Identification of reservoir types in deep carbonates has always been a great challenge due to complex logging responses caused by the heterogeneous scale and distribution of storage spaces.Traditional cross-plot analy...Identification of reservoir types in deep carbonates has always been a great challenge due to complex logging responses caused by the heterogeneous scale and distribution of storage spaces.Traditional cross-plot analysis and empirical formula methods for identifying reservoir types using geophysical logging data have high uncertainty and low efficiency,which cannot accurately reflect the nonlinear relationship between reservoir types and logging data.Recently,the kernel Fisher discriminant analysis(KFD),a kernel-based machine learning technique,attracts attention in many fields because of its strong nonlinear processing ability.However,the overall performance of KFD model may be limited as a single kernel function cannot simultaneously extrapolate and interpolate well,especially for highly complex data cases.To address this issue,in this study,a mixed kernel Fisher discriminant analysis(MKFD)model was established and applied to identify reservoir types of the deep Sinian carbonates in central Sichuan Basin,China.The MKFD model was trained and tested with 453 datasets from 7 coring wells,utilizing GR,CAL,DEN,AC,CNL and RT logs as input variables.The particle swarm optimization(PSO)was adopted for hyper-parameter optimization of MKFD model.To evaluate the model performance,prediction results of MKFD were compared with those of basic-kernel based KFD,RF and SVM models.Subsequently,the built MKFD model was applied in a blind well test,and a variable importance analysis was conducted.The comparison and blind test results demonstrated that MKFD outperformed traditional KFD,RF and SVM in the identification of reservoir types,which provided higher accuracy and stronger generalization.The MKFD can therefore be a reliable method for identifying reservoir types of deep carbonates.展开更多
Recently,exploration breakthroughs have been made in the Lower Cretaceous sandstone reservoirs in the Doseo Basin,but the identification of reservoir fluid property is difficult due to variable reservoir lithology,com...Recently,exploration breakthroughs have been made in the Lower Cretaceous sandstone reservoirs in the Doseo Basin,but the identification of reservoir fluid property is difficult due to variable reservoir lithology,complex oil-water contact within and faint responses of the oil zone,which causes the lower accuracy of reservoir fluid property identification with conventional mudlogging and wirelogging techniques.Applying the geochemical logging,fluorescent logging,mud logging and cutting logging technology,in combination with formation test data,this paper distinguishes the crude oil types,analyzes the logging response characteristics of oil zone after water washing,and establishes the interpretation charts and parameter standards for reservoir fluid properties.The crude oil can be divided into two types,namely viscous-heavy and thin-light,based on total hydrocarbon content and component concentration tested by mud logging,features of pyrolysis gas chromatogram and fluorescence spectroscopy.The general characteristics of oil layers experienced water washing include the decrease of total hydrocarbon content and component concentration from mud logging,the decrease of S1 and PS values from geochemical logging,the decrease of hydrocarbon abundance and absence of some light components in pyrolysis gas chromatogram,and the decrease of fluorescence area and intensity from fluorescence logging.According to crude oil types,the cross plots of S1 versus peak-baseline ratio,and the cross plots of rock wettability versus fluorescence area ratio are drawn and used to interpret reservoir fluid property.Meanwhile,the standards of reservoir fluid parameter are established combining with the parameters of PS and the parameters in above charts,and comprehensive multiparameter correlation in both vertical and horizontal ways is also performed to interpret reservoir fluid property.The application in the Doseo Basin achieved great success,improving interpretation ability of fluid property in the reservoir with complex oil-water contact,and also provided technical reference for the efficient exploration and development of similar reservoirs.展开更多
Investigating the formation mechanisms of carbonate geothermal reservoirs is of theoretical and practical significance for summarizing the formation pattern of geothermal resources and further guiding their effective ...Investigating the formation mechanisms of carbonate geothermal reservoirs is of theoretical and practical significance for summarizing the formation pattern of geothermal resources and further guiding their effective exploitation.The Beijing-Tianjin-Hebei Plain(BTHP),predominantly located within the Jizhong Depression and Cangxian Uplift in the Bohai Bay Basin,serves as the primary region for geothermal exploitation and utilization in China.More than 1500 geothermal wells have been drilled therein,with water temperature at the wellhead ranging from 55 to 110°C,single-well flow rate ranging between 80 and 120 m^(3)/h,and cumulative heating area exceeding 100×10^(6)m^(3).However,the exploration and research in the region remain limited overall.As per the previous geothermal and petroleum exploration results and the latest geothermal drilling data,this study comprehensively evaluated the geothermal resources of karst geothermal reservoirs.The results show that two suites of carbonate karst reservoirs,namely the Jxw Formation and the Ordovician strata,have primarily developed in the BTHP,and their formation and evolution can be divided into four stages:the Mesoproterozoic-Early Paleozoic stage with carbonate sedimentation and the development of interlayer karst,the Late Paleozoic stage with the development of direct sedimentary cover,the Mesozoic stage with compressional uplifting and development of buried hill karst,and the Cenozoic stage with regional cover deposition and the modification and finalization of karst geothermal reservoirs.Accordingly,the porosity evolution history of the geothermal reservoirs is composed of three stages,namely a significant decrease followed by a minor increase,a gradual decline,and then a small fluctuation from increase to decrease before slowly rising again.The karstification in geothermal reservoirs can be summarized into quasi-syngenetic karstification,epigenetic karstification,and burial karstification,which can be subdivided into seven subcategories.The carbonate geothermal reservoirs in the study area boast total geothermal resources of 53.821×10^(9)GJ,or 184.155×10^(9)t of standard coal equivalent(tce),and the annual exploitable geothermal resources in the urban area can heat an area of(400‒500)×10^(6)m^(3),indicating great potential of geothermal exploitation.展开更多
