Core Matrix Research Articles

Investigation of plugging performance and enhanced oil recovery of multi-scale polymer microspheres in low-permeability reservoirs

Advanced water injection has become an effective method for developing low-permeability reservoirs. However, after a period of high yield from fracturing, the injected water flows rapidly along high-capacity channels, which greatly reduces the sweep efficiency of reservoirs. In this work, the plugging process by microspheres and nanospheres from the fracture to the matrix was simulated through core experiments. The plugging performance of multi-scale microspheres (microspheres and nanospheres) on the core matrix was evaluated by measuring the plugging rate and other parameters. Enhanced oil recovery after synergistic plugging with multi-scale microspheres was used as the evaluation index, a sensitivity analysis of injection parameters was performed, and the best combination of injection parameters was optimized by orthogonal experiments. The experimental results showed that the plugging performance of nanospheres is mainly reflected in the filling of the core matrix, while the plugging performance of microspheres is mainly reflected by retention at the injection end of the core (as opposed to the fractured end face). The plugging rate of nanospheres reached 78.83%, which is much higher than the 30.28% rate achieved with microspheres. The maximum oil recovery after plugging was 19.12%, which corresponds to the following combination of injection parameters: total injection of 0.6 pore volume (PV), injection ratio between nanospheres and microspheres of 2:1, injection rate of 1.5 mL·min−1, and aging time of 6 days. Among the injection parameters, the injection ratio between nanospheres and microspheres had the greatest influence on the recovery of waterflooding after plugging, followed by the total injection of multi-scale microspheres. The injection rate and aging time had little effect.

Matrix metalloproteinase activity during methamphetamine cued relapse.

Relapse to drug seeking involves transient synaptic remodelling that occurs in response to drug-associated cues. This remodelling includes activation of matrix metalloproteinases (MMPs) to initiate catalytic signalling in the extracellular matrix in the nucleus accumbens core (NAcore). We hypothesized that MMP activity would be increased in the NAcore during cue-induced methamphetamine (meth) seeking in a rat model of meth use and relapse. Male and female rats had indwelling jugular catheters and bilateral intracranial cannula targeting the NAcore surgically implanted. Following recovery, rats underwent meth or saline self-administration (6h/day for 15 days) in which active lever responding was paired with a light + tone stimulus complex, followed by home cage abstinence. Testing occurred after 7 or 30 days of abstinence. On test day, rats were microinjected with a fluorescein isothiocyanate (FITC)-quenched gelatin substrate that fluoresces following cleavage by MMP-2,9, allowing for the quantification of gelatinase activity during cued-relapse testing. MMP-2,9 activity was significantly increased in the NAcore by meth cues presentation after 7 and 30 days of abstinence, indicating that remodelling by MMPs occurs during presentation of meth associated cues. Surprisingly, although cue-induced seeking increased between Days 7 and 30, MMP-2,9 activity did not increase. These findings indicate that although MMP activation is elicited during meth cue-induced seeking, MMP activation did not parallel the meth seeking that occurs during extended drug abstinence.

Controlled Release Levetiracetam Loaded Eudragits Microspheres for Oral Drug Delivery: Preparation and Evaluation

This work aims to prepare controlled release microspheres loaded with levetiracetam (LEV) for oral use that will have a targeted release site, thus reducing dose frequency and improving patient compliance. Levetiracetam is a 2nd generation antiepileptic medication with a T/half-life of 7 hours that is administered twice daily, which makes it suitable for formulation that will reduce dosing intake. The microspheres were prepared by solvent evaporation method using Eudragit E100, L100, and S100 polymers as matrix core polymers at diff erent ratios 1:1, 1:2 and 1:3 with levetiracetam. These polymers have diff erent pH sensitivity profi les, which will aid the release of levetiracetam in a controlled manner along the gastrointestinal tract. The prepared microspheres were evaluated for yield percentage, entrapment effi ciency (EE%), morphological characteristics and in-vitro release profi le. The yield percentage and EE% for the formulation at diff erent ratios ranged from 69–99%. The in-vitro release analysis showed favorable targeted release of the drug at specifi c pH ranges matching specifi c sites in the gastrointestinal tract.

