Temperature Salinity Research Articles

Improving ocean analyses in the ensemble-based data assimilation system using the Community Earth System Model by assimilating satellite sea surface salinity

ABSTRACT This study evaluates the impact of assimilating satellite Sea Surface Salinity (SSS) data into the Community Earth System Model (CESM), a fully coupled general circulation model, using the Ensemble Adjustment Kalman Filter (EAKF). Two data assimilation experiments spanning from January 2010 to December 2019 are compared: EXP1, assimilating Sea Surface Temperature (SST) and Temperature-Salinity (T-S) profiles, and EXP2, which adds satellite SSS assimilation. Results highlight EXP2′s notable enhancement in sea surface salinity accuracy and variability, particularly in coastal and tropical regions, compared to EXP1. Moreover, the assimilation of satellite SSS contributes to improved sea surface velocity in the analysis, indicating enhanced ocean dynamics. However, the impact of extra assimilation of SSS on seawater temperature, sea surface height, and sea ice is relatively minor when other data is assimilated. This study pioneers the evaluation of satellite SSS assimilation within the ensemble-based data assimilation system using CESM, promising advancements in both data assimilation and numerical forecasting based on CESM.

Characteristics of Submesoscale Compensated/Reinforced Fronts in the Northern Bay of Bengal

AbstractFronts in the Bay of Bengal (BoB) are active and can potentially impact the regional dynamics such as temperature variability, salinity distribution and oceanic circulation. Based on the high resolution model output (LLC4320), this study investigates the characteristics of submesoscale fronts in the northern BoB and associated compensation/reinforcement effects. At sea surface, horizontal gradients of salinity and density are remarkable in the northern BoB, and they are nearly 3 times larger than temperature gradients. As the depth deepens, temperature gradients increase and become comparable to salinity gradients, while density gradients decrease a lot due to the increasing effects of compensation at subsurface. Statistical results show the dominance of salinity‐controlled fronts over temperature‐controlled fronts, and compensated fronts over reinforced fronts. The surface cooling/heating results in significant temporal variation of compensation at surface, but this variation is limited at subsurface by the blocking of the mixed layer base. The submesoscale‐selective feature of compensation is much more pronounced at subsurface layer than surface layer. From statistical analysis and idealized numerical model, we found the slump of salinity‐controlled compensated fronts are important in generating temperature inversion and maintaining barrier layer. This study validates the compensation theories originating from observations, and further illustrates the importance of subsurface compensated fronts using spatially continuous, regionally extended and longer‐term model output. The subsurface‐intensified submesoscale‐selective compensation is proved for the first time in this study.

Modeling and Analysis of Resistance-Sensing Characteristics for Two-Way Shape Memory Alloy-Based Deep-Sea Actuators

Deep-sea actuators based on shape memory alloys (SMAs) are an emerging frontier field of multidisciplinary crossover, and the resistive sensing characteristics are the basis for the drive control of SMA deep-sea actuators. The resistance and resistivity of SMAs are complex and highly dependent on temperature and stress, and there is no complete description of SMAs for extreme environments of high pressure, low temperature, and high salinity in the deep sea. In this study, the logistic function is introduced to improve the kinetic equation of phase transition, and the macromechanical model, the law of resistance, and the resistivity mixing rule are integrated to model and analyze the resistive self-awareness characteristics of two-way shape memory alloy deep-sea actuators. The complex coupling relationships among resistance, strain, stress, resistivity, and temperature under constant load conditions are investigated, and the validity of the resistance-sensing model is verified by the water bath cycling test. The results show that the predicted values of the model agree well with the measured values. The self-perceived relationship between the resistance and deformation of the two-way shape memory alloy can be effectively expressed, which provides theoretical model support for the design of memory alloy deep sea actuators and sensorless drive control.

