence applicable to rock surfaces has been showing great promise in dating boulder and cobble surfaces from various environments. We performed Optically Stimulated Luminescence Rock Surface Dating (OSL RSD) on five cobbles from a basal transgressive lag deposit sealing a marine terrace referred to as the Last Interglacial (Marine Isotopic Stage 5e). We applied a consistent and highly selective 3-step acceptance criteria on five cobbles and obtained that only one was sufficiently well-bleached prior to burial. The resulting ages of 131 ± 8 ka and 127 ± 8 ka (obtained on 22 analyzed aliquots, n = 22) derived from the post-infrared infrared stimulated signal at 225oC (pIRIR225) and the preceding infrared stimulated signal at 50oC (pIR50/225), respectively, are consistent with each other as well as with the conventional luminescence age of ∼135 ka from the same sequence and with the U/Th age of ∼130 ka obtained from coral fragments. This work demonstrates that the RSD is a promising method for dating gravel veneer deposits overlaying marine terraces, enabling new chronologies for similar Quaternary deposits.

Characterizing the free-vibration response of a two-span rocking bridge with free-standing columns

For accelerated bridge construction (ABC), replacing traditional emulative connections of precast elements with simpler discontinuities may lead to more resilient structures with reduced expected damages after strong seismic events. This paper comprises novel free-vibration tests of a 1:10 scale two-span rocking bridge with free-standing columns with proper geometrical and dynamic similarity. The two spans induced in the model the interaction between frames with different tributary masses, as would be expected for a realistic bridge. To excite the bridge uniformly, the experimental protocol consisted of forty-nine incremental sinusoidal ground motions that were interrupted, letting the bridge vibrate freely to rest. The results were compared with six analytical models. The results showed that the structure remained undamaged for the free-vibration tests after drifts up to 6 % and did not wobble unrestricted. The results were used to obtain the dynamic properties of the system and their variation to displacement increments. Construction imperfections induced the model to rock for all excitations, including low-intensity excitations, and to vibrate with periods different from those of theoretical equations at low displacements. This behavior was critical in the comparison between experimental results and the estimates from analytical models. These findings demonstrate that rocking bridges are a suitable system to control structural damage during seismic events despite the apparent variability of the behavior under realistic conditions. However, the design of these structures must account for the effects of construction imperfections at the rocking surface. The experimental results are openly available for download in the DesignSafe Data Depot using this DOI https://doi.org/10.17603/ds2-znfv-8t55.

The effectiveness of chalk as a friction modifier for finger pad contact with rocks of varying roughness

The application of chalk (magnesium carbonate) in rock climbing is common practice as climbers attempt to improve their grip by removing moisture from their hands with the aim of increasing friction at the finger pad-rock interface. This novel work investigated the effectiveness of chalk as a friction modifier on four different rocks (sandstone, granite, dark limestone and light limestone) typically found in areas of the UK where the sport of climbing is undertaken, with varying surface roughness. The static coefficient of friction was measured for dry and wet fingertip conditions with and without chalk, under normal (‘grip’) forces of 5, 10 and 15 N. Results showed that the effectiveness of chalk as a friction modifier is dependent on a number of factors such as moisture level and the gradient of the asperity at the rock surface, however, in general chalk applied to dry fingertips had a more positive effect on the static coefficient of friction than in simulated sweaty conditions. During lab tests, chalk was also seen to be beneficial by making the static coefficient of friction more consistent across most test conditions. The results of this study, and the explanation of friction mechanisms involved, provides guidance for the use of chalk with consideration of the type of rock which is being climbed.