Attribute reduction and information granulation in Pythagorean fuzzy formal contexts

Pythagorean fuzzy set theory is one of the significant tools to deal with real-life problems which are prone to imprecision, partial truth or uncertainty. A Pythagorean fuzzy set reports the degree of truthness as well as falsity of a statement in order to illustrate the imprecision of that statement. Motivated by the resourcefulness of this theory, this paper is aimed to explore formal concept analysis in Pythagorean fuzzy environment. It defines Pythagorean fuzzy formal concept and Pythagorean fuzzy concept lattice associated with a Pythagorean fuzzy formal context. The proposed Pythagorean fuzzy formal concept is a duple whose first argument is (crisp) extension and second argument is Pythagorean fuzzy intension. Moreover, the join of different combinations of object concepts of a Pythagorean fuzzy formal context returns different Pythagorean fuzzy formal concepts. We also studied the knowledge reduction in Pythagorean fuzzy formal contexts in association with Pythagorean fuzzy concept lattice. The key ideas of attribute reduct, core and discernibility matrix for a Pythagorean fuzzy formal context are illustrated. Further, we merged the notions of information granulation and attribute reduction with Pythagorean fuzzy formal context. Various results of formal concepts and concept lattices are extended in Pythagorean fuzzy set theory. At last, an algorithm is developed which discovers non-redundant Pythagorean fuzzy formal concepts for a given Pythagorean fuzzy formal context. Eventually, an example is presented which elaborates the procedure of this algorithm.

Mechanical Properties of Pyramidal Lattice Sandwich CFRP Composites to Flat and Bending Loads

In this study, by rearranging the typical pyramid lattice structure of carbon fibre reinforced polymer composites to obtain a small node distance and simplify the fabrication procedure, a new type of pyramid lattice structure is designed and fabricated using the snap-fit method. The flatwise compression and bending properties of the new pyramid lattice structure are studied experimentally. The results show that the compression failure mode of the lattice structure is truss fracture, while the bending failure mode is truss fracture and debonding between face sheets and cores. The damage distribution of the fibre and matrix in the lattice structure core is obtained via a finite element simulation, and it is found that there are differences in the ply damage with different fibre directions. In addition, the influence of the core truss length and layering direction on compression and bending properties of the structure are analysed using a finite element simulation.

In Situ Combustion of Heavy Oil within a Vuggy Carbonate Reservoir: Part I—Feasibility Study

Worldwide, the known recoverable heavy oil and bitumen reserves make up more than 64% of the total reserves, of which more than 60% are trapped in carbonates. Air injection has immense potential for hydrocarbon recovery from various reservoirs. While most of the successful air-based techniques are performed within carbonate reservoirs containing light oil, theoretically, in situ combustion (ISC) has also shown great potential for recovering heavy oil and bitumen. Carbonates are complex in terms of geology and are often associated with fractures and vugs that affect the fluid flow, pressure propagation and progression of the ISC reactions. This paper describes the first experiment in which the triple-porosity concept was applied to simulate heterogeneity through artificially induced vugs, core matrix and fractures. This approach was used to study the feasibility of the ISC recovery technique for heavy oil (14° API) within a dolomite reservoir using a combustion tube (CT) in an experiment performed at 1740 psig. The combustion front advanced through 78% of the core length prior to the termination of air injection, producing 80% of the initial oil. To differentiate between the various sources of the CO2 gas (a product of carbonate decomposition vs. the combustion reaction) the atomic ratios of (CO2 + CO)/CO = 6 and (CO2 + CO)/N2 = 0.21 were applied. Additionally, partial upgrading of the produced heavy oil was observed.

A pore-scale study on the dynamics of spontaneous imbibition for heterogeneous sandstone gas reservoirs

The underlying mechanism for spontaneous imbibition in a water–gas system plays a significant role in hydraulic fracturing in sandstone gas reservoirs. The objective of this study is to characterize the heterogeneity of low-permeability sandstones and investigate their effect on spontaneous imbibition from the perspective of the pore scale. We selected different cores with various pore structures and heterogeneity to evaluate their impact on the dynamics of spontaneous imbibition. The heterogeneities of the cores are contributed from the clay mineral distribution and are characterized through CT scans. The results show that clay minerals have higher CT numbers than the core matrix and that micropores are predominantly distributed in clay particles rather than in the core matrix. Additionally, the water imbibition rate of micropores is larger than that of the macropores, and when the porosities are similar, the water imbibition rate is increased with decreasing permeability. Moreover, the results of 1D frequency scans show that the distribution of water at different locations in the core is governed by the distribution of clay particles. These findings can help us further understand the distribution of fracturing fluids in the heterogeneous low-permeability sandstone reservoirs.

