The study of shale lithofacies is the basic work of shale gas geological evaluation and layer selection. This paper takes the Wufeng Formation-Member 1 of Longmaxi Formation in Changning area of Sichuan basin as the research object. By using outcrop, drilling, and logging data, combined with rock and mineral, thin section, and geochemical data, the mineral composition, lithofacies characteristics, and their influence on gas content of shale are systematically studied, the favorable lithofacies are determined, and the spatial distribution characteristics of shale lithofacies in Changning area are characterized. The results show that there are five lithofacies in this area: Clay-siliceous mixed shale, mixed shale, siliceous shale, calcareous-siliceous mixed shale, and calcareous shale. Vertically, the volume fraction of carbonate minerals gradually decreases from bottom to top, and the integral number of clay minerals gradually increases. The lithofacies is a transition of calcareous siliceous shale-siliceous shale-clay-siliceous mixed shale. The subsidence center of the study area is located in the northeast of Changning area, and the lateral thickness of the siliceous shale lithofacies shows an increasing trend from southwest to northeast. The siliceous shale has the characteristics of high biogenic siliceous mass fraction, high w(TOC), high brittleness, and high pore structure parameters, so it has the best gas content. Although the clay minerals in the clay-siliceous mixed shale can generate secondary pores through diagenetic transformation, their plasticity is high, and the pores are difficult to preserve due to compaction. In addition, the higher plasticity leads to undeveloped shale fractures, which further reduces the physical properties of the reservoir, and the clay-siliceous mixed shale has poor gas-bearing properties.

 The qualitative and quantitative characterization of the microscopic pore structure of the reservoir can benefit the efficient development of the reservoir in the later stage. In this study, the microscopic pore structure of Chang 4+5 ultra-low permeable reservoir was characterized in  Baibao area of Wuqi oilfield by using blue-dye thin section， SEM， high pressure mercury penetration. A local pore structure classification standard of the study area was established. Based on the experimental results, a real sandstone model is built up to evaluate the quality of the pore structure by the oil-water two-phase seepage experiment, and the existence types and causes of the micro residual oil in different pore structures are analyzed through the microscopic visualization of the oil-water displacement experiment. The results show that the combination type of class Ⅰ pore structure is intergranular pore-dissolved pore, oil and water two-phase seepage characteristics are the best, after water flooding, the micro residual oil mainly exists in the form of small contiguous clusters, oil displacement efficiency is 35%; Type Ⅱ pore structure is dissolved pore-residual intergranular pore, oil-water two-phase seepage characteristics is similar to class Ⅰ, water storage capacity and water flooding effect are the best, oil displacement efficiency is 43%, after water flooding, the micro-residual oil mainly exists in cluster and ring form; Class Ⅲ pore structure combination type is intercrystalline pore-dissolved pore, it has the worst physical properties, oil and water have the worst seepage characteristics, oil displacement efficiency is only 21%, after water flooding, the micro residual oil exists in the form of contiguous clusters. The diagenesis and the pore filling content in the study area mainly affect the pore structure development, thus affecting the microscopic residual oil distribution of different pore structures after water flooding.

Gangdong fault is a critical reservoir-controlling fault in the north of Qikou sag. In order to study the oil and gas distribution of Sha-1 Lower Submember in the Gangdong fault of Qikou sag, there are two cases of oil and gas transporting forms recognized: The distribution position of the entire oil and gas transporting form from the Gangdong fault to the Sha-1 Lower Submember sand body was predicted based on the overlapping of the following three key factors, the transport site of the Gangdong fault in Sha-1 Lower Submember, the regional mudstone cap sealing site of Sha-1 Middle Submember, and the connected sandbody distribution site of Sha-1 Lower Submember. The distribution position of the partial oil and gas transporting form from the Gangdong fault to the Sha-1 Lower Submember sand body was predicted based on the overlapping of the following four key factors, the transport location of Gangdong fault within Sha-1 Lower Submember, the unsealed location of regional mudstone cap of Sha-1 Middle Submember, the distribution location of connected sandbodies of Sha-1 Lower Submember, and the overlying regional mudstone cover of Minghuazhen Formation. The results show that: The entire oil and gas transporting form is mainly distributed in the east and west, while partial oil and gas transporting form is mainly distributed in the middle and locally in the east. The distribution position of the entire and partial oil and gas transporting form controls the distribution of the entire oil and gas fault in Sha-1 Lower Submember of Gangdong fault.

