A new method regarding mesomechanics finite-element research is proposed to predict the peak shear strength of mudded intercalation materials on a mesoscopic scale. Based on geometric and mechanical parameters, along ...A new method regarding mesomechanics finite-element research is proposed to predict the peak shear strength of mudded intercalation materials on a mesoscopic scale. Based on geometric and mechanical parameters, along with the strain failure criteria obtained by sample＇s deformation characteristics, uniaxial compression tests on the sample were simulated through a finite-element model, which yielded values consistent with the data from the laboratory uniaxial compression tests, implying that the method is reasonable. Based on this model, a shear test was performed to calculate the peak shear strength of the mudded intercalation, consistent with values reported in the literature, thereby providing a new approach for investigating the mechanical properties of mudded intercalation materials.展开更多
To synergistically recover alumina and alkali from red mud(RM),the structural stability and conversion mechanism of hydroandradite(HA)from hydrogarnet(HG)were investigated via the First-principles,XRF,XRD,PSD and SEM ...To synergistically recover alumina and alkali from red mud(RM),the structural stability and conversion mechanism of hydroandradite(HA)from hydrogarnet(HG)were investigated via the First-principles,XRF,XRD,PSD and SEM methods,and a novel hydrothermal process based on the conversion principle was finally proposed.The crystal structure simulation shows that the HA with varied silicon saturation coefficients is more stable than HG,and the HA with a high iron substitution coefficient is more difficult to be converted from HG.The(110)plane of Fe_(2)O_(3) is easier to combine with HG to form HA,and the binding energy is 81.93 kJ/mol.The effects of raw material ratio,solution concentration and hydrothermal parameters on the conversion from HG to HA were revealed,and the optimal conditions for the alumina recovery were obtained.The recovery efficiencies of alumina and Na_(2)O from the RM are 63.06%and 97.34%,respectively,and the Na_(2)O content in the treated RM is only 0.13%.展开更多
1995年,北美的中国留学生团队,在全球第一代中文网络社区ACT(Alt Chinese Text)搭建起《侠客行》。这款基于文本交互的MUD(Multi-user Dungeon)游戏,用“输入文字触发剧情”的极简形式,开启了中文互联网的首个“虚拟江湖”。彼时中国网...1995年,北美的中国留学生团队,在全球第一代中文网络社区ACT(Alt Chinese Text)搭建起《侠客行》。这款基于文本交互的MUD(Multi-user Dungeon)游戏,用“输入文字触发剧情”的极简形式,开启了中文互联网的首个“虚拟江湖”。彼时中国网民不足10万,PC(Personal Computer)普及率仅0.2台/百人。谁都未曾预见,这个诞生于海外留学生技术探索的“文字玩具”,会在30年后从少数极客的娱乐,成长为规模超3500亿元、影响近7亿用户文化生活、输出全球文化符号的数字产业支柱。从《侠客行》的“文字江湖”到《原神》璃月港的“云蒸霞蔚”,从电话线端的拨号上网到元宇宙中的VR交互,中国网络游戏的30年,是技术演进、商业创新、政策规范与社会认知相互碰撞、相互塑造的发展史,更是中国数字经济从跟跑到领跑的缩影。展开更多
To improve the applicability of red mud in subgrade construction,we studied the effects of four traditional retarders,including borax,sodium hexametaphosphate,sodium gluconate,and sucrose,on the setting time,mechanica...To improve the applicability of red mud in subgrade construction,we studied the effects of four traditional retarders,including borax,sodium hexametaphosphate,sodium gluconate,and sucrose,on the setting time,mechanical properties and soil solidification of red mud-based subgrade engineered cementitious material(RCM).The mechanisms of the retarders on the hydration process of RCM were analyzed by hydration microcalorimeter,XRD,TG,and SEM-EDS.The experimental results show that four retarders have retarding effect on RCM,among which sodium gluconate and sucrose have significant retarding effect and do not have adverse effect on 28 d strength.Borax can slightly delay the setting time,and sodium hexametaphosphate has a better retarding effect,but they both reduce the 28 d strength.Microcosmic analysis shows that the retarders do not change the type of RCM hydration products,but mainly slow down the rate of hydration reaction through the adsorption and complexation or reaction of Ca^(2+)in the slurry.All the results show that the retarder has no weakening effect on the unconfined compressive strength,water stability and CBR properties of the stabilized subgrade soil based on RCM.展开更多
Wellbore drilling disturbs the equilibrium stress state in the rock mass,resulting in stress redistribution around the opening.Wellbore stability in the altered stress state is vital for engineering applications,as th...Wellbore drilling disturbs the equilibrium stress state in the rock mass,resulting in stress redistribution around the opening.Wellbore stability in the altered stress state is vital for engineering applications,as the wellbore instability results in cost overrun.Accurate estimation of rock mechanical properties,in-situ stresses,and required mud pressure is crucial for safe drilling.If the mud pressure is lower than required,the shear failure of the rock takes place,and conversely,if the mud pressure is higher than the upper limit,tensile failure occurs.A strength criterion that can accurately predict the mud pressure may help significantly reduce nonproductive time and cost in well drilling.The commonly used Mogi-Coulomb(MGC)failure criterion for estimating critical mud pressure neglects the few fundamental aspects of rock failure characteristics observed in the laboratory,such as nonlinear strength response in major-minor principal stress space and prediction of multiple failure stress values near the triaxial axial extension boundary.The present study uses the Modified Mohr-Coulomb true-triaxial failure criterion(MMC_TT),which predicts the strength of rock better than the MGC in laboratory true-triaxial tests to overcome the limitations.Moreover,based on the data from previously published five vertical wells in the Krishna-Godavari basin(K-G basin),an empirical relationship is proposed to obtain the strength parameters for the MMC_TT criterion for shaley sedimentary rocks as the existing correlations do not cater for the parameters required for MMC_TT criterion.The comparative study of the MMC_TT with MGC,Modified Mohr-Coulomb triaxial,and Mohr-Coulomb failure criteria,showed that for most of the K-G basin wells,the MMC_TT criterion predicted close to the MGC.However,for well-13,the MMC_TT criterion results are closer to the mud pressure used in actual drilling than the MGC.展开更多
The deep tunnels are prone to mud and water inrush disasters when crossing water-rich weak zones.A good understanding the hydromechanical behavior of the water-rich weak zone in deep tunnels is the prerequisite for de...The deep tunnels are prone to mud and water inrush disasters when crossing water-rich weak zones.A good understanding the hydromechanical behavior of the water-rich weak zone in deep tunnels is the prerequisite for determining the limit support pressure on the tunnel face.However,the seepage forces within the water-rich weak zone are not well estimated in existing models.To overcome this,an analytical model is proposed in this study to determine the limit support pressure of a deep tunnel crossing the water-rich weak zone.The seepage force in the water-rich weak zone is obtained by solving a group of Laplace equations about the hydraulic head,avoiding complex physical and mathematical approximation in existing models.Besides,the seepage boundary conditions in the water-rich weak zone are considered at the nodes on the Neumann boundary and the Dirichlet boundary.The effectiveness of the proposed model is then validated by numerical simulations and engineering practice.It shows that the proposed model has higher accuracy and wider applicability in estimating the hydraulic head.The proposed model can be used for stability analysis of tunnel faces.展开更多
