Northeast Sichuan Research Articles

The status quo and correlational analysis of nursing practices, burnout, and social support among nurses from private hospitals in Dazhou, a less developed area of China

ObjectiveTo investigate the status quo of nursing practices, job burnout and social support among private hospitals in Dazhou, Sichuan Province, and perform correlational analysis.MethodsA cross-sectional study was conducted. A total of 244 nurses were surveyed via convenience sampling from 7 private hospitals, which were randomly selected from Dazhou city. A self-designed demographic sociology questionnaire was applied, and the Chinese versions of the Maslach Burnout Scale and the Social Support scale administered from September to November 2022.ResultsThe investigated nurses were relatively young (26.84 ± 4.90 years), had a short duration of service, a low academic background, a low professional title and a low income; however, they were highly satisfied with their working environment and had a low level of burnout, and their level of personal achievement was low. Overtime work, education level and number of children had significant impacts on the level of nurse burnout. The level of social support was high, and various dimensions were negatively correlated with the emotional exhaustion and depersonalization dimensions of burnout (r=-0.438, P < 0.01; r=-0.372, P < 0.01) and positively correlated with personal achievement (r = 0.291, P < 0.01). However, the level of social support was not significantly associated with burnout (r=-0.060, p = 0.354).ConclusionsNursing managers in private hospitals should consider ways of improving nurses’ education, professional titles, working environment and increasing nurses’ income to stabilize the nursing team. Efforts should be made to relieve the nurses’ pressure, and notice the overtime work and professional development of nurses to enhance the personal sense of achievement. More measures should be taken to improve the level of social support, thereby promoting the continuous improvement of nursing quality. Due to the uneven level of social and economic development in different parts of China, the extensibility of the research needs to be confirmed by more studies, but it still has important reference significance for Northeast Sichuan, which represents areas with similar social and economic levels.

Characteristics of astigmatism in school-age children aged 5 to 13 years in northeast Sichuan: a cross-sectional school-based study.

Astigmatism is closely associated with myopia progression, vision loss, eye fatigue and amblyopia, which seriously endangers children's eye health. This study aims to investigate the prevalence and characteristic distribution of astigmatism in children in Langzhong City, providing valuable insights for allocating resources and develop prevention and control strategies. A cross-sectional study and random sampling survey were conducted. Between January and November 2021, 21,415 students aged 5 to 13 years from 14 primary schools in Langzhong City underwent non-cycloplegic refractive testing using autorefraction. The data on myopia were analyzed using SPSS (Statistical Package for the Social Sciences) version 23.0. The inclusion criterion was set at an absolute astigmatism value of ≥0.50D. Among the 21,415 children studied, 61.70% were found to have astigmatism. The prevalence of astigmatism varied significantly across different grades (χ2=501.414, P<0.001). The predominant types of astigmatism were mild astigmatism (0.50-1.00D) and with-the-rule astigmatism. Mixed astigmatism was primarily observed in children in grades 1 and 2, while compound myopic astigmatism was more common in children in grades 3 to 6. These differences were statistically significant. As the degree of astigmatism increased, the proportions of against-the-rule astigmatism, oblique astigmatism, compound myopic astigmatism, and simple hyperopic astigmatism decreased, whereas the proportions of with-the-rule astigmatism, mixed astigmatism, and compound hyperopic astigmatism increased. The prevalence of astigmatism among school-age children aged 5 to 13 years in northeast Sichuan is notably high, with compound myopic astigmatism and with-the-rule astigmatism being the most common types. Regular refractive examinations are crucial for the early detection and management of astigmatism.

