Efficient gas drainage in soft coal seams is commonly impeded by two coupled issues: coal-fines-induced clogging of screens and boreholes, and instability of the borehole wall. To overcome these limitations, an in situ grouted porous polyurethane system was developed for borehole completion. The polyurethane slurry, consisting of isocyanate, polyether polyol, catalyst, foam stabilizer, cell-opening agent, cross-linker, and water as a blowing agent, was formulated to coordinate foaming and gelation kinetics. By adjusting the type and dosage of catalyst, the gel time could be precisely controlled within 10–1500 s to suit different construction requirements. After curing, the material exhibited an interconnected open-cell structure with a porosity of approximately 83%, permeability greater than 4 D, and a uniaxial compressive strength of about 1.72 MPa. Mercury intrusion porosimetry revealed a highly connected, multiscale pore network, with an accessible porosity of 78.9%, a median pore size of 125 μm, and a dominant pore-size range of 1–301 μm, indicating favorable conditions for gas flow. Flow-through experiments under simulated methane drainage showed that coal-fine production is strongly dependent on flow rate: fines generation was negligible at flow rates ≤20 L/min and became noticeable at around 30 L/min. Scanning electron microscopy confirmed that coal fines were confined to the upper ~5 mm of the consolidation layer, where bridging and straining within small near-surface pores limited deeper penetration. Although near-surface fines deposition reduced permeability from the intrinsic polyurethane value (~4.0 D) to ~2.0 D, the permeability stabilized above ~1.5 D under dynamic conditions. Overall, these laboratory-scale results demonstrate that the porous polyurethane can effectively intercept coal fines within a shallow surface zone, provide sufficient mechanical support to stabilize the borehole, and maintain high permeability under the tested conditions, suggesting its potential as a candidate material for enhancing methane drainage performance in soft coal seams. Further field validation and comparative studies against conventional completion systems are needed to assess its true engineering viability.

Despite the potential of hydraulic fracturing to enhance development efficiency in low-permeability hydrate reservoirs, its effectiveness is hindered by the infiltration of fracturing fluid into the reservoir. This infiltration can lead to water blockages at the matrix-fracture interface, compromising reservoir permeability and optimal gas production. To address this, breakers, clay stabilizers, and cleanup additives were added into water-based fracturing fluids to mitigate water blockage. Our research was centered on the fluid invasion into hydrate-bearing sediments, particularly the impact and mechanism of these additives in reducing water blockage, and their contribution to boosting production. The results showed that nonionic surfactants, acting as cleanup additives, significantly reduced interfacial tension, altered reservoir wettability, and decreased the invasion distance of the fracturing fluid. This effectively limited the degree of permeability damage caused by water blockage. The inclusion of cleanup additives enhanced pore water flowback efficiency, which markedly reduced the water saturation of the invaded region. However, it was noted that both insufficient and excessive amounts of these surfactants and additives could lead to adsorption or blockages near the fracture surface, thus rendering them ineffective in deeper sediments. Permeability and gas production tests revealed that the simultaneous use of a cleanup additive and clay stabilizer resulted in more effective water blockage removal. Remarkably, with the combined addition of a gel breaker, 5 %wt cleanup additives and KCl, the damage degree near the fracture surface was reduced to only 10 %. Simultaneously, the gas production rate in the uninvaded zone increased by 74.3 % compared to the fracturing fluid without additives. These results suggest that including cleanup additives in the fracturing fluid system can mitigate water blockage damage and boost methane gas recovery, which is vital for the successful application of hydraulic fracturing technology in marine natural gas hydrate reservoirs.