Fluid inclusions and H–O isotopes of the super-large Nanyangtian tungsten deposit in southeastern Yunnan, southwestern China

The Nanyangtian deposit is a super-large reduced skarn tungsten deposit located in the Laojunshan WSn polymetallic ore province in southeastern Yunnan (SW China). The deposit is represented by three flat-lying mineralized zones formed vertically by the replacement of limestone or minor calcareous schist. The tungsten orebodies are mainly stratiform, lenticular, and vein types, hosted in the Paleoproterozoic Nanyangtian Formation. Three mineral formation stages have been identified based on the mineral assemblages and vein crosscutting relationships (pre-, syn-, and post-ore). The Nanyangtian is a calcic skarn deposit, dominated by a grossular-diopside-tremolite-actinolite assemblage. Scheelite, pyrrhotite, pyrite, and chalcopyrite are the main ore minerals. Detailed petrographic observations show three types of fluid inclusions (FIs) in various hydrothermal minerals: liquid-rich two-phase (type-I), gas-rich two-phase (type-II), daughter mineral-bearing three-phase (type-III). Their homogenization temperatures (193–298 °C) and salinities (1.2–9.3 wt% NaCl eq.) indicate that the Nanyangtian ore-forming fluids were of medium to low temperature and low salinity compared to the statistical data from representative skarn tungsten deposits in South China. Laser Raman microprobe analysis of the FIs shows that the inclusions are dominated by H2O with minor CH4 and N2. The δD values (relative to Vienna-Standard Mean Ocean Water, VSMOW) of fluid inclusions and calculated δ18Owater values (relative to VSMOW) of the fluids in equilibrium with hydrothermal minerals are −105 to −69 ‰ and − 1.9 to 7.6 ‰, respectively. These oxygen–hydrogen isotopic compositions indicate that the ore-forming fluids were magmatic-derived, which may have metasomatized the Nanyangtian Formation carbonaceous calcareous rocks along interlayer structures to form the prograde skarn minerals. Then the fluids mixed with meteoric water migrated along faults to form the retrograde skarn and tungsten ore. Mixing of magmatic fluid with meteoric water is likely the main factor for the ore precipitation at Nanyangtian.

Origin of the Narenwula quartz vein-type W deposit, Inner Mongolia, China: Insights from geochemistry of hosting granites, fluid inclusions, H-O-S isotopes, and wolframite trace elements

Wolframite that coexists with quartz is common hydrothermal mineral in tungsten deposits, and its geochemical features can be used to constrain the tungsten mineralization. Here we show that the Narenwula deposit is a typical quartz vein-type W deposit on the northern margin of the North China Craton, Northeast China, and temporally and spatially associated with Early Cretaceous granitoids, provides an opportunity to decipher the W mineralization process. All the orebodies are composed of a series of northeast- trending wolframite-polymetallic sulfides bearing quartz veins accompanied by intense alterations, mainly hosted in the Early Cretaceous monzogranite and porphyraceous monzogranite. Three paragenetic stages were identified: (I) quartz-wolframite, (II) quartz-wolframite-sulfide, and (III) quartz-fluorite-calcite. LA−ICP−MS trace element analyses revealed that both wolframite (I) and (II) have similar trace elements, REEN patterns, and overall consistent Nb/Ta and Y/Ho ratios, indicate a single fluid source and evolution in the W mineralization of the Narenwula deposit. Fluid inclusions microthermometry of quartz and wolframite, coupled with H-O isotopes suggest that the early ore-forming fluids of the Narenwula deposit are mainly magmatic water with relatively moderate-to-high temperature and salinity, while the late ore-forming fluids are mixed with meteoric water, with medium-to low temperature and low salinity. The δ34S values of pyrite (4.63–6.65 ‰, average = 5.44 ‰) further support a magmatic origin for the sulfides. The metallogenic mechanisms at the Narenwula deposit include fluid boiling and fluid-rock interactions were the two major factors controlling the deposition of wolframite and sulfide, while simple cooling and fluid mixing may have also promoted wolframite precipitation.