The large-scale accumulation of industrial solid waste,including red mud and coal gangue,coupled with goafs left by under-ground mining activities,poses significant challenges to sustainable human development.In this ...The large-scale accumulation of industrial solid waste,including red mud and coal gangue,coupled with goafs left by under-ground mining activities,poses significant challenges to sustainable human development.In this study,red mud,coal gangue,and othersolid wastes were used to prepare underground backfilling materials.The utilization rate of the total solid waste reached 95%,with redmud accounting for approximately 40wt% of the total.The unconfined compressive strength,setting time,and slump tests were conduc-ted to evaluate the mechanical properties of the material.At the optimal ratio,the 7-and 28-d strengths reach 4.4 and 6.9 MPa,respect-ively.The initial and final setting times were 200 and 250 min,respectively,whereas the initial and 1-h slump exceed 250 and 210 mm,respectively.X-ray diffraction(XRD),Fourier-transform infrared spectroscopy(FTIR),and scanning electron microscopy(SEM)wereemployed to explore the microstructure,phase composition,and chemical bonding within the material.Needle-like,clustered,and granu-lar hydration products were observed,and the primary crystalline structures were identified as ettringite,gmelinite,C-A-S-H,andC-S-H.In addition,a thorough environmental risk assessment was conducted,complemented by detailed economic cost and carbonemission calculations.During the creation of backfill material,hazardous elements from solid waste are immobilized through adsorption,precipitation,and incorporation into the crystal lattice.The immobilization efficiencies for Ni,Al,Cr^(6+),and As were 97.03%,94.32%,86.43%,and 84.22%,respectively,at a pH of 8.49.Moreover,the use of solid waste as a raw material results in considerable cost savingsand marked reduction in carbon emissions.This study innovatively promotes the green cycle of alumina production in the bauxite miningindustry.展开更多
Red mud is a solid waste discharged in the process of alumina production,and how to realize the efficient recovery of its iron is an urgent problem to be solved.In this study,the iron extraction test and mechanism stu...Red mud is a solid waste discharged in the process of alumina production,and how to realize the efficient recovery of its iron is an urgent problem to be solved.In this study,the iron extraction test and mechanism study of high iron red mud were carried out under the coupling conditions of multiple physical field(microwave field,gas-solid flow field and temperature field)with biomass as the reducing agent.The test results showed that under the optimal conditions,an iron concentrate with a yield of 78.4%,an iron grade of 59.23%,and a recovery rate of 86.65%was obtained.The analyses of XRD,XPS,TEM,and SEM-EDS showed that during the roasting process,the hematite in the high-iron red mud was completely converted to magnetite,and the biomass produced the reductant that provided the magnetization reaction;A large number of cracks and pores appeared in the surface of the hematite reduction product particles,which helped to induce iron minerals to undergo effective mineral phase transformation.The above study provides ideas for the phase transformation and efficient recovery of iron minerals in red mud.展开更多
This paper addresses the accuracy and timeliness limitations of traditional comprehensive prediction methods by proposing an approach of decision-level fusion of multisource data.A risk prediction indicator system was...This paper addresses the accuracy and timeliness limitations of traditional comprehensive prediction methods by proposing an approach of decision-level fusion of multisource data.A risk prediction indicator system was established for water and mud inrush in tunnels by analyzing advanced prediction data for specifi c tunnel segments.Additionally,the indicator weights were determined using the analytic hierarchy process combined with the Huber weighting method.Subsequently,a multisource data decision-layer fusion algorithm was utilized to generate fused imaging results for tunnel water and mud inrush risk predictions.Meanwhile,risk analysis was performed for different tunnel sections to achieve spatial and temporal complementarity within the indicator system and optimize redundant information.Finally,model feasibility was validated using the CZ Project Sejila Mountain Tunnel segment as a case study,yielding favorable risk prediction results and enabling effi cient information fusion and support for construction decision-making.展开更多
The effects of liquid-solid ratio and reaction time on the leaching rate of magnesium at room temperature were investigated,as well as the effects of the molar ratio of MgO/MgCl_(2),the amount of water added,and the a...The effects of liquid-solid ratio and reaction time on the leaching rate of magnesium at room temperature were investigated,as well as the effects of the molar ratio of MgO/MgCl_(2),the amount of water added,and the amount of acid-impregnated slag dosed on the compressive strength and water resistance of LR-MOC.The results showed that the magnesium element in the boron mud could be maximally leached under the conditions of 1:1 concentration of hydrochloric acid at room temperature,liquid-solid ratio of 2.5 mL·g^(-1),and reaction time of 5 h,and the main products were amorphous SiO_(2) as well as a small amount of magnesium olivine which had not been completely reacted.The LR-MOC prepared using the acid-soaked mixture could reach a softening coefficient of 0.85 for 28 d of water immersion when the molar ratio of MgO/MgCl_(2) was 2.2,the amount of water added was 0 g,and the acid-soaked slag dosing was 40 wt%,which also led to an appreciable late-strength,with an increase of 19.4%in compressive strength at 28 d compared to that at 7 d.Unlike previous studies,LR-MOC prepared in this way has a final strength phase that is not the more easily hydrolysed 3-phase but the lath-like 5-phase.For this phenomenon,we analyzed the mechanism and found that,during the acid leaching process,a part of amorphous SiO_(2) dissolved in the acid leaching solution formed a silica sol,in which Mg^(2+)played a bridging role to make the silica sol more stable.With the addition and hydrolysis of MgO,the silica sol gel coagulation slows down,providing a capping layer to inhibit the hydrolysis of the 5-phase crystals and providing some strength after coagulation.The amorphous SiO_(2) in the other part of the acid-impregnated slag generated M-S-H gel with Mg^(2+)and OH-,which synergised with the dense structure composed of interlocking crystals to improve the water resistance of LR-MOC.展开更多
Mercury removal from coal combustion flue gas remains a significant challenge for environmental protection due to the lack of cost-effective sorbents.In this study,a series of red mud(RM)-based sorbents impregnated wi...Mercury removal from coal combustion flue gas remains a significant challenge for environmental protection due to the lack of cost-effective sorbents.In this study,a series of red mud(RM)-based sorbents impregnated with sodium halides(NaBr and NaI)are presented to capture elemental mercury(Hg^(0))from flue gas.The modified RM underwent comprehensive characterization,including analysis of its textural qualities,crystal structure,chemical composition,and thermal properties.The results indicate that the halide impregnation substantially impacts the surface area and pore size of the RM.Hg^(0) removal performance was evaluated on a fixed-bed reactor in simulated flue gas(consisting of N_(2),O_(2),CO_(2),NO and SO_(2),etc.)on a modified RM.At an optimal adsorption temperature of 160℃,NaI-modified sorbent(RMI5)offers a removal efficiency of 98%in a mixture of gas,including O_(2),NO and HCl.Furthermore,pseudo-second-order model fitting results demonstrate the chemisorption mechanism for the adsorption of Hg^(0) in kinetic investigations.展开更多
