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Abstract Triple-negative breast cancer (TNBC) is widely recognized as the most aggressive form of breast cancer, occurring more frequently in younger patients and characterized by high heterogeneity, early distant metastases and poor prognosis. Multiple treatment options have failed to achieve the expected therapeutic effects due to the lack of clear molecular targets. Based on genomics, transcriptomics and metabolomics, the multi-omics analysis further clarifies TNBC subtyping, which provides a greater understanding of tumour heterogeneity and targeted therapy sensitivity. For instance, the luminal androgen receptor subtype (LAR) exhibits responsiveness to anti-AR therapy, and the basal-like immune-suppressed subtype (BLIS) tends to benefit from poly (ADP-ribose) polymerase inhibitors (PARPis) and anti-angiogenic therapy. The efficacy of multi-dimensional combination therapy holds immense importance in guiding personalized and precision medicine for TNBC. This review offers a systematic overview of recent FuDan TNBC molecular subtyping and its role in the instruction of clinical precision therapy.

Abstract Heart transplantation is the gold standard for treating patients with advanced heart failure. Although improvements in immunosuppressive therapies have significantly reduced the frequency of cardiac graft rejection, the incidences of T cell-mediated rejection (TCMR) and antibody-mediated rejection remain almost unchanged. A four-archetype analysis (4AA) model, developed by Philip F. Halloran, illustrated this problem well. It provided a new dimension to improve the accuracy of diagnoses and an independent system for recalibrating the histology guidelines. However, this model was based on the invasive method of endocardial biopsy, which undoubtedly increased the postoperative risk of heart transplant patients. Currently, little is known regarding the associated genes and specific functions of the different phenotypes. We performed bioinformatics analysis (using machine-learning methods and the WGCNA algorithm) to screen for hub-specific genes related to different phenotypes, based Gene Expression Omnibus accession number GSE124897. More immune cell infiltration was observed with the ABMR, TCMR, and injury phenotypes than with the stable phenotype. Hub-specific genes for each of the four archetypes were verified successfully using an external test set (accession number GSE2596). Logistic-regression models based on TCMR-specific hub genes and common hub genes were constructed with accurate diagnostic utility (area under the curve > 0.95). RELA, NFKB1, and SOX14 were identified as transcription factors important for TCMR/injury phenotypes and common genes, respectively. Additionally, 11 Food and Drug Administration-approved drugs were chosen from the DrugBank Database for each four-archetype model. Tyrosine kinase inhibitors may be a promising new option for transplant rejection treatment. KRAS signaling in cardiac transplant rejection is worth further investigation. Our results showed that heart transplant rejection subtypes can be accurately diagnosed by detecting expression of the corresponding specific genes, thereby enabling precise treatment or medication.

Abstract Background The aberrant secretion and excessive deposition of type I collagen (Col1) are important factors in the pathogenesis of myocardial fibrosis in dilated cardiomyopathy (DCM). However, the precise molecular mechanisms underlying the synthesis and secretion of Col1 remain unclear. Methods and results RNA-sequencing analysis revealed an increased HtrA serine peptidase 1 (HTRA1) expression in patients with DCM, which is strongly correlated with myocardial fibrosis. Consistent findings were observed in both human and mouse tissues by immunoblotting, quantitative reverse transcription polymerase chain reaction (qRT-PCR), immunohistochemistry, and immunofluorescence analyses. Pearson’s analysis showed a markedly positive correlation between HTRA1 level and myocardial fibrosis indicators, including extracellular volume fraction (ECV), native T1, and late gadolinium enhancement (LGE), in patients with DCM. In vitro experiments showed that the suppression of HTRA1 inhibited the conversion of cardiac fibroblasts into myofibroblasts and decreased Col1 secretion. Further investigations identified the role of HTRA1 in promoting the formation of endoplasmic reticulum (ER) exit sites, which facilitated the transportation of Col1 from the ER to the Golgi apparatus, thereby increasing its secretion. Conversely, HTRA1 knockdown impeded the retention of Col1 in the ER, triggering ER stress and subsequent induction of ER autophagy to degrade misfolded Col1 and maintain ER homeostasis. In vivo experiments using adeno-associated virus-serotype 9-shHTRA1-green fluorescent protein (AAV9-shHTRA1-GFP) showed that HTRA1 knockdown effectively suppressed myocardial fibrosis and improved left ventricular function in mice with DCM. Conclusions The findings of this study provide valuable insights regarding the treatment of DCM-associated myocardial fibrosis and highlight the therapeutic potential of targeting HTRA1-mediated collagen secretion.