Anatomy of a fumarole field: drone remote-sensing and petrological approaches reveal the degassing and alteration structure at La Fossa cone, Vulcano, Italy

Abstract. Hydrothermal alteration and mineralization processes can affect the physical and chemical properties of volcanic rocks. Aggressive acidic degassing and fluid flow often also lead to changes in the appearance of a rock, such as changes in surface coloration or intense bleaching. Although hydrothermal alteration can have far-reaching consequences for rock stability and permeability, limited knowledge exists on the detailed structures, extent, and dynamic changes that take place near the surface of hydrothermal venting systems. By integrating drone-based photogrammetry with mineralogical and chemical analyses of rock samples and surface gas flux, we investigate the structure of the evolving volcanic degassing and alteration system at the La Fossa cone on the island of Vulcano, Italy. Our image analysis combines principal component analysis (PCA) with image classification and thermal analysis through which we identify an area of approximately 70 000 m2 that outlines the maximum extent of hydrothermal alteration effects at the surface, represented by a shift in rock color from reddish to gray. Within this area, we identify distinct gradients of surface coloration and temperature that indicate a local variability in the degassing and alteration intensity and define several structural units within the fumarole field. At least seven such larger units of increased activity could be constrained. Through mineralogical and geochemical analysis of samples from the different alteration units, we define a relationship between surface appearance in drone imagery and the mineralogical and chemical composition. Gradients in surface color from reddish to gray correlate with a reduction in Fe2O3 from up to 3.2 % in the unaltered regime to 0.3 % in the altered regime, and the latter coincides with the area of increased diffuse acid gas flux. As the pixel brightness increases towards higher alteration gradients, we note a loss of the initial (igneous) mineral fraction and a change in the bulk chemical composition with a concomitant increase in sulfur content from close to 0 % in the unaltered samples to up to 60 % in samples from the altered domains. Using this approach of combined remote-sensing and in situ analyses, we define and spatially constrain several alteration units and compare them to the present-day thermally active surface and degassing pattern over the main crater area. The combined results permit us to present a detailed anatomy of the La Fossa fumarole field, including high-temperature fumaroles and seven larger units of increased alteration intensity, surface temperature, and variably intense surface degassing. Importantly, we also identify apparently sealed surface domains that prevent degassing, likely as a consequence of mineral precipitation from degassing and alteration processes. By assessing the thermal energy release of the identified spatial units quantitatively, we show that thermal radiation of high-temperature fumaroles accounts for < 50 % of the total thermal energy release only and that the larger part is emitted by diffuse degassing units. The integrated use of methods presented here has proven to be a useful combination for a detailed characterization of alteration and activity patterns of volcanic degassing sites and has the potential for application in alteration research and for the monitoring of volcanic degassing systems.

A comprehensive study of the enhanced oil recovery potential of low-salinity water in heavy oil sandstone reservoir

To determine the enhanced oil recovery potential of low-salinity brine for a heavy oil sandstone reservoir, a holistic approach including both experimental and theoretical studies was employed in this study. Macro-scale forced and spontaneous imbibition tests were performed to quantify the oil recovery potential by our considered three brines. Furthermore, micro-scale experiments, including FTIR (Fourier-Transform Infrared Spectroscopy), TGA (Thermogravimetric Analysis) and zeta potential, were executed to explore the micro-scale oil-brine-rock interactions (i.e., polar component desorption from the rock surface) that has controlled the macro-scale oil recovery efficiency. In addition, to further investigate the underlying physical mechanism that leads to the discrepancy in polar component desorption when subjected to different brines, charge-distribution multi-site complexation model (CD-MUSIC) and DLVO-based disjoining pressure calculation were performed to describe the molecular-level electrokinetic interactions at the oil-brine and rock-brine interfaces, as well as the total interaction force between these two interfaces. Our results show that the oil recovery efficiency of the low-salinity aquifer water (LSAW) was markedly higher than produced water (PW) and seawater (SW) from the forced and spontaneous imbibition tests. Combined with the marginal difference on interfacial tension (IFT) results, it guided us to conclude that the micro-scale oil-brine-rock interaction controlled the macro-scale oil recovery performance. FTIR and TGA experimental results on pristine quartz, oil aged quartz, as well as different water treated aged quartz powders revealed that the polar component desorption efficiency in different brines followed the order of LSAW > PW > SW, which was consistent with the macro-scale oil recovery trend. The total disjoining pressure result gave rise to the conclusion that the most repulsive disjoining pressure in LSAW leads to the most efficient desorption of polar oil component from the rock surface. In addition, the electrokinetic properties of the oil/brine and rock/brine interfaces, as well as the consequent electrical double layer force play a crucial role in differentiating the oil-brine-rock interactions in different brines. This study has shed light on the further application of low-salinity aquifer water in our target heavy oil reservoir.