In order to study the geochemical characteristics and enrichment patterns of the organic-rich black fine-grained rock series in the Middle Ordovician Yanxi Formation in the central and southern Hunan， samples from Ningyuan Mianhuaping (MHP)， Shuangpai Hejiadong (HJD)， Quanzhou Shazitang (SZT) and other sections are collected and analyzed for TOC, major elements,  trace elements and rare earth elements. The results show that the organic geochemical index of the Middle Ordovician Yanxi Formation in the central and southern Hunan is good, and the SiO2 content is high, which belongs to the high-quality source rock;The organic matter abundance of the black shale is relatively high， the average w（TOC）is 2.12%， which is generally higher than 2%， and the brittle mineral content is more than 50%， so it has good gas generating capacity. The large number of siliceous layers developed in the Yanxi Formation are mainly of sedimentary origin. The redox parameter U/Th,V/(V+Ni) and other indicators indicate that the overall water body is an oxygen-limited reductive environment， and the productivity of the Yanxi Formation was high； The terrigenous material input， redox environment， relative changes of sea level, and paleoproductivity affect the enrichment of organic matter together. The enrichment of organic matter in the shale of Yanxi Formation is mainly controlled by the anoxic environment, which belongs to the enrichment model of “deep-water retention basins”.

Echinoderms is one of the most primitive animal groups, and its evolutionary history is crucial for understanding the origin and early evolution of multicellular animals. In this paper, some echinoderm fossils, collected from the Meitan Formation in Wudang area of Guiyang, are identified as thecal plates of the Glyptocystitoida and Hemicosmitoida in the Rhombifera, belonging to Polycosmites and Macrocystella. We also conduct a study of the Ordovician paleogeographic distribution of the two superfamilies, and find that the presence of Polycosmites and Macrocystella in the Meitan Formation expands the biogeographic distribution of the two genera in Yangtze plate. At the same time, this discovery reveals the diversity of echinoderms in Wudang area, and provides new information on the evolutionary radiation of echinoderms during the Early Ordovician.

Based on the sporopollen analysis of the strata in the 21.47-38.26 m section of ZK004 borehole in the Lishu fault depression, Songliao basin, and combined with the quantitative analysis results of oxide samples, this stratum is divided into two sporopollen assemblages from bottom to top, of which the ZK004-Ⅰ assemblage is dominated by Classopollis-Cedripites-Schizaeoisporites-Callistopollenites-Borealipollis, reflecting the transition from semi-humid   tropical-subtropical  climate to  humid subtropical climate; the ZK004-Ⅱ assemblage is dominated by Cedripites-Rugubivesiculites-Schizaeoisporites-Deltoidospora-Cyathidites-Borealipollis, reflecting the transition from  humid subtropical climate to semi-humid subtropical climate, which generally displays semi-humid northern subtropical climate, providing new evidence for the recovery of the paleoclimate and paleovegetation of the second member of Nenjiang Formation in the Late Cretaceous.

In the forced regressive system at the top of the Cambrian Zhangxia Formation in the Zhucaoying section of Qinhuangdao, Hebei Province, a set of leiolitic bioherms with a thickness of tens of meters were intensively developed, indicating that these leiolitic bioherms formed in shallow sea and high energy environment. Field investigation and microscopic observation, the formation mechanism and sedimentary environment of leiolitic bioherms are analyzed.The results show that the leiolitic bioherms  dense and homogeneous massive micritic limestone,  obvious macro fabric and directly the lower stromatolite bioherms.Under the microscope, the leiolite is composed of dense micrite and a small amount of sparry. The dense micrite contains a variety of calcified cyanobacteria sheath fossils, including Hedstroemia, Epiphyton, Renalcis,   and Girvanella. The results showed that the leiolite was formed by the complex metabolism of microbes and  in-situ. More specifically, oolith and dolomite crystals, indicating that the microtexture related to the calcification of globular microbial film and the selective expression of dolomite in the process of leiolite production under eutrophic conditions. There are not many related examples of leiolite since its, therefore the leiolitic bioherms in Zhangxia Formation of Qinhuangdao provide a typical example for understanding the formation mechanism and depositional environment of leiolite.

