Core Recovery Research Articles

Investigation on the impact of CO2-Induced precipitation on microscopic pore structure of low-permeable reservoirs

CO2 injection into reservoirs might induce organic or inorganic precipitation in microscopic pores, and some of the pores are blocked by the precipitates, resulting in a decrease in the connectivity of pores and affecting oil recovery. In this paper, a set of experiments on CO2 displacement and CO2-water-oil-rock interaction are conducted to study the microscopic mechanisms of reservoir damage. In-situ Nuclear Magnetic Resonance (NMR) technology is applied to conduct the microscopic analysis of CO2-EOR and reservoir damage at real reservoir conditions. The results reveal that the particle size and the amount of inorganic precipitates formed in the formation water will increase with the rise of CO2 injection pressure, and the inorganic precipitates primarily consist of siderite and kaolinite. The change of NMR T2 spectra of the core samples reveals that the inorganic precipitates primarily block the small pores less than 0.89 μm. However, as a result of stronger mineral dissolution and solute transport, the pore volume of the large pores (greater than 0.89 μm) increases after the CO2-water-rock reaction. Ultimately, this interaction results in a 5.4% increment in pore volume. In addition, the displacement efficiency of water-saturated cores is improved after the first CO2 displacement, which indicates that CO2-water-rock interaction can effectively improve the seepage properties of reservoirs. Nevertheless, the reservoir damage caused by asphaltene precipitation during CO2 flooding is more significant. The asphaltene precipitation percentage in formation oil increases with the rise of CO2 injection pressure, reservoir temperature, and asphaltene content in virgin oil. CO2-induced asphaltene precipitation causes more severe blockage on small pores in comparison with large pores. After 2 h of CO2 injection to the oil-saturated core, permeability and oil recovery caused by CO2-induced precipitation decreased by 17.6% and 11.4%, respectively.

40 Years Later: Reassessing Views on the Core Deficit, Variability, Relapse/Recovery, and Attention in Stuttering

The current article reassessed the views expressed in two articles written 40 years ago about the core deficit, variability, relapse and recovery, and the role of attention in stuttering. Motor factors are now generally agreed to be the core deficit underlying stuttering, but they interact dynamically over time with other factors (Smith & Weber). Variability and unpredictability of stuttering are the norm (Tichenor & Yaruss), not the exception and should be directly addressed in therapy. PWS do think too much about speech production and this negatively impacts fluency (Eichorn et al.). In the last 40 years, it has become clear that PWS have different views about recovery and relapse. There is now less emphasis on fluency itself and more about managing impacts and quality of life. This is a dramatic change from how recovery and relapse were viewed 40 years ago.

High-precision U-Pb geochronology for the Miocene Climate Optimum and a novel approach for calibrating age models in deep-sea sediment cores

Abstract Scientific ocean drilling cores recovered years ago (legacy cores), especially as recovered by rotary drilling, commonly show incomplete recovery and core disturbance. We present a novel method to date such cores by presenting the first high-precision U-Pb zircon ages targeting the duration of the Miocene Climate Optimum (MCO; ca. 17–14 Ma) from volcanic ashes at Ocean Drilling Program Site 1000 (on the Nicaragua Rise in the Caribbean Sea). We place these ages within a newly developed framework to address incomplete core recovery and use them to calibrate a high-resolution bulk carbonate δ13C and δ18O record. Our Site 1000 ages show that volcanism of the Columbia River Basalt Group (CRBG) large igneous province was coincident with the interval of greatest sustained MCO warmth at this site. However, if the CRBG were the primary driver of the MCO, our chronology may allow for outgassing preceding volcanism as a major source of CO2. We thus document a promising new way to obtain highly resolved, accurate, and precise numerical age models for legacy deep-sea sediment cores that does not depend on correlation to other records.