Abstract Objectives Pro-protein convertase subtilisin/kexin 9 (PCSK9) decreases the clearance of the pathogenic lipids, supporting the potential role of PCSK9 in the prognosis of sepsis. Methods In this prospective cohort study, patients with sepsis were consecutively recruited from 1 to 2020 to 30 September 2021 at the First People’s Hospital of Huaihua, China. All the eligible patients were categorized into low-PCSK9 and high-PCSK9 groups, based on their PCSK9 levels at admission. Time-dependent receiver operating characteristic curves and Cox proportional hazards regression were used to evaluate the association between PCSK9 level and 28-day mortality of sepsis. Results Of the 203 enrolled patients, 56 (27.59%) died during the 28-day follow-up. The PCSK9 level was positively related to the C-reactive protein level. The cut-off point of PCSK9 levels for 28-day mortality risk was 370 ng/ml. Through comparison between high-PCSK9 (> 370 ng/ml) with low-PCSK9 (≤ 370 ng/ml) groups, the adjusted HR for mortality was 2.56 (95% CI: 1.25–5.23, p = 0.01). Conclusions The 28-day mortality of sepsis increased significantly as the baseline circulating PCSK9 level exceeded 370 ng/ml, indicating circulating PCSK9 levels may be a potential biomarker to predict the prognosis of sepsis.

Background and objectiveMacrophages play a crucial and dichotomous role cardiac repair following myocardial ischemia-reperfusion, as they can both facilitate tissue healing and contribute to injury. This duality is intricately linked to environmental factors, and the identification of macrophage subtypes within the context of myocardial ischemia-reperfusion injury (MIRI) may offer insights for the development of more precise intervention strategies.MethodsSpecific marker genes were used to identify macrophage subtypes in GSE227088 (mouse single-cell RNA sequencing dataset). Genome Set Enrichment Analysis (GSEA) was further employed to validate the identified LAM subtypes. Trajectory analysis and single-cell regulatory network inference were executed using the R packages Monocle2 and SCENIC, respectively. The conservation of LAM was verified using human ischemic cardiomyopathy heart failure samples from the GSE145154 (human single-cell RNA sequencing dataset). Fluorescent homologous double-labeling experiments were performed to determine the spatial localization of LAM-tagged gene expression in the MIRI mouse model.ResultsIn this study, single-cell RNA sequencing (scRNA-seq) was employed to investigate the cellular landscape in ischemia-reperfusion injury (IRI). Macrophage subtypes, including a novel Lipid-Associated Macrophage (LAM) subtype characterized by high expression of Spp1, Trem2, and other genes, were identified. Enrichment and Progeny pathway analyses highlighted the distinctive functional role of the SPP1+ LAM subtype, particularly in lipid metabolism and the regulation of the MAPK pathway. Pseudotime analysis revealed the dynamic differentiation of macrophage subtypes during IRI, with the activation of pro-inflammatory pathways in specific clusters. Transcription factor analysis using SCENIC identified key regulators associated with macrophage differentiation. Furthermore, validation in human samples confirmed the presence of SPP1+ LAM. Co-staining experiments provided definitive evidence of LAM marker expression in the infarct zone. These findings shed light on the role of LAM in IRI and its potential as a therapeutic target.ConclusionIn conclusion, the study identifies SPP1+ LAM macrophages in ischemia-reperfusion injury and highlights their potential in cardiac remodeling.