The paleosedimentary environment during the preservation of volcanic materials is one of the key factors influencing the volcanic oil-gas reservoir. During the interval of volcanic eruption, the deposited thin sedimentary lithologic layer has sedimentary characteristics. The trace elemental characteristics in the thin sedimentary layers are closed related to the paleosedimentary oxide-reductive environment and are important parameters for paleoenvironment identification. Thus, the paleosedimentary environment can be identified indirectly based on the trace element analysis on cores of the thin sedimentary layers during volcanic eruption intervals. Thin sedimentary lithologic layers, including mudstone and siltstone, had deposited during the interval of volcanic eruption in the Upper Carboniferous Haerjiawu Formation of Malang sag, Santanghu basin, Xinjiang. Eleven types of trace element ratios of these fine sediments, including U/Th, authigenic U, V/Cr, Ni/Co, V/Sc, V/(V+Ni), Cu/Zn, Fe3+/Fe2+, Sr/Ba, V/Zr, and B/Ga are used to trace the oxide-reductive paleoenvironment during the interval of volcanic eruption. Seven kinds of parameters, V/(V+Ni), V/Sc, Sr/Ba, V/Cr, V/Zr, Cu/Zn and B/Ga of mudstone, carbon mudstone, and siltstone indicate an underwater reduction environment and the coastal shallow sea environment with frequent water-land transition; It is concluded that the volcanic rocks of the Haerjiawu Formation are mainly deposited by eruption and preserved in underwater environment, and the complex sedimentary genetic environment of frequent water-land transition also exists.

The Tuanjiegou deposit, located in Jiayin County, Heilongjiang Province, is the largest epithermal gold deposit in Northeast China. This study systematically investigated the petrography, zircon U-Pb dating, whole-rock major and trace elements, LA-ICP-MS zircon in-situ trace elements and Hf isotopes of granodiorite porphyry and granite porphyry. Additionally, single mineral Pb-He isotope and LA-ICP-MS in-situ S isotope analyses of gold-bearing pyrite were conducted. The zircon U-Pb ages of granodiorite porphyry and granite porphyry are (105.9±1.1) Ma and (102.3±1.2) Ma, respectively, belonging to calc-alkaline to high-K calc-alkaline series. These rocks are enriched in light rare earth elements and large ion lithophile elements such as Rb and K, but depleted in P, Ti, Nb, Ta and other high field strength elements. The Ce4+/Ce3+ values of zircons in granodiorite porphyry range from 165 to 656 ℃ (mean 322 ℃), with Ti saturation temperatures ranging from 605 to 715 ℃ (mean 658 ℃). On the other hand, the Ce4+/Ce3+ values of zircons in granite porphyry range from 359 to 868 (mean 480), with Ti saturation temperatures ranging from 606 to 680 ℃ (mean 646 ℃). Zircon εHf (t) values of these two rocks are 6.9-8.1 and 5.6-8.2, respectively. The δ34S value of pyrite ranges from -7.8‰ to -0.2‰ with an average of -3.5‰, and the common Pb isotope ratios are 206Pb/204Pb=18.160-18.399, 207Pb/204Pb=15.538-15.590, and 208Pb/204Pb=38.135-38.340. The R/Ra values of fluid inclusions in pyrite range from 0.75 to 1.23. Comprehensive characteristics suggest that the mineralization-related magma is derived from the evolution of homologous crystalline magma, and the of magma emplacement occurred during the Early Cretaceous. The initial magma may have originated from the partial melting of the young lower crust material during the subduction of the Paleo-Pacific plate, with some mantle-derived materials mixed in during the formation process. The ore-forming fluid comes from deep magma and exhibits the characteristics of a mixed crust-mantle source (with the crust being the main source and mantle fluid accounting for 8.23% to 13.62%). The higher oxygen fugidity and lower magmatic crystallization temperature of granite porphyry provide favorable conditions for gold accumulation and migration, thus facilitating large-scale gold mineralization.