Assessment of ozone pollution on rice yield reduction and economic losses in Sichuan province during 2015–2020

In recent years, there has been a significant increase in surface ozone (O3) concentrations in the troposphere. Ozone pollution has significant adverse effects on ecosystems, human health, and climate change, particularly on crop growth and yield. This study utilized the observational hourly O3 data, cumulative O3 concentration over 40 ppb per h (AOT40), and the mean daytime 7-h O3 concentration (M7) to analyze the spatiotemporal distributions of relative yield losses (RYLs) and evaluate the yield reduction and economic losses of rice in Sichuan province from 2015 to 2020. The results indicated that the average O3 concentration during the growing rice season ranged from 55.4 to 69.3 μg/m3, with the highest O3 concentration observed in 2017, and the AOT40 ranged from 4.5 to 8.7 ppm h from 2015 to 2020. At the county level, the O3 concentration, AOT40, and the relative yield loss (RYL) of rice based on AOT40 exhibited clear spatiotemporal differences in Sichuan. The RYLs of AOT40 were 4.9–9.2% from 2015 to 2020. According to AOT40 and M7 metrics, the yield loss and economic losses attributed to O3 pollution amounted to 78.75–150.36 (9.74–21.54) ten thousand tons, and 2079.08–4149.89 (257.25–594.45) million Yuan, respectively. Rice yield and economic losses were relatively large in the Chengdu Plain, southern Sichuan, and northeast Sichuan. These findings will contribute to a deeper understanding of the detrimental effects of elevated surface O3 concentrations on rice crops. It is imperative to implement more stringent O3 reduction measures aimed at lowering O3 concentrations, enhancing rice quality, and safeguarding food security in Sichuan.

Winter indoor thermal environment and livability analysis of traditional residential houses in northeast Sichuan, China

With the rapid development of the national economy, increasing attention has been given to the living environment in rural areas, especially indoor thermal and wind environments. This study conducted on-site measurements and questionnaire surveys during winter in the indoor environment of five villages in northeastern Sichuan. Eighty-nine traditional residences were selected to investigate their fundamental characteristics, indoor thermal environment, humidity conditions, and comfort levels. Questionnaires and comparative experiments were also conducted with natives and locals. This combination of objective data and subjective feedback provides a comprehensive perspective for assessing the indoor thermal environment. The results showed that when expressed as neutral temperature and humidity, the temperature difference was 2.36 °C, with little humidity difference. Residents exhibited higher tolerance towards the local thermal and humidity environment than nonlocal volunteers, who showed greater sensitivity to it. In addition, residents had a Predicted Mean Vote (PMV) value of −0.69 and a heat acceptance value of −1.78, while non-local volunteers had a PMV value of −0.76 and a heat acceptance value of −1.32. A detailed evaluation and analysis of the relationship between the indoor thermal environment and human comfort of local residential houses was carried out, providing technical guidance for energy conservation and thermal insulation of local buildings.

Microbially induced fabrics in the Upper Ediacaran coated grain dolostone, Northeast Sichuan Basin, SW China: Implications for reconstruction of the paleoceanic environment

In the Upper Ediacaran Dengying Formation of the Sichuan Basin, the presence of abundant, well-preserved microbial carbonates provides a unique opportunity to study Precambrian paleoceanography and microbial carbonate origins. Particularly, the underexplored coated grain dolostones of this formation, characterized by distinct microbially induced fabrics and intragranular dissolution, offer crucial insights for understanding late Ediacaran microbial mineralization and diagenetic sequences. Utilizing selected typical samples, we conducted detailed petrographic and geochemical analyses, revealing a dynamic interplay between microbial processes and sedimentary dynamics. We observe the coexistence of constructive micrite envelopes with microbially induced fabrics such as clots and laminations, highlighting microbial biomineralization's key role in fabric formation. The sedimentary dynamics critically determines the formation processes of the coated grains: low-energy settings foster grain agglomeration and consolidation through clot precipitation between grains, while high-energy settings favor smaller grains binding to microbial mats. Geochemically, micrite envelopes play an essential role in preserving distinct rare earth element (REE) signatures. The weak negative Ce anomalies and positive Eu anomalies within these envelopes point to a suboxic to anoxic depositional environment, directly indicative of the microenvironmental conditions conducive to microbial mineralization processes. Furthermore, our study sheds light on the structural evolution of coated grains with hollow nuclei, proposing that their internal pore formations are influenced by both mineral instability and selective dissolution by meteoric freshwater. These findings not only provide fresh insights into complex diagenetic processes in the Dengying Formation but also substantially advance our understanding of early microbial life and environmental adaptations during the Precambrian.