The quantitative understanding of hydraulic fracture(HF)properties guides accurate production forecasts and reserve estimation.Type curve is a powerful technique to characterize HF and reservoir properties from flowba...The quantitative understanding of hydraulic fracture(HF)properties guides accurate production forecasts and reserve estimation.Type curve is a powerful technique to characterize HF and reservoir properties from flowback and long-term production data.However,two-phase flow of water and hydrocarbon after an HF stimulation together with the complex transport mechanisms in shale nanopores exacerbate the nonlinearity of the transport equation,causing errors in type-curve analysis.Accordingly,we propose a new two-phase type-curve method to estimate HF properties,such as HF volume and permeability of fracture,through the analysis of flowback data of multi-fractured shale wells.The proposed type curve is based on a semianalytical solution that couples the two-phase flow from the matrix with the flow in HF by incorporating matrix influx,slippage effect,stress dependence,and the spatial variation of fluid properties in inorganic and organic pores.For the first time,multiple fluid transport mechanisms are considered into two-phase type-curve analysis for shale reservoirs.We analyze the flowback data from a multi-fractured horizontal well in a shale gas reservoir to verify the field application of the proposed method.The results show that the fracture properties calculated by the type-curve method are in good agreement with the long-time production data.展开更多
BACKGROUND In recent years,pure laparoscopic radical surgery for Bismuth-Corlette type Ⅲ and Ⅳ hilar cholangiocarcinoma(HCCA)has been preliminarily explored and applied,but the surgical strategy and safety are still...BACKGROUND In recent years,pure laparoscopic radical surgery for Bismuth-Corlette type Ⅲ and Ⅳ hilar cholangiocarcinoma(HCCA)has been preliminarily explored and applied,but the surgical strategy and safety are still worthy of further improvement and attention.AIM To summarize and share the application experience of the emerging strategy of“hepatic hilum area dissection priority,liver posterior separation first”in pure laparoscopic radical resection for patients with HCCA of Bismuth-Corlette types Ⅲ and IV.METHODS The clinical data and surgical videos of 6 patients with HCCA of Bismuth-Corlette types Ⅲ and Ⅳ who underwent pure laparoscopic radical resection in our department from December 2021 to December 2023 were retrospectively analyzed.RESULTS Among the 6 patients,4 were males and 2 were females.The average age was 62.2±11.0 years,and the median body mass index was 20.7(19.2-24.1)kg/m^(2).The preoperative median total bilirubin was 57.7(16.0-155.7)μmol/L.One patient had Bismuth-Corlette type Ⅲa,4 patients had Bismuth-Corlette type Ⅲb,and 1 patient had Bismuth-Corlette type Ⅳ.All patients successfully underwent pure laparoscopic radical resection following the strategy of“hepatic hilum area dissection priority,liver posterior separation first”.The operation time was 358.3±85.0 minutes,and the intraoperative blood loss volume was 195.0±108.4 mL.None of the patients received blood transfusions during the perioperative period.The median length of stay was 8.3(7.0-10.0)days.Mild bile leakage occurred in 2 patients,and all patients were discharged without serious surgery-related complications.CONCLUSION The emerging strategy of“hepatic hilum area dissection priority,liver posterior separation first”is safe and feasible in pure laparoscopic radical surgery for patients with HCCA of Bismuth-Corlette types Ⅲ and Ⅳ.This strategy is helpful for promoting the modularization and process of pure laparoscopic radical surgery for complicated HCCA,shortens the learning curve,and is worthy of further clinical application.展开更多
This study analyzed the characteristics and types of the Lower Silurian shale gas reservoirs in and around Sichuan Basin through field observations, slices, Ar-ion-beam milling, scanning electron microscopy, and x-ray...This study analyzed the characteristics and types of the Lower Silurian shale gas reservoirs in and around Sichuan Basin through field observations, slices, Ar-ion-beam milling, scanning electron microscopy, and x-ray diffraction analysis of 25 black shale outcrops and samples. Two main types of shale gas reservoirs were determined, i.e., fractures and pores. Fractures were classified into five categories, i.e., giant, large, medium, small, and micro, according to the features of the shale gas reservoirs, effect of fracture on gas accumulation, and fracture nature. Pore types include organic matter pores, mineral pores(mineral surface, intraparticle, interparticle, and corrosional pore), and nanofractures. The various fracture types, fracture scales, pore types, and pore sizes exert different controls over the gas storage and production capacity. Pores serve as a reservoir for gas storage and, the gas storage capacity can be determined using pores; fractures serve as pathways for gas migration, and gas production capacity can be determined using them.展开更多
The diversity of sandstone diagenesis mechanisms caused by the complex geological conditions of oil/gas basins in China could hardly be reasonably explained by the traditional concept of burial diagenesis. Three genes...The diversity of sandstone diagenesis mechanisms caused by the complex geological conditions of oil/gas basins in China could hardly be reasonably explained by the traditional concept of burial diagenesis. Three genesis types of thermal diagenesis, tectonic diagenesis and fluid diagenesis are presented on the basis of the dynamic environment of the oil/gas basins and.the controlling factors and mechanisms of sandstone diagenesis. Thermal diagenesis of sandstone reservoirs is related not only to the effect of formation temperature on diagenesis, but also to the significant changes in diagenesis caused by geothermal gradients. The concept of thermal compaction is presented. Thermal compaction becomes weaker with increasing depth and becomes stronger at a higher geothermal gradient. At the same formation temperature, the sandstone porosity in the region with a lower geothermal gradient is e^0.077+0.0042T times higher than that in the region with a higher geothermal gradient. Both sudden and gradual changes are observed in diagenetic evolution caused by structural deformation. Average sandstone compaction increased by 0.1051% for every 1.0MPa increase of lateral tectonic compressional stress, while late tectonic napping helped to preserve a higher porosity of underlying sandstone reservoir. Fluid diagenesis is a general phenomenon. The compaction caused by fluid properties is significant. The coarser the grain size, the stronger the fluid effect on compaction. The greater the burial depth, the weaker the fluid effect on compaction for the specific reservoir lithology and the greater the difference in the fluid effects on compaction between different grain sizes.展开更多