A Framework for Susceptibility Analysis of Brain Tumours Based on Uncertain Analytical Cum Algorithmic Modeling.

Susceptibility analysis is an intelligent technique that not only assists decision makers in assessing the suspected severity of any sort of brain tumour in a patient but also helps them diagnose and cure these tumours. This technique has been proven more useful in those developing countries where the available health-based and funding-based resources are limited. By employing set-based operations of an arithmetical model, namely fuzzy parameterised complex intuitionistic fuzzy hypersoft set (FPCIFHSS), this study seeks to develop a robust multi-attribute decision support mechanism for appraising patients' susceptibility to brain tumours. The FPCIFHSS is regarded as more reliable and generalised for handling information-based uncertainties because its complex components and fuzzy parameterisation are designed to deal with the periodic nature of the data and dubious parameters (sub-parameters), respectively. In the proposed FPCIFHSS-susceptibility model, some suitable types of brain tumours are approximated with respect to the most relevant symptoms (parameters) based on the expert opinions of decision makers in terms of complex intuitionistic fuzzy numbers (CIFNs). After determining the fuzzy parameterised values of multi-argument-based tuples and converting the CIFNs into fuzzy values, the scores for such types of tumours are computed based on a core matrix which relates them with fuzzy parameterised multi-argument-based tuples. The sub-intervals within [0, 1] denote the susceptibility degrees of patients corresponding to these types of brain tumours. The susceptibility of patients is examined by observing the membership of score values in the sub-intervals.

Implementation of Floating‐Point Arithmetic Processing on Content Addressable Memory‐Based Massive‐Parallel SIMD matriX Core

AbstractSeveral multimedia applications have recently been implemented on mobile devices, including digital image compression, video compression, and audio processing. Furthermore, Artificial Intelligence (AI) processing has grown in popularity, necessitating the execution of large amounts of data in mobile devices. Therefore, the processing core in a mobile device requires high performance, programmability, and versatility. Multimedia apps for mobile devices typically comprise repeated arithmetic and table‐lookup coding operations. A Content Addressable Memory‐based massive‐parallel SIMD matriX core (CAMX) is presented to increase the processing speed of both operations on a processing core. The CAMX serves as a CPU core accelerator for mobile devices. The CAMX supports high‐parallel processing and is equipped with two CAM modules for high‐speed repeated arithmetic and table‐lookup coding operations. The CAMX has great performance, programmability, and versatility on mobile devices because it can handle logical, arithmetic, search, and shift operations in parallel. This paper shows that the CAMX can process parallel repeated arithmetic and table‐lookup coding operations; single‐precision floating‐point arithmetic can calculate 1024 entries in 5613 clock cycles in parallel without embedding a dedicated floating‐point arithmetic unit. This clock cycle using two's complement‐reduced floating‐point addition implementation decreases 59% than the implementation of straight‐forward floating‐point addition. The implementation of straight‐forward floating‐point additions is improved as two's complement instruction reduced algorithms. Thus, this paper proposes an instruction reduction architecture by modulating the CAMX to directly access the data in the left and right CAM modules from the preserve register. The CAMX has achieved high performance, programmability, and versatility by not embedding a dedicated processing unit. Moreover, assuming the CAMX processes at an operating frequency of 0.1, 0.5, 1.0, or 1.5 GHz, it can process floating‐point additions above approximately 4500 parallelized data, with better performance than an ARM core using NEON and Vector Floating‐Point (VFP). In addition, related works executed by software instruction, dedicated floating‐point arithmetic unit, or both and the CAMX are compared while assuming the same operation frequency. From this result, the CAMX which has 128‐bit and 1024‐entry CAM modules achieves higher performance than the related works executed by only software instructions and by combining software instructions and a dedicated floating‐point arithmetic unit. © 2023 Institute of Electrical Engineers of Japan. Published by Wiley Periodicals LLC.

Anti-inflammatory and pro-anabolic effects of 5-aminosalicylic acid on human inflammatory osteoarthritis models.