The conformance control and enhanced oil recovery performance of CO2 foam reinforced by regenerated cellulose

CO2 foam flooding is one of the most promising technologies for conformance control and enhanced oil recovery (EOR) in heterogenous tight oil reservoirs. However, it is challenging to maintain foam stability at in-situ high temperature and high salinity reservoir conditions, thus seriously limiting the flooding efficiency. Herein, a new approach of CO2 foam reinforced by regenerated cellulose (RC) was proposed and evaluated by multiple light scattering method and microscopic detection; afterwards, the conformance control and EOR performances were evaluated via flooding experiments at representative reservoir conditions of 85 °C and 59737.6 mg/L, using artificial micro-models and heterogenous core test. Results have demonstrated that: Compared with CO2 foam without RC, the foam with 1 % RC could elongate the foam half-life by ∼30 times (i.e., from 18 to 543 mins) and the drainage half-time by ∼4 times (i.e., from 2.5 to 9.5 mins), respectively; For the conformance control, the CO2 foam flooding with RC improved the sweep efficiency from the respective 42.4 % and 15.8 % to 95.4 % compared with water flooding and CO2 flooding in the micromodel experiments; the CO2 foam with RC increased the injection pressure from 0.20 to 3.1 MPa in the core flooding experiments, suggesting the diversion of fluid from high permeable to low permeable zone. In terms of the EOR, the CO2 foam flooding with RC improved the oil recovery from the respective 29.7 % and 12.9 % to 92.3 % in contrast with water flooding and CO2 flooding in micro-flooding experiments and from 35.5 % to 56.4 % by core-flooding experiments; the underlying mechanisms are attributed to oil emulsification, rock wettability alteration and foam deformation. These insights provide new approaches to maintain foam stability, improve conformance control and EOR performances in heterogenous tight oil reservoirs under harsh conditions.

Preparation and Characterization of Preformed Polyelectrolyte and Polyampholyte Gel Particles for Plugging of High-Permeability Porous Media.

Excessive reservoir water poses significant challenges in the oil and gas industry by diminishing hydrocarbon recovery efficiency and generating environmental and economic complications. Conventional polymer flooding techniques, although beneficial, often prove inadequate under conditions of elevated temperature and salinity, highlighting the need for more resilient materials. In this research, two types of acrylamide-based preformed particle gels (PPGs) were synthesized, as follows: polyelectrolyte and polyampholyte. These PPGs were engineered to improve plugging efficiency and endure extreme reservoir environments. The polyelectrolyte gels were synthesized using acrylamide (AAm) and sodium acrylate (SA), while the polyampholyte gels incorporated AAm, AMPS, and APTAC, with crosslinking achieved through MBAA. The swelling properties, modulated by temperature, salinity, and pH, were evaluated using the Ritger-Peppas and Yavari-Azizian models. The mechanical characteristics and surface morphology of the gels were analyzed using SEM and BET techniques. In sand pack experiments designed to mimic high-permeability reservoirs, the inclusion of 0.5 wt.% of fine PPGs substantially reduced water permeability, outperforming traditional hydrogels. Notably, the polyampholyte PPGs demonstrated superior resilience and efficacy in plugging. However, the experiments were limited by the low test temperature (25 °C) and brine salinity (26.6 g/L). Future investigations will aim to apply these PPGs in high-temperature, fractured carbonate reservoirs.

Design of hybrid multi-crosslinked hydrogel with a combination of high stiffness, elastic applied in high temperature and high salinity reservoirs

