Water Invasion Research Articles

A free-standing humidity sensor with high sensing reliability for environmental and wearable detection

Humidity measurement has been of extreme importance in both conventional environment monitoring and emerging digital health management. State-of-the-art flexible humidity sensors with combined structures, however, lack sensing reliability when they subject to high humidity with condensation and/or liquid water invasion. Here, we report a free-standing humidity sensor by creating a stable open porous graphite structure and controlling the number of oxygen-related groups at the molecular level. The sensor indicates high sensing reliability against water liquid wetting and machine washing as well as many mechanical deformations. We demonstrate the sensor has wide potential applications in challenge environmental monitoring and wearable body area sensing networks. Particularly, the concept of the humidity sensing strategy is applicative to not only cellulose-based materials such as cotton and linen, but also protein-based materials such as silk, paving a new route for producing high-performance and cost-effective humidity sensors.

Multi-scale flow mechanism and water control strategy of ultra-deep multi-porosity fractured tight sandstone gas reservoirs

The Keshen gas field in the Kuqa Depression, the Tarim Basin, China, contains multiple ultra-deep fractured tight sandstone gas reservoirs with edge/bottom water, which are remarkably complex in geologic structure, with fracture systems at different scales. There is still a lack of a method for effectively describing the flow behaviors of such reservoirs. In this paper, the fracture system was characterized by classes using the actual static and dynamic data of the gas reservoirs, and the mathematical models of gas (single-phase) and gas-water two-phase flows in “pore–fracture–fault” multi-porosity discrete systems. A fracture network system was generated randomly by the Monte-Carlo method and then discretized by unstructured grid. The flow models were solved by the hybrid-unit finite element method. Taking Keshen-2/8 reservoirs as examples, four types of dynamic formation modes were built up. Performances of reservoir of the same category were systematically analyzed, which revealed the coupling of gas supply and water invasion mechanisms in different fracture systems. The gas single-phase flow was found with the characteristic of “fault–fracture gas produced successively and matric-fracture system coupling overlaid”, while the gas-water two-phase flow showed the characteristic of “rapid water dash in fault, drained successive in fractures and matric block divided separately”. This study reveals the development features of this unique reservoir effectively, and designs development strategies of full life cycle water control for enhancing the gas recovery. It can be expected that the recovery factor of newly commissioning reservoirs would be increased by more than 10% as compared with the Keshen-2 gas reservoir. These findings will play an important role in guiding high and stable production of Keshen gas field development in the long term.

Water imbibition and water sealing in water-driven gas reservoirs development

To improve the poor understanding of the mechanism of spontaneous water imbibition in water invasion in gas reservoirs and overcome the difficulty in quantifying imbibed water and its impact on reservoir development, a study is carried out based on development simulation experiments and theoretical analysis of fluid mechanics. Spontaneous water imbibition is an important mechanical mechanism for the formation of a water seal zone in a low-permeability matrix through water invasion in gas reservoirs. Water imbibition experiments into the reservoir were carried out to clarify the trends of the imbibed distance and imbibed fluid volume to establish the theoretical model of imbibition and to make experimental corrections. An application study was performed based on the understanding of water imbibition and water sealing mechanisms and the building of an imbibition model. The water seal zones formed by imbibition during exploitation are predicted, and the seal-breaking pressure and influx of imbibed water in the water seal zone are evaluated. The research findings fully revealed the large impact of water imbibition on the development of water-driven gas reservoirs, providing technical support for the assessment of water sealing and the establishment of water control measures in water-driven gas reservoirs.

Source Apportionment, Hydrodynamic Influence, and Environmental Stress of Pharmaceuticals in a Microtidal Estuary with Multiple Outlets in South China.