Production decline analysis has been considered as an important method to obtain the flow parameters, reservoir properties and original gas in place. Although advanced Blasingame production decline analysis methods fo...Production decline analysis has been considered as an important method to obtain the flow parameters, reservoir properties and original gas in place. Although advanced Blasingame production decline analysis methods for vertical wells, fractured wells and horizontal wells are widely used, limited study has conducted on Blasingame production decline type curves for multi-fractured horizontal well(MFHW). Based on the perpendicular bisection(PEBI) grids, a numerical model was developed and the solution was obtained using control volume finite element method and the fully implicit method. Blasingame production decline-type curves of the infinitely conductive MFHW were plotted through computer programming. A field case was presented to analyse and verify the model developed. Five flow regimes, including early formation linear flow, early radial flow, compound linear flow, transient flow and pseudo-radial flow, are recognized. Fracture spacing is the main factor that affects early radial flow, compound linear flow and transient flow, the distance from the well to the circular boundary affects the pseudo-radial flow, and the type curves are also significantly affected by the formation permeability, fracture number and fracture half-length. The validation of field case suggests that the Blasingame production decline type curves proposed in this work can be applied to the production decline analysis for MFHW in tight gas reservoirs.展开更多
Carbonate reservoirs exhibit strong heterogeneity in the distribution of pore types that can be quantitatively characterized by applying Xu–Payne multi-porosity model.However,there are some prerequisites to this mode...Carbonate reservoirs exhibit strong heterogeneity in the distribution of pore types that can be quantitatively characterized by applying Xu–Payne multi-porosity model.However,there are some prerequisites to this model the porosity and saturation need to be provided.In general,these application conditions are difficult to satisfy for seismic data.In order to overcome this problem,we present a two-step method to estimate the porosity and saturation and pore type of carbonate reservoirs from seismic data.In step one,the pore space of the carbonate reservoir is equivalent to a single-porosity system with an effective pore aspect ratio;then,a 3D rock-physics template(RPT)is established through the Gassmann’s equations and effective medium models;and then,the effective aspect ratio of pore,porosity and fluid saturation are simultaneously estimated from the seismic data based on 3D RPT.In step two,the pore space of the carbonate reservoir is equivalent to a triple-porosity system.Combined with the inverted porosity and saturation in the first step,the porosities of three pore types can be inverted from the seismic elastic properties.The application results indicate that our method can obtain accurate physical properties consistent with logging data and ensure the reliability of characterization of pore type.展开更多
The buried hill in the Jizhong depression contains abundant petroleum reserves and are important production areas.The Ordovician buried hill has restricted the discovery of new oil and gas exploration targets because ...The buried hill in the Jizhong depression contains abundant petroleum reserves and are important production areas.The Ordovician buried hill has restricted the discovery of new oil and gas exploration targets because of its strong reservoir heterogeneity and complex reservoir-controlling factors.Based on a large volume of core,thin section,logging,seismic,and geochemical data and numerous geological analyses,the reservoir-forming conditions and modes were systematically analyzed to guide the exploration and achieve important breakthroughs in the Yangshuiwu and Wen an slope buried hills.The study revealed that three sets of source rocks of the third and fourth members of the Shahejie Formation from the Paleogene and Carboniferous-Permian were developed in the Jizhong depression,providing sufficient material basis for the formation of buried hill oil and gas reservoirs.The reservoir control mechanism involving the three major factors of“cloud-karst-fault”was clarified,and karst cave,fracture fissure-pore,and cloud pore type reservoir models were established,thereby expanding the exploration potential.Controlled by the superposition of multi-stage tectonic processes during the Indosinian,Yanshanian,and Himalayan,two genetic buried hill trap types of uplift-depression and depression-uplift were formed.Based on the analysis of reservoir-forming factors of the Ordovician buried hill,three buried hill oil and gas reservoir-forming models were identified:low-level tectonic-lithologic composite quasi-layered buried hill,medium-level paleo-storage paleo-block buried hill,and high-level paleo-storage new-block buried hill.Comprehensive evaluations indicate that the reservoir-forming conditions of the low-level tectonic-lithologic composite quasi-layered buried hill in the northern portion of the Jizhong depression are the most favorable and that the Sicundian and Xinzhen buried hills are favorable areas for future exploration.展开更多