The mechanical strength of conventional hydrogels is inadequate for preventing leakage in high-temperature and high-salinity reservoirs, primarily due to the increased mobility of polymer chains and the degradation of crosslinked networks. Herein, we employed the strategy of ’network nesting and layer reinforcement’ to design a hybrid multi-site crosslinked hydrogel. This approach enhances the interconnections between polymer chains and fortifies the crosslinked network. The shear rheological behavior and temperature sensitive characteristics of the profile control working fluids were evaluated based on rheological dynamics. In the high temperature (140 ℃) and high salinity (21.81 × 104 mg/L) preparation environment, the effects of different components to the mechanical strength of the hydrogel were investigated under dynamic shear and uniaxial compression conditions. The incorporation of N-(hydroxymethyl)acrylamide (NMA) in the copolymerization with acrylamide (AM) resulted in an increase in the covalent cross-linking density, leading to a rise in the shear elastic modulus from 105 Pa to 238 Pa. The use of pre-gelatinized cassava starch (PGCM) as the grafting framework enhanced the bonding between the polymer chains, as evidenced by the increase in uniaxial compressive strength from 0.018 MPa to 0.081 MPa and the rise in peak strain from 55.0 % to 72.9 %. Furthermore, the synergistic effect of fumed silica (AEROSIL), which exploits mechanical coupling between inorganic nano-fillers and organic polymers, increased the compressive strength from 0.081 MPa to 0.418 MPa and raised the peak strain from 72.9 % to 81.8 %. It provides an effective approach to enhance the plugging performance of hydrogels in high temperature and high salinity reservoirs.

Evaluation of CMIP6 models for sea surface temperature and sea surface salinity variability over the Arabian Sea

The capability of Coupled Model Inter-comparison Project Phase-6 (CMIP6) is analysed in simulating the seasonal variability of Sea Surface Temperature (SST) and Sea Surface Salinity (SSS) over the Arabian Sea in this study. The historical simulations of 11 CMIP6 models, which come from various source are validated with the observational data (HadISST for SST and SODA for SSS). This study covers the Arabian Sea, spanning 5°S to 32°N and 33°E to 80°E from 1985 to 2014 (30 years). Seasonal mean climatology and annual cycle of SST and SSS are estimated over the Arabian Sea. The deviation of coupled model-simulated SST and SSS from the observation is quantified by determining the biases during all the seasons. Four distinct model evaluation measures are used to access the performance of CMIP6 models: root mean square error (RMSE), standard deviation (STD), correlation coefficient (CC) and interannual variability skill score (IVS). CMCC-CM2-SR5, NESM3 and IITM-ESM models for SST yield CC/RMSE values of 0.988/0.174, 0.983/0.204 and 0.963/0.299, respectively. CMCC-CM2-SR5, IPSL-CM6A-LR and CanESM5 models for SSS yield CC/RMSE values of 0.956/0.035, 0.937/0.042 and 0.820/0.069, respectively. Thus, these models having higher CC and lower RMSE among all models, give better performance. The present study is important as the future scenarios can be predicted using the best models.

Preparation and performance evaluation of heat resistant and salt resistant anionic fluid loss reducer for water‐based drilling fluid

AbstractIn this investigation, a new micro‐crosslinked anionic polymer resistant to elevated temperature and high salinity, PKDASN, was synthesized using 3‐chloropropyltriethoxysilane (KMB703), N, N‐Dimethylacrylamide (DMAM), 2‐acrylamido‐2‐methylpropanesulfonic acid (AMPS), N‐vinyl caprolactam (NVCL), and sodium (4‐vinyl phenyl)methanesulfonate (SVM) employing free radical polymerization in a water‐based solution. The structure of PKDASN was analyzed using Fourier‐transform infrared spectroscopy, nuclear magnetic resonance spectroscopy, and X‐ray photoelectron spectroscopy, while its microstructure was analyzed using scanning electron microscopy. Thermogravimetric analysis showed that the pyrolysis temperature of PKDASN was above 294°C. Adding KMB703 enables the polymer to form a dense and stable spatial network. This intensified polymer network could interact with bentonite via intermolecular force and Coulomb force and form a dual grid structure, which presents impressive stability and control of filtration in saltwater. This is mainly achieved through creating a “silane coupling layer” on the particle surface by KMB703, which facilitates the crosslinking and aggregation of the polymer, thereby reinforcing the polymer's framework. This implies that under high‐temperature conditions of 230°C, 3 wt% PKDASN can improve the filtration effectiveness of drilling fluids and exhibit resistance to 15 wt% NaCl contamination. American Petroleum Institute filtration(FLAPI) and High temperature and high pressure filtration(FLHTHP) values were 4.6 and 23.0 mL, respectively. Therefore, this investigation provides a novel approach to utilizing the designated silane agent for the advancement of filtration loss additives in drilling fluids resistant to elevated temperature and high salinity.