Design and dynamic analysis of the scissor deployable mechanism used in the drill for replicating ice cores from the borehole wall

The deep ice cores preserved within the polar ice sheets hold a wealth of valuable information, and the demand for ice cores in related scientific research is on the rise. Thus, the replication of ice cores from the borehole wall holds significant importance. However, current methods face limitations such as difficulties in whipstock retrieval, extended auxiliary working hours, structural complexity, and the necessity of ice core depth calibration. To address this, this study proposes a novel method for replicating ice cores from the borehole wall utilizing a thermal coring drill bit. The design and dynamic analysis of the scissor deployable mechanism employed to drive the drill bit movement were thoroughly examined through theoretical and simulation studies. The motion characteristics of the drill bit during the replication coring process and the stress–strain behavior of the scissor rods were determined and validated through drill bit movement experiments, demonstrating a maximum error of 10%. The findings reveal that the mechanism can meet the strength requirements across three operating stages: horizontal drilling, vertical coring, and ice core recovery, with maximum loads of approximately 284 N, 749 N, and 970 N, respectively. Increasing the thickness of the scissor rods and reducing their length can augment the load-bearing capacity of the structure. Additionally, the speed transmission characteristics derived from the scissor mechanism can offer theoretical support for the drill's control system.

Improved Recovery of Complete Spinal Cord Transection by a Plasma-Modified Fibrillar Scaffold.

Complete spinal cord injury causes an irreversible disruption in the central nervous system, leading to motor, sensory, and autonomic function loss, and a secondary injury that constitutes a physical barrier preventing tissue repair. Tissue engineering scaffolds are presented as a permissive platform for cell migration and the reconnection of spared tissue. Iodine-doped plasma pyrrole polymer (pPPy-I), a neuroprotective material, was applied to polylactic acid (PLA) fibers and implanted in a rat complete spinal cord transection injury model to evaluate whether the resulting composite implants provided structural and functional recovery, using magnetic resonance (MR) imaging, diffusion tensor imaging and tractography, magnetic resonance spectroscopy, locomotion analysis, histology, and immunofluorescence. In vivo, MR studies evidenced a tissue response to the implant, demonstrating that the fibrillar composite scaffold moderated the structural effects of secondary damage by providing mechanical stability to the lesion core, tissue reconstruction, and significant motor recovery. Histologic analyses demonstrated that the composite scaffold provided a permissive environment for cell attachment and neural tissue guidance over the fibers, reducing cyst formation. These results supply evidence that pPPy-I enhanced the properties of PLA fibrillar scaffolds as a promising treatment for spinal cord injury recovery.

Late Pleistocene to Holocene event stratigraphy of Lake Hallstatt (Salzkammergut, Austria): revealed by the Hipercorig drilling system and borehole logging

Abstract. The Hipercorig Hallstatt History (H3) project aims to unravel the entire Late Glacial to Holocene sedimentary succession recording past climate, environment, natural hazard impacts, human–environment interactions, and prehistoric mining history. We successfully cored 51 m of the sedimentary succession of Lake Hallstatt, revealing a high-resolution Late Pleistocene to Holocene sediment record, overcoming the previous coring limit of 15.63 m (dated to ∼ 2.3 ka cal BP). The novel drilling platform Hipercorig allows the recovery of undisturbed long cores and the acquisition of borehole logging data of deep lakes. The sedimentary record is spliced to a composite core profile, and for the first time borehole logging data are linked to a core–log seismic correlation of an intra-mountainous lake of the Eastern Alps. The recovered sequence consists of two major lithostratigraphic units: (i) Unit 1 (Holocene, 0–41.7 m below lake floor) with 10 (up to 5.1 m thick) instantaneous deposits and (ii) Unit 2 (Late Pleistocene, > 41.7 m below lake floor). The Late Pleistocene sediments comprise the Younger Dryas and the deepest recovered sediments likely date back to the Allerød interstadial. Within the Holocene, six different periods are observed in the core and borehole logging data, showing distinct physical property fluctuations and an overall increase in sedimentation rate upcore. Lake Hallstatt provides a unique prehistoric archive, being located within the UNESCO World Heritage area Hallstatt–Dachstein/Salzkammergut, a region with a rich history of human salt mining dating back to 3400 cal BP (Middle/Late Bronze Age) and one of the oldest documented cultural landscapes worldwide.