The Feixianguan Formation reservoirs in northeastern Sichuan are mainly a suite of carbonate platform deposits.The reservoir types are diverse with high heterogeneity and complex genetic mechanisms.Pores,vugs and frac...The Feixianguan Formation reservoirs in northeastern Sichuan are mainly a suite of carbonate platform deposits.The reservoir types are diverse with high heterogeneity and complex genetic mechanisms.Pores,vugs and fractures of different genetic mechanisms and scales are often developed in association,and it is difficult to classify reservoir types merely based on static data such as outcrop observation,and cores and logging data.In the study,the reservoirs in the Feixianguan Formation are grouped into five types by combining dynamic and static data,that is,karst breccia-residual vuggy type,solution-enhanced vuggy type,fractured-vuggy type,fractured type and matrix type(non-reservoir).Based on conventional logging data,core data and formation microscanner image(FMI)data of the Qilibei block,northeastern Sichuan Basin,the reservoirs are classified in accordance with fracture-vug matching relationship.Based on the principle of cluster analysis,K-Nearest Neighbor(KNN)classification templates are established,and the applicability of the model is verified by using the reservoir data from wells uninvolved in modeling.Following the analysis of the results of reservoir type discrimination and the production of corresponding reservoir intervals,the contributions of various reservoir types to production are evaluated and the reliability of reservoir type classification is verified.The results show that the solution-enhanced vuggy type is of high-quality sweet spot reservoir in the study area with good physical property and high gas production,followed by the fractured-vuggy type,and the fractured and karst breccia-residual vuggy types are the least promising.展开更多
Class III tight oil reservoirs have low porosity and permeability,which are often responsible for low production rates and limited recovery.Extensive repeated fracturing is a well-known technique to fix some of these ...Class III tight oil reservoirs have low porosity and permeability,which are often responsible for low production rates and limited recovery.Extensive repeated fracturing is a well-known technique to fix some of these issues.With such methods,existing fractures are refractured,and/or new fractures are created to facilitate communication with natural fractures.This study explored how different refracturing methods affect horizontal well fracture networks,with a special focus on morphology and related fluid flow changes.In particular,the study relied on the unconventional fracture model(UFM).The evolution of fracture morphology and flow field after the initial fracturing were analyzed accordingly.The simulation results indicated that increased formation energy and reduced reservoir stress differences can promote fracture expansion.It was shown that the length of the fracture network,the width of the fracture network,and the complexity of the fracture can be improved,the oil drainage area can be increased,the distance of oil and gas seepage can be reduced,and the production of a single well can be significantly increased.展开更多
目的探讨成人骨型Ⅲ类患者矫治前后上下前牙区牙槽高度和宽度变化以及前牙区牙根位置变化。方法选取2020年5月—2022年11月在中山市小榄人民医院口腔科正畸掩饰治疗的成人骨型Ⅲ类患者50例,比较正畸治疗前后患者上下颌前牙牙槽骨厚度和...目的探讨成人骨型Ⅲ类患者矫治前后上下前牙区牙槽高度和宽度变化以及前牙区牙根位置变化。方法选取2020年5月—2022年11月在中山市小榄人民医院口腔科正畸掩饰治疗的成人骨型Ⅲ类患者50例,比较正畸治疗前后患者上下颌前牙牙槽骨厚度和高度,其中包括上前牙槽骨厚度(upper anterior alveolar bonethickness,UA)、上后牙槽骨厚度(upper posterior alveolar bone thickness,UP)、上牙槽骨总厚度(upper alveolar bone width,UW)、下前牙槽骨厚度(lower anterior alveolar bone thickness,LA)、下后牙槽骨厚度(lower posterior alveolar bone thickness,LP)、下牙槽骨总厚度(lower alveolar bone width,LW)、根中水平上前牙槽骨厚度(upper anterior alveolar bone thickness at the mid-root level,UA-m)、根中水平上后牙槽骨厚度(upper posterior alveolar bone thickness at the mid-root level,UP-m)、根中水平上牙槽骨总厚度(upper alveolar bone thickness at the mid-root level,UW-m)、根中水平下前牙槽骨厚度(lower anterior alveolar bone thickness at the mid-root level,LA-m)、根中水平下后牙槽骨厚度(lower posterior alveolar bone thickness at the mid-root level,LP-m)、根中水平下牙槽骨总厚度(lower alveolar bone thickness at the mid-root level,LW-m)以及上前牙槽骨高度(upper anterior alveolar bone height,UAH)和下前牙槽骨高度(lower anterior alveolarbone height,LAH)。结果正畸治疗前后患者UA、UP-m测量值比较,差异无统计学意义(P>0.05)。与正畸治疗前比较,正畸治疗后患者UP、UW、UA-m、UW-m测量值均显著降低(P<0.05)。正畸治疗后患者LP、LA-m测量值与正畸治疗前比较,差异无统计学意义(P>0.05)。与正畸治疗前比较,正畸治疗后患者LA、LW、LP-m、LW-m测量值均降低(P<0.05)。与正畸治疗前比较,正畸治疗后患者UAH、LAH测量值均显著降低(P<0.05)。正畸治疗后,患者上下颌前牙解剖牙根长度分别为(10.62±0.57)mm、(9.65±0.48)mm,正畸治疗前患者上下颌前牙解剖牙根长度分别为(11.01±0.58)mm、(10.37±0.48)mm,与正畸治疗前比较,患者上下颌前牙解剖牙根长度明显减小(P<0.05)。结论成人骨型Ⅲ类患者进行正畸掩饰治疗后,牙槽形态会发生相应改变,患者上下前牙牙槽骨厚度和高度会一定程度地减少。因此,在矫治过程中应当对患者牙槽形态的变化给予密切关注,尽量避免上下前牙发生代偿性移动,从而降低不良反应情况发生的风险。展开更多
The permeability or/and porosity in low-permeability reservoirs mainly depends on fracture system. Wthin this kind of low-permeability reservior, fractures play a very important role on exploration and development. Be...The permeability or/and porosity in low-permeability reservoirs mainly depends on fracture system. Wthin this kind of low-permeability reservior, fractures play a very important role on exploration and development. Because there are so many differences, such as basin properties and tectonic characteristics, among the eastern,western and central basins, the types and distribution characteristics of fractures are also obviously different. Quantitative information on fracture distribution is very important. Through the contrastive study of 7 oilfield, the differences and distribution characteristics of fractures in three types of oil-bearing basins are summarized. Due to the different geological conditions and stress state during the formation of fractures, the fracture systems in three types of basins are also different. Fractures are mainly composed of tectonic fractutres related to normal faultes in eastern basins, related to folds and reverse faultes in western basins, and regional fractures which widely distributed not only in outcrops but also at depth of the relatively undeformed strata in central basins. So, besides jointed-fractures, we can often see faulted-fractures similar to normal faults in eastern basins and similar to reverse faults in western basins. According to statistical data, fracture spacing generally has a lognormal distribution and is linearly proportional to layer thickness. The development degree of fractures is controlled by lithology, bed thickness, sedimentary microfacies and faults or folds, etc. The permeability, aperture and connectedness of fractures are related to the modern stress field. Though there are 3-4 sets of fractures in a oilfield, the fractures parallel to the maximum principal stress direction are main for the pattern arrangement of low-permeability reservoirs.展开更多
目的:基于上皮细胞-间充质细胞转分化(EMT)学说观察化纤Ⅳ号方、艾灸以及二者相配合治疗肺纤维化大鼠Collagen TypeⅢ(Ⅲ-C)和PDGF的变化,探讨其治疗效应及生物学机制。方法:将鼠龄约为6周的SD大鼠随机分为空白组、模型组、化纤Ⅳ号方...目的:基于上皮细胞-间充质细胞转分化(EMT)学说观察化纤Ⅳ号方、艾灸以及二者相配合治疗肺纤维化大鼠Collagen TypeⅢ(Ⅲ-C)和PDGF的变化,探讨其治疗效应及生物学机制。方法:将鼠龄约为6周的SD大鼠随机分为空白组、模型组、化纤Ⅳ号方组、艾灸组、化纤Ⅳ号方与艾灸配合治疗组(简称为"灸药组"),治疗30 d后处死观察其肺组织病理改变,并检测其Collagen TypeⅢ、PDGF的基因和蛋白表达情况。结果:实时荧光定量结果显示:与空白组相比,各组Ⅲ-C和PDGF m RNA表达增高(P<0.05)。与模型组相比,各组的Ⅲ-C和PDGF m RNA表达有明显降低(P<0.01)。而各组中,灸药组疗效最明显,Ⅲ-C和PDGF的表达最低。蛋白免疫印迹法检测结果显示:与模型组相比各组的Ⅲ-C蛋白表达有差异。结论:1艾灸、化纤Ⅳ号方均可减轻博莱霉素诱导肺纤维化大鼠的肺纤维化程度。2艾灸配合化纤Ⅳ号方可减轻博莱霉素诱导肺纤维化大鼠的肺纤维化程度,且其效果优于单用艾灸或单用化纤Ⅳ号方。3艾灸、化纤Ⅳ号方及其二者配合使用不同程度阻抑博莱霉素诱导肺纤维化大鼠肺纤维化进程的效应机制,可能与通过调控其EMT过程中的Ⅲ-C和PDGF表达环节紧密相关。展开更多