Osteoarthritis (OA) is the most common degenerative joint disease, mainly affecting the elderly worldwide, for which the drug treatment remains a major challenge. Low-grade inflammation plays a pivotal role in OA onset and progression. Exploration of notable anti-inflammatory and disease-modifying drugs on human samples could facilitate the evaluation of therapeutic strategies for OA. The anti-inflammatory drug 5-aminosalicylic acid (5-ASA) is a first-line drug for ulcerative colitis (UC), however no study has explored the effects of 5-ASA on articular chondrocytes. In this work, both in vitro (chondrocyte pellets) and ex vivo (osteochondral explants) human inflammatory OA models were applied to evaluate the effects of 5-ASA. In the inflammatory pellet model, 5-ASA remarkably downregulated the gene expression of interleukin-6 (IL-6), and cyclooxygenase-2 (COX-2) while upregulating proteoglycan 4 (PRG4) and cartilage oligomeric matrix protein (COMP) gene expression. Total glycosaminoglycan (GAG) synthesis by pellets was markedly increased in 5-ASA-treated groups compared with the inflammatory group. In conditioned medium, inflammatory mediators (IL-8, nitric oxide) were markedly inhibited upon 5-ASA treatment. Moreover, histological staining showed 5-ASA retained proteoglycan content and inhibited degradation of extracellular matrix (ECM) core components, aggrecan (ACAN) and collagen type II (COL2). In the inflammatory explant model, 5-ASA mitigated signs of OA development by reducing inflammatory mediators and GAG loss. These findings suggest that 5-ASA has anti-inflammatory and pro-anabolic effects on human chondrocyte pellet and osteochondral explant inflammatory OA models. Disease-modifying OA drugs are an unmet clinical need for the treatment of OA. Our study explored and demonstrated the anti-inflammatory and protective effects of 5-ASA on in vitro and ex vivo human inflammatory OA models, showing its translational potential for OA treatment.

Formulation Development and Evaluation of Divalproex Sodium Extended-release Tablets

There are two important parameters for a control release formulation. Primarily, it should be available in the form of a single-dose formulation. It should be given to the patient per day or few days a week during the treatment of patients suffering from diseases like arthritis, angina and diabetes. The second important characteristic of such formulation is that they release the active molecule at the site of action. This will reduce the chances and the level of the side effects of the drug. Among the available such type of dosage form, sustained-release formulations (SR) give the most promising and desirable results. In the SR dosage form, the drug release profile is controlled by the pharmaceutical engineering in the core matrix of tablet. In this study, SR oral tablet of divalproex sodium was manufactured by varying the quantity of drug release-controlling polymers like metolose 65 SH and metolose 90 SH. In the formulations, these polymers were used in different proportions and evaluated their impact on the physical and chemical characteristics of the finished drug product. The results of all formulations were as per the requirement of standard pharmacopoeial monograph. However, drug dissolution results of two formulations viz. DF9 and DF16 were observed to be optimum and excellent among all batches.

Radiation Therapy Modulates Tumor Physical Characteristics to Reduce Intratumoral Pressure and Enhance Intratumoral Drug Delivery and Retention

PurposeHigh intratumoral pressure, caused by tumor cell-to-cell interactions, interstitial fluid pressure, and surrounding stromal composition, plays a substantial role in resistance to intratumoral drug delivery and distribution. Radiation therapy (XRT) is commonly administered in conjunction with different intratumoral drugs, but assessing how radiation can reduce pressure locally and help intratumoral drug administration and retention is important. Methods and Materials344SQ-parental or 344SQ-anti-programmed cell death protein 1-resistant lung adenocarcinoma cells were established in 129Sv/Ev mice, and irradiated with either 1 Gy × 2, 5 Gy × 3, 8 Gy × 3, 12 Gy × 3, or 20 Gy × 1. Intratumoral pressure was measured every 3 to 4 days after XRT. Contrast dye was injected into the tumors 3- and 6-days after XRT, and imaged to measure drug retention. ResultsIn the 344SQ-parental model, low-dose radiation (1 Gy × 2) created an early window of reduced intratumoral pressure 1 to 3 days after XRT compared with untreated control. High-dose stereotactic radiation (12 Gy × 3) reduced intratumoral pressure 3 to 12 days after XRT, and 20 Gy × 1 showed a delayed pressure reduction on day 12. Intermediate doses of radiation did not significantly affect intratumoral pressure. In the more aggressive 344SQ-anti-programmed cell death protein 1-resistant model, low-dose radiation reduced pressure 1 to 5 days after XRT, and 12 Gy × 3 reduced pressure 1 to 3 days after XRT. Moreover, both 1 Gy × 2 and 12 Gy × 3 significantly improved drug retention 3 days after XRT; however, there was no significance detected 6 days after XRT. Lastly, a histopathologic evaluation showed that 1 Gy × 2 reduced collagen deposition within the tumor, and 12 Gy × 3 led to more necrotic core and higher extracellular matrix formation in the tumor periphery. ConclusionsOptimized low-dose XRT, as well as higher stereotactic XRT regimen led to a reduction in intratumoral pressure and increased drug retention. The findings from this work can be readily translated into the clinic to enhance intratumoral injections of various anticancer agents.