CHEMOMETRIC EVIDENCE FOR SR AND RB ISOTOPES DUE TO THE SPECIFIC SOIL CHEMISTRY IN DIFFERENT GEOGRAPHICAL REGIONS

Strontium and rubidium are the commonly used metals for isotope-ratio analysis. Moreover, this geochemical marker varies between different rock types and formations. The 87Sr/86Sr ratio has been shown to vary widely in surface rocks, so any Sr released into soils, rivers, and groundwater has an isotopic signature that reflects its source. Sr and Rb isotopes have also been used to trace agricultural products, which have incorporated Sr, along with Ca, from soils incorporating the Sr-isotope ratios of the underlying rocks. The specific conditions in the soil represent characteristic conditions of the environment which is reflected in a certain way in the plants. Despite uncertainty about the organic compounds in a sample, the content of selected elements (trace and rare earth elements, REEs) reflects the growing conditions in the environment. For that instance, in the present research, we will give focus on the inorganic compounds’ identifications, due to the more stable response to the lithogenic nature of the soil-plant interaction. For the present study, the target isotopes were 88Sr, 87Sr, 86Sr, and 85Rb. The isotope analysis was conducted with the application of ICP-MS, following the protocol provided in the EPA METHOD 6020. In the validation process, no significant interference occurred that could affect the sensitivity of the measurement of the selected isotopes. Data analysis has been applied to the comparative issues between Sr and Rb content in soil from North Macedonia and selected regions in China. Moreover, the same chemometric model was applied for data analysis for selected plant species for both regions. Data analyses has improved the significant differences within the element contents and ratios as well between both geographical regions.

Mechanisms of surfactant improving water injection huff and puff efficiency in tight reservoir

Water injection huff and puff is an economical and effective method to enhance the recovery of tight oil reservoir, in which the addition of suitable surfactants is critical, but its mechanism needs to be further studied. In this paper, the huff and puff process is divided into replenishment, imbibition and water flooding stages. This study compared and analyzed the effects of various surfactants on interfacial tension, wettability, flow resistance, and oil washing efficiency, using mineralized water as the control group. The relationships between different surfactants and imbibition recovery efficiency, water flooding recovery efficiency, and flooding pressure were investigated. The mechanisms by which surfactants influence the imbibition and flooding processes were also explored. The results show that, the effect of permeability on imbibition and water flooding recovery efficiency in natural cores can be ignored. During the imbibition stage, the maximum recovery efficiency with mineralized water is 18.33 %, while with surfactants it is 21.40 %. In the water flooding stage, the maximum recovery efficiency with mineralized water is 3.89 %. The addition of surfactants significantly increases the water flooding recovery efficiency to 19.82 %. Furthermore, surfactants can reduce the water flooding pressure by approximately 7.00 MPa and increase the total recovery rate by about 5.00 %. The primary mechanisms by which surfactants improve the water injection huff and puff effect include reducing interfacial tension, altering wettability, facilitating crude oil detachment from rock surfaces, and enhancing oil washing efficiency. Reduction of flow resistance, leading to a decrease in the pressure required for flooding. The research results provide a theoretical basis for the practical application of surfactants in water injection huff and puff in tight reservoirs.