A temperature-sensitive mud cake remover(G315)was developed using ethyl lactate as the primary component.Based on this,a temperature-sensitive acidic completion fluid(CF-G315)was formulated.Core evaluation tests,mud c...A temperature-sensitive mud cake remover(G315)was developed using ethyl lactate as the primary component.Based on this,a temperature-sensitive acidic completion fluid(CF-G315)was formulated.Core evaluation tests,mud cake dissolution tests and corrosion tests were conducted to analyze the mud cake removal performance of G315,the removal efficiency of CF-G315,and its ability to modify the near-wellbore reservoirs,corrosion to casing and hydrolysis performance.Results indicate that ethyl lactate in G315 exhibits weak acidity at room temperature and decomposes into lactic acid under high temperatures.The lactic acid reacts with the calcium carbonate in the mud cake,generating bubbles that dislodge the mud cake and form soluble salts that are subsequently removed by fluid flow,thereby ensuring effective mud cake clearance.CF-G315 removes mud cake efficiently and enhances near-wellbore reservoir permeability.It demonstrates low corrosivity and environmental compatibility,contributing to equipment safety,simplified operational procedures and reduced operational risks.CF-G315 is promising for application in scenarios such as horizontal wells,open-hole completions and gravel pack completions.展开更多
The phenomenon of mud volcanism has a connection with the processes of hydrocarbon generation.However,the genesis of sediments is not often taken into consideration.The study of mud volcanoes in the West Kuban margina...The phenomenon of mud volcanism has a connection with the processes of hydrocarbon generation.However,the genesis of sediments is not often taken into consideration.The study of mud volcanoes in the West Kuban marginal marine basin and the Junggar freshwater basin revealed significant isotope-geochemical differences due to various types of sedimentation.The waters from both basins exhibit three principal geochemical facies:Na-HCO_(3),Na-Cl-HCO_(3),and Na-Cl,of which the latter type of water is the dominant.The analysis of genetic coefficients(Cl/Br,Na/Br,and B/Cl)allowed us to distinguish different pathways of mud volcanic water evolution:evaporite dissolution,formation(sedimentation)waters,and waters formed by active water-rock interaction.Through statistical research,we were able to determine that noticeable variations in the behavior of chemical elements in waters from different areas can reflect discrepancies in the geological environment and the evolutionary stage of the diagenetic water transformation.Using thermodynamic modeling,the main directions of mass transfer were shown.It was established that the waters of the Junggar Basin were at a relatively early stage of evolution and had reached equilibrium only with carbonates,while in the formation waters of the West Kuban Basin,element concentrations were also controlled by silicate minerals.The correlations betweenδ^(18)O andδ~2H values and saturation indices of halides,aluminosilicates,sulfates,and borates confirm the enrichment of water with heavy isotopes during interactions with rocks without evaporation or thermal water partition.These reactions are characterized by clay dehydration and water enrichment with^(18)O and B.The data obtained made it possible to clarify the depths of formation of mud-volcanic fluids and their possible stratigraphic sources.展开更多
Red mud(RM) is an industrial solid waste produced during the extraction of alumina from bauxite.The strong alkaline and heavy metal leaching issues are the primary factors limiting its utilization.This paper proposes ...Red mud(RM) is an industrial solid waste produced during the extraction of alumina from bauxite.The strong alkaline and heavy metal leaching issues are the primary factors limiting its utilization.This paper proposes a method for dealkalization and chromium(Cr) removal by repeated freeze and thaw to enhance the comprehensive utilization rate of RM.This study focused on the Bayer RM and investigated the effects of freeze-thaw(FT)-acid washing(AW) for dealkalization and Cr removal.The variables were the eluent concentration and FT cycles.The results showed that the synergistic action of FT-AW significantly improved the efficiency of dealkalization and Cr removal.After five FT cycles with 0.5 mol/L oxalic acid,the dealkalization and Cr removal rates reached 97.5% and 65.38%,respectively,16.1% and 7.40% higher than those achieved at room temperature.The repeated FT disrupted the structure of the RM particles,leading to an increase in the pore space between the soil particles.This enables complete eluent contact and reaction with Cr and alkali,thereby enhancing the removal rate.The FT-AW process is suitable for practical engineering applications.It offers a novel method for RM dealkalization and Cr removal by using the FT alternation phenomena in seasonally frozen regions.展开更多
The aim of this study is to enhance the value of local earth materials used in the construction of certain homes in the Republic of Guinea. Thus, a trial study to improve the quality of mud bricks using paper fibers o...The aim of this study is to enhance the value of local earth materials used in the construction of certain homes in the Republic of Guinea. Thus, a trial study to improve the quality of mud bricks using paper fibers obtained by grinding and soaking in water and then drying were used as a stabilizer in the manufacture of these mud bricks from the sample of two sites Dounkiwal (DK) (in Mamou and the sample from the urban commune of Kouroussa). To do this, certain methods and means of identification were carried out, namely: geotechnical, mineralogical and chemical analyses. Sample DK from Mamou has a silty-clay geotechnical characteristic with a plasticity index Ip of 12.75%. However, mineralogical and chemical studies showed that sample Dounkiwal (DK) (Mamou) contains a high proportion of silica and iron oxides (79.63%) and Fe2O3 (11.85%), associated with other alkaline earth oxides and ions: CaO;MgO;SO32−;Cl−, i.e. 3.96%;0.96%;0.28% and 0.039% respectively. Its loss on ignition (LOI) and insoluble residues are 15.40% and 56.36%. The evaluation of the number of huts in Upper and Middle Guinea showed that the populations of these areas have been using mud bricks for several decades in the construction of dwellings. The average value found for the compressive strength of these bricks (from samples I, II and III from Kouroussa) is 0.16 MPa. This value is appreciable in the construction of mud houses.展开更多
Red mud(RM)is a solid waste generated in the aluminum industry after the extraction of alumina oxide;its multiple elements and higher pH value likely pose a severe threat to the environment after treatment.However,RM&...Red mud(RM)is a solid waste generated in the aluminum industry after the extraction of alumina oxide;its multiple elements and higher pH value likely pose a severe threat to the environment after treatment.However,RM's higher concentrations of metal components,particularly Fe_(2)O_(3)and rare earth elements(REEs),render RM promising for catalytic application.Hence,this work showed an efficient high-speed RM to catalyze electrocatalytic nitrate-to-ammonia reduction reaction(NARR).RM calcined at 500℃(RM-500)exhibited excellent catalytic performance.Faradaic efficiency of ammonia(FENH_(3))in an electrolyte solution containing 1 mol·L^(-1)NO_(3)-achieved a maximum value of 92.3%at-0.8 V(vs.RHE).Additionally,24-h cycle testing and post-reaction PXRD and SEM indicated that the RM-500 electrocatalyst is stable during NARR.The RM-500 demonstrated a high FE of NH_(3)-to-NO_(3)-of 89.7%at 1.85 V(vs.RHE),showing great potential in the ammonia fuel cells technology and achieving the nitrogen cycle.展开更多