Experimental Study on the Influence of Heavy Mud Pollution on Tight Sandstone for Deep Wells

Heavy mud pollution tends to occur during the workover of deep tight sandstone gas wells in Tarim, resulting in a significant reduction in gas well production. In order to study the impact of heavy mud pollution in deep sandstone gas reservoirs in the Tarim Basin, the physical properties and mechanical parameters of cores before and after heavy mud pollution were tested by non-destructive testing methods such as porosity, permeability, and acoustic waves. The results show that after the matrix core is polluted by heavy mud, the overall damage of permeability is ≥60%. Low-density mud causes more damage than high-density mud. The effect of increasing displacement time on permeability damage is higher than that of increasing displacement pressure. Heavy mud has an obvious influence on matrix porosity, but with the change in displacement pressure and displacement time, the change in core porosity has no obvious regularity. After the matrix core is polluted by heavy mud, the Poisson’s ratio increases by about 70% on average, but the change in elastic modulus is small, only -1.15%−4.25%. The experimental results provide significant guidance for reservoir damage assessment of mud-contaminated wells in Tarim.

Channel Responses for the Molecule Release From Spherical Homogeneous Matrix Carriers

Molecular communications is a promising framework for the design of controlled-release drug delivery systems. Under this framework, drug carriers, diseased cells, and the channel in between are modeled as transmitters, absorbing receivers, and diffusive channel, respectively. However, existing works on drug delivery systems consider only simple drug carrier models, which limits their practical applicability. In this paper, we investigate diffusion-based spherical matrix-type drug carriers, which are employed in medical applications. In a matrix carrier, the drug molecules are dispersed in the matrix core and diffuse from the inner to the outer layers of the carrier once immersed in a dissolution medium. We derive the channel response of the matrix carrier transmitter for an absorbing receiver. The results are validated by particle-based simulations and compared with commonly used point and transparent spherical transmitters to highlight the necessity of considering practical models. Moreover, we show that a transparent spherical transmitter, with the drug molecules uniformly distributed over the entire volume, is a special case of the considered matrix system. For this case, we provide an analytical expression for the channel response. Furthermore, we derive a criterion for evaluating whether the release process or the channel dynamics are more important for the overall characteristics of the channel response of a drug delivery system. For the limiting regimes, where only the release process or only the channel determine the behavior of the end-to-end system, we propose closed-form approximations for the channel response. Finally, as a scenario of practical relevance, we investigate the channel responses for the release of common therapeutic drugs, e.g., doxorubicin, from a diblock copolymer micelle acting as drug carrier.

In vivo efficacy of a polymer layered decellularized matrix composite as a cell honing cardiovascular tissue substitute.

Cardiovascular surgery involves reconstruction of tissues that are under cyclical mechanical loading, and in constant contact with pulsatile blood flow. Durable biomaterials for such tissue reconstruction are scarce, as they need to be mechanically strong, hemocompatible, and resist structural deterioration from calcification. While homografts are ideal, they are scarce; xenografts are immunogenic and rendered inactive from glutaraldehyde fixation, causing them to calficy and structurally deteriorate over time; decellularized xenografts are devoid of cells, mechanically weak; and synthetic polymeric scaffolds are thrombogenic or too dense to enable host cell infiltration. In this work, we report the in vivo feasibility of a new polymer-decellularized matrix composite material (decellularized bovine pericardium-polycaprolactone: chitosan) fabricated by electrospinning, which is designed to be mechanically strong and achieve programmed host cell honing to integrate into the host. In a rodent and sheep model, this new material was found to be hemocompatible, and enabled host cell infiltration into the polymer and the decellularized matrix core underlying the polymer. Presence of M2 macrophages and several vascular cell types, with matrix remodeling in the vicinity of the cells was observed in the explanted tissues. In summary, the proposed composite material is a novel approach to create in-situ host integrating tissue substitutes, with better non-thrombogenicity, reduced infections and endocarditis, and potentially the ability to grow with the patient and remodeling into a native tissue structure.