In situ shale wettability regulation using hydrophobic ionic liquid functionalized nano-silica to enhance wellbore stability in deep well drilling

Shale wellbore instability due to hydration significantly hinders the efficient extraction of clean shale gas resources, making the development of effective shale stabilizers for safe drilling in shale reservoirs an urgent priority. In this study, we proposed an innovative application of hydrophobic ionic liquids functionalized nano-SiO2 (ILs@SiO2) specifically designed to maximize hold wellbore strength and effectively inhibit shale hydration. The chemical composition and microstructure of ILs@SiO2 were characterized, and their effects on wellbore stability were thoroughly investigated along with the underlying mechanisms. The shale stabilizer demonstrated significant clay swelling inhibition (9.5 %), as well as effective hydration and dispersion inhibition of shale cuttings at 150 °C (88.0 %), and a reduced spontaneous imbibition of shale (0.997 g). Particularly, ILs@SiO2 maximized maintained wellbore strength (203.4 MPa) and minimized water invasion (5.5 mL). Mechanism analysis revealed that ILs@SiO2 improved wellbore stability through electrostatic adsorption weakening osmotic hydration, physical plugging establishing a dense preventing water barrier, altering wettability decreasing rocks surface free energy, inhibiting surface hydration, and reversing the direction of capillary forces. This study offers new strategies and insights for constructing methods to plug shale nanopores and inhibit surface and osmotic hydration.

Unveiling heavy metal pollution dynamics in sediments of river Ulhas, Maharashtra, India: a comprehensive analysis of anthropogenic influence, pollution indices, and health risk assessment.

Metals and metalloids tainting sediments is an eminent issue, predominantly in megacities like Mumbai and Navi Mumbai, requiring an exhaustive examination to identify metal levels in river bodies that serve various populations. Thus, utilising pollution indices, multivariate analysis, and health risk assessment studies, we propose a novel investigation to examine the metal content in the Ulhas River sediments, a prominent agricultural and drinking water supply (320 million-litre per day) near Mumbai in Maharashtra, India. The eleven metals and metalloids (As, Cd, Cr, Cu, Fe, Hg, Mn, Ni, Pb, Se, and Zn) were examined monthly from 10 stations totaling 120 sediment specimens from October 2022 to September 2023. Investigations revealed that average values of Cr, Cu, Hg, and Ni exceeded Australian and New Zealand Environment and Conservation Council and Agriculture and Resource Management Council values, while all metals exceeded World surface rock average limits except As. Various pollution indices showed that upstream sites had noneto low levelcontamination, whereas downstream locations had moderate to considerablecontamination, suggesting anthropogenic influences. Furthermore, multivariate analysis including correlation, cluster, and principal component analysis identified that sediment pollution was mostly caused by anthropogenic activities. Lastly, health risk assessment indicated Fe was non-carcinogenic to children, whereas Cr and Ni were carcinogenic to children and adults, with children being more susceptible. Thus, from the findings of the study it is clear that, despite low to moderate pollution levels, metals may have significant repercussions, thus requiring long-term planning, frequent monitoring, and metal abatement strategies to mitigate river contamination.

Comparative investigation of heat extraction performance in 3D self-affine rough single fractures using CO2,N2O and H2O as heat transfer fluid