BackgroundIschemic Heart Disease (IHD) is a leading cause of morbidity and mortality worldwide. Hypercholesterolaemia, a metabolic syndrome distinguished by elevated cholesterol levels, is positively correlated with IHD, yet the precise causal relationship between these two health conditions remains to be clearly defined.MethodsWe conducted a two-sample MR analysis using genetic variants associated with hypercholesterolemia and IHD. Various statistical techniques including MR-Egger, Weighted Median, Inverse Variance Weighted (IVW), Simple Mode, and Weighted Mode were employed. We also performed sensitivity analyses to assess pleiotropy, heterogeneity, and influence of individual SNPs. Furthermore, genetic co-localization analysis was performed to identify shared genes between hypercholesterolemia and IHD.ResultsOur MR study illuminated a bidirectional causal relationship between hypercholesterolaemia and ischaemic heart disease. Utilising the IVW with multiplicative random effects, upon considering IHD as the outcome, we identified an OR of 2.27 (95% CI: 1.91–2.70, p = 1.68 × 10−20). Conversely, when hypercholesterolaemia was viewed as the outcome, the OR detected was 1.80 (95% CI: 1.58–2.05, p = 2.79 × 10−19). These findings remained consistent across various MR methods and sensitivity analyses. Additionally, our research pinpointed four co-localised genes CELSR2, PCSK9, LPA, and APOE as integral candidates implicated in the pathogenesis of both conditions, thereby suggesting shared common genetic causal variants and offering potential targets for innovative therapeutic strategies.Conclusionbidirectional MR studies reveal genetic evidence of a potential causal link between hypercholesterolaemia and IHD. Notably, these findings also lend credence to the less traditional hypothesis that IHD may instigate hypercholesterolaemia episodes. Moreover, co-localisation analyses intimate the presence of shared genetic causal variants, paving the way for the development of new therapeutic strategies.

The goal of tissue-engineered heart valves (TEHV) is to replace normal heart valves and overcome the shortcomings of heart valve replacement commonly used in clinical practice. However, calcification of TEHV is the major bottleneck to break for both clinical workers and researchers. Endothelialization of TEHV plays a crucial role in delaying valve calcification by reducing platelet adhesion and covering the calcified spots. In the present study, we loaded RunX2-siRNA and VEGF into mesoporous silica nanoparticles and investigated the properties of anti-calcification and endothelialization in vitro. Then, the mesoporous silica nanoparticle was immobilized on the decellularized porcine aortic valve (DPAV) by layer self-assembly and investigated the anti-calcification and endothelialization. Our results demonstrated that the mesoporous silica nanoparticles delivery vehicle demonstrated good biocompatibility, and a stable release of RunX2-siRNA and VEGF. The hybrid decellularized valve exhibited a low hemolysis rate and promoted endothelial cell proliferation and adhesion while silencing RunX2 gene expression in valve interstitial cells, and the hybrid decellularized valve showed good mechanical properties. Finally, the in vivo experiment showed that the mesoporous silica nanoparticles delivery vehicle could enhance the endothelialization of the hybrid valve. In summary, we constructed a delivery system based on mesoporous silica to biofunctionalized TEHV scaffold for endothelialization and anti-calcification.

The problem of global warming has become a major global concern, and reducing greenhouse gas emissions is crucial to mitigate its effects. Photovoltaic power generation is clean, low-carbon energy. Photovoltaic products can convert solar energy into electricity, reducing CO2 emissions to an extent. This paper introduces the life cycle evaluation theory to assess the carbon emissions of photovoltaic curtain walls. PVsyst software allows for the simulation and calculation of power generation under different influencing factors, which provides valuable information about the carbon reduction potential of photovoltaic curtain walls. The evaluation of carbon emissions and their influencing factors using grey correlation analysis further enhances the understanding of the benefits and limitations of photovoltaic curtain walls. According to the results of grey correlation analysis, this paper concludes that the degree of various influencing factors on carbon emission of a photovoltaic curtain wall under different scenarios in descending order is as follows: orientation, location, inclination, shadow occlusion, and seasonal changes. The research findings of this paper provide a theoretical reference for the future development and application of photovoltaic curtain walls. By demonstrating the carbon reduction potential of this technology, this study contributes to promoting the adoption of photovoltaic curtain walls as a sustainable solution to mitigate the effects of global warming.