Pharmaceutical residues in the environment are of great concern as ubiquitous emerging contaminants. This study investigated the presence of 40 pharmaceuticals in water and sediment of the Pearl River Estuary (PRE) in the wet season of 2020. Among psychiatric drugs, only diazepam was found in water samples while six of them were detected in the sediment. The Σantibiotics levels ranged from 6.18 to 35.9 ng/L and 2.63 to 140 ng/g dry weight in water and sediment samples, respectively. Fluoroquinolones and tetracyclines were found well settling in the outlet sediment, while sulfonamides could be released from disturbed sediment under stronger tidal wash-out conditions. After entering the marine waters, pharmaceuticals tended to deposit at the PRE mouth by the influence of the plume bulge and onshore invasion of deep shelf waters. Low ecological risks to the aquatic organisms and of causing antimicrobial resistance were identified. Likewise, hydrological modeling results revealed insignificant risks: erythromycin-H2O and sulfamethoxazole discharged through the outlets constituted 30.8% and 6.74% of their environmental capacity, respectively. Source apportionment revealed that pharmaceutical discharges through the Humen and Yamen outlets were predominantly of animal origin. Overall, our findings provide strategic insights on environmental regulations to further minimize the environmental stress of pharmaceuticals in the PRE.

Key technologies and progress of enhanced gas recovery in water-bearing carbonate gas reservoirs

Global oil and gas consumption continues to rise and new strategies are required to meet the growing demand. Carbonate gas reservoirs are an important natural gas resource that are often accompanied by water intrusion during the development process. The efficient development of such reservoirs has therefore been extensively studied and met with difficulty. This paper summarizes the basic geological and water invasion characteristics of water-bearing carbonate gas reservoirs and correlates the two. A method for identifying water invasion types by production dynamics is introduced. The variation curve of the production water to gas ratio is shown to correspond with the reservoir geological characteristics. Typical development methods and the advantages/disadvantages of different water control techniques are summarized. The findings are used to propose a full-cycle water control plan for water-bearing carbonate gas reservoirs, and the development strategies of “early preparation, early discovery, and early treatment” and “re-analyze, re-assess, and re-adjust” are implemented to organically combine water control, drainage, and water blocking methods. The results provide a reference for formulating efficient and scientific development plans of water-bearing carbonate gas reservoirs.

A Modified Langmuir Model for Moisture Diffusion in UGFRE of Composite Insulator Considering the Composite Degradation.

Water invasion induced aging and degradation of the unidirectional glass fiber reinforced epoxy resin (UGFRE) rod is inferred as the primary reason for the decay-like fracture of the composite insulator. In this paper, the moisture diffusion processes in the UGFRE from different directions at various test humidities and temperatures are studied. The moisture diffusion of the UGFRE sample obeys the Langmuir diffusion law under the humidity conditions of 53%, 82% and 100% at 40 °C. In deionized water, the moisture diffusion of the UGFRE sample also obeys the Langmuir diffusion law when the invading direction is vertical to the glass fiber. However, when the water invades the UGFRE sample, parallel with the glass fiber, the weight loss caused by composite degradation should not be neglected. A modified Langmuir model, taking Arrhenius Theory and the nonlinear aging characteristic of the composite into consideration, is proposed and can successfully describe the moisture diffusion process. Both the glass fibers and epoxy resin will degrade in the deionized water. The glass fibers show better resistance to degradation than the epoxy resin. The epoxy resin degrades from the glass fiber/epoxy resin interface and become fragments. For composite insulators, the water invasion through the ends should be avoided as far as possible, or the degradation of the UGFRE rod will result in decay-like fracture.

Enhancing the production of tight sandstone gas well through fuzzy-ball fluid temporary plugging with diverting fractures and water cutting after refracturing in one operation

Refracturing is one of the most effective techniques to enhance the production of tight sandstone gas (TSG) well. Many TSG gas wells are facing the problem of water invasion after refracturing, the formation water may gradually occupy the gas-producing channels, preventing high gas productivity. In this paper, we newly developed a fuzzy-ball temporary plugging fluid (FTPF) with diverting fractures and water cutting after refracturing in one operation. The temporary plugging and water breakthrough control capabilities of the FTPF system were evaluated through the true triaxial large-scale core diversion fracturing experiment and matrix core and artificial fracture waterproof experiments. Meanwhile, the permeability damage evaluation experiments were performed to analyze the reservoir recovery ability. Results showed that the pressure-bearing capacity could reach up to 62.6 MPa, the rock fracture pressure was increased by 5–10 MPa compared with the initial hydraulic fracturing and an apparent fracture network structure was formed after refracturing. The breakthrough pressure gradients of simulated formation water were 2–10 times higher than that of nitrogen after the cores (including matrix and cores with 4 mm fractures) were plugged with FTPF, indicating its good water cutting ability. Before and after gel breaking, the permeability recovery value of the matrix core and the artificial fracture core was about 85–98%. The on-site application of FTPF to the refracturing of two TSG wells in the Sulige Gas Field in Northwest of China displayed that the average gas production has been enhanced by 64.8%. It is proposed that fuzzy balls can easily enter and gather at the tip of the initial fractures and form a stable pressure-bearing structure due to its viscoelastic properties and deformability. In addition, the hydrophilic fuzzy-ball core agents can adsorb on the rock's surface and form a polymer membrane, increasing the resistance of water flow.