The type and thermophysical properties of heat transfer fluids significantly impact the heat extraction rate of Enhanced Geothermal Systems (EGS). Studies based on field-scale stochastic discrete fracture network geometric models have certain limitations and uncertainties. To compare the heat extraction performance of heat transfer fluids H2O, CO2, and N2O in a core-scale (φ50 × 100 mm) rough single fracture in hot dry rock, we first constructed the fracture geometry with rock surface roughness characteristics using a fractal self-affine function, with a joint roughness coefficient (JRC) of 12.38. Then, at temperatures ranging from 37 to 300°C and a pressure of 30 MPa, we established a thermo-hydraulic (TH) coupling model based on the thermophysical parameter equations of the three heat transfer fluids. Finally, we conducted a comparative study of the changes in the outlet mean temperature and heat extraction rate after flowing through the fracture, as well as the temperature distribution on the fracture surface, under conditions of constant inlet flow velocity with varying inlet temperature and constant inlet temperature with varying inlet flow velocity. The results indicate that (1) with the increase in inlet flow velocity and temperature, the outlet mean temperature and heat extraction rate of CO2 and N2O at the fracture outlet are essentially the same and lower than those of H2O. (2) When the inlet flow velocity increases from 0.005 m/s to 0.025 m/s, the thermal convection effect from the rock matrix to the fluid in the fracture predominates, and flow velocity is the main factor affecting the heat transfer process between the fluid and the rock matrix. When the inlet temperature increases from 37°C to 57°C, the thermal conduction effect from the rock matrix to the fluid in the fracture predominates, and temperature is the main factor affecting the heat transfer process between the fluid and the rock matrix.(3)When maintaining constant inlet temperature, increasing inlet flow velocity from 0.005 m/s to 0.025 m/s results in CO2 experiencing a maximum heat extraction rate increase of 118.85 W. In contrast, N2O experiences 117.05 W, and H2O experiences 266.4 W.(4) When the inlet flow rate is constant, the maximum increase in heat extraction rate for CO2 is 15.34 W as the inlet temperature increases from 37 °C to 57 °C; for N2O, it is 13.9 W; and for H2O, it is 45.45 W.

Unveiling the menace of lampenflora to underground tourist environments

Permanent artificial lighting systems in tourist underground environments promote the proliferation of photoautotrophic biofilms, commonly referred to as lampenflora, on damp rock and sediment surfaces. These green-colored biofilms play a key role in the alteration of native community biodiversity and the irreversible deterioration of colonized substrates. Comprehensive chemical or physical treatments to sustainably remove and control lampenflora are still lacking. This study employs an integrated approach to explore the biodiversity, eco-physiology and molecular composition of lampenflora from the Pertosa-Auletta Cave, in Italy. Reflectance analysis showed that photoautotrophic biofilms are able to absorb the totality of the visible spectrum, reflecting only the near-infrared light. This phenomenon results from the production of secondary pigments and the adaptability of these organisms to different metabolic regimes. The biofilm structure mainly comprises filamentous organisms intertwined with the underlying mineral layer, which promote structural alterations of the rock layer due to the biochemical attack of both prokaryotes (mostly represented by Brasilonema angustatum) and eukaryotes (Ephemerum spinulosum and Pseudostichococcus monallantoides), composing the community. Regardless of the corrosion processes, secondary CaCO3 minerals are also found in the biological matrix, which are probably biologically mediated. These findings provide valuable information for the sustainable control of lampenflora.

Effect of artificially induced microcracks near the rock surface on granite fragmentation performance under heating treatment

Various novel assisted drilling technologies enhance rock fragmentation performance by introducing microcracks on the rock surface to weaken rock strength. However, the quantitative relationship between artificially induced microcracks and rock fragmentation characteristics is not clear. In this study, we induced artificial microcracks of varying degrees on the rock surface through one-dimensional heat conduction. With the aid of the fluorescent resin, we visualized the microcrack patterns and quantitatively assessed the artificially induced microcracks. Subsequently, we performed quasi-static indentation tests on granite samples containing microcracks to establish the quantitative relationship between microcracks and rock fragmentation performance. The results indicate that the release of crystal water within the temperature range of 200 °C–300 °C is the primary factor leading to a significant increase in microcracks. Load drop signals correlate with the propagation of microcracks, including the competitive interactions between mechanically induced microcracks and artificially induced microcracks. Artificially induced microcracks require a certain initial length to continue propagating under mechanical stress, and excessively short microcracks are detrimental to subsequent propagation. A higher density of microcracks implies a more complex microcrack network, facilitating the merging of cracks to form rock chips under smaller mechanical loads. The consistency between the length density and number density of microcracks in influencing the crater parameters reflects their equal importance in affecting rock fragmentation performance. These findings could help determine the extent of rock weakening by artificially induced microcracks and reveal the mechanisms of rock fracture behavior influenced by microcrack, holding significant implications for the optimization of the process parameters of various assisted rock drilling techniques.

