Using ideas from computational electromagnetics and the basic procedure from the domain decomposition method, we present a biaxial parabolic approximation method for enlarging the angle domain in which the parabolic approximation to the acoustic wave equation is multiple applied and that can be used for migrating data with super-wide angles. Mathematically, the biaxial approximation is a special case of the multiaxial parabolic approximation, and thus can be straightforwardly extended to multiaxial approximations. In detail, we first divide the subsurface into several fan-shaped subdomains and use the axis of each subdomain as the local wave propagation direction. Then, we make a parabolic approximation to the wave equation in each subdomain with respect to the corresponding symmetry axis and compute the forward-propagating wave alternately using a high-order parabolic approximated wave equation in two subdomains. Finally, we use the computed forward-propagating wave as the boundary condition for calculating the back-scattered wave and Green's function by applying the thin slab approximation. Compared with most one-way methods, the proposed method can deal with the strong velocity contrast in the horizontal direction at a large scattering angles. Moreover, compared with certain full-wave methods that have been published in recent years, the proposed method is considerably more efficient and sacrifices only a little in terms of accuracy. Numerical results from comparisons with models of different complexities demonstrate that our method is cost-effective and has considerable potential for use in seismic modeling and imaging.

In order to improve the quality of oil shale exploration, according to the results of exploration and evaluation of 47 typical oil shale deposits in China, the metallogenic geological conditions and ore bed occurrence regularity, it is proposed that two geological factors are used to determine the types of exploration and evaluation of oil shale in China, including structural complexity and ore layer stability. The structural complexity is divided into three kinds: simple, medium and complex, and the ore layer stability consists of three types: Stable, relatively stable and unstable, that is, "three kinds and three types". When the kind and type is simple and stable, the exploration engineering interval is 1 000-2 000 m; when the kind and type is medium and relatively stable, exploration engineering interval is 500-1 000 m; when the kind and type is complex and unstable, exploration engineering interval is 250-500 m. In the oil shale actual exploration work, the exploration engineering interval should be chosen basing on the more complicated one in the structural complexity and the stability of the ore layer.

The genesis and distribution of tight sandstones are the key factors that restrict the exploration of tight gas in Shahezi Formation. We studied the diagenetic characteristics of tight sandstones in Shahezi Formation and divided it into 5 kinds of diagenetic facies according to the multiple qualitative and quantitative parameters and on the basis of making full use of core, thin-section, SEM, physical properties and X-ray analysis. They are strongly compacted argillaceous filling facies, moderately compacted feldspar detritus dissolution facies, moderately compacted quartz secondary enlargement facies, moderately compacted chlorite rim cementation facies, and weakly compacted carbonate cementation facies. The different mineral constituent and texture of clastic rocks controlled by sedimentation are the material basis and origin of porosity evolution of different diagenetic facies, the compaction and filling of matrix are the material cause that lead to the loss of porosity in early diagenetic system, and the physical properties are retained and improved by the chlorite rim cementation and feldspar detritus dissolution. The type and intensity of diagenesis are different in different diagenetic facies, which results in the difference of macro properties and micro pore structures. The moderately compacted chlorite rim cementation facies and moderately compacted feldspar detritus dissolution facies show the best reservoir quality in Shahezi Formation, which can be taken as the best future exploration target in the study area.

Fluid mobility of tight sandstone reservoirs is of great significance for oil and gas development, prediction,and evaluation. According to relevant domestic achievements in the past ten years, the fluidity parameters, test methods, distribution characteristics,and influencing factors of tight reservoirs were analyzed. It is found that the T₂ value of tight sandstone reservoirs is 0.540-41.600 ms, the porosity of the movable fluid is 0.12%-14.35%, the saturation of the movable fluid is 2.16%-90.30%, the lower limit of the pore throat radius of movable fluids in tight reservoirs is 0.013-0.110 μm, the lower limit of pore-throat radius of high pressure mercury injection, nuclear magnetic resonance,and constant velocity mercury injection are 0.037 5 μm, 0.070 0-0.200 0 μm,and 0.120 0 μm respectively, and the water film thickness is 0.05-1.00 μm. Ⅲ-Ⅳ reservoirs are the main types of tight sandstone reservoirs. Statistical analysis shows that the mobile flow saturation of tight reservoirs is low, which is measured by nuclear magnetic resonance and constant velocity mercury injection. The water film thickness is the main factor affecting fluid seepage in tight sandstone reservoirs. The saturation of movable fluid of low-rank coal seams is the highest, the second is that of tight sandstone reservoirs, and the lowest is that of shale reservoirs. The movable fluid porosity of tight sandstone reservoirs is 10 times more than that of shale reservoirs and low-rank coal seams. The movable fluids in sandstone reservoirs exist in pores and throats, and are controlled by these pores and throats. Tight sandstone has a concentrated throat distribution and poor effective pore development, and most of the pores are micropores with a throat diameter less than 1.000 μm. The more concentrated the throat radius, the larger the effective throat radius, and the more favorable the seepage of the reservoir fluid. Lower sandstone permeability (<2×10^-3 μm²) leads to faster decay of movable fluid parameters; and higher permeability (>2×10^-3 μm²) leads to slower rise of movable fluid parameters. The throat radius is the main factor controlling fluid mobility of tight reservoirs.