The Gema Pb polymetallic deposit was discovered by our team in 2010. It is currently the only medium-sized Pb-Zn-Ag polymetallic deposit in the eastern section of Bangong Lake-Nujiang metallogenic belt. The deposit is located in the eastern section of the Anglonggangri-Bange-Tengchong magmatic arc zone. The ore bodies are produced in the surrounding rocks of the outer contact zone of the Early Cretaceous granodiorite in the form of veins. The shapes and locations of the ore bodies are strictly controlled by two groups of faults in the nearly east-west and northwest directions. The ore-bearing surrounding rocks are sandstone and siltstone of the Mali Formation (hornfelization) of the Middle Jurassic. Based on the geological characteristics of the Gema Pb polymetallic deposit and the studies of the geochemistry of the surrounding rocks and ores, and the LA-ICP-MS zircon U-Pb chronology of granodiorite, this paper examined the source of ore-forming materials, the ore-forming age and the ore-forming geological background, also discussed the ore-forming process of the deposit, and established a preliminarily metallogenic geological model of the Pb-Zn-Ag polymetallic deposit in the eastern section of the Bangong Lake-Nujiang  metallogenic belt. The results show that the granodiorite in the area has low silicon, high aluminum and relatively rich potassium, which is the product of magmatism in the subduction stage before plate collision. The LA-ICP-MS zircon U-Pb dating of granodiorite yields an age of (119.86 ± 0.45) Ma, indicating an Early Cretaceous diagenetic age. The rare earth element (REE) of granodiorite, ore and surrounding rocks show enrichment in light REEs, depletion in heavy REEs, and a negative Eu anomaly, suggesting a common origin. Compared to the abundance values of Chinese continental crust, the granodiorite contains relatively enriched Pb and Ag, while Zn is deficient. In the metamorphic siltstone of Mali Formation, Pb and Ag are extremely strong enriched elements, and Zn is also strongly enriched. The ore-forming materials of this deposit are derived not only from granodiorite but also from the surrounding rocks of Mali Formation, indicating obvious “double source” feature. The deposit was formed in an island arc environment before the closure of the Bangong Lake-Nujiang Ocean basin. The ore forming age is Early Cretaceous, and the genetic type of the deposit is a post-magmatic hydrothermal deposit.

Hainan Island is located at the intersection of Pacific, Indo-Australian and Eurasian plates. It is an ideal location to reveal the tectonic evolution of plate tectonics. In order to gain a better understanding of the Early Paleozoic tectonic evolution of the island, systematic zircon U-Pb geochronological and Hf isotopic analyses of the andesite from the northwestern Hainan Island have been carried out. The results of zircon U-Pb dating show that two representative andesite samples yield ages of LA-ICP-MS(448±5) Ma and (447±11) Ma, respectively. This suggests that Early Paleozoic (Late Ordovician) magmatism occurred on the Island. In-situ zircon Hf isotopic results show that the εHf(t) values of the andesites are -16.48-5.22 and their two-stage model ages (TDM2) are 2 030-953 Ma. Combined with regional geological data, it is evident that the andesites were produced by mixture of mafic and felsic magmas, and their formation is related to the subduction of the Proto-Tethys Oceanic crust.

 In order to explore the drainage status and the associated impact of loess in engineering practice, strain increment ratio by triaxial test are used to investigate the shear behavior of saturated remolded loess subjected to five drainage conditions, which are no drainage condition, forced water absorption condition, free drainage condition, forced drainage condition, and partial drainage condition. The results show that, the shear behavior of saturated remolded loess are closely related to drainage conditions. In no drainage condition and forced water absorption condition, the loess samples exhibit strain softening behavior. Taken broadly, under the condition of forced water absorption, the shear expansion of the sample is forcibly exerted. In free drainage condition and forced drainage condition, the loess samples exhibit a strain hardening behavior, and the dilatancy is inhibited in the imposed drained samples. In partial drainage condition, the loess samples show a strain softening behavior or a transition state from strain softening to hardening, in which it is not only related to the strain increment ratio, but also to the void ratio. The closer the strain increment ratio is to 0, the more obvious the softening degree of the sample is. While the smaller the pore ratio of the sample, the more obvious the shear expansion trend is in the initial shear stage, and the higher the peak strength and residual strength of the sample. Besides, based on the asymptotic state equation and the stress-dilatancy relationship, the asymptotic behavior of loess and the associated dilatancy are analyzed. The result shows that the stress ratio of remolded loess at asymptotic state is negatively correlated with the sample dilatancy. 