In recent years, the fire safety problems in self-build housing in China’s vast rural areas have become increasingly prominent. We analyzed the interaction of causative factors and logical structure of self-build housing fire accidents (SBHFAs) to find their key causes and reduce their occurrence. Using the 24Model, 30 SBHFA investigation reports were analyzed, and 44 SBHFA causative factors and 97 causal relationship codes were obtained. The causality and centrality degree of causative factors were analyzed using the decision-making trial and evaluation laboratory (DEMATEL) method to obtain the causal attribute and importance of causative factors. An adversarial hierarchical topology model of causative factors was conducted using the adversarial interpretive structural modeling (AISM) method, and the causal hierarchical relationships were obtained. Using the Matrices Impacts Croises-Multiplication Appliance Classement (MICMAC) analysis, the causative factors’ dependency degree and driving force were calculated. Combining and comparing the results of DEMATEL, AISM, and MICMAC analyses, we found that the adversarial hierarchical topology model of causative factors was reasonable, and key direct causative factors, key transitional causative factors, and key root causative factors were mined. Controlling the key causative factors could effectively reduce the occurrence of SBHFAs and guide the fire safety management of self-build housings in rural areas of China.

The popularity of green building and BIM technology has increased globally, with strong government support in China. However, the integration of green requirements into interior decoration poses practical difficulties. Despite the few studies on the combination of green evaluation and BIM in building decoration, current methods largely rely on expert scores after completion. This research proposes a green evaluation index system for building interior decoration, examining the inter-index relationships and contribute to the final green degree of the project. Additionally, a green evaluation method based on BIM technology and the Bayesian network is explored, aimed at evaluating the green degree of design schemes, providing feedback, and supporting the realization of green interior decoration. With a focus on green evaluation, the current methods that rely solely on expert scores after completion will be improved. The results will provide technical support for the realization of green decoration and offer a reference for the improvement of green evaluation methods in the future.

Abstract There is an increasing challenge to prevent illicit drug smuggling across borders and seaports. However, the existing techniques in-and-of-themselves are not sufficient to identify the illicit drugs rapidly and accurately. In the present study, combining nuclear resonance fluorescence (NRF) spectroscopy and the element (or isotope) ratio approach, we present a novel inspection method that can simultaneously reveal the elemental (or isotopic) composition of the illicit drugs, such as widely abused methamphetamine, cocaine, heroin, ketamine and morphine. In the NRF spectroscopy, the nuclei are excited by the induced photon beam, and measurement of the characteristic energies of the emitted $$\gamma $$ γ rays from the distinct energy levels in the excited nuclei provides “fingerprints” of the interested elements in the illicit drugs. The element ratio approach is further used to identify drug elemental composition in principle. Monte Carlo simulations show that four NRF peaks from the nuclei $$^{12}$$ 12 C, $$^{14}$$ 14 N and $$^{16}$$ 16 O can be detected with high significance of 7−24 $$\sigma $$ σ using an induced photon beam flux of $$10^{11}$$ 10 11 . The ratio of $$^{14}N$$ 14 N / $$^{12}C$$ 12 C and/or $$^{16}O$$ 16 O / $$^{12}C$$ 12 C for illicit drugs inspected are then extracted using the element ratio approach. It is found that the present results of simulations are in good agreement with the theoretical calculations. The feasibility to detect the illicit drugs, inside the 15-mm-thick iron shielding, or surrounded by thin benign materials, is also discussed. It is indicated that, using the state-of-the-art $$\gamma $$ γ -ray source of high intensity and energy-tunability, the proposed method has a great potential for identifying drugs and explosives in a realistic measurement time.