Characterizing shallow fault zones by integrating profile, borehole and array measurements of seismic data and distributed acoustic sensing

AbstractWithin the framework of the Intercontinental Scientific Drilling Programme (ICDP) ‘Drilling the Eger Rift’ project, five boreholes were drilled in the Vogtland (Germany) and West Bohemia (Czech Republic) regions. Three of them will be used to install high‐frequency three‐dimensional (3D) seismic arrays. The pilot 3D array is located 1.5 km south of Landwüst (Vogtland). The borehole, with a depth of 402 m, was equipped with eight geophones and a fibre optic cable behind the casing used for distributed acoustic sensing (DAS) measurements. The borehole is surrounded by a surface array consisting of 12 seismic stations with an aperture of 400 m. During drilling, a highly fractured zone was detected between 90 m and 165 m depth and interpreted as a possible fault zone. To characterize the fault zone, two vertical seismic profiling (VSP) experiments with drop weight sources at the surface were conducted. The aim of the VSP experiments was to estimate a local 3D seismic velocity tomography including the imaging of the steep fault zone. Our 3D tomography indicates P‐wave velocities between 1500 m/s and 3000 m/s at shallow depths (0–20 m) and higher P‐wave velocities of up to 5000 m/s at greater depths. In addition, the results suggest a NW–SE striking low‐velocity zone (LVZ; characterized by = 1500–3000 m/s), which crosses the borehole at a depth of about 90–165 m. This LVZ is inferred to be a shallow non‐tectonic, steep fault zone with a dip angle of about . The depth and width of the fault zone are supported by logging data as electrical conductivity, core recovery and changes in lithology. In this study, we present an example to test and verify 3D tomography and imaging approaches of shallow non‐tectonic fault zones based on active seismic experiments using simple surface drop weights as sources and borehole chains as well as borehole DAS behind casing as sensors, complemented by seismic stand‐alone surface arrays.

It is Monday again: Weekend sleep differentially relates to the workweek via reattachment on Monday

SummaryThe weekend constitutes an important recovery period for employees. However, psychologically reattaching to work on Monday can be difficult because employees must transition from their private to their work role. Building on boundary theory and integrating a sleep and circadian perspective, we shed light on this transition by investigating antecedents and outcomes of Monday reattachment. We propose that three weekend sleep characteristics differentially relate to reattachment on Monday: weekend sleep quality, catch‐up sleep (extended sleep duration on the weekend), and social sleep lag (differences in sleep times workweek vs. weekend). Successful reattachment on Monday should, in turn, be related to lower levels of exhaustion and higher task performance during the workweek. We conducted a weekly diary study with 310 employees (933 weeks) over four workweeks. Two‐level path models demonstrated that higher weekend sleep quality was indirectly related to lower levels of workweek exhaustion via higher levels of Monday reattachment. In contrast, higher catch‐up sleep was related to higher levels of workweek exhaustion via lower levels of Monday reattachment. Accordingly, we demonstrate that Monday reattachment can set the tone for the entire workweek, but the capability to reattach can depend on weekend sleep as a core recovery process.

A Prediction Model of Coal Seam Roof Water Abundance Based on PSO-GA-BP Neural Network