Design and Demonstration of a 100 kW High-Frequency Matrix Core Transformer for More Electric Aircraft Power Distribution

The rapid development of more electric aircraft (MEA) raises the demand for high-power converters with significant weight and volume reduction for onboard power distribution. The isolated dc/dc converter using the medium-frequency transformer (MFT) is a feasible solution. To design an MFT with improved electromagnetic and thermal performance, a matrix core transformer (MCT) architecture is proposed with accurate models in this article. With superior heat dissipation ability, the high current windings can be effectively cooled with both natural and forced air convection. In addition, an optimization methodology for MCT design is presented. As a result, the prototype of a 100-kW, 50-kHz MCT with an additive manufactured bobbin is built. The results of both finite element analysis (FEA) simulation and experimental study in a full power dual active bridge (DAB) with the MCT prototype are presented to verify the theoretical design. The power density and efficiency of the MCT reach 17.7 kW/L and 99.63%, respectively.

Conceptual design and feasibility analysis of a megawatt level low enriched uranium heat pipe cooled reactor core

Micro reactors are gaining popularity due to their lower cost, increased safety, and flexibility as compared to normal commercial nuclear power plants. This paper presents a design concept for a multi-purpose heat pipe cooled micro-reactor with enrichment of 19.75 %, which can operate for more than 5 years at 2 MWt without refueling. A new Accident Tolerant Fuel called Fuel-in-Fibers is used and in addition, both control drums and control rods are applied for safety consideration. Besides, graphite is used as the core matrix material to reduce uranium enrichment because it can reduce the parasitic absorption of neutrons and moderate neutrons. For longer burnup and more stable operation, Integral Fuel Burnable Absorber (IFBA) pin with burnable poison Gd2O3 is used to reduce initial excess reactivity. Monte Carlo simulation is performed to calculate the reactivity, burnup, power distribution, temperature coefficient and other parameters on normal and accident conditions. According to the neutron physics results, the preliminary design satisfies the economy and safety requirements. This work may provide a reference for the design of multi-purpose heat pipe cooled reactor core using low enriched uranium fuel.

Getting to the CoRe of Collaborative Online International Learning (COIL)

In response to the COVID-19 pandemic in 2020, there was a worldwide pivot of education to online communication and the utilization of diverse digital technologies to enhance global learning and foster cultural understanding. Within higher education, educators faced unprecedented challenges in the conversion of face-to-face interactions into online, virtual classrooms, with many educators unprepared and untrained to do so. Yet, the introduction of online digital technologies for pedagogical interactions expanded the internationalization of previously limited curriculum prospects, to create global interconnectedness with the potential to invoke Students’ awareness and appreciation of cultural differences in communication, leadership, and conflict. The development of international knowledge, pedagogical knowledge, and the linkage between the two is key for the internationalization of the curriculum. With the growth of new digital communication, learning opportunities such as Collaborative Online International Learning (COIL), aims to foster the development of intercultural competencies (ICC) in our students for future career advancement in an expanding global community. Despite the acknowledgment that faculty are underprepared and lack pedagogical knowledge to translate their lived experiences into their curriculum, there remains a tenable lack of available tools for educators to facilitate students actively participating in objective, equitable and inclusive intercultural communication. Herein, is proposed the novel application of a conceptual tool, a “content representation” or CoRe matrix, which explicitly separates a particular topic into divergent, yet linked dimensions of the knowledge and skills attributed to its content, teaching, and learning. It was hypothesized the CoRe tool could be applied to enhance an educator’s PCK of ICC, providing the valuable link between international and pedagogical knowledge, for effective internationalization of the curriculum. The novel ICC CoRe matrix successfully addressed the 4 dimensions of ICC demonstrating the robust nature of the application of the CoRe matrix in the development of an educator’s ICC PCK in the COIL classroom. With the exponential increase in digital technologies creating dynamic worldwide networks in education and the workplace, the development of conceptual tools such as the ICC CoRe matrix has the potential to develop and integrate an educator’s pedagogical knowledge with ICC, to support the development of effective, objective and inclusive student participation in global twenty-first-century classrooms and beyond.