Permafrost thawing induced by heat transfer from circulating drilling fluid poses a significant threat to wellbore integrity and drilling safety in Arctic hydrocarbon exploration. The absence of clear application boundaries for the two primary mitigation strategies, passive insulation and active cooling, impedes the cost-effective selection of engineering measures. This study presents a comparative numerical evaluation of insulated-casing technology and refrigerant-fluid circulation technology using a coupled hydrothermal heat transfer model solved via the finite difference method. Passive insulation reduces thawed volume by increasing radial thermal resistance, with performance improving sharply as apparent thermal conductivity declines below 0.02 W/(m·K). At an optimal conductivity of 0.006 W/(m·K), insulated casing achieves a thawed volume of 2.3 m3 after 7 days, comparable to aggressive active cooling at −15 °C and 20 L/s, demonstrating its viability as an energy-free alternative. Active cooling offers superior operational controllability, yet its effectiveness hinges critically on inlet temperature; lowering this temperature exerts a dominant influence on thaw suppression, whereas increasing flow rate yields diminishing returns beyond 12.5 to 15.0 L/s. A critical caveat is that operating at 0 °C and 5 L/s paradoxically reverses the cooling effect and exacerbates thawing. Sensitivity analyses reveal that refrigerant-fluid circulation technology excels in permafrost layers up to 500 m, reducing thaw volume by a factor of two to three compared with high-performance insulation. This advantage diminishes for thicknesses exceeding 600 m, where insulated casing provides robust, thickness-independent protection. These findings establish a quantitative framework for context-specific technology selection, enabling engineers to balance thermal performance, operational controllability, and energy efficiency in permafrost drilling operations.

Abstract. There are numerous subglacial lakes in Antarctica, typically covered by thick ice sheets. Qilin subglacial lake is one of the largest subglacial lakes in Antarctica, lying beneath approximately 3600 m of ice. The exploration of this unique environment is of considerable scientific importance. Recoverable Autonomous Sonde (RECAS) has been proposed for exploring Qilin subglacial lake. However, drilling into the lakes with such probe may be impeded by volcanic ash or small rock clasts within the ice sheet. In addition, RECAS is incapable of withstanding the extreme hydrostatic pressure existing in the Qilin subglacial lake. To address these challenges, the thermal head of RECAS was redesigned and fabricated. Compared with the original RECAS thermal head, the updated thermal head has extra water circulation unit. Laboratory test validated that the redesigned RECAS thermal head can operate at water pressures of up to 40 MPa. Moreover, its rate of penetration (ROP) improved by 21.1 % in clean ice, by 41.1 % in dust-laden ice, and by 253.4 % in ice with debris-rich ice. The updated RECAS thermal head is expected to be utilized to drill Qilin Subglacial Lake in the coming Antarctic work season.

Fiber-reinforced thermoplastic composite hoses have increasingly replaced traditional metal hoses due to their high specific modulus, high specific strength, and excellent corrosion resistance. These materials have gained significant attention and now widely used in industries such as deep-sea oil and gas extraction, offshore engineering, and polar exploration. This paper analyzes the mechanical response of defective fiber-reinforced thermoplastic composite hoses under tensile loading using finite element analysis. The study combines full-size tensile tests with numerical simulations to develop a parameter inversion model. The mechanical parameters influencing the tensile behavior of thermoplastic composite hoses are assessed using random forest feature importance, and the key mechanical parameters are identified through inversion. Given the presence of eccentricity and ovality defects during the manufacturing process, a semi-empirical formula for the ultimate tensile force and eccentricity of thermoplastic composite hose is derived by analyzing failure evolution. The results indicate that the ultimate bearing capacity of the composite hose negatively correlates with increasing eccentricity. As the ovality increases, both the number and volume of the damaged units of the tensile layer grow, leading to a faster rate of bearing capacity loss.

Unlike traditional fracture grouting methods for reinforcing soft soils, a novel technique known as Dual-enhanced fracture grouting (DEFG) has been proposed. By utilizing a specially designed dual-enhanced slurry in fracture grouting, which, upon solidification, forms high-strength, highly-permeable slurry veins within the reservoir. Marine hydrate reservoirs, with weak mechanical properties and poor permeability, exhibit low production efficiency, making this technique shows strong potential for enhancing gas production. To explore the effects of soil properties on fracture initiation and slurry diffusion, DEFG experiments were conducted on clayey-silty sediments with water saturation ranging from 40 % to 100 %, the slurry diffusion behavior was analyzed, and the morphology and pore structure of slurry veins were examined. The results showed that higher sediment cohesion and permeability increased initiation pressure, slurry diffused more easily in sediments with higher water saturation, leading to the formation of more slurry vein wings and a larger coverage area. Porosity analysis showed that the slurry veins have a porosity of about 60 % and are dominated by large pores (similar to 7.4 mu m), with the proportion of macropores slightly increasing in sediments with higher water saturation, which exhibit excellent permeability. As the slurry veins develop into complex and widely distributed networks, their high porosity and large pore sizes promote efficient gas and water transport, ultimately enhancing the efficiency of hydrate extraction. These findings confirm the feasibility of DEFG technology for efficient hydrate development and demonstrate its potential as a new geotechnical approach for foundation reinforcement and drainage.