基金supported by the National Natural Science Foundation of China(No.U21B2062)the Natural Science Foundation of Hubei Province(No.2023AFB307)。
文摘Identification of reservoir types in deep carbonates has always been a great challenge due to complex logging responses caused by the heterogeneous scale and distribution of storage spaces.Traditional cross-plot analysis and empirical formula methods for identifying reservoir types using geophysical logging data have high uncertainty and low efficiency,which cannot accurately reflect the nonlinear relationship between reservoir types and logging data.Recently,the kernel Fisher discriminant analysis(KFD),a kernel-based machine learning technique,attracts attention in many fields because of its strong nonlinear processing ability.However,the overall performance of KFD model may be limited as a single kernel function cannot simultaneously extrapolate and interpolate well,especially for highly complex data cases.To address this issue,in this study,a mixed kernel Fisher discriminant analysis(MKFD)model was established and applied to identify reservoir types of the deep Sinian carbonates in central Sichuan Basin,China.The MKFD model was trained and tested with 453 datasets from 7 coring wells,utilizing GR,CAL,DEN,AC,CNL and RT logs as input variables.The particle swarm optimization(PSO)was adopted for hyper-parameter optimization of MKFD model.To evaluate the model performance,prediction results of MKFD were compared with those of basic-kernel based KFD,RF and SVM models.Subsequently,the built MKFD model was applied in a blind well test,and a variable importance analysis was conducted.The comparison and blind test results demonstrated that MKFD outperformed traditional KFD,RF and SVM in the identification of reservoir types,which provided higher accuracy and stronger generalization.The MKFD can therefore be a reliable method for identifying reservoir types of deep carbonates.
基金funded by a project entitled exploration field evaluation and target optimization of key basins in Chad and Niger(No.2019D-4308)initiated by the scientific research and technology development project of china national petroleum corporation.
文摘Recently,exploration breakthroughs have been made in the Lower Cretaceous sandstone reservoirs in the Doseo Basin,but the identification of reservoir fluid property is difficult due to variable reservoir lithology,complex oil-water contact within and faint responses of the oil zone,which causes the lower accuracy of reservoir fluid property identification with conventional mudlogging and wirelogging techniques.Applying the geochemical logging,fluorescent logging,mud logging and cutting logging technology,in combination with formation test data,this paper distinguishes the crude oil types,analyzes the logging response characteristics of oil zone after water washing,and establishes the interpretation charts and parameter standards for reservoir fluid properties.The crude oil can be divided into two types,namely viscous-heavy and thin-light,based on total hydrocarbon content and component concentration tested by mud logging,features of pyrolysis gas chromatogram and fluorescence spectroscopy.The general characteristics of oil layers experienced water washing include the decrease of total hydrocarbon content and component concentration from mud logging,the decrease of S1 and PS values from geochemical logging,the decrease of hydrocarbon abundance and absence of some light components in pyrolysis gas chromatogram,and the decrease of fluorescence area and intensity from fluorescence logging.According to crude oil types,the cross plots of S1 versus peak-baseline ratio,and the cross plots of rock wettability versus fluorescence area ratio are drawn and used to interpret reservoir fluid property.Meanwhile,the standards of reservoir fluid parameter are established combining with the parameters of PS and the parameters in above charts,and comprehensive multiparameter correlation in both vertical and horizontal ways is also performed to interpret reservoir fluid property.The application in the Doseo Basin achieved great success,improving interpretation ability of fluid property in the reservoir with complex oil-water contact,and also provided technical reference for the efficient exploration and development of similar reservoirs.
文摘Investigating the formation mechanisms of carbonate geothermal reservoirs is of theoretical and practical significance for summarizing the formation pattern of geothermal resources and further guiding their effective exploitation.The Beijing-Tianjin-Hebei Plain(BTHP),predominantly located within the Jizhong Depression and Cangxian Uplift in the Bohai Bay Basin,serves as the primary region for geothermal exploitation and utilization in China.More than 1500 geothermal wells have been drilled therein,with water temperature at the wellhead ranging from 55 to 110°C,single-well flow rate ranging between 80 and 120 m^(3)/h,and cumulative heating area exceeding 100×10^(6)m^(3).However,the exploration and research in the region remain limited overall.As per the previous geothermal and petroleum exploration results and the latest geothermal drilling data,this study comprehensively evaluated the geothermal resources of karst geothermal reservoirs.The results show that two suites of carbonate karst reservoirs,namely the Jxw Formation and the Ordovician strata,have primarily developed in the BTHP,and their formation and evolution can be divided into four stages:the Mesoproterozoic-Early Paleozoic stage with carbonate sedimentation and the development of interlayer karst,the Late Paleozoic stage with the development of direct sedimentary cover,the Mesozoic stage with compressional uplifting and development of buried hill karst,and the Cenozoic stage with regional cover deposition and the modification and finalization of karst geothermal reservoirs.Accordingly,the porosity evolution history of the geothermal reservoirs is composed of three stages,namely a significant decrease followed by a minor increase,a gradual decline,and then a small fluctuation from increase to decrease before slowly rising again.The karstification in geothermal reservoirs can be summarized into quasi-syngenetic karstification,epigenetic karstification,and burial karstification,which can be subdivided into seven subcategories.The carbonate geothermal reservoirs in the study area boast total geothermal resources of 53.821×10^(9)GJ,or 184.155×10^(9)t of standard coal equivalent(tce),and the annual exploitable geothermal resources in the urban area can heat an area of(400‒500)×10^(6)m^(3),indicating great potential of geothermal exploitation.