Optimization and Renovation Design of Indoor Thermal Environment in Traditional Houses in Northeast Sichuan (China)—A Case Study of a Three-Section Courtyard House

The three-section courtyard is the most representative traditional residence in the traditional villages in northeast Sichuan. As a unique cultural landscape, it carries the local historical style and cultural connotation. However, the high temperature weather in summer leads to a poor thermal environment in traditional residential buildings, which cannot meet the needs of building users for human thermal comfort, and the wall is the most critical factor affecting the indoor thermal environment. Therefore, to optimise the indoor thermal environment of traditional residential buildings, this study designed four groups of wall renovation schemes according to the original traditional residential buildings and modern technology, and simulated and verified the feasibility of the building renovation schemes by using Design Builder. Then, the four groups of wall renovation schemes were compared and tested based on the Design Builder. Comparative results of the thermal-performance evaluation index revealed that compared with Case 1 and Case 2, the building refrigeration energy consumption of Case 3 in the hottest week was the least, only 427.7 kW·h, which indicates that the external wall renovation scheme using aerated concrete blocks had the best thermal insulation and energy-saving effects. The cooling energy consumption of Case 4 in the hottest week was 422 kW·h, which was 4.3 kW·h less than that of Case 3, indicating that the wall renovation scheme with an air inter-layer had better thermal insulation and energy-saving effects. The refrigeration energy consumption of Case 7 in the hottest week was only 409.8 kW·h, which was 4.19% lower than Case 3 (without insulation material), indicating that the scheme of selecting central insulation and extruded polystyrene board (XPS) had better thermal insulation and energy-saving effects in practical projects. In summary, the above transformation scheme not only improves the indoor thermal environment of traditional residential buildings, but also provides guidance for architectural designers on green, energy-saving and sustainable design.

Organic Petrologic Characterization and Paleoenvironmental Analysis of Permian Shale in Northeast Sichuan Province, China

The Permian shale in Northeast Sichuan is an important shale oil and gas resource potential area, and the study of its organic matter characteristics and paleoenvironmental analysis is of great significance for revealing the shale oil and gas formation mechanism and resource evaluation. In this study, the organic matter of Permian shales in northeast Sichuan was carefully studied based on various analytical tools, such as petrology, laser Raman, microscopy, and principal trace elements, and the paleoenvironmental parameters of the shales were comprehensively analysed. A detailed study of the organic matter characteristics of Permian shales in northeast Sichuan reveals important features such as organic matter fractions, structural characteristics, maturity and sources. The results show that the organic matter of the shale consists mainly of solid bitumen, putrescine group, specular group and multicellular planktonic algae. Petrological observations and laser Raman analyses indicate a high maturity of the organic matter and a high content of organic carbon (TOC), showing good hydrocarbon potential. In this study, we reconstructed the palaeoenvironmental parameters and inferred the palaeoenvironmental evolution through palaeoenvironmental analyses of Permian shales in northeast Sichuan. The results of the comprehensive multi-indicator study show that the type of palaeoenvironment at the time of shale deposition was mainly an anoxic-reducing environment, and the depositional conditions were favourable to the enrichment and preservation of organic matter. In summary, the organic matter characteristics and paleoenvironmental analyses of the Permian shales in Northeast Sichuan provide important geological background information for an in-depth understanding of the formation mechanism, exploration potential and development prospect of shale hydrocarbons in this area. The results of this study can provide a scientific basis for the evaluation and development of shale oil and gas resources in this area, which is of great significance to geologists and the energy industry.

Investigation and analysis of the status of myopia and related behavior in children and adolescents in Northeast Sichuan.