The release of accumulated stress through earthquakes is known to devote to the mud volcanism occurrence,which may in turn affect subsequent regional seismicity.Mud volcanoes have been observed on the northeast contin...The release of accumulated stress through earthquakes is known to devote to the mud volcanism occurrence,which may in turn affect subsequent regional seismicity.Mud volcanoes have been observed on the northeast continental margin of the South China Sea as well.Based on the mud volcanoes and earthquakes catalogue,we measured the spatial and temporal distribution of z and b values,to explore the geodynamic process of the repeated eruptions of mud volcanoes influence on the regional seismicity.The results suggest a close correlation between the b-z values and mud volcanism occurrence in the SW Taiwan.Generally,the z-value anomalies in where the mud volcanoes eruptions show unchanged negative values and indicate seismic quiescence before a big earthquake,whereas the b-values often show periodicity fluctuations around the value of 0.5.This may indicate a mutual triggering relationship between the mud volcanoes and earthquakes.We infer that mud volcano eruptions help to partition and release part of the regional stress accumulation from the seismogenic structures,thus balancing the local stress and mitigating large-magnitude seismicity occurring probability.展开更多
The oil-based mud(OBM) borehole measurement environment presents significant limitations on the application of existing electrical logging instruments in high-resistance formations. In this paper, we propose a novel l...The oil-based mud(OBM) borehole measurement environment presents significant limitations on the application of existing electrical logging instruments in high-resistance formations. In this paper, we propose a novel logging method for detection of high-resistance formations in OBM using highfrequency electrodes. The method addresses the issue of shallow depth of investigation(DOI) in existing electrical logging instruments, while simultaneously ensuring the vertical resolution. Based on the principle of current continuity, the total impedance of the loop is obtained by equating the measurement loop to the series form of a capacitively coupled circuit. and its validity is verified in a homogeneous formation model and a radial two-layer formation model with a mud standoff. Then, the instrument operating frequency and electrode system parameters were preferentially determined by numerical simulation, and the effect of mud gap on impedance measurement was investigated. Subsequently, the DOI of the instrument was investigated utilizing the pseudo-geometric factor defined by the real part of impedance. It was determined that the detection depth of the instrument is 8.74 cm, while the effective vertical resolution was not less than 2 cm. Finally, a focused high-frequency electrode-type instrument was designed by introducing a pair of focused electrodes, which effectively enhanced the DOI of the instrument and was successfully deployed in the Oklahoma formation model. The simulation results demonstrate that the novel method can achieve a detection depth of 17.40 cm in highly-resistive formations drilling with OBM, which is approximately twice the depth of detection of the existing oil-based mud microimager instruments. Furthermore, its effective vertical resolution remains at or above 2 cm,which is comparable to the resolution of the existing OBM electrical logging instrument.展开更多
The precise and real-time prediction of pore pressure is critical for optimizing drilling efficiency and mitigating the potential risks associated with drilling operations.In order to surmount the limitations of empir...The precise and real-time prediction of pore pressure is critical for optimizing drilling efficiency and mitigating the potential risks associated with drilling operations.In order to surmount the limitations of empirical methods and to reduce reliance on logging-while-drilling data,this study proposed a stacking ensemble approach that utilized only conventional mud log data.The workflow involves the preliminary processing of data using isolation forest and wavelet thresholding techniques to effectively eliminate outliers and noise.The Eaton index was estimated using a Bayesian inversion algorithm,and pore pressure was estimated by integrating the dc exponent and Eaton method.A feature selection strategy combining data distribution characteristics and regression-based importance ranking was used to optimize the input parameters.Subsequently,a stacking approach was developed for predicting pore pressure,and the corresponding base learner,meta learner,and hyperparameters were optimized.Finally,the validity of the optimized model was substantiated through field data from three test wells(X1,X5,X3)under different drilling scenarios.The results indicated that the global optimal Eaton index of the block was 0.2449,the maximum percentage error of pore pressure estimation was 3.66%,and the corresponding average error was 1.59%compared to the wireline formation test data.The optimal combination of input features was determined to be R-ROP,WOB,TG,PT,MW,PFI,TVD,H,BR,BT,and SPP.The optimal basic learners were identified as BPNN,CNN,LSTM,and LightGBM,while the optimal meta learners were XGBoost.Prediction accuracy is improved when offset wells are densely distributed,spatially balanced,and proximal to the target well;conversely,sparse or distant offset wells result in reduced prediction performance.The mean absolute percentage errors for test offset well X1,X5,and X3 were 0.4353%,0.4646%,and 0.6856%,respectively,with the corresponding R2 values of 0.9362,0.9078,and 0.8950,respectively.Consequently,this approach has the capacity to accurately and in real-time predict pore pressure using solely conventional mud log data.This capability enables timely adjustments to drilling parameters,thereby enhancing operational efficiency and mitigating drilling risks.展开更多
Red mud is a kind of industrial waste residue produced in the process of alumina production,which has strong suspension and is difficult to precipitate and filter.This study compared the effects of 4 kinds of filter a...Red mud is a kind of industrial waste residue produced in the process of alumina production,which has strong suspension and is difficult to precipitate and filter.This study compared the effects of 4 kinds of filter aids,including CaCl2,polymerized ferrous sulfate(PFS),steel slag(SS),and Portland cement(PC),on the filtration rate,filter cake moisture content,and Na2O content of red mud slurry.At a dosage of 10 g·L^(-1),the filtration effects were in the following order:PFS>CaCl_(2)>SS>PC.Under the combination of 5 g·L^(-1) SS and 5 g·L^(-1) PC,the better filtration effect was achieved with a filtration time of 205.17 s,which was reduced by 58.52%compared to the original red mud.The combined use of SS and PC exhibits better advantages in terms of cost and filtration effect.This study provides a data foundation for the rapid filtration of red mud slurry.The use of SS and PC as filter aids for red mud holds broad application pro-spects.展开更多
基金Funded by the National Natural Science Foundation of China(No.51574201)the State Key Laboratory of Geohazard Prevention and Geoenvironment Protection(Chengdu University of Technology)(KLGP2015K006)the Scientific and Technical Youth Innovation Group(Southwest Petroleum University)(2015CXTD05)
文摘A new method regarding mesomechanics finite-element research is proposed to predict the peak shear strength of mudded intercalation materials on a mesoscopic scale. Based on geometric and mechanical parameters, along with the strain failure criteria obtained by sample＇s deformation characteristics, uniaxial compression tests on the sample were simulated through a finite-element model, which yielded values consistent with the data from the laboratory uniaxial compression tests, implying that the method is reasonable. Based on this model, a shear test was performed to calculate the peak shear strength of the mudded intercalation, consistent with values reported in the literature, thereby providing a new approach for investigating the mechanical properties of mudded intercalation materials.