基金This research is supported by National Natural Science Foundation of China(No.52204057)the Science Foundation of China University of Petroleum,Beijing(No.2462021BJRC003 and 2462021YJRC012).
文摘The quantitative understanding of hydraulic fracture(HF)properties guides accurate production forecasts and reserve estimation.Type curve is a powerful technique to characterize HF and reservoir properties from flowback and long-term production data.However,two-phase flow of water and hydrocarbon after an HF stimulation together with the complex transport mechanisms in shale nanopores exacerbate the nonlinearity of the transport equation,causing errors in type-curve analysis.Accordingly,we propose a new two-phase type-curve method to estimate HF properties,such as HF volume and permeability of fracture,through the analysis of flowback data of multi-fractured shale wells.The proposed type curve is based on a semianalytical solution that couples the two-phase flow from the matrix with the flow in HF by incorporating matrix influx,slippage effect,stress dependence,and the spatial variation of fluid properties in inorganic and organic pores.For the first time,multiple fluid transport mechanisms are considered into two-phase type-curve analysis for shale reservoirs.We analyze the flowback data from a multi-fractured horizontal well in a shale gas reservoir to verify the field application of the proposed method.The results show that the fracture properties calculated by the type-curve method are in good agreement with the long-time production data.
基金Supported by the Health Research Program of Anhui,No.AHWJ2022b032 and No.AHWJ2023A30034.
文摘BACKGROUND In recent years,pure laparoscopic radical surgery for Bismuth-Corlette type Ⅲ and Ⅳ hilar cholangiocarcinoma(HCCA)has been preliminarily explored and applied,but the surgical strategy and safety are still worthy of further improvement and attention.AIM To summarize and share the application experience of the emerging strategy of“hepatic hilum area dissection priority,liver posterior separation first”in pure laparoscopic radical resection for patients with HCCA of Bismuth-Corlette types Ⅲ and IV.METHODS The clinical data and surgical videos of 6 patients with HCCA of Bismuth-Corlette types Ⅲ and Ⅳ who underwent pure laparoscopic radical resection in our department from December 2021 to December 2023 were retrospectively analyzed.RESULTS Among the 6 patients,4 were males and 2 were females.The average age was 62.2±11.0 years,and the median body mass index was 20.7(19.2-24.1)kg/m^(2).The preoperative median total bilirubin was 57.7(16.0-155.7)μmol/L.One patient had Bismuth-Corlette type Ⅲa,4 patients had Bismuth-Corlette type Ⅲb,and 1 patient had Bismuth-Corlette type Ⅳ.All patients successfully underwent pure laparoscopic radical resection following the strategy of“hepatic hilum area dissection priority,liver posterior separation first”.The operation time was 358.3±85.0 minutes,and the intraoperative blood loss volume was 195.0±108.4 mL.None of the patients received blood transfusions during the perioperative period.The median length of stay was 8.3(7.0-10.0)days.Mild bile leakage occurred in 2 patients,and all patients were discharged without serious surgery-related complications.CONCLUSION The emerging strategy of“hepatic hilum area dissection priority,liver posterior separation first”is safe and feasible in pure laparoscopic radical surgery for patients with HCCA of Bismuth-Corlette types Ⅲ and Ⅳ.This strategy is helpful for promoting the modularization and process of pure laparoscopic radical surgery for complicated HCCA,shortens the learning curve,and is worthy of further clinical application.
基金supported by the National Natural Science Foundation of China(Grant No.41202103)
文摘This study analyzed the characteristics and types of the Lower Silurian shale gas reservoirs in and around Sichuan Basin through field observations, slices, Ar-ion-beam milling, scanning electron microscopy, and x-ray diffraction analysis of 25 black shale outcrops and samples. Two main types of shale gas reservoirs were determined, i.e., fractures and pores. Fractures were classified into five categories, i.e., giant, large, medium, small, and micro, according to the features of the shale gas reservoirs, effect of fracture on gas accumulation, and fracture nature. Pore types include organic matter pores, mineral pores(mineral surface, intraparticle, interparticle, and corrosional pore), and nanofractures. The various fracture types, fracture scales, pore types, and pore sizes exert different controls over the gas storage and production capacity. Pores serve as a reservoir for gas storage and, the gas storage capacity can be determined using pores; fractures serve as pathways for gas migration, and gas production capacity can be determined using them.
文摘The diversity of sandstone diagenesis mechanisms caused by the complex geological conditions of oil/gas basins in China could hardly be reasonably explained by the traditional concept of burial diagenesis. Three genesis types of thermal diagenesis, tectonic diagenesis and fluid diagenesis are presented on the basis of the dynamic environment of the oil/gas basins and.the controlling factors and mechanisms of sandstone diagenesis. Thermal diagenesis of sandstone reservoirs is related not only to the effect of formation temperature on diagenesis, but also to the significant changes in diagenesis caused by geothermal gradients. The concept of thermal compaction is presented. Thermal compaction becomes weaker with increasing depth and becomes stronger at a higher geothermal gradient. At the same formation temperature, the sandstone porosity in the region with a lower geothermal gradient is e^0.077+0.0042T times higher than that in the region with a higher geothermal gradient. Both sudden and gradual changes are observed in diagenetic evolution caused by structural deformation. Average sandstone compaction increased by 0.1051% for every 1.0MPa increase of lateral tectonic compressional stress, while late tectonic napping helped to preserve a higher porosity of underlying sandstone reservoir. Fluid diagenesis is a general phenomenon. The compaction caused by fluid properties is significant. The coarser the grain size, the stronger the fluid effect on compaction. The greater the burial depth, the weaker the fluid effect on compaction for the specific reservoir lithology and the greater the difference in the fluid effects on compaction between different grain sizes.