Permanent Stress Adaptation and Unexpected High Light Tolerance in the Shade-Adapted Chlamydomonas priscui.

The Antarctic photopsychrophile, Chlamydomonas priscui UWO241, is adapted to extreme environmental conditions, including permanent low temperatures, high salt, and shade. During long-term exposure to this extreme habitat, UWO241 appears to have lost several short-term mechanisms in favor of constitutive protection against environmental stress. This study investigated the physiological and growth responses of UWO241 to high-light conditions, evaluating the impacts of long-term acclimation to high light, low temperature, and high salinity on its ability to manage short-term photoinhibition. We found that UWO241 significantly increased its growth rate and photosynthetic activity at growth irradiances far exceeding native light conditions. Furthermore, UWO241 exhibited robust protection against short-term photoinhibition, particularly in photosystem I. Lastly, pre-acclimation to high light or low temperatures, but not high salinity, enhanced photoinhibition tolerance. These findings extend our understanding of stress tolerance in extremophilic algae. In the past 2 decades, climate change-related increasing glacial stream flow has perturbed long-term stable conditions, which has been associated with lake level rise, the thinning of ice covers, and the expansion of ice-free perimeters, leading to perturbations in light and salinity conditions. Our findings have implications for phytoplankton survival and the response to change scenarios in the light-limited environment of Antarctic ice-covered lakes.

Impact assessment of polymer, cross-linker, and nanoparticles on gelation kinetics and properties of silica nanocomposite hydrogel for water shut-off treatment in harsh reservoir conditions

The study presented the impacts of various parameters like compositional combinations of PHPA (partially hydrolyzed polyacrylamide), organic cross-linker (hydroquinone-HQ and hexamethylenetetramine-HX), and silica nanoparticles (SNP) in addition to the degree of hydrolysis and molecular weight of PHPA on the efficacy of hydrogel for water shut-off jobs. The investigation indicated that the gelation time, gel strength of the gel, tolerance against salinity, and temperature were tuned as required by the field conditions by changing the variables mentioned above. The gelation time was found to vary inversely with the concentration of polymer, cross-linkers, and silica nanoparticles, whereas the gel strength and temperature tolerance followed the reverse trend. SNP was observed to control the gel properties significantly, even at the lower polymer and cross-linker compositions, as evidenced by the stronger network in FESEM, rheological, and other related properties. The hydrogels prepared with the PHPA-LM (low molecular wt) and PHPA-HM (high molecular wt) polymers and HX-HQ cross-linkers showed improved temperature tolerance from 126.49 °C to 131.78 °C and 99.88 °C to 164.34 °C, respectively when improvised with SNP. The gel’s microstructure (FE-SEM image) exhibited significant silica nanoparticle aggregation and evenly distributed compact three-dimensional network structure. The prepared nanohydrogel with optimized composition maintained its stability even at a salinity of 60000 ppm and 120 °C for more than two years. Sand-pack flooding with the nanohydrogel proved very effective, with a permeability reduction of ∼ 90 %. Thus, the prepared nano-hydrogel could be effectively used for high temperature and high salinity conditions with preferred resistance to water flow.

Turbulent Ice–Ocean Boundary Layers in the Well-Mixed Regime: Insights from Direct Numerical Simulations