A driving factor for harmful algal blooms in the East China Sea coastal marine ecosystems — Implications of Kuroshio subsurface water invasion

Quantitative calculation of the supply ratio of nutrients by different water masses suggests that the intrusion of Kuroshio subsurface water (KSSW) may indeed be an important factor in the formation of harmful algal blooms (HABs) in the Min-Zhe coastal area. This region in China has a complex hydrographic structure as well as a high incidence of HABs. The results of the calculations of the dissolved neodymium and its isotopes show that KSSW is an important provider of dissolved inorganic nitrogen (30–90 %) and phosphates (80–100 %) compared to the cases of the Taiwan Warm Current and the Changjiang Diluted Water. Sensitivity analysis results indicate that the percent contribution of KSSW in volume increased to 50–60 % in June, supplying favorable conditions for the growth of harmful algae. Our study implies that the invasion of the Kuroshio is likely to be a driving factor of HABs and, accordingly, a key factor in predicting HABs.

Experimental Study on Production Characteristics of Bottom Water Fractured-Vuggy Reservoir

To assess the high-pressure production characteristics of double-vug reservoirs with bottom water in the Tahe Oilfield, in this study, a high-pressure physical simulation experiment apparatus is built for double-vug reservoirs with bottom water. The high-pressure production characteristics of “vug-fracture-vug” reservoirs under different bottom water characteristics are studied experimentally, and fracture-vug relationship and oil recovery rates are explored. According to the findings, the oil recovery rate significantly affects the development effect of double-vug reservoirs with bottom water, and bottom water provides sufficient energy for reservoir development. Furthermore, considering the possible occurrence of water invasions, the production rate control must receive close attention in the development process to avoid strong water channeling. Constant-pressure bottom water has sufficient energy and can quickly replenish vug energy. Therefore, the recovery percentage and bottom water invasion and retention volume of fractured-vuggy reservoirs with constant-pressure bottom water are higher than those of fractured-vuggy reservoirs with constant-volume bottom water. Under the appropriate control of production factors, the presence of bottom water can noticeably improve the development effect of fractured-vuggy reservoirs.

Fluorine Functionalized MXene QDs for Near‐Record‐Efficiency CsPbI3 Solar Cell with High Open‐Circuit Voltage

AbstractCsPbI3 inorganic perovskites have attracted significant attention due to their desirable bandgap for tandem solar cells and excellent thermal stability. However, CsPbI3 perovskite solar cells (PSCs) still exhibit low efficiency and high energy loss due to nonradiative recombination. Herein, functionalized Ti3C2Fx quantum dots (QDs) are prepared and selected as interface passivators to enhance the performance of CsPbI3 PSCs. The systematic experimental results reveal that Ti3C2Fx QDs serve as effective passivators mainly in three aspects: 1) p‐type Ti3C2Fx QDs can tune the energy level of perovskite films and provide an efficient pathway for hole transfer; 2) Ti3C2Fx QDs can effectively passivate defects and reduce interfacial nonradiative recombination, and 3) Ti3C2Fx QDs form a barrier layer to prevent water invasion and improve the stability of CsPbI3 PSCs. Consequently, the champion CsPbI3 PSC with Ti3C2Fx QDs treatment exhibits an excellent efficiency of 20.44% with a high open‐circuit voltage of 1.22 V. Meanwhile, the corresponding device without encapsulation retained 93% of its initial efficiency after 600 h of storage in ambient air.