基金Project(2013CB228005)supported by the National Basic Research Program of China
文摘Production decline analysis has been considered as an important method to obtain the flow parameters, reservoir properties and original gas in place. Although advanced Blasingame production decline analysis methods for vertical wells, fractured wells and horizontal wells are widely used, limited study has conducted on Blasingame production decline type curves for multi-fractured horizontal well(MFHW). Based on the perpendicular bisection(PEBI) grids, a numerical model was developed and the solution was obtained using control volume finite element method and the fully implicit method. Blasingame production decline-type curves of the infinitely conductive MFHW were plotted through computer programming. A field case was presented to analyse and verify the model developed. Five flow regimes, including early formation linear flow, early radial flow, compound linear flow, transient flow and pseudo-radial flow, are recognized. Fracture spacing is the main factor that affects early radial flow, compound linear flow and transient flow, the distance from the well to the circular boundary affects the pseudo-radial flow, and the type curves are also significantly affected by the formation permeability, fracture number and fracture half-length. The validation of field case suggests that the Blasingame production decline type curves proposed in this work can be applied to the production decline analysis for MFHW in tight gas reservoirs.
基金supported by the China National Key R D plan(2019YFC0605504)Scientific Research&Technology Development Project of China National Petroleum Corporation(Grant Nos.2017D-3504 and 2018D-4305)
文摘Carbonate reservoirs exhibit strong heterogeneity in the distribution of pore types that can be quantitatively characterized by applying Xu–Payne multi-porosity model.However,there are some prerequisites to this model the porosity and saturation need to be provided.In general,these application conditions are difficult to satisfy for seismic data.In order to overcome this problem,we present a two-step method to estimate the porosity and saturation and pore type of carbonate reservoirs from seismic data.In step one,the pore space of the carbonate reservoir is equivalent to a single-porosity system with an effective pore aspect ratio;then,a 3D rock-physics template(RPT)is established through the Gassmann’s equations and effective medium models;and then,the effective aspect ratio of pore,porosity and fluid saturation are simultaneously estimated from the seismic data based on 3D RPT.In step two,the pore space of the carbonate reservoir is equivalent to a triple-porosity system.Combined with the inverted porosity and saturation in the first step,the porosities of three pore types can be inverted from the seismic elastic properties.The application results indicate that our method can obtain accurate physical properties consistent with logging data and ensure the reliability of characterization of pore type.
基金major science and technology project of PetroChina“Research and application of key technologies for sustainable,effective and stable production exploration and development of North China Oilfield(2017e-15)”。
文摘The buried hill in the Jizhong depression contains abundant petroleum reserves and are important production areas.The Ordovician buried hill has restricted the discovery of new oil and gas exploration targets because of its strong reservoir heterogeneity and complex reservoir-controlling factors.Based on a large volume of core,thin section,logging,seismic,and geochemical data and numerous geological analyses,the reservoir-forming conditions and modes were systematically analyzed to guide the exploration and achieve important breakthroughs in the Yangshuiwu and Wen an slope buried hills.The study revealed that three sets of source rocks of the third and fourth members of the Shahejie Formation from the Paleogene and Carboniferous-Permian were developed in the Jizhong depression,providing sufficient material basis for the formation of buried hill oil and gas reservoirs.The reservoir control mechanism involving the three major factors of“cloud-karst-fault”was clarified,and karst cave,fracture fissure-pore,and cloud pore type reservoir models were established,thereby expanding the exploration potential.Controlled by the superposition of multi-stage tectonic processes during the Indosinian,Yanshanian,and Himalayan,two genetic buried hill trap types of uplift-depression and depression-uplift were formed.Based on the analysis of reservoir-forming factors of the Ordovician buried hill,three buried hill oil and gas reservoir-forming models were identified:low-level tectonic-lithologic composite quasi-layered buried hill,medium-level paleo-storage paleo-block buried hill,and high-level paleo-storage new-block buried hill.Comprehensive evaluations indicate that the reservoir-forming conditions of the low-level tectonic-lithologic composite quasi-layered buried hill in the northern portion of the Jizhong depression are the most favorable and that the Sicundian and Xinzhen buried hills are favorable areas for future exploration.
文摘The Feixianguan Formation reservoirs in northeastern Sichuan are mainly a suite of carbonate platform deposits.The reservoir types are diverse with high heterogeneity and complex genetic mechanisms.Pores,vugs and fractures of different genetic mechanisms and scales are often developed in association,and it is difficult to classify reservoir types merely based on static data such as outcrop observation,and cores and logging data.In the study,the reservoirs in the Feixianguan Formation are grouped into five types by combining dynamic and static data,that is,karst breccia-residual vuggy type,solution-enhanced vuggy type,fractured-vuggy type,fractured type and matrix type(non-reservoir).Based on conventional logging data,core data and formation microscanner image(FMI)data of the Qilibei block,northeastern Sichuan Basin,the reservoirs are classified in accordance with fracture-vug matching relationship.Based on the principle of cluster analysis,K-Nearest Neighbor(KNN)classification templates are established,and the applicability of the model is verified by using the reservoir data from wells uninvolved in modeling.Following the analysis of the results of reservoir type discrimination and the production of corresponding reservoir intervals,the contributions of various reservoir types to production are evaluated and the reliability of reservoir type classification is verified.The results show that the solution-enhanced vuggy type is of high-quality sweet spot reservoir in the study area with good physical property and high gas production,followed by the fractured-vuggy type,and the fractured and karst breccia-residual vuggy types are the least promising.
基金the China Research and Pilot Test on Key Technology of Efficient Production of Changqing Tight Oil(Grant No.2021DJ2202).
文摘Class III tight oil reservoirs have low porosity and permeability,which are often responsible for low production rates and limited recovery.Extensive repeated fracturing is a well-known technique to fix some of these issues.With such methods,existing fractures are refractured,and/or new fractures are created to facilitate communication with natural fractures.This study explored how different refracturing methods affect horizontal well fracture networks,with a special focus on morphology and related fluid flow changes.In particular,the study relied on the unconventional fracture model(UFM).The evolution of fracture morphology and flow field after the initial fracturing were analyzed accordingly.The simulation results indicated that increased formation energy and reduced reservoir stress differences can promote fracture expansion.It was shown that the length of the fracture network,the width of the fracture network,and the complexity of the fracture can be improved,the oil drainage area can be increased,the distance of oil and gas seepage can be reduced,and the production of a single well can be significantly increased.