Hundreds of large, buried subglacial lakes have been discovered in Antarctica, and deep hot-water drilling is an essential technology for their exploration. A multifunctional drilling hose is one of the core components of this technique, as it enables high-pressure hot-water delivery, long-distance power and signal transmission, and lifting of the drilling tool. However, no existing hose integrates all these functions. This paper presents the design methodology for a new multifunctional hot-water drilling hose. Based on theoretical calculations and numerical simulations, key parameters such as the inner diameter, equivalent thermal conductivity, and reinforcement layer structure were determined. The resulting hose has an inner diameter of 40 mm and an equivalent thermal conductivity below 0.4 W/(m & sdot;K).Experimental results show that the hose has a bursting pressure of approximately 53 MPa, an ultimate tensile strength of about 178 kN, and an equivalent thermal conductivity of roughly 0.145 W/(m & sdot;K), all of which meet the design specifications. The close agreement between theoretical predictions and experimental results demonstrates both the reliability of the design method and the stability of the developed hose.

Offshore shallow gas resources, once considered geological hazards, are now valuable unconventional energy sources. Preliminary tests in the Pearl River Mouth Basin show gas production rates of 55,000 m³/day, nearing commercial viability. However, optimizing extraction strategies remains a challenge due to vertical heterogeneity in the reservoirs, with alternating gas layers and low-permeability interlayers. This study proposes a stereoscopic exploitation model integrating horizontal and vertical wells. The horizontal well targets high-yield gas layers, while the vertical well ensures comprehensive extraction. Simulations reveal that with a 400-meter horizontal section, gas production reached approximately 88,000 m³/day after two years. This production level met the commercial requirements for shallow offshore gas fields. Notably, the horizontal well contributed 93% of the output during later stages. Gas production ranged from 2.70 × 10⁷ m³ to 6.07 × 10⁷ m³ over two years, depending on the horizontal well's positioning. Pressure distribution evolved from multi-peak to single-peak depletion, driven by the horizontal well. The distribution of interlayers caused varying levels of water invasion, with gas saturation damage ranging from 4.6% to 36.7%. The hybrid well strategy enhances efficiency, highlighting its broad applicability for developing heterogeneous shallow gas reservoirs.

Glaciers, ice sheets, and sea ice play a major role in the global climate changes. They act as a natural laboratory, providing us with valuable insights into the processes that connect ice with the atmosphere, lithosphere, hydrosphere, and biosphere. The inner processes and interactions between ice and the main spheres of the Earth are currently being studied using a variety of instruments, including remote sensing techniques and in situ geophysical observations. Remote sensing methods offer a non-invasive approach for continuous, large-scale, and long-term monitoring of ice, which is crucial for understanding its dynamics in the context of climate change. However, the validation of large-scale monitoring results and climate models requires the determination of ice physical parameters on-site. This is done through various ice core studies and geophysical investigations in boreholes, which can be broadly divided into logging methods and in-situ observatories. Borehole logging involves the use of specialized sondes, which take measurements while being lowered into or raised from a drilled borehole. In our previous paper, we provided an overview of current and emerging borehole logging techniques and their applications in glacier research. Unlike short-term logging, which creates a snapshot of data at a specific point in time, borehole in situ observatories are fixed systems that take usually long-term measurements over extended periods, often ranging from weeks to years. To study the ablation, inner physical and mechanical properties of glaciers and ice sheets in situ observatories use a variety of sensors. These include temperature sensors, borehole markers, strainmeters, pressure transducers, draw-wire sensors, tilt and inclinometer sensors, electrical resistivity detectors, expanding pressuremeters, and borehole jacks. Borehole in situ observatories can also detect natural inner and subglacial cryoseismic events and neutrinos from cosmological sources. Most in-situ observatories are installed in hot water-drilled holes and remain frozen until their task is completed or they fail. Usually, sensors are lowered to a predetermined depth or to the bottom of the borehole, and cables are used for power supply and data transmission to the surface. However, some progress has also been made in borehole wireless probes, which are powered by batteries and transmit data to the surface using radio signals, eliminating the need for cables. Through this review, we analyze each method of in situ borehole observatories in glaciers in terms of their working principles, applicability, measurement accuracy, and limitations, referring to the most significant examples.