基金the financial support from the National Key R&D Program of China(No.2022YFC2904405)the National Natural Science Foundation of China(Nos.22078055,51774079)。
文摘To synergistically recover alumina and alkali from red mud(RM),the structural stability and conversion mechanism of hydroandradite(HA)from hydrogarnet(HG)were investigated via the First-principles,XRF,XRD,PSD and SEM methods,and a novel hydrothermal process based on the conversion principle was finally proposed.The crystal structure simulation shows that the HA with varied silicon saturation coefficients is more stable than HG,and the HA with a high iron substitution coefficient is more difficult to be converted from HG.The(110)plane of Fe_(2)O_(3) is easier to combine with HG to form HA,and the binding energy is 81.93 kJ/mol.The effects of raw material ratio,solution concentration and hydrothermal parameters on the conversion from HG to HA were revealed,and the optimal conditions for the alumina recovery were obtained.The recovery efficiencies of alumina and Na_(2)O from the RM are 63.06%and 97.34%,respectively,and the Na_(2)O content in the treated RM is only 0.13%.
文摘1995年,北美的中国留学生团队,在全球第一代中文网络社区ACT(Alt Chinese Text)搭建起《侠客行》。这款基于文本交互的MUD(Multi-user Dungeon)游戏,用“输入文字触发剧情”的极简形式,开启了中文互联网的首个“虚拟江湖”。彼时中国网民不足10万,PC(Personal Computer)普及率仅0.2台/百人。谁都未曾预见,这个诞生于海外留学生技术探索的“文字玩具”,会在30年后从少数极客的娱乐,成长为规模超3500亿元、影响近7亿用户文化生活、输出全球文化符号的数字产业支柱。从《侠客行》的“文字江湖”到《原神》璃月港的“云蒸霞蔚”,从电话线端的拨号上网到元宇宙中的VR交互,中国网络游戏的30年,是技术演进、商业创新、政策规范与社会认知相互碰撞、相互塑造的发展史,更是中国数字经济从跟跑到领跑的缩影。
基金Funded by the Shandong Province Key R&D Program(Major Technological Innovation Project(Nos.2023ZLGX01 and 2021CXGC010301)the Youth Project of National Natural Science Foundation(No.52309136)+1 种基金the Competitive Innovation Platform Project of Shandong Province(No.2023CXPT-080)the Postdoctoral Innovation Project(No.SDCX-ZG-202203037)。
文摘To improve the applicability of red mud in subgrade construction,we studied the effects of four traditional retarders,including borax,sodium hexametaphosphate,sodium gluconate,and sucrose,on the setting time,mechanical properties and soil solidification of red mud-based subgrade engineered cementitious material(RCM).The mechanisms of the retarders on the hydration process of RCM were analyzed by hydration microcalorimeter,XRD,TG,and SEM-EDS.The experimental results show that four retarders have retarding effect on RCM,among which sodium gluconate and sucrose have significant retarding effect and do not have adverse effect on 28 d strength.Borax can slightly delay the setting time,and sodium hexametaphosphate has a better retarding effect,but they both reduce the 28 d strength.Microcosmic analysis shows that the retarders do not change the type of RCM hydration products,but mainly slow down the rate of hydration reaction through the adsorption and complexation or reaction of Ca^(2+)in the slurry.All the results show that the retarder has no weakening effect on the unconfined compressive strength,water stability and CBR properties of the stabilized subgrade soil based on RCM.
文摘Wellbore drilling disturbs the equilibrium stress state in the rock mass,resulting in stress redistribution around the opening.Wellbore stability in the altered stress state is vital for engineering applications,as the wellbore instability results in cost overrun.Accurate estimation of rock mechanical properties,in-situ stresses,and required mud pressure is crucial for safe drilling.If the mud pressure is lower than required,the shear failure of the rock takes place,and conversely,if the mud pressure is higher than the upper limit,tensile failure occurs.A strength criterion that can accurately predict the mud pressure may help significantly reduce nonproductive time and cost in well drilling.The commonly used Mogi-Coulomb(MGC)failure criterion for estimating critical mud pressure neglects the few fundamental aspects of rock failure characteristics observed in the laboratory,such as nonlinear strength response in major-minor principal stress space and prediction of multiple failure stress values near the triaxial axial extension boundary.The present study uses the Modified Mohr-Coulomb true-triaxial failure criterion(MMC_TT),which predicts the strength of rock better than the MGC in laboratory true-triaxial tests to overcome the limitations.Moreover,based on the data from previously published five vertical wells in the Krishna-Godavari basin(K-G basin),an empirical relationship is proposed to obtain the strength parameters for the MMC_TT criterion for shaley sedimentary rocks as the existing correlations do not cater for the parameters required for MMC_TT criterion.The comparative study of the MMC_TT with MGC,Modified Mohr-Coulomb triaxial,and Mohr-Coulomb failure criteria,showed that for most of the K-G basin wells,the MMC_TT criterion predicted close to the MGC.However,for well-13,the MMC_TT criterion results are closer to the mud pressure used in actual drilling than the MGC.
基金support from the National Natural Science Foun-dation of China(Grant Nos.U24A20599 and 42277173)the National Science and Technology Major Project of China(Grant No.2024ZD1004300)is gratefully acknowledged.
文摘The deep tunnels are prone to mud and water inrush disasters when crossing water-rich weak zones.A good understanding the hydromechanical behavior of the water-rich weak zone in deep tunnels is the prerequisite for determining the limit support pressure on the tunnel face.However,the seepage forces within the water-rich weak zone are not well estimated in existing models.To overcome this,an analytical model is proposed in this study to determine the limit support pressure of a deep tunnel crossing the water-rich weak zone.The seepage force in the water-rich weak zone is obtained by solving a group of Laplace equations about the hydraulic head,avoiding complex physical and mathematical approximation in existing models.Besides,the seepage boundary conditions in the water-rich weak zone are considered at the nodes on the Neumann boundary and the Dirichlet boundary.The effectiveness of the proposed model is then validated by numerical simulations and engineering practice.It shows that the proposed model has higher accuracy and wider applicability in estimating the hydraulic head.The proposed model can be used for stability analysis of tunnel faces.