With the gradual increase of coal production capacity, the issue of water hazards in coal seam roofs is increasing in prominence. Accurate and effective prediction of the water content of the roof aquifer, based on limited hydrogeological data, is critical to the identification of the central area of prevention and control of coal seam roof water damage and the reduction of the incidence of such accidents in coal mines. In this paper, we establish a prediction model for the water abundance of the roof slab aquifer, using a PSO-GA-BP neural network. Our model is based on five key factors: aquifer thickness, permeability coefficient, core recovery, number of sandstone and mudstone interbedded layers, and fold fluctuation. The model integrates the genetic algorithm (GA) into the particle swarm optimization (PSO) algorithm, with the particle swarm optimization algorithm serving as the primary approach. It utilizes adaptive inertia weight and quadratic optimization of the weights and thresholds of the backpropagation neural network to minimize the output error threshold for the purpose of minimizing output errors. The prediction model is applied to hydrogeology and coal mine production for the first time. The model is trained using 100 data samples collected by the Surfer 13 software. These samples help to accurately predict the unit inflow of water. The model is then compared with traditional forecasting methods such as FAHP, BP, and GA-BP neural network models to determine its efficiency. The study found that the PSO-GA-BP neural network model accurately predicts aquifer water abundance with higher precision. The root mean square error (RMSE) of the test set is determined to be 8.7 × 10−4, and the fitting result is measured at 0.9999, indicating minimal error with actual values of the sample. According to the prediction results of the test set, the water abundance capacity of the No. 7 coal mine in Hami Danan Lake is divided, and it is found that the overall difference between the results and the actual value is small, which verifies the reliability of the model. According to the results of the water abundance division, strong water abundance areas are mainly concentrated in the third-partition area. This study provides a new method for the prediction of aquifer water abundance, improves the prediction accuracy of aquifer water abundance, reduces the cost of coal mine production, and provides a scientific evaluation method and a theoretical basis for the prevention and control of water disasters in coal seam roofs.

Initial results of coring at Prees, Cheshire Basin, UK (ICDP JET project): towards an integrated stratigraphy, timescale, and Earth system understanding for the Early Jurassic

Abstract. Drilling for the International Continental Scientific Drilling Program (ICDP) Early Jurassic Earth System and Timescale project (JET) was undertaken between October 2020 and January 2021. The drill site is situated in a small-scale synformal basin of the latest Triassic to Early Jurassic age that formed above the major Permian–Triassic half-graben system of the Cheshire Basin. The borehole is located to recover an expanded and complete succession to complement the legacy core from the Llanbedr (Mochras Farm) borehole drilled through 1967–1969 on the edge of the Cardigan Bay Basin, North Wales. The overall aim of the project is to construct an astronomically calibrated integrated timescale for the Early Jurassic and to provide insights into the operation of the Early Jurassic Earth system. Core of Quaternary age cover and Early Jurassic mudstone was obtained from two shallow partially cored geotechnical holes (Prees 2A to 32.2 m below surface (m b.s.) and Prees 2B to 37.0 m b.s.) together with Early Jurassic and Late Triassic mudstone from the principal hole, Prees 2C, which was cored from 32.92 to 651.32 m (corrected core depth scale). Core recovery was 99.7 % for Prees 2C. The ages of the recovered stratigraphy range from the Late Triassic (probably Rhaetian) to the Early Jurassic, Early Pliensbachian (Ibex Ammonoid Chronozone). All ammonoid chronozones have been identified for the drilled Early Jurassic strata. The full lithological succession comprises the Branscombe Mudstone and Blue Anchor formations of the Mercia Mudstone Group, the Westbury and Lilstock formations of the Penarth Group, and the Redcar Mudstone Formation of the Lias Group. A distinct interval of siltstone is recognized within the Late Sinemurian of the Redcar Mudstone Formation, and the name “Prees Siltstone Member” is proposed. Depositional environments range from playa lake in the Late Triassic to distal offshore marine in the Early Jurassic. Initial datasets compiled from the core include radiography, natural gamma ray, density, magnetic susceptibility, and X-ray fluorescence (XRF). A full suite of downhole logs was also run. Intervals of organic carbon enrichment occur in the Rhaetian (Late Triassic) Westbury Formation and in the earliest Hettangian and earliest Pliensbachian strata of the Redcar Mudstone Formation, where up to 4 % total organic carbon (TOC) is recorded. Other parts of the succession are generally organic-lean, containing less than 1 % TOC. Carbon-isotope values from bulk organic matter have also been determined, initially at a resolution of ∼ 1 m, and these provide the basis for detailed correlation between the Prees 2 succession and adjacent boreholes and Global Stratotype Section and Point (GSSP) outcrops. Multiple complementary studies are currently underway and preliminary results promise an astronomically calibrated biostratigraphy, magnetostratigraphy, and chemostratigraphy for the combined Prees and Mochras successions as well as insights into the dynamics of background processes and major palaeo-environmental changes.