CO2 lasers can effectively melt ice and snow, presenting significant potential as an innovative drilling technique for polar environments. This study investigated the melting and drilling characteristics of ice and snow using a continuous-wave (CW) 10.6 mu m CO2 laser. Experiments were conducted with a laser beam radius of 2.5 mm and laser powers ranging from 60 W to 210 W in 30 W increments. A lifting device was employed to maintain the laser in a focused state, while a suction pump removed accumulated meltwater from the drilled hole. The rates of penetration (ROP) were measured for ice-snow samples with densities of 500, 600, 800, and 917 kg/m3 under both unfocused and focused conditions. Under unfocused conditions, the ROP values were 22.0-27.7, 14.5-20.5, 3.0-3.8, and 2.1-2.9 mm/s, respectively. Under focused conditions, the ROP values increased to 29.4-42.5, 20.6-31.6, 4.5-5.5, and 3.4-4.5 mm/s, representing speed increments of 34-53%, 42-54%, 45-50%, and 55-62% compared to the unfocused state for the four densities. Furthermore, meltwater accumulation in the drilled hole was observed to hinder drilling efficiency when the ice-snow density exceeded 700 kg/m3. A nonlinear relationship between laser power and ROP was identified, characterized by an initial increase followed by a plateau or slight decrease. The optimal laser power ranges from 90 to 120 W under which the fastest ROP and relatively low energy consumption can be achieved. Thus, the optimal laser power should be considered in drilling operations to balance energy consumption and ROP in future study.

The mechanical behavior and failure mechanisms of Antarctic ice play a key role on borehole stability and structural integrity during polar drilling. Understanding these properties is essential for the design and operation in polar and offshore engineering. Due to long-term natural compaction and formation processes, Antarctic ice exhibits mechanical characteristics that differ from freshwater and sea ice. Existing constitutive models are inadequate for predicting mechanical response of Antarctic ice. This paper focuses on compressive behavior and constitutive relation of real Antarctic ice from polar scientific expedition. Uniaxial and triaxial tests are performed to analyze the effects of loading rate, temperature, and confining pressure. The results show that under uniaxial compression, increasing loading rates change the failure mode from shear to splitting, reflecting a rate-dependent ductile-brittle behavior. In the triaxial tests, confining pressure suppresses crack propagation, resulting in radial expansion without cracking. Based on experimental results, a constitutive model is developed for Antarctic ice, integrating both the nonlinear elastic and rate-dependent viscoelastic behavior. The proposed model shows excellent predictive accuracy, with peak stress errors below 3.52% and overall trends that matched experimental results (R-2 > 0.977). The model is implemented within peridynamics to analyze ice borehole fracturing, highlighting the influence of loading rate on failure evolution. These findings enhance the understanding of Antarctic ice mechanics, providing experimental and theoretical insights for borehole fracturing in polar and offshore drilling.

This paper presents the results of a study of bedrock samples obtained by drilling through 541 m of ice in north-western Princess Elizabeth Land. The drilling was aimed to decipher the geological nature of a high-amplitude linear magnetic anomaly running parallel to the coast for over 500 km from Princess Elizabeth Land to Mac. Robertson Land. The rock obtained by drilling is a melanocratic orthopyroxene-hornblende-biotite crystalline schist (mafic granulite) with a protolith age of similar to 970 Ma. Two metamorphic events are identified: early metamorphism with an age of similar to 890 Ma and peak parameters of 740-780 degrees C and 4.0-4.5 kbar; and late metamorphism with an age of similar to 800 Ma and parameters of about 650 degrees C and similar to 3 kbar. According to the data obtained, the linear magnetic anomaly can be interpreted as an island arc that was accreted to Antarctica during the assembly of Rayner Province.