Abstract The meltwater mixing line (MML) model provides a theoretical prediction of near-ice water mass properties that is useful to compare with observations. If oceanographic measurements reported in a temperature–salinity diagram overlap with the MML prediction, then it is usually concluded that the local dynamics are dominated by the turbulent mixing of an ambient water mass with near-ice meltwater. While the MML model is consistent with numerous observations, it is built on an assumption that is difficult to test with field measurements, especially near the ice boundary, namely, that the effective (turbulent and molecular) salt and temperature diffusivities are equal. In this paper, this assumption is tested via direct numerical simulations of a canonical model for externally forced ice–ocean boundary layers in a uniform ambient. We focus on the well-mixed regime by considering an ambient temperature close to freezing and run the simulations until a statistical steady state is reached. The results validate the assumption of equal effective diffusivities across most of the boundary layer. Importantly, the validity of the MML model implies a linear correlation between the mean salinity and temperature profiles normal to the interface that can be leveraged to construct a reduced ice–ocean boundary layer model based on a single scalar variable called thermal driving. We demonstrate that the bulk dynamics predicted by the reduced thermal driving model are in good agreement with the bulk dynamics predicted by the full temperature–salinity model. Then, we show how the results from the thermal driving model can be used to estimate the interfacial heat and salt fluxes and the melt rate. Significance Statement We investigate the turbulent dynamics and thermodynamical properties of water masses below ice shelves using new data from high-resolution simulations. This is important because there are currently too few observations of ice–ocean boundary layer dynamics to construct reliable models of ice-shelf melting as a function of ocean conditions. Our results demonstrate that the turbulent diffusivities of salt and temperature are approximately equal in the well-mixed regime. This implies a linear correlation between the mean temperature and salinity profiles, consistent with the meltwater mixing line prediction that is often used to interpret polar observations. We take advantage of this correlation to propose a reduced model of ice–ocean boundary layers that can predict ice-shelf melt rates at relatively low computational cost.

Effect of carvacrol on the inhibitory of gas-producing spoilage microbes and volatile flavor in fermented pepper (Capsicum annuum L.)

In this study, two gas-producing spoilage microbes, namely CQ17 and CQ22, were isolated from fermented pepper. Combining the physiological and biochemical characteristics, molecular biological identification, and specific colony morphology, CQ17 was identified as Pichia manshurica while CQ22 was identified as Lentilactobacillus buchneri. Subsequently, our findings indicated that the CQ17 and CQ22 strains exhibited resistance to high temperature, low-pH, and high salinity environments. Meanwhile, our findings revealed that carvacrol, a commonly utilized preservative, exhibited remarkable inhibitory activities against Pichia manshurica and Lentilactobacillus buchneri with the EC50 values of 0.28 and 0.68 mg/L respectively, effectively suppressing the growth of gas-producing strains to prolong the shelf life of fermented pepper. Simultaneously, volatile components of the fermented pepper were analyzed using HS-GC-IMS technology resulting in identification of 55 volatile flavor compounds including acids, alcohols, esters, aldehydes, ketones, alkenes, and other compounds. Among them, (R/S)-linalool, 3-methyl-1-butanol acetate butanoic acid ethyl ester, 2-methyl butanoic acid ethyl ester, and ethyl 2-methylpropionate were identified as crucial components contributing to sensory attributes in fermented pepper as well as (E)-3-hexen-1-ol and l-Pentanol exhibited the highest VIP values and can be considered as the best reliable markers for differentiating fermented pepper samples with the addition of carvacrol as a preservative.

Regions of the southern Atlantic Ocean: A study on the sea surface temperature and sea surface salinity of the southern Atlantic Ocean region

Followed by the fast advancement of computer science and technology, studies involving massive datasets, especially environmental sciences, have been more accessible for researchers. Yet, with the completion of high-resolution data about the southern Atlantic Ocean region, there has not been sufficient academic research focusing on this specific area. In this regard, this paper investigates the connection between the Sea Surface Temperature (SST) and Sea Surface Salinity (SSS). The researchers chose South Atlantic as the research subject, and based on the visualization of the datasets from year 2010 to year 2014 to determine the number of clusters, the team applied k-means clustering to analyze the relation between SSS and SST by MATLAB. As a result, the research team found that the variation of the value of SSS and SST within the five years showed a stable tendency. The team classified the South Atlantic Ocean into four different oceanographical regions (based on the clusters acquired from the k-means technique), which each area showed a distinct feature in SSS and SST.