Janus SiO2-surfactant dispersion designed for enhanced imbibition oil recovery in ultra-low permeability reservoirs

The use of nanofluids in formations with high temperatures and high salinity is currently encountering significant obstacles. Therefore, a Janus SiO2-surfactant dispersion consisting of Janus nanoparticles and surfactants was constructed in the current study. The Janus SiO2-surfactant dispersion is resistant to both high temperatures and high salinity. The Janus SiO2-surfactant dispersion, consisting of Janus SiO2 nanoparticles and the non-ionic surfactant Tween80, is abbreviated as JASN-T80 hereafter. The system can be dispersed and kept stable for one week at a salinity of 30,000 mg/L and a temperature of 85 ℃. The concentration of f nanoparticles and surfactant in the system was optimized at 0.02 wt% Janus SiO2 nanoparticles + 0.04 wt% Tween80 based on the particle size. An assessment was conducted to measure the system's capacity to decrease interfacial tension and alternate wettability. The interfacial tension between oil and water was reduced to 1.21 mN/m. The JASN-T80 system demonstrates a notable capacity to change wettability by decreasing the contact angle of water on an oil-wet rock surface from 100.6° to 70.5°. The combination of nanoparticle and surfactant leads to a synergistic effect, resulting in an imbibition recovery of 44.28 % for ultra-low permeability core. This work provides a novel concept for the advancement and utilization of nanofluid imbibition system for unconventional reservoir.

Quantifying the effects of carborundum rock surface smoothing for Schmidt hammer R‐value metrics measured on glacial erratics in the North American Great Lakes region

AbstractSchmidt hammer R‐values, which reflect the degree of rock surface weathering, can be paired with independent rock surface exposure ages to produce Schmidt hammer exposure‐age dating (SHD) calibration curves that are used to provide rapid estimations of exposure ages for undated rock surfaces. In this Letter, we lay the groundwork for later establishing a SHD calibration curve based on glacial erratics deposited by the Laurentide Ice Sheet in the North American Great Lakes region. First, we establish a reference R‐value for a calibration boulder, which may be used to facilitate direct comparison of R‐values collected by different individuals using mechanical N‐type Schmidt hammers, specifically. We then assess how no, light or heavy use of a carborundum puck to smooth rock surfaces affects resulting R‐value data. Lastly, we compare two different R‐value metrics on the same rock surface: Rmean (n = 30) versus ΔR (Rmax − Rmin of five consecutive R‐values on the same spot). In all assessments, Rmean is similar for erratic surfaces with no and light surface treatment, and both are significantly lower than Rmean of surfaces with heavy treatment. Thus, we advise against the use of heavy surface treatment in SHD applications. We observe no relationship between inferred erratic age and either Rmean or ΔR, which could arise from inferred ages of erratics being inaccurate, from inferred ages of erratics being too similar or from measuring too few erratics from each landform.

Towards accurate modelling of rock surface exposure dating using luminescence to estimate post-exposure erosion rate

Depth-dependent luminescence in the top few millimetres of rock surface emerges as a potential tool to estimate rock surface exposure age and post-exposure erosion rate. It relies on the principle that the luminescence depth profile (LDP) propagates deeper with the time of sunlight exposure and moves to shallower depth with the erosion rate. The propagation of LDP is generally assumed to follow the first-order kinetic (FOK) model, except for a few recent studies. The FOK model predicts an exponential decay of infrared stimulated luminescence (IRSL) signal with light exposure time, which rarely corroborates experimental observation; IRSL signal decay is much slower than exponential decay. The faster decay of IRSL, predicted by the FOK model, results in faster propagation of LDP and thus always underestimates the exposure age and translates into a higher erosion rate. Interestingly, the slower-than-exponential decay of the IRSL signal can be better explained by general order kinetics (GOK). Thus, recent studies on rock surface luminescence dating have employed the GOK model. However, the GOK model is yet to be explored to predict post-exposure erosion rates. Here, we apply the GOK model and theoretically demonstrate the impact of the order of kinetics on the calibration and propagation of LDP in the presence of erosion and how the LDP's transient to steady state transition depends on the order of kinetics. We have performed a series of synthetic tests to assess the impact of selecting an incorrect model on the prediction of erosion rate. Finally, using the revised rate equation, the erosion rates are recalculated for natural samples (data available in the literature: Lehmann et al. (2019b)) and the impact of GOK on the predicted erosion rate is discussed.