基金financially supported by the National Nature Science Foundation of China(No.U23A20557)the Young Elite Scientists Sponsorship Program by China Association for Science and Technology(No.2022QNRC001)Fundamental Research Funds for the Central Universities,China(No.00007720)。
文摘The large-scale accumulation of industrial solid waste,including red mud and coal gangue,coupled with goafs left by under-ground mining activities,poses significant challenges to sustainable human development.In this study,red mud,coal gangue,and othersolid wastes were used to prepare underground backfilling materials.The utilization rate of the total solid waste reached 95%,with redmud accounting for approximately 40wt% of the total.The unconfined compressive strength,setting time,and slump tests were conduc-ted to evaluate the mechanical properties of the material.At the optimal ratio,the 7-and 28-d strengths reach 4.4 and 6.9 MPa,respect-ively.The initial and final setting times were 200 and 250 min,respectively,whereas the initial and 1-h slump exceed 250 and 210 mm,respectively.X-ray diffraction(XRD),Fourier-transform infrared spectroscopy(FTIR),and scanning electron microscopy(SEM)wereemployed to explore the microstructure,phase composition,and chemical bonding within the material.Needle-like,clustered,and granu-lar hydration products were observed,and the primary crystalline structures were identified as ettringite,gmelinite,C-A-S-H,andC-S-H.In addition,a thorough environmental risk assessment was conducted,complemented by detailed economic cost and carbonemission calculations.During the creation of backfill material,hazardous elements from solid waste are immobilized through adsorption,precipitation,and incorporation into the crystal lattice.The immobilization efficiencies for Ni,Al,Cr^(6+),and As were 97.03%,94.32%,86.43%,and 84.22%,respectively,at a pH of 8.49.Moreover,the use of solid waste as a raw material results in considerable cost savingsand marked reduction in carbon emissions.This study innovatively promotes the green cycle of alumina production in the bauxite miningindustry.
基金Project(MMCS2023OF02)supported by the Open Foundation of State Key Laboratory of Featured Metal Materials and Life-cycle Safety for Composite Structures,ChinaProject(AA23073018)supported by the Guangxi Science and Technology,ChinaProject(2024M751861)supported by the China Postdoctoral Science Foundation。
文摘Red mud is a solid waste discharged in the process of alumina production,and how to realize the efficient recovery of its iron is an urgent problem to be solved.In this study,the iron extraction test and mechanism study of high iron red mud were carried out under the coupling conditions of multiple physical field(microwave field,gas-solid flow field and temperature field)with biomass as the reducing agent.The test results showed that under the optimal conditions,an iron concentrate with a yield of 78.4%,an iron grade of 59.23%,and a recovery rate of 86.65%was obtained.The analyses of XRD,XPS,TEM,and SEM-EDS showed that during the roasting process,the hematite in the high-iron red mud was completely converted to magnetite,and the biomass produced the reductant that provided the magnetization reaction;A large number of cracks and pores appeared in the surface of the hematite reduction product particles,which helped to induce iron minerals to undergo effective mineral phase transformation.The above study provides ideas for the phase transformation and efficient recovery of iron minerals in red mud.
基金supported by the National Natural Science Foundation of China (grant numbers 42293351, and U2468221)。
文摘This paper addresses the accuracy and timeliness limitations of traditional comprehensive prediction methods by proposing an approach of decision-level fusion of multisource data.A risk prediction indicator system was established for water and mud inrush in tunnels by analyzing advanced prediction data for specifi c tunnel segments.Additionally,the indicator weights were determined using the analytic hierarchy process combined with the Huber weighting method.Subsequently,a multisource data decision-layer fusion algorithm was utilized to generate fused imaging results for tunnel water and mud inrush risk predictions.Meanwhile,risk analysis was performed for different tunnel sections to achieve spatial and temporal complementarity within the indicator system and optimize redundant information.Finally,model feasibility was validated using the CZ Project Sejila Mountain Tunnel segment as a case study,yielding favorable risk prediction results and enabling effi cient information fusion and support for construction decision-making.
基金Funded by Provincial Basic Research Projects(No.LJKMZ20220947)。
文摘The effects of liquid-solid ratio and reaction time on the leaching rate of magnesium at room temperature were investigated,as well as the effects of the molar ratio of MgO/MgCl_(2),the amount of water added,and the amount of acid-impregnated slag dosed on the compressive strength and water resistance of LR-MOC.The results showed that the magnesium element in the boron mud could be maximally leached under the conditions of 1:1 concentration of hydrochloric acid at room temperature,liquid-solid ratio of 2.5 mL·g^(-1),and reaction time of 5 h,and the main products were amorphous SiO_(2) as well as a small amount of magnesium olivine which had not been completely reacted.The LR-MOC prepared using the acid-soaked mixture could reach a softening coefficient of 0.85 for 28 d of water immersion when the molar ratio of MgO/MgCl_(2) was 2.2,the amount of water added was 0 g,and the acid-soaked slag dosing was 40 wt%,which also led to an appreciable late-strength,with an increase of 19.4%in compressive strength at 28 d compared to that at 7 d.Unlike previous studies,LR-MOC prepared in this way has a final strength phase that is not the more easily hydrolysed 3-phase but the lath-like 5-phase.For this phenomenon,we analyzed the mechanism and found that,during the acid leaching process,a part of amorphous SiO_(2) dissolved in the acid leaching solution formed a silica sol,in which Mg^(2+)played a bridging role to make the silica sol more stable.With the addition and hydrolysis of MgO,the silica sol gel coagulation slows down,providing a capping layer to inhibit the hydrolysis of the 5-phase crystals and providing some strength after coagulation.The amorphous SiO_(2) in the other part of the acid-impregnated slag generated M-S-H gel with Mg^(2+)and OH-,which synergised with the dense structure composed of interlocking crystals to improve the water resistance of LR-MOC.
基金supported by the National Natural Science Foundation of China(22278066,21776039)the National Key R&D Program of China(2023YFB4103001)The Fundamental Research Funds for the Central Universities(DUT2021TB03).
文摘Mercury removal from coal combustion flue gas remains a significant challenge for environmental protection due to the lack of cost-effective sorbents.In this study,a series of red mud(RM)-based sorbents impregnated with sodium halides(NaBr and NaI)are presented to capture elemental mercury(Hg^(0))from flue gas.The modified RM underwent comprehensive characterization,including analysis of its textural qualities,crystal structure,chemical composition,and thermal properties.The results indicate that the halide impregnation substantially impacts the surface area and pore size of the RM.Hg^(0) removal performance was evaluated on a fixed-bed reactor in simulated flue gas(consisting of N_(2),O_(2),CO_(2),NO and SO_(2),etc.)on a modified RM.At an optimal adsorption temperature of 160℃,NaI-modified sorbent(RMI5)offers a removal efficiency of 98%in a mixture of gas,including O_(2),NO and HCl.Furthermore,pseudo-second-order model fitting results demonstrate the chemisorption mechanism for the adsorption of Hg^(0) in kinetic investigations.