Victim Recovery in Restorative Justice: A Theoretical Framework

Restorative justice was initially used for minor crimes, but it has been increasingly used to address the aftermath of violent crimes. Previous studies have indicated that restorative justice can be effective in reducing the harmful effects of violent victimization. However, there is limited research on how restorative justice can support victim recovery. This article presents a theoretical framework to better understand the relationship between victim recovery and restorative justice. The framework identifies core recovery factors that are common to victims of different types of violence, as well as those that are relevant to the restorative justice process. In addition, the framework highlights enabling factors that can facilitate the victim recovery process when present in restorative justice as well as inhibiting factors that can impede the victim recovery process if they are present in restorative justice.

Daily trajectories of evening recovery experiences and their role for next-day mood.

Focusing on the definition of recovery as a process, we examined how the four core recovery experiences (i.e., psychological detachment, relaxation, control, and mastery) develop during the evening. We tested whether the specific developments of recovery experiences are important for next-day favorable mood states-beyond the mean levels of recovery experiences. We collected data from 92 employees who completed daily morning and afternoon surveys over 10 workdays. In the morning surveys, we implemented the day-reconstruction method to assess detailed information about employees' recovery experiences during several episodes of the previous evening. Our final data set included 477 morning surveys with a total of 1,998 episodes and 383 afternoon surveys. Multilevel growth curve analyses showed that, in general, psychological detachment, relaxation, and control follow a positive linear trend and mastery a negative quadratic trend during the evening. Moreover, path analyses showed that the day-level increase of psychological detachment is important for next-day mood. Specifically, we found that after evenings during which employees experienced a higher increase in psychological detachment than they usually did, they had higher favorable mood states in the subsequent afternoon. Further, our results did not support associations between day-level slopes of relaxation, control, and mastery as well as next-day mood. Hence, our study demonstrates that recovery experiences systematically change during an evening and that this change is partially relevant for next-afternoon mood. (PsycInfo Database Record (c) 2023 APA, all rights reserved).

Prediction of the Water Inrush Risk from an Overlying Separation Layer in the Thick Overburden of a Thick Coal Seam

With the expansion of coal mining westward in China, water inrush from seam roofs has become a prominent safety problem during mining. The roof rock of the coal seam in the Shilawusu coal mine has the characteristics of a double-layer structure, and the overlying separation space formed in the mining process of the coal seam poses a risk of water inrush. To ensure the safety of coal mine production, considering the geological and hydrogeological data of the mining area, the core recovery rate, lithologic assemblage index, key aquifer thickness, hydrostatic head and lithologic structure index of the Zhidan Formation are selected as evaluation indexes. The index weights are calculated based on the attribute hierarchical model and coefficient of variation methods, and subjective and objective preference coefficients are introduced to determine the ranking of comprehensive indexes. The catastrophe progression method is improved, and a zoning prediction model for water inrush risk is established by the improved catastrophe progression method. The results show that only a tiny part of the mining area is in danger, and most areas are in the safe and transition zones. The model realizes the prediction of the risk of water inrush from the overlying separation layer in the study area and provides a theoretical basis for the prevention and control of water inrush from the overlying separation layer in coal mining.