In this study, we examined the current status of myopia among primary and secondary school children in northeastern Sichuan to analyze the factors connected to myopia and provide data support and a theoretical foundation for the prevention and control of myopia. Using a cross-sectional study and a comprehensive sampling survey, 34,138 students aged 5-19 years were screened for refraction in 22 primary and secondary schools in Langzhong, and 4000 behavioral questionnaires were delivered at random. After evaluation and rational problem-solving, a total of 3764 valid questionnaires were obtained. SPSS 23.0 statistical software was used for data analysis. The percentage of myopia among primary and secondary school students in Langzhong was 65.61%, with female students having a higher rate than male students ( P < 0.05); 52.81% of primary school students, 86.26% of secondary school students, and 88.17% of high school students had myopia. The incidence of myopia detection increased with school age ( P < 0.001), indicating a correlation between age and myopia prevalence. The prevalence of myopia was mainly low (40.53%) and moderate myopia (19.89%). The prevalence of high myopia (5.19%) was relatively high. The prevalence of myopia among female students (5.54%) was greater than that in male students ( P < 0.05) and increased with age ( P < 0.001). The proportion of students who wore eyeglasses was 24.36%, with a larger proportion of female students (25.93%) than male students (22.61%) ( P < 0.001). In addition, the rate of eyeglass use increased with school age ( P < 0.001). A logistic regression analysis revealed that higher grade point averages, female gender, and long-term usage of electronic items were risk factors for myopia. The results of the questionnaire survey revealed that students in this region were under immense pressure to perform well academically, spent a lot of time engaged in near-work activities, and had a low rate of myopia awareness; 24.43% of the students had not had a vision examination in the previous year, indicating that parents did not pay sufficient attention to eye health. The incidence of myopia among children and teenagers is high in Northeast Sichuan, and the outlook for addressing the problem is bleak. Therefore, it is critical to improve vision monitoring and eye health education.

Analysis of the indoor thermal environment and livability of traditional residences in summer in Northeast Sichuan, China

Abstract With the rapid development of the national economy, increasing attention has been given to the living environment in rural areas, especially indoor thermal and wind environments. This study conducted onsite measurements and questionnaire surveys during summer in the indoor environment of five villages in northeastern Sichuan. A total of 89 traditional residences were selected to investigate their fundamental characteristics, indoor thermal environment, humidity conditions and comfort levels. The results showed that when expressed as neutral temperature and humidity, the temperature difference was 1.35°C and the humidity difference was 8.14%. Local residents exhibited higher tolerance toward the local thermal and humidity environment compared to nonlocal volunteers, who displayed greater sensitivity toward it. In addition, local residents had a thermal comfort value of 0.03 and a thermal acceptance value of 1.16, whereas nonlocal volunteers had a thermal comfort value of 1.42 and a thermal acceptance value of −0.45.

Reservoir characteristics and controlling factors of the middle–high maturity multiple lithofacies reservoirs of the Lianggaoshan Formation shale strata in the northeastern Sichuan basin, China

The Lianggaoshan Formation, which is located in the northeastern part of the Sichuan Basin, is an important shale oil producer. However, due to the effects of complex petrography, a wide range of maturity, and lower organic matter (OM) content in comparison to other areas, the pore characteristics of different lithofacies are unclear, which severely limits exploration and development. Therefore, by using geochemical, petrological and pore structure characterization experiments, this study thoroughly examines the pore properties of several lithofacies in the Lianggaoshan Formation in Northeast Sichuan. The deposits in the study area are OM-rich laminated argillaceous shale (ORLAS), silty mudstone (SM), OM-low laminated siliceous shale (OLLSS), organic-laminated argillaceous shale (OLLAS), OM-low bedded shale (OLBMS), and (fine) siltstone (FS). With higher porosity and macropore + microfracture volume ratio, ORLAS and OLLSS have better reservoir qualities than the other lithologies, while the reservoir properties of SM and FS are the worst. Hydrocarbon generation and diagenesis affecting pore development include thermal maturation of OM, mechanical compaction, dissolution, and cementation. The porosity and medium–large scale pore volume ratio show a tendency to increase and then decrease with maturity, reaching their highest values at an Eq range of (Ro) = ∼1.6%. Dissolution greatly contributes to pore development. The pore space is primarily sealed by cementation and compaction, which is most evident in SM and FS. In addition to thermal maturity, factors affecting the reservoir properties include clay minerals, siliceous minerals, and total organic carbon (TOC). Clay minerals and OM often form OM–clay mineral complexes, which can promote hydrocarbon generation and pore enlargement through interaction. The properties of the reservoir significantly improved when TOC and clay contents increased. However, the lithology of the study area, which contains a significant concentration of siliceous minerals, is unfavorable to reservoir properties.