Annulus pressure control is critical to well safety in deepwater oil and gas wells, and it is crucial for deepwater high-pressure oil and gas wells, which are related to production safety. At present, the deepwater annular pressure analysis model is mainly based on the trapped annulus principle. For the high annular pressure of deepwater high-pressure oil and gas wells, it brings great management and control challenges. This paper proposes a deepwater high-pressure oil and gas well annular pressure analysis method considering formation connectivity. According to the existing measures of annular pressure management and control, the differences between various types of annular pressure management and control technology are systematically analyzed and expounded, and the annular pressure management and control technology of deepwater high-pressure oil and gas wells is proposed accordingly. At the same time, combined with the actual case of a deepwater high-pressure well in the South China Sea, the annular pressure considering different influencing factors is analyzed, and the appropriate management and control methods of annular pressure are recommended. This paper systematically summarizes and studies the analysis and control technology of annular pressure in deepwater high-pressure oil and gas wells, which provides a technical basis for China’s deep water to move from conventional deepwater to deepwater high-pressure, and can provide a reference for the management and control of annular pressure in oil and gas wells in subsequent deepwater projects.

As artificial intelligence technology has progressed, numerous businesses have used intelligent diagnostic technology. This study developed a deep LSTM neural network for a nuclear power plant to defect diagnostics. PCTRAN is used to accomplish data extraction for distinct faults and varied fault degrees of the PCTRAN code, and some essential nuclear parameters are chosen as feature quantities. The training, validation, and test sets are collected using random sampling at a ratio of 7:1:2, and the proper hyperparameters are selected to construct the deep LSTM neural network. The test findings indicate that the fault identification rate of the nuclear power plant fault diagnostic model based on a deep LSTM neural network is more than 99 percent, first validating the applicability of a deep LSTM neural network for a nuclear power plant fault-diagnosis model.

Developing a fluorescent probe for UO22+, which is resistant to interference from other ions such as Cu2+ and can be applied in acidic and high-water systems, has been a major challenge. In this study, a “turn-off” fluorescent probe for triamine-modified flavonoid derivatives, 2-triphenylamine-3-hydroxy-4H-chromen-4-one (abbreviated to HTPAF), was synthesized. In the solvent system of dimethyl sulfoxide:H2O (abbreviated to DMSO:H2O) (v/v = 5:95 pH = 4.5), the HTPAF solution was excited with 364 nm light and showed a strong fluorescence emission peak at 474 nm with a Stokes shift of 110 nm. After the addition of UO22+, the fluorescence at 474 nm was quenched. More importantly, there was no interference in the presence of metal ions (Pb2+, Cd2+, Cr3+, Fe3+, Co2+, Th4+, La3+, etc.), especially Cu2+ and Al3+. It is worth noting that the theoretical model for the binding of UO22+ to HTPAF was derived by more detailed density functional theory (DFT) calculations in this study, while the coordination mode was further verified using HRMS, FT-IR and 1HNMR, demonstrating a coordination ratio of 1:2. In addition, the corresponding photo-induced electron transfer (PET) fluorescence quenching mechanism was also proposed.

The complex temperature and pressure conditions of deepwater wells have a serious impact on cementing quality. Therefore, the integrity of the cement seal becomes a critical factor that can restrict the safety of the wellbore, especially for wells ranging from the conventional deep water to deep water with more prominent deep stratum problems. The operating conditions of deep wells in deep water (referred as the dual-deep well) are complex and harsh. For the conventional evaluation device, it is difficult to accurately simulate the alternating HTHP conditions and to clarify the location and situation of the cement sheath leakage, which directly leads to the deviation of the evaluation results from the engineering reality. To solve this defect, based on the condition and structure characteristics of dual-deep wells, a device and method for casing/cement sheath/formation seal integrity evaluation for dual-deep wells at HTHP has been developed and established. Combined with the analysis of microstructure and micromorphology, the sealing ability and integrity of different cement slurry systems were evaluated. Through this study, a set of cement slurry systems suitable for dual-deep wells is selected that can satisfy the requirements of dual-deep wells with excellent isolation ability and seal integrity under temperature and stress changes. The research results provide a reference for deepwater wells’ wellbore integrity evaluation and research.