Water Abundance Evaluation of Aquifer Using GA-SVR-BP: A Case Study in the Hongliulin Coal Mine, China

At present, coal accounts for more than 56% of China’s primary energy consumption and will continue to dominate for a long time in the future. With the continuous expansion of the mining intensity and scale of Jurassic coal resources in Northwestern China, the problem of mine roof water disasters is becoming increasingly serious. The degree of harm is related to the hydrogeological structure of the overlying strata of the coal seam. Reasonable and effective prediction and evaluation of the water abundance of the coal seam roof aquifer is conducive to making scientific decisions on the prevention and control of roof water disasters, so as to achieve safe mining. In order to solve the problem of water abundance evaluation in mining areas lacking hydrological holes, taking the Hongliulin coal mine in Shennan mining area as an example, four main control factors for water abundance were selected: sandstone thickness, core recovery ratio, brittle rock thickness ratio, and flushing fluid consumption. Combined with unit water inflow and multiple factor comprehensive analysis, a back propagation (BP) artificial neural network and support vector machine regression (SVR) were introduced into water abundance evaluation. The reciprocal variance method was used to predict the measured unit water inflow. Finally, according to the “Detailed Rules for Coal Mine Water Prevention and Control”, the water abundance of aquifers was classified to verify the accuracy of the model and partition the water abundance of the study area. The results indicate that, based on the predicted results of unit water inflow, out of 37 borehole data, 22 weak water abundance holes and 15 medium water abundance holes were evaluated correctly, verifying their applicability. The study area was generally weak in water abundance, with two grades of medium and weak. The medium water abundance area was mainly located in the north and south of the study area, and the weak water abundance area was mainly located in the east and west. It can be seen that this evaluation model has certain applicability for evaluating the water abundance of coal seam roofs. It is of great significance, especially for the evaluation of water abundance in mining areas where hydrological holes are lacking.

Quantitative evaluation of water-alternative-natural gas flooding in enhancing oil recovery of fractured tight cores by NMR

As the associated gas of tight reservoirs, natural gas is abundant and noncorrosive, which is more suitable for the development of tight oil reservoirs in China. However, the mechanism of gas injection development is unclear, and the gas channeling is serious in tight reservoirs after fracturing. The water-alternating-gas (WAG) flooding is an effective means to delay gas channeling and improve oil recovery. Therefore, it is significant to clarify the mechanism of preventing gas channeling and recovering oil by water-alternation-natural gas (WANG) flooding. The WANG flooding experiments with different water–gas slugs were conducted in non-fracture and fractured tight cores. Besides, the oil distribution of different pore spaces of cores before and after displacement and the main contribution spaces on oil recovery were quantitatively analyzed by using nuclear magnetic resonance and core mercury porosimetry techniques. The results indicate that compared with natural gas flooding, the WANG flooding can retard gas channeling, increase formation energy, and enhance oil recovery by up to 14.1%, especially in fractured cores. Under the resistance of water slugs, the gas was allowed to enter smaller pores and its swept volume was expanded. Oil is mainly stored in mesopores (0.1–1 μm) and small pores (0.01–0.1 μm), accounting for over 90% of the total volume. The oil recovered mainly comes from mesopores, which accounts for over 75% of the total amount. Moreover, the WANG flooding strengthens the recovery of oil in mesopores and macropores (1–10 μm), but it also squeezes oil into small pores and micropores (0.001–0.01 μm).

Abrupt transitions in a southwest USA desert grassland related to the Pacific Decadal Oscillation.

Prediction of abrupt ecosystem transitions resulting from climatic change will be an essential element of adaptation strategies in the coming decades. In the arid southwest USA, the collapse and recovery of long-lived perennial grasses have important effects on ecosystem services, but the causes of these variations have been poorly understood. Here we use a quality-controlled vegetation monitoring dataset initiated in 1915 to show that grass cover dynamics during the 20th century were closely correlated to the Pacific decadal oscillation (PDO) index. The relationship out-performed models correlating grasses to yearly precipitation and drought indices, suggesting that ecosystem transitions attributed only to local disturbances were instead influenced by climate teleconnections. Shifts in PDO phase over time were associated with the persistent loss of core grass species and recovery of transient species, so recovery of grasses in aggregate concealed significant changes in species composition. However, the relationship between PDO and grass cover broke down after 1995; grass cover is consistently lower than PDO would predict. The decoupling of grass cover from the PDO suggests that a threshold had been crossed in which warming or land degradation overwhelmed the ability of any grass species to recover during favorable periods.