Research on the Development Status and Countermeasures of Middle School Girls’ Football in Northeast Sichuan —Take Xichong Middle School in Nanchong City as an Example

Research on the Development Status and Countermeasures of Middle School Girls’ Football in Northeast Sichuan —Take Xichong Middle School in Nanchong City as an Example

Natural Fractures and Their Contribution to Natural Gas Migration and Accumulation in Marine Carbonate Reservoirs: Lower Triassic Feixianguan Formation, Northeast Sichuan Basin, China

The Lower Triassic carbonate succession of the Feixianguan Formation represents a primary focus for gas exploration in the northwestern Sichuan Basin. This study area includes the massive Puguang gas field and other nearby gas fields of considerable size. These carbonate reservoirs display significant heterogeneity, which is primarily influenced by the presence of natural fractures. Extensive documentation of fracture types, characteristics, effectiveness, and their role in enhancing reservoir properties was conducted by examining and analyzing various data sources, including cores, thin sections, image logs, and experimental measurements. Shear fractures primarily characterize the Feixianguan Formation carbonate reservoir, although tensile and diagenetic fractures are also present, albeit in fewer numbers. Tectonic fractures are the dominant type, particularly unfilled ones with dip angles greater than 60° in the NEE–SWW direction. These fractures are mainly filled with calcite. The tectonic fractures were formed in three stages: Late Indosinian-Early Yanshanian, Late Yanshanian-Early Himalayan, and Late Himalayan. These fractures intersect with the in situ stress direction at a small angle in the NE–SW, NEE–SWW, and near E–W directions, contributing to their effectiveness. Compared with the total fracture density, the effective fracture density is the factor in controlling gas production. An increase in the proportion of effective fractures tends to result in a rise in gas productivity. Additionally, the orientation of effective fractures also influences natural gas production. Fractures striking in the E–W and NE–SW directions, which are particularly effective, are associated with high natural gas production.

A dataset of gas reservoir microscopic images in Xujiahe Formation in northeast Sichuan Basin

The gas reservoir in Xujiahe Formation in northeast Sichuan Basin holds promising potential for exploration and development. In this paper, we collected and sorted the microscopic image data of the clastic reservoir of Xujiahe Formation gas reservoir in the study area, so as to further study the petrological characteristics, diagenesis, reservoir space and physical properties of the region. The reservoir rocks are mainly lithic sandstone, lithic arkose sandstone and quartz sandstone. There are intergranular solution pores, residual intergranular solution pores, intragranular solution pores, clay mineral intergranular (solution) pores and various microfractures in the reservoir space. According to the observation of the cast thin section, the pores are relatively undeveloped, while some thin sections (micro-cracks) are relatively developed. Based on thin section identification and observation, the sandstone reservoirs of Xujiahe Formation in the study area have undergone processes such as compaction, cementation, dissolution and tectonic fracture. This dataset can provide a direct source for the comparative analysis and reference of sandstone image data. Moreover, it can serve as a benchmark for the intelligent identification of lithology.

Survey and Research on the Development State of Sports Education in Special Schools in the Context of the "14th Five-Year Plan"-A Case Study of Nanchong City, a Core City in Northeast Sichuan

Since the beginning of reform and opening-up, the development of sports cause of the disabled in China has markedly improved, especially the development of competitive sports of the disabled has been remarkable, by contrast, the reform and development of sports education in special schools in China are lack of focus. Sports education is not only an important content of education for students in special schools, but also an important means, and it plays an important role in promoting the physical and mental development of students in special education schools. This paper adopts the literature method, questionnaire method, logical analysis method and mathematical statistics method, takes the teachers of special schools in the three major urban areas of Nanchong City as the objects, understands the current development situation of special physical education in Nanchong City, solves the problems encountered by special schools in the development of physical education, and puts forward relevant constructive opinions and countermeasures for the problems.