Due to the growing complexity of mechanical, electrical, and plumbing (MEP) designs and the rules that govern them, performing rule checks manually has become expensive. However, MEP-based rule checking has not received adequate attention compared to automated rule checking in other domains. Based on Knowledge Management and Building Information Modeling (BIM), an automated rule checking system integrated knowledge base management system (KBMS) for model information expansion, information extraction, system integrity checking, and element spacing checking was developed. MEP rules for automated rule checking were collected, optimized, and stored in the MEP knowledge base. The KBMS facilitates the management of MEP rules in the knowledge base. A Revit plug-in of MEP rule checking system was developed including functions of KBMS, Model Integrity Checking, Elements Space Checking, and Locating the non-compliant element in model view. This study integrated both KBMS and BIM technologies to achieve automated rule checking for MEP. This simplifies the process of rule checking of MEP systems in an automated manner.

With the huge demand for building underground spaces, deep foundation pits are becoming more and more common in underground construction. Due to the serious effects associated with accidents that occur in deep foundation pits, it is very important for underground construction safety management to be proactive, targeted, and effective. This research develops a conceptual framework adopting BIM and IoT to aid the identification and evaluation of hazards in deep foundation pit construction sites using an automated early warning system. Based on the accident analysis, the system framework of Safety Management System of Deep Foundation Pits (SMSoDFP) is proposed; it includes a function requirement, system modules, and information needs. Further, the implementation principles are studied; they cover hazardous areas, namely, visualization, personnel position monitoring, structural deformation monitoring, and automatic warning. Finally, a case study is used to demonstrate the effectiveness and feasibility of the system proposed. This research provides suggestions for on-site management and information integration of deep foundation pits, with a view to improving the safety management efficiency of construction sites and reducing accidents.

Metro plays an indispensable role in promoting social and economic development of the big cities. However, the safety operation of the metro system is believed to be an arduous work for its operation being susceptible to various factors, especially equipment failure, which could bring about delay, interruption, and even accidents. In consideration of the seriousness of metro accident, it is becoming more and more crucial to conduct proactive, targeted, and effective risk management to reduce failures. Firstly, based on the FMECA and influence diagram theory, this paper proposes a new analytical framework to study metro equipment failure in accordance with system decomposition. Furthermore, a case study is implemented to verify the feasibility and availability of this framework in evaluating criticality of failure modes and assessing its influence factors based on the collected data from metro operation company. As indicated by the research results, wheel damage is the most serious failure mode in the bogie system, and its most paramount influence factor is the shortage of professional skills. Finally, a discussion about the research methods and results is carried out, and several recommendations are put forward to improve safety management on the basis of research findings. This study has the potential to offer suggestions in regard to metro equipment design, operation, and maintenance for raising the safety level in metro operation.