基金Supported by National Natural Science Foundation of China(52404010).
文摘A temperature-sensitive mud cake remover(G315)was developed using ethyl lactate as the primary component.Based on this,a temperature-sensitive acidic completion fluid(CF-G315)was formulated.Core evaluation tests,mud cake dissolution tests and corrosion tests were conducted to analyze the mud cake removal performance of G315,the removal efficiency of CF-G315,and its ability to modify the near-wellbore reservoirs,corrosion to casing and hydrolysis performance.Results indicate that ethyl lactate in G315 exhibits weak acidity at room temperature and decomposes into lactic acid under high temperatures.The lactic acid reacts with the calcium carbonate in the mud cake,generating bubbles that dislodge the mud cake and form soluble salts that are subsequently removed by fluid flow,thereby ensuring effective mud cake clearance.CF-G315 removes mud cake efficiently and enhances near-wellbore reservoir permeability.It demonstrates low corrosivity and environmental compatibility,contributing to equipment safety,simplified operational procedures and reduced operational risks.CF-G315 is promising for application in scenarios such as horizontal wells,open-hole completions and gravel pack completions.
基金partly supported by the NSFC-RSF Joint Research project(Nos.42261134534,23-47-00035)funded by the Chinese Academy of Sciences President’s International Fellowship Initiative(Nos.2024VCA0006,2024VCB0013)the National Natural Science Foundation of China(No.42442006)。
文摘The phenomenon of mud volcanism has a connection with the processes of hydrocarbon generation.However,the genesis of sediments is not often taken into consideration.The study of mud volcanoes in the West Kuban marginal marine basin and the Junggar freshwater basin revealed significant isotope-geochemical differences due to various types of sedimentation.The waters from both basins exhibit three principal geochemical facies:Na-HCO_(3),Na-Cl-HCO_(3),and Na-Cl,of which the latter type of water is the dominant.The analysis of genetic coefficients(Cl/Br,Na/Br,and B/Cl)allowed us to distinguish different pathways of mud volcanic water evolution:evaporite dissolution,formation(sedimentation)waters,and waters formed by active water-rock interaction.Through statistical research,we were able to determine that noticeable variations in the behavior of chemical elements in waters from different areas can reflect discrepancies in the geological environment and the evolutionary stage of the diagenetic water transformation.Using thermodynamic modeling,the main directions of mass transfer were shown.It was established that the waters of the Junggar Basin were at a relatively early stage of evolution and had reached equilibrium only with carbonates,while in the formation waters of the West Kuban Basin,element concentrations were also controlled by silicate minerals.The correlations betweenδ^(18)O andδ~2H values and saturation indices of halides,aluminosilicates,sulfates,and borates confirm the enrichment of water with heavy isotopes during interactions with rocks without evaporation or thermal water partition.These reactions are characterized by clay dehydration and water enrichment with^(18)O and B.The data obtained made it possible to clarify the depths of formation of mud-volcanic fluids and their possible stratigraphic sources.
基金supported by the National Natural Science Foundation of China (No. U2004181)State Key Laboratory of Frozen Soil Engineering (No. SKLFSE20191702)+2 种基金the key scientific and technological project of Henan Province (222102320226)Basic research expenses of Henan Polytechnic University (NSFRF230424)the Natural Science Foundation of Henan Province (242300421650)。
文摘Red mud(RM) is an industrial solid waste produced during the extraction of alumina from bauxite.The strong alkaline and heavy metal leaching issues are the primary factors limiting its utilization.This paper proposes a method for dealkalization and chromium(Cr) removal by repeated freeze and thaw to enhance the comprehensive utilization rate of RM.This study focused on the Bayer RM and investigated the effects of freeze-thaw(FT)-acid washing(AW) for dealkalization and Cr removal.The variables were the eluent concentration and FT cycles.The results showed that the synergistic action of FT-AW significantly improved the efficiency of dealkalization and Cr removal.After five FT cycles with 0.5 mol/L oxalic acid,the dealkalization and Cr removal rates reached 97.5% and 65.38%,respectively,16.1% and 7.40% higher than those achieved at room temperature.The repeated FT disrupted the structure of the RM particles,leading to an increase in the pore space between the soil particles.This enables complete eluent contact and reaction with Cr and alkali,thereby enhancing the removal rate.The FT-AW process is suitable for practical engineering applications.It offers a novel method for RM dealkalization and Cr removal by using the FT alternation phenomena in seasonally frozen regions.
文摘The aim of this study is to enhance the value of local earth materials used in the construction of certain homes in the Republic of Guinea. Thus, a trial study to improve the quality of mud bricks using paper fibers obtained by grinding and soaking in water and then drying were used as a stabilizer in the manufacture of these mud bricks from the sample of two sites Dounkiwal (DK) (in Mamou and the sample from the urban commune of Kouroussa). To do this, certain methods and means of identification were carried out, namely: geotechnical, mineralogical and chemical analyses. Sample DK from Mamou has a silty-clay geotechnical characteristic with a plasticity index Ip of 12.75%. However, mineralogical and chemical studies showed that sample Dounkiwal (DK) (Mamou) contains a high proportion of silica and iron oxides (79.63%) and Fe2O3 (11.85%), associated with other alkaline earth oxides and ions: CaO;MgO;SO32−;Cl−, i.e. 3.96%;0.96%;0.28% and 0.039% respectively. Its loss on ignition (LOI) and insoluble residues are 15.40% and 56.36%. The evaluation of the number of huts in Upper and Middle Guinea showed that the populations of these areas have been using mud bricks for several decades in the construction of dwellings. The average value found for the compressive strength of these bricks (from samples I, II and III from Kouroussa) is 0.16 MPa. This value is appreciable in the construction of mud houses.
基金supported by grants from the National Natural Science Foundation of China (22178339)2023 Innovation-driven Development Special Foundation of Guangxi(AA23023021)the Hundred Talents Program (A) of the Chinese Academy of Sciences
文摘Red mud(RM)is a solid waste generated in the aluminum industry after the extraction of alumina oxide;its multiple elements and higher pH value likely pose a severe threat to the environment after treatment.However,RM's higher concentrations of metal components,particularly Fe_(2)O_(3)and rare earth elements(REEs),render RM promising for catalytic application.Hence,this work showed an efficient high-speed RM to catalyze electrocatalytic nitrate-to-ammonia reduction reaction(NARR).RM calcined at 500℃(RM-500)exhibited excellent catalytic performance.Faradaic efficiency of ammonia(FENH_(3))in an electrolyte solution containing 1 mol·L^(-1)NO_(3)-achieved a maximum value of 92.3%at-0.8 V(vs.RHE).Additionally,24-h cycle testing and post-reaction PXRD and SEM indicated that the RM-500 electrocatalyst is stable during NARR.The RM-500 demonstrated a high FE of NH_(3)-to-NO_(3)-of 89.7%at 1.85 V(vs.RHE),showing great potential in the ammonia fuel cells technology and achieving the nitrogen cycle.