Clinical Characteristics and Risk Factors of Polymyositis and Dermatomyositis Combined with Interstitial Lung Disease in Patients Residing in the Northeast Sichuan Province of China.

Polymyositis (PM) and dermatomyositis (DM) are non-suppurative and autoimmune inflammatory diseases of striated muscle. Interstitial lung disease (ILD) is a group of heterogeneous diseases that mainly involve the pulmonary interstitium, alveoli, and/or bronchioles, also known as diffuse parenchymal lung disease (DPLD). A significant cause of death in persons with polymyositis (PM) and dermatomyositis (DM) is concurrent interstitial lung disease (ILD). However, research on the clinical characteristics and associated influencing factors of PM/DM combined with ILD (PM/DM-ILD) is currently scarce in China. The study aimed to probe the clinical features and risk factors of PM/DM-ILD. The data of 130 patients with PM/DM were gathered. General medical status, clinical symptoms, laboratory parameters, high-resolution CT, therapeutic outcomes, and prognoses were retrospectively reviewed in patients with PM/DM with (ILD group) and without (NILD) ILD. The age of the ILD group (n=65) was more than the NILD group (n=65), and the difference was statistically significant; there were no significant between-group variations in the PM/DM ratio, sex, or duration of the disease. The initial symptoms were arthritis and respiratory symptoms in the ILD group, and myasthenia symptoms in the NILD group. Incidences of Raynaud's phenomenon, dry cough, expectoration, dyspnea on exertion, arthritis, fever, total globulin (GLOB), erythrocyte sedimentation rate (ESR), and anti-Jo-1 antibody rate were higher for ILD; however, albumin (ALB), creatine kinase aspartate aminotransferase activity ratio (CK/AST) and CK levels were significantly lower in the ILD group. Bivariate logistic regression analysis showed age, dry cough, arthritis, dyspnea on exertion, anti-Jo-1 antibody, and elevated GLOB to be independent risk factors for ILD among patients with PM/DM. Advanced age, dry cough, arthritis, dyspnea on exertion, anti-Jo-1 antibody positivity, and elevated GLOB level are risk factors for PM/DM-ILD. This information could be utilized to carefully monitor changing lung function in these patients.

Characteristics and Evolution of Tectonic Fractures in the Jurassic Lianggaoshan Formation Shale in the Northeast Sichuan Basin

The features and formation stages of natural fractures have significant influences on the fracturing of shale reservoirs and the accumulation of oil and gas. The characteristics and evolution of tectonic fractures in the Lianggaoshan Formation in Northeast Sichuan were investigated based on outcrops, drill cores, geochemical data, and acoustic emission test results. Our results demonstrated that the fracture types of the Lianggaoshan Formation were mainly low-degree bedding-slip fractures, followed by high-degree through-strata shear fractures and vertical tensile fractures. The influences of strike-slip faults on the fractures were stronger than those of thrust faults; fractures in thrust faults were concentrated in the hanging wall. The densities of tensile and shear fractures were inversely proportional to the formation thickness, while the density of interlayer slip fractures was independent of the formation thickness. The density of tectonic fractures was proportional to the quartz content. The fractures of the Lianggaoshan Formation were generated in three stages during uplift: (1) Late Yanshan–Early Himalayan tectonic movement (72~55 Ma), (2) Middle Himalayan tectonic movement (48~32 Ma), (3) Late Himalayan tectonic movement (15 Ma~4 Ma). Fractures greatly improve the oil and gas storage capacity and increase the contents of free and total hydrocarbons. At the same time, they also reduce the breakdown pressure of strata. This study facilitated the prediction of the fracture distribution and oil and gas reservoirs in the Lianggaoshan Formation and provided references for the selection of favourable areas for shale oil and the evaluation of desert sections in the study area.