In order to compare the effects of different water-rock interactions on the damage and deterioration of filled jointed rock. The longitudinal wave velocity test, static uniaxial compression test and dynamic impact test are carried out on the filled jointed rock under the conditions of dry-wet cycle and continuous immersion. The effects of two different water-rock interactions on the wave velocity value, static and dynamic compressive strength，energy dissipation characteristics of filled jointed rocks are analyzed. Furthermore, the differences are compared in the degradation effects of mechanical parameters of filled jointed rock under different states (dry and water containing) after dry-wet cycle. The results show that, when the number of water-rock interactions is less than 10, the wave velocity of the rock sample under dry-wet cycle is significantly lower than that under continuous immersion. Howerver, with the increase of the water-rock interaction times, the difference in wave velocity values between the two cases is constantly narrowing. With the increase of the number of water-rock interactions, the static compressive strength, dynamic compressive strength and energy dissipation rate of the filled jointed rock decrease. Under 20 dry-wet cycles and continuous immersion, the static compressive strength of filled jointed rock decreased by 27.16% and 18.94%, the dynamic compressive strength decreased by 23.33% and 21.76%, and the energy dissipation rate decreased by 74.29% and 59.71%, respectively. It can be seen that the damage and deterioration of the filled jointed rock caused by the dry-wet cycles is greater than that caused by continuous immersion. In addition, the static compressive strength of the dry state rock sample is higher than that of the water-containing state rock sample after the action of dry-wet cycle, while the dynamic compressive strength of the dry state rock sample is lower than that of the water-containing state rock sample.

To further explore the geothermal storage resources in the Chengning uplift region of Shandong, it is necessary to make reasonable and sustainable development plans to provide scientific basis for further exploration and comprehensive development of geothermal resources . In this paper, the geological survey data and field test results are used to analyze the genesis of geothermal fluids. Using the thermal storage method and comprehensive index method to estimate the resource quantity and analyze the development prospects of the Cambrian-Ordovician karst geothermal resources and provide scientific basis for further exploration. The result shows that the available geothermal resources of Cambrian-Ordovician karst heat reservoir are 1.97×1019 J, equivalent to 6.72×108 t of standard coal; The annual recoverable amount of geothermal fluid is 29 777.40×104 m3 /a. The area available  for development is 1 538.29 km2, accounting for 86.18% of the total karst geothermal area. The Cambrian-Ordovician karst geothermal reservoirs in the area have great potential for development and utilization, so that exploration efforts should be increased to promote the development and utilization process.

The balance of exploitation and reinjection is an effective model for the sustainable development and utilization of hydrothermal geothermal resources. In order to simulate the temperature and pressure response of geothermal reservoir under different exploitation and reinjection scenarios, and to provide theoretical support for the sustainable development of geothermal resources, a mathematical model of Jixian system carbonate geothermal reservoir in Rongcheng geothermal field in Xiongan New Area was established by using numerical simulation technology. Firstly, COMSOL software was used to simulate the exploitation history data of existing geothermal wells in 300 km2 area. The simulation results are in good agreement with the monitoring data. Then, on this basis,the variation trends of temperature and pressure field of Jixian geothermal reservoir in the future 50 years under the single well exploitation model were predicted. Finally, according to the the declining trend of water level, the reinjection scheme was established, and the influence degree of different well spacing on the temperature field and pressure field of geothermal reservoir was analyzed. The results show that in the non-reinjection mode, the buried depth of water level decreases to 150 m in about 40 a, and the water level decreases about 1.13 m/a. The geothermal doublet system of  “one exploitation and one reinjection” scheme is adopted, and the well spacing is considered to be 600, 800 and 1 000 m respectively. Although increasing the well spacing reduces the number of arranged wells, it increases the exploitation amount and prolongs the thermal breakthrough time, so that more heat can be exploited. In practical engineering, the well spacing should be optimized by numerical simulation method to ensure the increase of production and prolong the thermal breakthrough time, so as to extract more heat.