Quantitative Investigation on Natural Gas Flooding Characteristics in Tight Oil Cores after Fracturing Based on Nuclear Magnetic Resonance Technique

SummaryTight reservoirs are mainly developed by injecting various gases after fracturing. However, the formed fractures are complex, and different fracture conditions have an important impact on the gas injection effect. In addition, natural gas is considered to be suitable for the development of tight reservoirs in China because of the abundant gas source and no corrosion. For this paper, the natural gas injection experiments were studied by combining mercury intrusion porosimetry (MIP) measurements and nuclear magnetic resonance (NMR) measurements. The method can be used to study the distribution characteristics of core pore structure and the recovery characteristics of oil in different pore spaces.In this work, the tight cores of the Changqing Oil Field were selected for fracturing for the natural gas flooding experiments. At first, the distribution characteristics of the core pore structure were studied based on the MIP and NMR measurements. The conversion relationship between the core pore throat radius and the relaxation time (T2) was decided. The NMR T2 distribution was transformed into the distribution of oil in pore space with different throat radii. Then, the gasflooding experiments were conducted to study the oil recovery law of tight cores with different fracture conditions. Finally, the recovery characteristics of oil in different pore spaces were analyzed based on the NMR results of cores.The results show that the pore throat radius of the core is mainly distributed in the range of 0.001 to 10 μm. The oil is mainly stored in the pore space whose pore throat radius ranges from 0.01 to 1 μm. The natural gas also mainly drives the saturated oil in the pore space with a pore throat radius of 0.01 to 1 μm. The increase in fracture area improves the distribution of oil in the larger pore space. In the process of natural gasflooding, with the increase of gas injection, the oil began to be recovered, and then gas was observed at the end of the core. With the continuous injection of natural gas, the rate of recovering oil gradually slowed down, and finally gas breakthrough occurred. The displacement oil process of the nonfractured core was uniform and slow. However, the oil and gas rapidly flowed along the fracture when the natural gas displaced the oil in the fractured core. The oil in the matrix was poorly recovered. Gasflooding mainly recovered the saturated oil in the matrix of nonfractured cores and the saturated oil in the fracture of fractured cores. As the fracture length increased, the oil recovery became lower and the gas breakthrough occurred earlier. The higher fracture density increased the fracture area, which also increased the oil recovery and caused a more intense gas breakthrough.In this paper, the displacement law of tight oil cores by injecting natural gas and the recovery characteristics of oil in different space pores were illuminated. The results can provide theoretical guidance for the formulation of the natural gas injection development plan in tight reservoirs.

Experiment on Gas–Liquid Sulfur Relative Permeability under High-Temperature High-Pressure Sour Gas Reservoir Condition

In the development of high temperature sour gas reservoirs, gas–liquid sulfur two phase percolations exist, which have a significant impact on the gas permeability and gas well productivity. There are currently few reports on experimental studies on gas–liquid sulfur relative permeability. This study improves the experimental equipment and process, and it proposes an experimental method for measuring the gas–liquid sulfur relative permeability curve. Several typical core samples from a sour gas reservoir in Sichuan Basin, China were selected for experimental study, and the gas–liquid sulfur relative permeability under high temperature and high pressure (HTHP) was measured. The results show that, first, the critical flowing saturation of liquid sulfur was 40%, and the gas–liquid sulfur co-flow zone was narrow. With the increase in the liquid sulfur saturation, the gas relative permeability decreased rapidly. Second, the better the physical properties of the core, the greater the damage of liquid sulfur to the core properties. The residual liquid sulfur saturation of the fractured core was higher than matrix core, and as liquid sulfur saturation increased, so did the damage to gas permeability. Third, temperature had an effect on the gas–liquid sulfur relative permeability. Gas relative permeability decreased as the temperature rose, while the liquid sulfur relative permeability remained essentially constant. Fourth, the rock effective stress had a significant impact on the gas–liquid sulfur relative permeability. The relative permeability of gas and liquid sulfur decreased as the effective stress increased, and the fractured core was more sensitive to stress.