Highly transparent and super-wettable nanocoatings hybridized with isocyanate-silane modified surfactant for multifunctional applications

Highly transparent and super-wettable nanocoatings for multifunctional applications with outstanding physical properties are in high demanded. However, such nanocoatings resistant to water invasion and Ultraviolet (UV) weathering remain a significant challenge. In this work, physically durable coatings based on inorganic nanoparticles (NPs) and an organic segment (isocyanate-silane modified surfactant) have been synthesized via a sol-gel approach. It is noteworthy the isocyanate-silane with –NH–CO- functional group creates a strong bonding between the highly hydrophilic surfactant and the inorganic NPs. This in-house synthesized organic segment can render the coating long-lasting wetting properties and resist to be washed away by water, while the inorganic NPs can form sturdy covalent bonds with the nano-scale hierarchical structure on the glazing substrate to improve the durability. This nanocoating demonstrates high transparency with superwetting property (water contact angle, WCA ​= ​4.4 ​± ​0.3°), effective de-frosting performance. Water invasion or UV accelerated weathering tests do not significantly affect the self-cleaning performance of nanocoating. Physical properties, including coating adhesion, hardness, Young's modulus, and abrasion resistance are systematically investigated. Interestingly, this clear coating shows prominent infrared shielding property attributed to Antimony-doped tin oxide (Sb-doped SnO2) NPs. The developed nanocoating process is easy to scale up for larger areas that require multipurpose self-cleaning functions.

Groundwater quality assessment of north of Iran (Golestan Province) using multivariate factor analysis and GIS techniques

AbstractGroundwater is one of the most important sources of drinking water. Since the quality of water directly influences consumers' health, it is essential to assess the quality of water and related factors. This descriptive-analytical study was performed on physical and chemical variables of water samples collected in the dry and wet seasons during 2006–2020 period. Changes in groundwater quality were investigated by factor analysis (FA) model and geographic information system (GIS) software. Based on factor analysis model, EC, TDS, TH and Mg+2 levels were the most important factors affecting the quality of water. Due to the high level of hardness (dry seasons; 389.4 mg/l and wet seasons; 418.4 mg/l) and sodium in water (dry seasons; 138 mg/l and wet seasons; 158 mg/l), necessary measures should be taken before drinking and agriculture uses. Changes in the water quality were more related to natural factors and human activities. The invasion of saline water into the groundwater aquifers in the study area should be considered.

The sub-fossil diatom distribution in the Beibu Gulf (northwest South China Sea) and related environmental interpretation.

Located in northwestern South China Sea (SCS), the Beibu Gulf constitutes an environmentally sensitive region shaped by land-ocean-atmosphere interactions in Asia between the western Pacific and eastern Indian Oceans. This study aims to provide a comprehensive view of the sub-fossil diatom biogeography, distribution pattern and oceanographic environmental controls with support of multivariate methods based on Beibu Gulf core-top samples. Cluster analysis of diatom assemblages divides the distribution pattern into four subclusters. Sea surface salinity (SSS), temperature (SST), trophic state (chlorophyll a concentration in this study) and water depth constrain the diatom distribution pattern through canonical redundancy analysis although only partly support an interpretation of the relationship between these various variables. Chlorophyll a has a strong correlation to diatom distribution, and responds to Paralia sulcata occurrence, while SSS and SST also have significant influence and indicate warm water invasion from the open SCS. Water depth is a subordinate factor in terms of Beibu Gulf diatom distribution. The ca. 25 m water-depth marks the upper extent of Paralia sulcata dominance in the northern Beibu Gulf. A strong mixing area with a complex diatom distribution exists below this water depth in the middle of Beibu Gulf. Coastal currents from north of SCS invade Beibu Gulf through Qiongzhou Strait and south of Hainan Island, as recorded by higher percentages of Paralia sulcata and Cyclotella striata at these sites. Our results provide a selection of evaluation method for a marine ecological red-line definition for sustainable development. This study highlights the perspective relationships between the spatial distribution of sub-fossil diatom assemblages in surface sediments and oceanographic variables, which could serve as a model for paleoenvironmental and paleoclimatic reconstruction in future marginal sea geoscience research for the Beibu Gulf, northwestern SCS.