When the RECoverable Autonomous Sonde (RECAS) penetrates ice, hot point drilling drives ice water phase change that governs borehole closure and cavity formation above the sonde. This study develops a Stefan problem-based numerical model for ice-water phase change material (PCM) under RECAS conditions with ice ambient temperature from -60 degrees C to -2 degrees C and meltwater at 0 degrees C. An implicit finite difference scheme tracks the phase interface and the temperature field to quantify the closure process. During the freezing process, the average and minimum closure rate range from 0.33 to 23.30 mm/h and from 0.24 to 17.39 mm/h. The minimum closure rate occurs from 2.00 to 88.75 h, and appears at radii from 52.48 to 74.91 mm. The average closure rate is 1.34-1.39 times the minimum value across the ambient temperature range. Using three detection resolutions, the maximum values of the Thermal Influence Boundary (TIB) during freezing and cooling are 10.48 and 12.26 times the initial radius, respectively. Accordingly, empirical fitting formulas are established to parameterize characteristic closure rates, their radial positions and occurrence time, and cavity height, providing the guidance for RECAS engineering decisions.

Abstract Mafic-ultramafic intrusions represent the primary source of global scandium (Sc) resources worldwide. These intrusions typically originate from fertile mantle sources in arc systems. While fluid- and melt-driven metasomatism are widely recognized as crucial mechanisms for Sc enrichment in the mantle, key aspects, including the precise composition of these metasomatic agents and their operating conditions remain poorly constrained. To address these knowledge gaps, we conducted a comprehensive investigation of Sc enrichment and release using clinopyroxene and orthopyroxene chemistry from charnockites and mafic granulites in East Antarctica’s Prydz Bay Belt. We reveal a multi-stage Sc evolution pathway within the accretionary belt that is initiated by dehydration of carbonate rocks, generating reduced carbonatite melts which trigger mantle metasomatism and significantly enrich Sc in the pyroxene. This enrichment is followed by post-peak decompression melting at 800-1000 °C and 6.5-12.8 kbar, which triggers metasomatism by an oxidized silicate melt, facilitating Sc release from both orthopyroxene and clinopyroxene. The subsequent arc accretion stage involves interaction with an external, oxidized, and likely phosphorus-rich aqueous fluid, leading to Sc release. The findings of Sc-rich pyroxene in mafic granulite and charnockite, together with the presence of CO₂-rich fluid inclusions in East Gondwana (Antarctica), collectively indicate that scandium enrichment may be a regional event. This study provides further implications for the exploration of Sc deposits in metamorphic rocks.

Background The effective coalbed methane (CBM) exploitation using hydraulic fracturing wells is severely constrained by two major solid-phase production issues: coal fines blockage and proppant flowback. The mechanisms behind both issues are associated with complex interplays between geological conditions and engineering disturbances. This study presents a systematic review of the current status of domestic and international research on the mechanisms of the solid-phase production, as well as relevant prevention and control methods. Furthermore, future research directions are proposed.AdvancesThe solid-phase production in hydraulically fractured CBM wells essentially arises from flow-solid-chemical multi-field coupling processes under interplays between geological conditions and engineering disturbances. Specifically, coal fines generation is attributed to the synergistic effect between intrinsic factors (i.e., coal properties) and extrinsic factors (e.g., coal seam abrasion by drilling tools, fracturing impact, and CBM production-induced pressure differences). The coal fines migration is jointly governed by the critical flow velocity, particle-size distribution, and fracture geometry, with coal fines undergoing a dynamic evolutionary process from banded to blocky morphologies. Coal fines blockage results from geometric straining (e.g., the “one-sixth rule”) and physicochemical adsorption within proppant packs. Additionally, proppant flowback occurs when the hydrodynamic drag force exceeds the particle retention force and is comprehensively governed by the fracture closure pressure, the ratio of the fracture width to proppant particle diameter (i.e., the w/d ratio, a ratio of greater than 3 leads to lower proppant stability), and fracturing fluid flowback velocity. Regarding technologies for the prevention and control of solid-phase production, a multi-tiered technical framework has been developed, covering source control, process control, and end treatment. In this framework, the preventive and control measures against coal fines blockage include coal surface modification using chemicals, proppant optimization, the application of fracturing fluid additives, and the fine-scale control of drilling and production parameters. Meanwhile, primary preventive and control measures against proppant flowback include fracturing fluid infilling by fiber, proppant modification, and the optimization of fracturing parameters. Prospects There is an urgent need to address several critical challenges, including poorly understood microdynamic mechanisms underlying solid-phase production, a lack of mechanisms controlling coal-proppant-fracturing fluid multi-phase interfaces, and less complete geological-engineering integrated technologies for the prevention and control of solid-phase production. Future research should focus on (1) the exploration of mechanisms behind coal fines migration and retention using multi-scale dynamic imaging combined with intelligent algorithms; (2) the R&D of coal rank-specific interfacial modifiers for coordinated multiphase control; and (3) the construction of geology-engineering integrated intelligent prevention and control systems based on digital twin and real-time monitoring. These efforts will facilitate the shift from passive response to proactive control, thereby ensuring safe and efficient CBM production.