Determine SST and SSS distribution and tendency of variation in the northern Atlantic Ocean using k-means clustering

Sea surface temperature (SST) and sea surface salinity (SSS) are crucial parameters in oceanographic research and have important implications for understanding the Earths climate system, ecosystems, and global change. This paper will ascertain SSS and SST in the North Atlantic Ocean. Besides, K-means clustering was utilized to separate the data into several clusters once the data were installed in Matlab. According to the research results, the temperature dropped from the equator to the high northern latitudes. In contrast, salinity showed an initial increase and then a following reduction in trend. Despite rising temperatures and salinity, the region distribution of high SST and high SSS throughout the year remained mostly stable, but the area became larger. One of the regions with high salinity in North Africa has a strong connection to that is adjacent to the Mediterranean. The Earths climate system includes essential elements, including SST and SSS, which are essential to the development and control of the climate. Its better to comprehend seasonal changes in climate patterns and long-term climate trends by investigating temperature and salinity.

Carboxymethyl cellulose-based preformed particle gels for water management in oil and gas reservoirs

Carboxymethyl cellulose (CMC) based materials have been proposed as preformed particle gels (PPGs) for reducing excessive water production in oil and gas reservoirs. Multi-sized dry particles ranging between 100 and 1180 μm have been synthesized using microwave-assisted grafting copolymerization of CMC and acrylamide (AM)/n,n''-methylene-bisacrylamide (MBA). FTIR and SEM confirmed CMC crosslinked polyacrylamide's chemical structure and morphology (CMC/CPAM). Thermo-gravimetric analysis has demonstrated the thermal stability of dry PPGs up to 309 °C. CMC/CPAM showed slightly high absorbency in brine 2 (TDS = 67.3 g/L) compared to brine 1 (TDS = 33.65 g/L), 1% NaCl, and deionized water, with swelling ratios (SR) between 7.1 and 12.9 g/g at room temperature regulated by MBA weight ratio. The effect of particle size, pH, temperature, and aging on SR and mechanical strength was investigated and discussed based on the CMC/CPAM structures. The swollen PPGs showed excellent resistance to temperatures up to 100 °C with a storage modulus of 9 kPa. The particle size was estimated based on salinity, pH, and temperature and controlled between 118 μm and 3 mm at high temperature (100 °C) and high salinity (TDS = 67.3 g/L) conditions to match the need for carbonate reservoirs. Core flooding experiments demonstrated the effective plugging efficiency of the PPG in open fracture models.

Hydroxysulfobetaine foamer for potential mobility control application in high-temperature and ultra-high salt reservoirs

A good foamer should have good solubility in the formation of water, strong foaming ability, and also meet the requirements of thermal stability and low adsorption capacity under high temperature and high salinity conditions. The foam properties of hydroxylsulfobetaine surfactant with different carbon chain lengths were measured at 130 °C, 30 MPa, and in brine with a salinity of 22 × 104 mg·L−1. The results showed that hydroxylsulfobetaine surfactant with long carbon chains exhibited strong foam stability, with foam decay half-lives reaching 13 days for 0.4 wt% EHSB (erucamide propyl hydroxysulfobetaine) and 2.9 days for 0.4 wt% HSB18 (octadecyl dimethyl hydroxypropyl sulfobetaine), respectively. Hydroxysulfobetaine surfactant with short carbon chains had a foam decay half-life of less than 10 h. Considering the poor thermal stability of EHSB at 130 °C, HSB18 was primarily chosen as the foamer. HSB18 and HSB12 (dodecyl dimethyl hydroxypropyl sulfobetaine) were combined in a ratio of 3:1 to form the compound hydroxysulfobetaine MHSB31, which demonstrated good solubility in saline solution with KP (Krafft point) lower than 30 °C. The evaluation, using different concentrations of MHSB31, showed that the foam decay half-life ranged from 88 h for 0.03 wt% MHSB31 compared to 42 h for 0.1 wt% MHSB31. The excellent foaming performance of the compound system is attributed to its high surface dilational modulus and the formation of wormlike micelles. The adsorption capacity test demonstrated that when the concentration was less than 1 wt%, the adsorption capacity of MHSB31 on quartz sand surface was less than 1 mg·g−1, satisfying oilfield requirements. The results of the flow experiment at 130 °C and 10 MPa, in brine with a salinity of 22 × 104 mg·L−1, show that when the concentration of MHSB31 is greater than 0.1 wt%, the foam formed in the core with permeability of 632 mD and 2005 mD has a higher apparent viscosity and resistance factor. Additionally, the relative mobility of the foam formed in the core with a permeability of 2005 mD is lower than that formed in the core with a permeability of 632 mD. This indicates a certain selective reduction effect on mobility. Due to the influence of ultimate capillary pressure, both foam resistance factor and apparent viscosity are lower for the 47 mD core injected with different concentrations of MHSB31 ranging from 0.05 wt% to 0.5 wt%. The evaluation data presented in this paper regarding bulk foam and flow foam, using hydroxysulfobetaine surfactant under high temperature, high pressure, and high salinity conditions, have significant guiding significance for selecting and applying foamers in reservoirs with such harsh conditions.