Rapid bentonite-cement-oil hydration: Implications to fluid loss control

Conventional particulate additives fail to control drilling fluid losses into large-aperture fractures. The separate injections of a bentonite-cement-oil suspension and water can cause rapid hydration, swelling and hardening to effectively plug fractures. This experimental study investigates underlying processes and implications in view of optimal fluid flow control in fractures. Results identify several concurrent hydro-chemo-mechanical coupled processes: capillarity-driven water invasion; cement hydration and the release of Ca2+ and OH− ions; bentonite contractive aggregation and increased hydrophilicity; enlarged inter-aggregate pores that facilitate fluid flow; oil pressurization leading to the formation of oil-filled opening mode discontinuities that facilitate oil escape towards free draining boundaries, and calcium silicate hydrate formation and growth resulting in hardening. The hydration of bentonite-cement-oil suspensions proceeds several times faster than in bentonite-oil suspensions. The optimal mixture should balance competing requirements between flowability, water invasion speed, swelling pressure and plug strength.

Microscopic Seepage Mechanism of Gas and Water in Ultra-Deep Fractured Sandstone Gas Reservoirs of Low Porosity: A Case Study of Keshen Gas Field in Kuqa Depression of Tarim Basin, China

To study the microscopic seepage mechanism of gas and water in fractured sandstone gas reservoirs of low porosity, this kind of reservoir in the Keshen gas field, Kuqa depression of Tarim basin in China, was taken as an example. Based on rock samples and microscopic visualization technology, nuclear magnetic resonance experiments of saturated water–gas drive and CT scanning experiments of saturated gas–water drive were conducted. The seepage mechanism of water invasion during the gas development were simulated. Subsequently, the distribution of irreducible water saturation and the influence factors on the efficiency of drive were analyzed. The results show that the distribution of gas and water is mainly related to structures of matrix pores, fracture development pattern, and density. The main factors resulting into good reservoirs include large matrix pores and high angle fractures, low irreducible water saturation, and high separation between gas and water. The efficiency of water drive is positively correlated with fracture porosity and dip angle. High angle fractures can effectively improve the seepage capability and then increase the efficiency of water drive. Besides, the great proportion of large pore size in matrix, high fracture dip, porosity, and density can also improve the efficiency of water drive. Therefore, for the development of fractured sandstone gas reservoirs of low porosity, the study of matrix pores and fractures is quite important since it can provide guidance for the efficient deployment of wells. The increase of fracture density is significant by large-scale sand fracturing in order to improve the efficiency of water drive. It is necessary to strictly control the gas production rate of the gas reservoir and delay the water invasion rate as far as possible. In case of serious waterlogging, shut-in all wells in gas reservoirs is a choice to strengthen the gas–water imbibition between fractures and matrix, which can improve the recovery of the gas reservoir.

Water-Triggered Self-Healing Composite Coating: Fabrication and Anti-Corrosion Application.

Self-healing coatings formulated by stimuli-responsive container technology are regarded as a prospective strategy for long-term corrosion protection. However, such types of coatings suffer from low coating adaptability and delays in corrosion protection because the occurrence of corrosion is prior to the release of healants from containers. Herein, we took advantage of the easy hydrolysis of MOF-199 for water-induced self-healing properties. Mixed corrosion inhibitors were loaded into MOF-199 and then incorporated into acrylic coating. The water sensitivity of MOF-199 was investigated and EIS tests were used to evaluate the self-healing performance. Due to the collapse of the porous MOF-199 structure, corrosion inhibitors could be released from MOF-199 with the invasion of water into acrylic coating. The corrosion resistance performance of damaged self-healing coating gradually increased. The metal exposed to artificial defects was well protected due to a barrier formed by corrosion inhibitors. Owing to these merits, this self-healing coating is recommended for use in various fields of engineering for corrosion resistance.