The salt lake area of the Qaidam basin has abundant reserves of underground brine resources, the regional brine reservoirs have the characteristics of lower porosity, strong heterogeneity and anisotropy, and large differences in regional brine-rich properties. In order to accurately detect the underground brine enrichment area and determine variation range of salt rock distribution density difference of the Mahai Salt Lake, it is aimed at the unique salt rock medium, the high salinity of intercrystalline brine, and the coexistence of various brine storage modes such as pore brine storage and structural brine control in the salt lake area of the Qaidam basin. The multi-scale and multi-geophysical exploration method including pumping test, high-precision gravity method, audio magnetotelluric method and high-resolution seismic method were used to detect the distribution density difference variation range of salt rock layer, the electrical change of crystalline salt layer and brine-rich stratum. The pumping test shows that the brine enrichment area composed of Wells K12, K13, K14 etc. has a water yield of 37 297 m3/d in brine rich area Ⅰ. The brine enrichment area composed of T1, K1, K4 etc. has a water yield of 35 736 m3/d in brine rich area Ⅱ. Based on pumping test and integration technology of various geophysical exploration information, two underground brine enrichment areas that can be sustainably and stably exploitated were determined, stratigraphic structure and geological structure in the Mahai Salt Lake were delineated and established.

The time-domain airborne electromagnetic (AEM) method is an efficient geophysical exploration technique. Yet, due to the presence of the induced polarization (IP) effect, electromagnetic (EM) data from late-time channels often exhibit a phenomenon known as sign reversal. The traditional imaging and inversion methods without considering the IP effect cannot recover the real electrical structure of the underground, so it is necessary to develop the EM forward and reverse modeling technology with IP effect. This study introduces a three-dimensional (3D) forward algorithm for AEM with IP effect in the time-domain built upon the unstructured finite-element method. To capture the IP effect within the medium, we use the Debye model, transforming it into a derivative form in the time-domain through frequency-time conversion. For temporal discretization, an unconditionally stable second-order backward Euler's scheme is applied. Maxwell’s equations are discretized in space using a vector finite element method based on an unstructured tetrahedral mesh. The algorithm's accuracy is verified through a comparison with the 1D semi-analytical solution of the uniform half-space model. We compute EM responses for both a half-space and 3D geological formations under various polarization conditions. We observe that the polarization characteristics of surrounding rocks and anomalous bodies can be effectively identified according to the attenuation characteristics of the AEM response curves. In addition, by studying the characteristics of the influence of IP parameters on the time-domain AEM system, we show that the larger the resistivity of the geological body or the larger the chargeability, the stronger the IP effect.

Due to surface obstacles or economic constraints, seismic data recorded is often incomplete. Consequently, seismic data reconstruction is an important topic in seismic research. This study presents a seismic data reconstruction approach based on joint accelerated proximal gradient and log-weighted nuclear norm minimization. The process begins by subjecting the original seismic data to low-rank preprocessing through texture-patch operators. Subsequently, the accelerated proximal gradient algorithm is employed for an initial reconstruction of the low-rank seismic data. Finally, an algorithm based on the log-weighted nuclear norm is presented to tackle the optimization problem and reconstruct the missing data. For synthetic seismic data and real seismic data, the reconstruction results of the joint accelerated proximal gradient and log-weighted nuclear norm method have improved both in quantitative and qualitative analysis: The signal-to-noise ratio of the synthetic data set with a 40% missing rate is 26.135 7 dB and the reconstruction error is 6.789 4; The signal-to-noise ratio of the Mobil Avo Viking Graben Line 12 data set with a 30% missing rate is 17.247 8 dB and the reconstruction error is 4.762 5; The signal-to-noise ratio of the Netherlands F3 data set with a 60% missing rate is 26.058 1 dB and the reconstruction error is 7.464 1.