More than 90% of natural gas hydrates (hereinafter, hydrate for short) in the South China Sea are non-diagenetic ore bodies, so they cannot be exploited easily by means of the conventional methods. In this paper, the solid fluidization method, as one of the revolutionary technologies in efficient exploitation of non-diagenetic natural gas hydrates, was, for the first time, put forward by Academician Zhou Shouwei. And it is successfully applied in the Shenhu Area of the South China Sea based on the technologies, equipment and processes which rely on domestic independent intellectual property rights. During the production test of fluidization, the ore bodies of hydrates are broken by the jet at the bottom hole into fine particles and carried upward by the drilling fluid. When the phase equilibrium state is reached with the increase of temperature and the decrease of pressure affected by the operation parameters, which is different from conventional phase equilibrium state, the hydrates bearing solid particles are decomposed, and consequently liquid–solid flow in the annulus becomes complex gas–liquid–solid multiphase flow. Therefore, it is necessary to optimize the construction parameters design so as to meet the high-level requirements of well control safety. In this paper, the engineering parameters are optimally designed based on the engineering geological characteristics of the target block, combined with the analysis on complex multiphase flow in the wellbore. Then, a theoretical model and a numerical calculation method for the multiphase flow, temperature and pressure of complex media in wellbores and the phase equilibrium and decomposition of natural gas hydrates were established. And the multiphase flow in the wellbore during the production test of fluidization was analyzed under different operating parameters by means of numerical simulation, software emulation and experimental verification. And thus, the design optimization scheme of on-site engineering parameters of production test of marine natural gas hydrate fluidization was prepared. It is pointed out that the diameter of jet fluidization well section shall not be excessively large; and that it is necessary to increase the flow rate and density of drilling fluid and apply wellhead back pressure to ensure the cutting carrying safety and to mitigate well control risks. The results of this basic theoretical study can provide significant support to field operation and improvement of output in production tests. Keywords: Marine, Natural gas hydrate, Non-diagenetic, Solid fluidization, Production test, Jet breakup, Multiphase flow, Engineering parameter, Numerical simulation, Optimal design, China, Shenhu sea area, South China sea

To decrease the risk in deep water drilling and shorten the drilling period, a conductor soaking time design method for deep-water jetting was provided and verified by oil field application. Based on the field simulation experiment of soil-pile interaction, the relationship between soaking time and bearing capacity was achieved, and a real-time bearing capacity calculation model of conductor was established. The mechanical properties of conductor in two conditions were analyzed, including Cam Activated Drilling Ahead (CADA) tool releasing stage and surface casing cementing stage, and the soaking time windows of the two stages were designed. Field application results show that: This method can ensure the safety in deep water drilling, optimize driving depth of conductor, and also improve the drilling efficiency. More than 12 hours per well on average in CADA tool releasing stage and 24 hours per well on average in surface casing cementing stage were saved. Key words: deepwater drilling, conductor, jetting, soaking time, bearing capacity

In view of the absence of a theoretical model for choosing the bit stick-out in deepwater conductor jetting operation, and the existing operational blindness and risks, a bit stick-out calculation model was built up through theoretical derivation and field tests to provide the theoretical basis for the design of reasonable bit stick-out. Theoretical analysis assumes that bit stick-out is the best when the upper edge of the jet flow sprayed from the bit nozzle tip is internally tangent to the lower edge of surface conductor, based on which a formula to calculate the reasonable bit stick-out was derived, and the rationality of the theoretical assumption and correctness of calculation model were proved through field tests. Field test results show that the conductor running speed is in positive correlation with bit stick-out, while the restoration of friction between the conductor and surrounding soil body is in negative correlation with bit stick-out. The calculation model was applied in the drilling operation of 12 deepwater wells in the South China Sea and got good application effects. It saved 14.96 h per well on average, enhanced operational efficiency, and met the safety requirements at the same time. Key words: deepwater, jetting, surface conductor, bit stick-out, calculation model, field test

This article models the contact between the drillstring with large slenderness ratio and the extending rigid wellbore based on the multibody dynamics method. The drillstring is modeled as absolute nodal coordinate formulation beams with contact detection points. An algorithm is developed to locate the contact points and calculate the contact forces when the drillstring is sliding and rotating in the wellbore. This provides support force and friction for the moving drillstring and effectively confines it inside the wellbore. A rock penetration model is established based on the rock-breaking velocity equation. The governing equation for the full-hole drilling system including the drillstring and the contact model is established and solved. A rock penetration correction method is proposed to stabilize the computation and to model and simulate the slide drilling process. A field drilling process is modeled and simulated. The simulation result fits the experimental result well.