Preparation and properties of integrally hydrophobic self-compacting rubberized concrete

Brittleness and water invasion are critical reasons for the deterioration and failure of ordinary self-compacting concrete (SCC). To enhance the deformability and water repellency of SCC, integrally hydrophobic self-compacting rubberized concrete (HSCRC) was prepared by adding crumb rubber (CR) and a hydrophobic agent (HA) into ordinary SCC. Furthermore, the combined effect of CR and HA on the fresh properties, hydrophobicity and mechanical properties of HSCRC were comprehensively studied. The results showed that the addition of CR resulted in a decline in the flowability, filling ability and passing ability and an enhancement in the viscosity and anti-segregation properties. However, the effect of adding HA on the fresh properties was opposite to that of adding CR. The surfaces of the samples mixed with the HA obtained contact angles greater than 130°, and the 48-hour capillary water absorption and the 48-hour immersion water absorption of these samples were significantly reduced. Moreover, the compressive strength, splitting tensile strength, axial compressive strength and elastic modulus of the concrete samples decreased gradually with the increase of CR and HA content. Multiple regression models between different mechanical properties and CR and HA contents, as well as the conversion formulas between different mechanical properties, were obtained.

A water invasion unit numerical simulation model for the distribution of water and water invasion channel in complex edge water reservoir

In order to accurately and intuitively characterize the distribution of water and water invasion channel in complex edge water reservoir, a water invasion unit numerical simulation model (WINS) that can simulate complex edge water invasion dynamics is established, based on well geological data and production data. The model discretizes the edge water into water unit connected to the production well unit, and discretizes the locations with clear geological understanding into dense unit. The more dense units, the more accurate the water invasion dynamics. Based on the water unit, production well unit, dense unit, the material balance method is used to calculate the pressure of each unit, the water flooding front propulsion equation is used to calculate the saturation and water cut of each unit, and the genetic algorithm is combined to modify characteristic parameters of the water unit and the water invasion channel, fit automatically production data, realize the re-identification of water distribution and water invasion channel. Different edge water and high-permeability bands are constructed through numerical simulator, and the simulated production results are substituted into the model to automatically fit. The results show that the edge water distribution and water invasion dominant channel inversely performed by WINS are consistent with the results constructed by the numerical simulator. Compared with the process of constructing edge water at the reservoir by Eclipse numerical simulator, WINS saves the tedious steps of building a model, and its calculation efficiency is higher. Not only that, WINS can intelligently and automatically fit parameters, reducing errors caused by human interference.

Pore-Scale Spontaneous Imbibition at High Advancing Contact Angles in Mixed-Wet Media: Theory and Experiment

Mixed wettability develops naturally on a pore scale in oil reservoirs after primary drainage. The invading oil fills pore interiors that become oil-wet by asphaltene deposition, while the residual water retreats into the pore corners, masking them and retaining their water wetness. This wettability alteration hinders oil mobilization during secondary waterflood. Therefore, a proper understanding of the conditions controlling pore-scale imbibition into mixed-wet pores may lead to a substantial increase in oil recovery from the portions of reservoir rocks bypassed during the original waterflood. We use selective silane coating to fabricate reservoir-representative mixed-wet capillaries with angular cross-sections. We validate our procedure on silica and glass substrates and characterize the mixed-wet surfaces by atomic force microscopy, scanning electron microscopy, and contact angle measurements. Subsequently, we investigate experimentally the invasion of water against air in mixed-wet, water-wet, and oil-wet square capillaries and compare our findings with the theoretical predictions of dynamic (Washburn, Szekely, and Bosanquet) and quasi-static [Mayer–Stowe–Princen (MSP)] meniscus-invasion models. None of the dynamic models for ducts of uniform wettability can fully describe our experimental data in mixed-wet capillaries. However, the experimental results agree with the predictions of MSP theory. We discuss the similarities and differences between experiment and theory and the reasons for the failure of the dynamic models. To our knowledge, this is the first direct experimental validation of MSP theory under mixed-wet conditions in such a controlled manner. We confirm the possibility of spontaneous piston-type imbibition with high (>90°) advancing contact angles into mixed-wet pores, given that the contact angle is lowered below a critical value that is a function of the pore geometry and water saturation. In oil reservoirs, injection of custom-designed brines would be required to change the contact angle to values below the imbibition threshold.

Water Invasion Mode of Carbonate Gas Reservoirs Controlled by Edge Water: Three Invasion Modes

Water Invasion Mode of Carbonate Gas Reservoirs Controlled by Edge Water: Three Invasion Modes