Reverse-time migration (RTM) is widely employed for its ability to produce high-resolution imaging results. Nevertheless, wavefield extrapolation based on the two-way wave equation often leads to pronounced low-frequency noise under cross-correlation imaging condition. This issue significantly impacts the quality of the resulting images. In this study, we introduce a convolution-deconvolution neural network (DeCNN) built upon the U-Net architecture to mitigate the presence of low-frequency noise in RTM. We utilize source-normalized imaging results with  low-frequency noise as training data， and the Laplace filtering results   as labels to abtain  the neural network model, grounded in a data-driven approach. The comparison results of   model trials and transfer learning demonstrations highlight the superior denoising proficiency of  DeCNN. It outperforms  U-Net, effectively suppressing noise in scenarios such as the transfer  SEG/EAGE standard salt dome model and  Marmousi model. In contrast to conventional techniques aimed at mitigating low-frequency noise through up and down traveling wave decomposition, DeCNN  can input the source-normalized imaging results into the network after training, and the network can output high resolution imaging results in seconds. The efficiency is much higher than that of conventional low-frequency noise suppression methods using wavefield decomposition, and it has certain advantages in noise suppression effect.

Aiming at the problems of underwater distributary channel sand body, such as thin single layer thickness, serious superimposition and crossing, strong lateral heterogeneity, and poor consistency of well seismic relationship, this study presents a prediction method of CV-XGBoost reservoir thickness based on cross validation. Firstly, correlation analysis and multicollinearity evaluation are used to remove redundant attributes, then the model training and parameter set optimization are carried out, and finally thickness prediction is carried out with verification set. The results show that: 1) For reservoir prediction with few samples, it is necessary to do cross validation to improve the accuracy of reservoir prediction; 2) XGBoost uses a regular term with the second order partial derivative to control the convergence progress of the model, and its prediction accuracy is better than that of conventional LASSO (least absolute shrinkage and selection operator) regression, GBDT (gradient boosting decision tree) and SVM (support vector machine) methods; 3) The reservoir prediction results with low verification set ratio can be used to understand the macro distribution of sand body, and the higher verification set ratio is helpful to improve the accuracy of sand body description; 4) The average amplitude, average energy, arc length and dominant frequency in this study area are the attributes that contribute greatly to thickness prediction.

The recognition and classification of lithological information hold significant importance for categorizing oil and gas reservoirs and evaluating the compressibility of reservoir rocks. This study presents enhancements to the deep learning  network U-Net and conducts a comparative validation using experimental data from  central depression  of  Songliao Basin. We propose a more suitable feature attention fusion Unet (FAF-Unet) designed for well logging data. The selection of logging data primarily involves sensitivity analysis to identify characteristic parameters, including natural potential, acoustic time difference, photoelectric absorption cross-section index, wellbore diameter, density, natural gamma, and deep and shallow lateral resistivity. These parameters are analyzed to understand reservoir rock lithology. FAF-Unet is a network that amalgamates residual blocks and channel attention mechanisms. Residual blocks can better retain the data with lower-level features of the depth direction, and channel attention mechanisms can make up for the problem of ignoring the connection between  horizontal channels during vertical convolution. Comparing the accuracy and recall of six recognition methods, including support vector machine, decision tree, U-Net, U-Net with effective channel attention (ECA) mechanism, U-Net with residual block (Res-Unet), and FAF-Unet with both ECA and residual block, experimental results demonstrate that FAF-Unet achieves an accuracy and recall rate exceeding 89.00%. FAF-Unet outperforms the other five methods in terms of recognition performance and exhibits a narrower fluctuation range between accuracy and recall.

This study focuses on measuring the physical parameters of rock samples sourced from diverse geological units within the geological corridor of western Liaoning Province. For igneous and sedimentary rocks, we establish both qualitative and semi-quantitative relationships between density, elastic wave velocity, magnetic susceptibility, resistivity and spectral data, and study the correlation between petrophysical properties and rock characteristics, so as to study the diagenetic environment of rocks. Through statistical analysis of correlation coefficient curves specific to different rock types, we present a comprehensive summary of the interplay between rock types and strength of correlation coefficient between spectral reflectance and the intensity of correlations with density, elastic wave velocity, magnetic susceptibility, and resistivity. According to the characteristics of strength of correlation, it is analyzed that the difference of diagenetic environment leads to different physical properties of different rocks. The physical sedimentary environment of sedimentary rocks fosters a robust correlation between its spectral reflectance and both density and elastic wave velocity. The stable diagenetic setting of igneous rock yields a strong connection between its spectral reflectance and magnetic susceptibility. The spectral reflectance of both sedimentary and igneous rocks exhibits a positive correlation with density and elastic wave velocity.