Study on the Disaster Prevention Capacity of Residential Buildings in Enyang Ancient Town

In the background of protecting the development of historical and traditional cultural buildings, the exploration of disaster prevention technology of ancient town buildings is of great significance. Enyang ancient town has a long history, and its residential buildings have typical Ming dynasty and Qing dynasty architectural features and regional characteristics of northeast Sichuan. Enyang ancient town has experienced many natural disasters such as floods and earthquakes in its history, and the disaster resistance of its residential buildings is worth exploring. Taking the dwellings in Enyang Ancient town as the research object, its architectural space form and architectural structure are analyzed. On this basis, the flood resistance, earthquake resistance and fire resistance of the ancient town’s residential buildings were further studied. The research results can provide reference for the analysis of disaster prevention performance and reinforcement protection of similar ancient towns.

Research on the Development of Intangible Cultural Heritage Tourism Products in Nanchong

Promoting the integrated development of intangible cultural heritage and tourism is an important direction of China's development. Nanchong City, the central city of Northeast Sichuan Economic Zone of China, is selected as the research object. Based on the statistics of the existing intangible cultural heritage tourism resources in Nanchong City, the development status of its intangible cultural heritage tourism products is deeply analyzed by using ASEB grid analysis method. Based on the analysis results, it is proposed that the intangible cultural heritage tourism in Nanchong should be strengthened by constructing the product spectrum of cultural tourism, broadening the channels of tourism publicity, optimizing the design of tourist routes and creating distinctive brand images.

Influencing Factors of the Brittleness of Continental Shales Containing Shell Limestone Interlayer

Brittleness is important in the evaluation of the fracturing ability of shale reservoir and has a significant impact on shale gas exploration and development. This paper discusses the characteristics and controlling factors of brittleness of continental shale in the Da’anzhai Member of the Ziliujing Formation of Lower Jurassic age in the northeast Sichuan Basin. Continental shale lithofacies and their associations were grouped into four main rock types: clayey shale, silty shale, shell calcareous clayey shale, and silty clayey shale, characterized by the high clay content and local enrichment of carbonate minerals as a whole. Compared with the marine shale, the continental shale contained a low content of siliceous minerals, a high content of carbonate minerals, and a large number of shell limestone interlayers. Carbonate minerals play an important role in controlling the brittleness of continental shale. The shale interlayers were mainly shell limestone interlayers with a thickness of several centimeters and a large number of shell laminates with thicknesses of several millimeters were also observed. The shell laminates were mainly filled with calcite. Due to the dissolution process, a large number of bedding joints and corrosion joints were formed in the calcite shell layers. In the interlayers with a high shell content, a large number of microfractures developed. The energy consumption required for maintaining fracture expansion was lower after fracturing; the fractures greatly improved the reservoir’s brittleness.

Pore Structure and Gas Content Characteristics of Lower Jurassic Continental Shale Reservoirs in Northeast Sichuan, China

The Jurassic shale in the northeastern Sichuan Basin is one of the main target intervals for continental shale gas exploitation. Research on the pore structure and gas-bearing properties of shales is the key issue in target interval optimization. Through core observation, geochemistry, bulk minerals, scanning electron microscopy, nitrogen adsorption, and isothermal adsorption experiments, various lithofacies with different pore structure characteristics were clarified. In addition, the factors that control gas-bearing properties were discussed, and a continental shale gas enrichment model was finally established. The results show that the Jurassic continental shale in the northeastern Sichuan Basin can be classified into six lithofacies. Organic pores, intergranular pores, interlayer pores in clay minerals, intercrystalline pores in pyrite framboids, and dissolution pores can be observed in shale samples. Pore structures varied in different shale lithofacies. The contact angle of shales is commonly less than 45°, leading to complex wettability of pores in the shales. Free gas content is mainly controlled by the organic matter (OM) content and the brittleness in the Jurassic shale. The adsorbed gas content is mainly controlled by the OM content, clay mineral type, and water saturation of the shales. The enrichment mode of the Lower Jurassic continental shale gas in the northeastern Sichuan Basin is established. Paleoenvironments control the formation of organic-rich shales in the center part of lakes. The "baffle" layer helps the confinement and high pressure, and the complex syncline controls the preservation, forming the enrichment pattern of the complex syncline-central baffle layer.