Remote Water Quality Monitoring System In Shrimp Ponds With Photovoltaic (PV)-Based Energy Source

Introduction: Shrimp has great potential to be used as a business field in Indonesia. Especially in Parigi Regency itself, there are now many shrimp ponds that can be found because of the benefits obtained, so people are interested in making shrimp farming a livelihood. One of the main problems of shrimp ponds is pond water quality. There are several factors that affect pond water quality, namely water temperature, water pH, and water salinity, good pond water quality management can maintain quality standards and can increase shrimp yield and productivity Method: To facilitate the shrimp farmers, innovations need to be made in order to help the shrimp farmers manage their shrimp ponds, therefore using a remote water quality monitoring was system in shrimp ponds with photovoltaic (PV) based energy sources is expected to be an innovation in managing shrimp ponds, especially in monitoring water quality in shrimp ponds. The monitoring system designed using the NRF24L01 module as a remote communication module, at the research location the distance from the shrimp pond to the house is approximately 100 meters, so the tools that have been designed can facilitate shrimp farmers to monitor the shrimp pond Results and Disscussion: The results of testing the DS18B20 temperature sensor compared with a digital thermometer measuring instrument get an average error of 0.014%. The test results of the pH sensor compared to the pH meter get an average error of 0.026%. TDS sensor test results compared with the TDS meter get an average error of 0.04%. Conclusion: The temperature, pH, and salinity monitoring system uses transmitter and receiver modules, where the transmitter module reads and sends data to the receiver module wirelessly with NRF24L01. Using DS18B20 temperature, pH, and TDS sensors, as well as energy from photovoltaics, this system helps shrimp farmers monitor pond water quality remotely.

A Robust Sparse Sensor Placement Strategy Based on Indicators of Noise for Ocean Monitoring

A well-performing data-driven sparse sensor deployment strategy is critical for marine monitoring systems, as it enables the optimal reconstruction of marine physical quantities with fewer sensors. However, ocean data typically contain substantial amounts of noise, including outliers (incomplete data) and inherent measurement noise, which heightens the complexity of sensor deployment. Therefore, this study optimizes the sparse sensor placement model by establishing noise indicators, including small noise weight and large noise weight, which are measured by entropy to minimize the prediction bias. Building on this, a robust sparse sensor placement algorithm is proposed, which utilizes the block coordinate update (BCU) iteration method to solve the function. During the iterative updating process, the proposed algorithm simultaneously updates the selection matrix, reconstruction matrix, and noise matrix. This allows for effective identification and mitigation of noise in the data through evaluation. Consequently, the deployed sensors achieve superior reconstruction performance compared to other deployment methods that do not incorporate noise evaluation. Experiments are also conducted on datasets of sea surface temperature (SST) and global ocean salinity, which demonstrate that our strategy significantly outperforms several other considered methods in terms of reconstruction accuracy while enabling autonomous sensor deployment under noisy conditions.