Technology Focus: Oilfield Chemistry (September 2024)

In an era marked by a growing emphasis on sustainability, industries are increasingly adopting innovative technologies to address resource-management challenges and environmental impacts. Three notable advancements in this field are the extraction of lithium from produced water, the use of rhamnolipids as biosurfactants, and the application of graphene nanoplatelets (GNPs) as scale inhibitors. Each of these technologies offers a unique approach to improving efficiency and reducing environmental footprint. Lithium, a critical component in lithium-ion batteries used for electric vehicles and renewable energy storage, has seen a surge in demand. Traditionally, lithium is extracted through energy-intensive methods such as mining hard rock deposits or evaporating brines from salt flats. A novel approach, however, involves extracting lithium from produced water, a byproduct of oil and gas extraction. Produced water, once considered waste, contains dissolved minerals, including lithium. This method involves treating the water to remove contaminants, and chemical processes such as adsorption or ion exchange to concentrate and isolate lithium ions. By repurposing produced water, this approach not only reduces the environmental impact of oil and gas operations but also provides a valuable domestic source of lithium, enhancing energy security, generating additional revenue streams, and reducing reliance on imports. Rhamnolipids—a class of biosurfactants produced by bacteria such as Pseudomonas aeruginosa—are gaining recognition for their eco-friendly and versatile applications. Rhamnolipids are glycolipid compounds consisting of rhamnose sugar rings linked to fatty acid chains, and they exhibit exceptional emulsifying and surface-tension-reducing properties. Their biodegradability and reduced toxicity compared with synthetic surfactants make them suitable for various applications. In environmental bioremediation, rhamnolipids enhance the breakdown of hydrophobic pollutants in contaminated soils and water bodies, such as hydrocarbons. This capability is particularly valuable in addressing oil spills and other environmental disasters. Additionally, rhamnolipids are increasingly used in personal-care products because of their gentle cleansing properties and potential to enhance the absorption of active ingredients. As the demand for sustainable and eco-friendly alternatives rises, rhamnolipids represent a promising shift toward sustainable industrial practices. In the oil and gas industry, the problem of scaling—where mineral layers deposit on surfaces, hindering fluid flow and causing equipment damage—has led to the exploration of GNPs as a solution. GNPs are distinguished by their high surface area, chemical stability, mechanical strength, and dispersibility. They act as nucleation sites that alter the crystal growth of scaling minerals, preventing the formation of hard, adherent layers. Additionally, GNPs can adsorb scaling ions, reducing their concentration in the fluid and decreasing scale formation. In squeeze treatments, where scale inhibitors are injected into reservoirs, GNPs can adsorb onto rock surfaces and release slowly over time, offering long-term protection. Their robustness under high temperatures and pressures makes them particularly effective for such applications. While further research is needed to optimize their use fully, GNPs offer significant potential to improve the efficiency and longevity of industrial operations. By repurposing waste, using eco-friendly compounds, and enhancing operational efficiency, these technologies contribute to a more-sustainable and resource-efficient future. As industries navigate the complexities of environmental and economic challenges, integrating such innovations will be crucial in achieving global sustainability goals and fostering a balanced approach to resource management. Recommended additional reading at OnePetro: www.onepetro.org. OTC 32809 Impacts of Water-in-Oil Emulsion and Stage Equilibrium for Produced Water Analysis With Benchtop XRF by V.C.C. Gallo, Petrobras, et al. SPE 218053 Critical Elements Extraction From Flowback and Produced Water: From Lab to Field by A. Ghanizadeh, University of Calgary, et al.