基金supported by the Southern Marine Science and Engineering Guangdong Laboratory(Zhuhai)(No.SML2021SP318)the National Postdoctoral Program for Innovative Talents(No.BX20190391)+1 种基金the Guangdong Province Introduced Innovative R&D Team of Geological Processes and Natural Disasters around the South China Sea founded by the Science and Technology Department of Guangdong Province(No.2016ZT06N331)the Guangdong Basic and Applied Basic Research Foundation(Nos.2019A1515110305,2021A1515011130,2021A1515110288)。
文摘The release of accumulated stress through earthquakes is known to devote to the mud volcanism occurrence,which may in turn affect subsequent regional seismicity.Mud volcanoes have been observed on the northeast continental margin of the South China Sea as well.Based on the mud volcanoes and earthquakes catalogue,we measured the spatial and temporal distribution of z and b values,to explore the geodynamic process of the repeated eruptions of mud volcanoes influence on the regional seismicity.The results suggest a close correlation between the b-z values and mud volcanism occurrence in the SW Taiwan.Generally,the z-value anomalies in where the mud volcanoes eruptions show unchanged negative values and indicate seismic quiescence before a big earthquake,whereas the b-values often show periodicity fluctuations around the value of 0.5.This may indicate a mutual triggering relationship between the mud volcanoes and earthquakes.We infer that mud volcano eruptions help to partition and release part of the regional stress accumulation from the seismogenic structures,thus balancing the local stress and mitigating large-magnitude seismicity occurring probability.
基金the National Natural Science Foundation of China(42074134,42474152,42374150)CNPC Innovation Found(2024DQ02-0152).
文摘The oil-based mud(OBM) borehole measurement environment presents significant limitations on the application of existing electrical logging instruments in high-resistance formations. In this paper, we propose a novel logging method for detection of high-resistance formations in OBM using highfrequency electrodes. The method addresses the issue of shallow depth of investigation(DOI) in existing electrical logging instruments, while simultaneously ensuring the vertical resolution. Based on the principle of current continuity, the total impedance of the loop is obtained by equating the measurement loop to the series form of a capacitively coupled circuit. and its validity is verified in a homogeneous formation model and a radial two-layer formation model with a mud standoff. Then, the instrument operating frequency and electrode system parameters were preferentially determined by numerical simulation, and the effect of mud gap on impedance measurement was investigated. Subsequently, the DOI of the instrument was investigated utilizing the pseudo-geometric factor defined by the real part of impedance. It was determined that the detection depth of the instrument is 8.74 cm, while the effective vertical resolution was not less than 2 cm. Finally, a focused high-frequency electrode-type instrument was designed by introducing a pair of focused electrodes, which effectively enhanced the DOI of the instrument and was successfully deployed in the Oklahoma formation model. The simulation results demonstrate that the novel method can achieve a detection depth of 17.40 cm in highly-resistive formations drilling with OBM, which is approximately twice the depth of detection of the existing oil-based mud microimager instruments. Furthermore, its effective vertical resolution remains at or above 2 cm,which is comparable to the resolution of the existing OBM electrical logging instrument.
基金supported by the National Natural Science Foundation of China(Grant No.52474010)the Sichuan Science and Technology Program(Grant No.2025YFHZ0079)the Program of Introducing Talents of Discipline to Chinese Universities(111 Plan)(Grant No.D18016).
文摘The precise and real-time prediction of pore pressure is critical for optimizing drilling efficiency and mitigating the potential risks associated with drilling operations.In order to surmount the limitations of empirical methods and to reduce reliance on logging-while-drilling data,this study proposed a stacking ensemble approach that utilized only conventional mud log data.The workflow involves the preliminary processing of data using isolation forest and wavelet thresholding techniques to effectively eliminate outliers and noise.The Eaton index was estimated using a Bayesian inversion algorithm,and pore pressure was estimated by integrating the dc exponent and Eaton method.A feature selection strategy combining data distribution characteristics and regression-based importance ranking was used to optimize the input parameters.Subsequently,a stacking approach was developed for predicting pore pressure,and the corresponding base learner,meta learner,and hyperparameters were optimized.Finally,the validity of the optimized model was substantiated through field data from three test wells(X1,X5,X3)under different drilling scenarios.The results indicated that the global optimal Eaton index of the block was 0.2449,the maximum percentage error of pore pressure estimation was 3.66%,and the corresponding average error was 1.59%compared to the wireline formation test data.The optimal combination of input features was determined to be R-ROP,WOB,TG,PT,MW,PFI,TVD,H,BR,BT,and SPP.The optimal basic learners were identified as BPNN,CNN,LSTM,and LightGBM,while the optimal meta learners were XGBoost.Prediction accuracy is improved when offset wells are densely distributed,spatially balanced,and proximal to the target well;conversely,sparse or distant offset wells result in reduced prediction performance.The mean absolute percentage errors for test offset well X1,X5,and X3 were 0.4353%,0.4646%,and 0.6856%,respectively,with the corresponding R2 values of 0.9362,0.9078,and 0.8950,respectively.Consequently,this approach has the capacity to accurately and in real-time predict pore pressure using solely conventional mud log data.This capability enables timely adjustments to drilling parameters,thereby enhancing operational efficiency and mitigating drilling risks.
基金supported by the Science and Technology Innovation Program of Hunan Province,China(No.2023RC3053)the National Key Research and Development Program of China(No.2023YFC3904201)the National Natural Science Foundation of China(No.52004343).
文摘Red mud is a kind of industrial waste residue produced in the process of alumina production,which has strong suspension and is difficult to precipitate and filter.This study compared the effects of 4 kinds of filter aids,including CaCl2,polymerized ferrous sulfate(PFS),steel slag(SS),and Portland cement(PC),on the filtration rate,filter cake moisture content,and Na2O content of red mud slurry.At a dosage of 10 g·L^(-1),the filtration effects were in the following order:PFS>CaCl_(2)>SS>PC.Under the combination of 5 g·L^(-1) SS and 5 g·L^(-1) PC,the better filtration effect was achieved with a filtration time of 205.17 s,which was reduced by 58.52%compared to the original red mud.The combined use of SS and PC exhibits better advantages in terms of cost and filtration effect.This study provides a data foundation for the rapid filtration of red mud slurry.The use of SS and PC as filter aids for red mud holds broad application pro-spects.