文摘目的探讨成人骨型Ⅲ类患者矫治前后上下前牙区牙槽高度和宽度变化以及前牙区牙根位置变化。方法选取2020年5月—2022年11月在中山市小榄人民医院口腔科正畸掩饰治疗的成人骨型Ⅲ类患者50例,比较正畸治疗前后患者上下颌前牙牙槽骨厚度和高度,其中包括上前牙槽骨厚度(upper anterior alveolar bonethickness,UA)、上后牙槽骨厚度(upper posterior alveolar bone thickness,UP)、上牙槽骨总厚度(upper alveolar bone width,UW)、下前牙槽骨厚度(lower anterior alveolar bone thickness,LA)、下后牙槽骨厚度(lower posterior alveolar bone thickness,LP)、下牙槽骨总厚度(lower alveolar bone width,LW)、根中水平上前牙槽骨厚度(upper anterior alveolar bone thickness at the mid-root level,UA-m)、根中水平上后牙槽骨厚度(upper posterior alveolar bone thickness at the mid-root level,UP-m)、根中水平上牙槽骨总厚度(upper alveolar bone thickness at the mid-root level,UW-m)、根中水平下前牙槽骨厚度(lower anterior alveolar bone thickness at the mid-root level,LA-m)、根中水平下后牙槽骨厚度(lower posterior alveolar bone thickness at the mid-root level,LP-m)、根中水平下牙槽骨总厚度(lower alveolar bone thickness at the mid-root level,LW-m)以及上前牙槽骨高度(upper anterior alveolar bone height,UAH)和下前牙槽骨高度(lower anterior alveolarbone height,LAH)。结果正畸治疗前后患者UA、UP-m测量值比较,差异无统计学意义(P>0.05)。与正畸治疗前比较,正畸治疗后患者UP、UW、UA-m、UW-m测量值均显著降低(P<0.05)。正畸治疗后患者LP、LA-m测量值与正畸治疗前比较,差异无统计学意义(P>0.05)。与正畸治疗前比较,正畸治疗后患者LA、LW、LP-m、LW-m测量值均降低(P<0.05)。与正畸治疗前比较,正畸治疗后患者UAH、LAH测量值均显著降低(P<0.05)。正畸治疗后,患者上下颌前牙解剖牙根长度分别为(10.62±0.57)mm、(9.65±0.48)mm,正畸治疗前患者上下颌前牙解剖牙根长度分别为(11.01±0.58)mm、(10.37±0.48)mm,与正畸治疗前比较,患者上下颌前牙解剖牙根长度明显减小(P<0.05)。结论成人骨型Ⅲ类患者进行正畸掩饰治疗后,牙槽形态会发生相应改变,患者上下前牙牙槽骨厚度和高度会一定程度地减少。因此,在矫治过程中应当对患者牙槽形态的变化给予密切关注,尽量避免上下前牙发生代偿性移动,从而降低不良反应情况发生的风险。
文摘The permeability or/and porosity in low-permeability reservoirs mainly depends on fracture system. Wthin this kind of low-permeability reservior, fractures play a very important role on exploration and development. Because there are so many differences, such as basin properties and tectonic characteristics, among the eastern,western and central basins, the types and distribution characteristics of fractures are also obviously different. Quantitative information on fracture distribution is very important. Through the contrastive study of 7 oilfield, the differences and distribution characteristics of fractures in three types of oil-bearing basins are summarized. Due to the different geological conditions and stress state during the formation of fractures, the fracture systems in three types of basins are also different. Fractures are mainly composed of tectonic fractutres related to normal faultes in eastern basins, related to folds and reverse faultes in western basins, and regional fractures which widely distributed not only in outcrops but also at depth of the relatively undeformed strata in central basins. So, besides jointed-fractures, we can often see faulted-fractures similar to normal faults in eastern basins and similar to reverse faults in western basins. According to statistical data, fracture spacing generally has a lognormal distribution and is linearly proportional to layer thickness. The development degree of fractures is controlled by lithology, bed thickness, sedimentary microfacies and faults or folds, etc. The permeability, aperture and connectedness of fractures are related to the modern stress field. Though there are 3-4 sets of fractures in a oilfield, the fractures parallel to the maximum principal stress direction are main for the pattern arrangement of low-permeability reservoirs.
文摘目的:基于上皮细胞-间充质细胞转分化(EMT)学说观察化纤Ⅳ号方、艾灸以及二者相配合治疗肺纤维化大鼠Collagen TypeⅢ(Ⅲ-C)和PDGF的变化,探讨其治疗效应及生物学机制。方法:将鼠龄约为6周的SD大鼠随机分为空白组、模型组、化纤Ⅳ号方组、艾灸组、化纤Ⅳ号方与艾灸配合治疗组(简称为"灸药组"),治疗30 d后处死观察其肺组织病理改变,并检测其Collagen TypeⅢ、PDGF的基因和蛋白表达情况。结果:实时荧光定量结果显示:与空白组相比,各组Ⅲ-C和PDGF m RNA表达增高(P<0.05)。与模型组相比,各组的Ⅲ-C和PDGF m RNA表达有明显降低(P<0.01)。而各组中,灸药组疗效最明显,Ⅲ-C和PDGF的表达最低。蛋白免疫印迹法检测结果显示:与模型组相比各组的Ⅲ-C蛋白表达有差异。结论:1艾灸、化纤Ⅳ号方均可减轻博莱霉素诱导肺纤维化大鼠的肺纤维化程度。2艾灸配合化纤Ⅳ号方可减轻博莱霉素诱导肺纤维化大鼠的肺纤维化程度,且其效果优于单用艾灸或单用化纤Ⅳ号方。3艾灸、化纤Ⅳ号方及其二者配合使用不同程度阻抑博莱霉素诱导肺纤维化大鼠肺纤维化进程的效应机制,可能与通过调控其EMT过程中的Ⅲ-C和PDGF表达环节紧密相关。