Antarctic drilling projects provide critical information for investigating ice-sheet stability, reconstructing paleoclimate evolution, and characterizing subglacial geological structures through ice-core and bedrock recovery. Drilling site selection currently relies on high-resolution geophysical methods such as radio echo sounding and active-source seismic methods; however, radar imaging near the ice–bedrock interface is limited by electromagnetic attenuation, while active-source seismic methods in polar regions are constrained by logistical complexity and high cost. To address these limitations, this study proposes a passive integrated imaging approach that integrates P-wave responses and vertical-component Rayleigh-wave information retrieved from continuous ambient noise recordings near drilling sites using seismic interferometry. Based on their distinct propagation characteristics, signal selection and processing workflows are developed to jointly image near-surface firn structure, ice-sheet thickness, and subglacial bedrock structure. Application to the Princess Elizabeth Land drilling project in East Antarctica demonstrates that high- signal-to-noise-ratio P-wave responses and vertical-component Rayleigh-wave signals can be retrieved from as little as 24 h of ambient noise data, while stacking the full 20-day record further suppresses incoherent noise and yields more reliable imaging of the ice–bedrock interface. These results indicate that passive seismic imaging provides a rapid, cost-effective, and environmentally friendly complement for drilling site selection and operational support.

Due to the difficulty in achieving commercial extraction from marine natural gas hydrate (NGH) reservoirs, hydraulic fracturing technology is employed for reservoir stimulation. Our research group has developed a novel fracturing fluid-a dual-enhanced stimulation slurry. However, the impact of this dual-enhanced slurry invasion on the permeability of the NGH reservoir, as well as the properties of the interfacial transition zone (ITZ) between the slurry and the reservoir, remains unclear. Therefore, this study conducted laboratory experiments to investigate the microstructure and permeability characteristics of the ITZ between the slurry and hydrate-bearing sediment (HBS) under various influencing factors. Using scanning electron microscopy with energy dispersive spectroscopy (SEM-EDS) technology, line scanning tests were performed on cemented interface samples. The thickness of the ITZ was calibrated based on differences in elemental content. It was found that an increase in effective pressure, sediment porosity, and the thickness of the slurry consolidation body (SCB) led to an increase in the thickness of the ITZ, reaching a maximum of 118 mu m, which led to a reduction in sediment porosity at the interface, hindering gas flow. The porosity reduction at the interface ranged from 12.56% to 22.9%. Furthermore, pore diameters within the sediment were categorized, revealing that micropores (with diameters distributed between 0 and 2 mu m) predominated. Due to the porosity reduction at the interface and the increased proportion of micropores, interface permeability was impaired. The permeability damage rate ranged from 37.9% to 90%.

The sampling and observation of subglacial lakes play a vital role in studying the physical and chemical properties as well as the microbial characteristics of water within these Antarctic subglacial lakes. Compared to existing techniques, such as deep ice core drilling and clean hot water drilling, recoverable autonomous sondes, inspired by the spinning and reeling silk behavior of spiders, offer several advantages, including lightweight design, low power consumption, and minimal external pollution. Over the past six years, Jilin University, with support from the Ministry of Science and Technology of China, has developed an environmentally friendly sampling and observation system for Antarctic subglacial lakes, utilizing a recoverable autonomous sonde. The whole system includes a melting sonde, detection and control unit, scientific load platform, and ice surface auxiliaries. Extensive laboratory and joint system tests were conducted, both on key components and the complete system, including field tests in ice lakes. The results of these tests validated the feasibility of the underlying principles, the long-term reliability of the system operation, and the cleanliness of the drilling process. Ice penetration speed up to 2.14 m/h was reached with 6~6.5 kW melting tip power and a 660 mL lake water sample was collected. The relevant design concepts and technologies of the system are expected to play an important role in the clean detection and sampling of subglacial lakes in Antarctica, Greenland, and other regions.