Risk Assessment of Water and Sand Inrush in Mining under Thick Loose Layer Based on Comprehensive Weight-Cloud Model

Many deep mining mines in southwestern Shandong Province of China are covered with thick loose layers. When mining near the loose layers, there is a risk of water and sand inrush, which threatens the personal safety of miners. The prediction of sudden water and sand inrush is difficult due to the comprehensive influence of many factors, and the influencing factors are fuzzy and random. To solve this problem, in this paper, a new risk assessment method of water and sand inrush based on comprehensive weight and cloud model was proposed. Seven factors are selected as indexes: the aquifer thickness, the thickness ratio of sand layer to clay layer, the thickness of bottom clay layer, the coal seam thickness, the percentage of core recovery, the geological structure, and the bedrock thickness. The assessment index system is established, and the index is divided into three grades. A comprehensive weighting method, which combines analytic hierarchy process (AHP), entropy weight method (EWM), and minimum entropy principle, is used to reasonably assign the weight of index. Based on the cloud generator equation, the membership function is obtained. The assessment result of the assessment object is obtained by combining the membership degree and the weight of index. The comprehensive weight-cloud model assessment method is applied to the risk assessment of water and sand inrush in the 6311-2 working face in the sixth mining area of Baodian Coal Mine. According to the assessment results, the following conclusions can be drawn: (1) the bedrock thickness and the coal seam thickness are the main factors of water and sand inrush under loose layer mining; (2) the assessment results obtained by the comprehensive weight-cloud model method are consistent with the actual situation. The assessment method can provide scientific reference for the safe mining under the thick loose layer in the deep mines of southwest Shandong.

Core recovery improvement due to innovative solutions

Core recovery improvement due to innovative solutions

알코올 중독 회복경험에 대한 질적 메타요약

The purpose of this study is to identify key experiences found in domestic qualitative studies on recovery from alcoholism and to derive recovery support measures based on them. To achieve this research purpose, this study applied a qualitative meta-summary. Qualitative meta-summary is a method that summarizes the results of various qualitative studies into abbreviated statements and calculates the size of the frequency effect for each abbreviated statement to identify more core experiences in the research area. As a result of examining the abbreviated statements with a large frequency effect, the core recovery experience was the experience of deciding to abstain from drinking through repeated relapse experiences, self-understanding and acceptance. When comparing the new concept of recovery with the core experiences found in this study, it was confirmed that the recovery experiences found in Korea do not show respect for the diversity of recovery experiences and promote a positive outlook on recovery. Based on the results of this analysis, this study discussed the importance of the expansion of recovery support services and advocacy movements.

An improved risk zoning method of bed-separation water inrush in underground coal mines: a case study in Ningxia, China.

Bed-separation water inrush (BSWI) is a new type of coal mine disaster that has caused serious damage. The shortcomings of previous studies on this topic are as follows: 1) most studies focused on the BSWI mechanism, evolution, and control methods, and there is a lack of research on BSWI risk assessment methods and 2) previous risk assessment studies ignored the factors of the water yield property. First, based on the proposed BSWI engineering geological model, three first-order factors are proposed: 1) separation space between layers, 2) water production characteristics, and 3) water resistance effect. Then, eight secondary factors are determined: 1) production thickness (MT), 2) hard rock thickness (HRT), 3) improved lithology index (ILCI), 4) core recovery (CR), 5) aquifer depth (AD), 6) drilling fluid consumption (DFC), 7) protective layer thickness (PLT), and 8) self-healing potential index (SPI). Subsequently, the corresponding weights are calculated, and the multifactor superposition method is used to draw the BSWI risk map. The area is divided into three risk grades: low, medium, and high. The results are validated by observations of BSWI accidents and bed-separation water exploration and discharge boreholes in the study area. The proposed method can be used to effectively prevent BSWI disasters in other coal mines with similar geological conditions.