Xijiang main sag is one of the low exploration sags in the Pearl River Mouth basin. The existing oil and gas traps have obvious differential accumulation patterns, whose formation mechanisms are unclear. Under the guidance of hydrocarbon accumulation theory of fault basins, the source rocks, faults and cap rocks combinations, reservoirs, migration and accumulation patterns are studied by using geological, geophysical and geochemical data. The subsiding centers and primary source rocks transferred from east to west, from the WC 4 Member to the WC 3 Member and the WC 1+2 Member, in the rifting periods. These transferences control the differences of oil-gas distribution between the east and the west. The mudstones in Enping Formation have good quality and large volume. Vertically, high grade source rocks and the lack of later active faults make the oil and gas accumulate in the lower structural layer more easily. In the area where the the mudstone become thinning regionally or the cap rocks are cut partly by later active faults, oil and gas distribute in upper structural layers. The types of "source-to-sink" controls the quality of reservoirs and impacts on the oil and gas accumulating to the lower structural layer. "Storage" migration is the primary mode of the oil and gas accumulating to the upper structural layer. The lower Paleogene structural layer could be one of the key exploration directions, which are the petroleum system around source rocks of the WC 4 Member in the east and the WC 3 & WC 1+2 Members in the west. In the upper structural layers, explorationist should pay more attention on Zhuhai Formation, and find the potential oil and gas zones with "storage" migration mode around the uplifts.

Fault sealing is crucial for hydrocarbon migration and reservoir formation. The fault sealing properties refer to the pressure difference caused by the lithological and physical natures between the upper and lower walls of the fault, which controls the ability of fluid to pass through the upper and lower walls of the faults. The types of fault sealing can be divided into vertical sealing and lateral sealing according to the hydrocarbon migration direction, or sectional sealing and lithological sealing according to the nature of the isolation zone. The controlling factors of the fault sealing are juxtaposition, fragmentation, cementation, smear filling, and asphaltene precipitation, etc. The research methods include Allan section diagram method, section pressure method, mudstone smearing method, acoustic wave time difference method, seismic velocity spectrum identification method, logical information method, non-linear mapping analysis method, fuzzy mathematics method,and connectivity probability method. The current research methods are single quantitative or semi-quantitative analysis at a certain scale. The breakthrough direction of the fault sealing research method will be multi-scale comprehensive quantitative analysis.

Taoyuan Pb-Zn deposit is a newly discovered medium-sized Pb-Zn deposit in the central section of Qingchengzi ore concentration area in eastern Liaoning Province. The orebodies occur in the paleoproterozoic Dashiqiao Formation of Liaohe Group, which is controlled by the strata and fractures obviously. Due to the lack of research on the ore-forming material sources of the deposit, the genesis of the deposit is still unclear. Based on the field investigation and microscopic observation, the S and Pb isotopic characteristics of Taoyuan Pb-Zn deposit were studied in detail. The analysis results of sulfides show that the δ³⁴S values of the sulfides from Taoyuan Pb-Zn deposit range from 3.5‰ to 8.9‰, with an average of 5.5‰, which indicates the characteristics of mantle source sulfur; the Pb isotopic ratios of ²⁰⁶Pb/²⁰⁴Pb are 17.969-18.309, with an average of 18.076; the Pb ratios of ²⁰⁷Pb/²⁰⁴Pb are 15.572-15.669, with an average of 15.617, and those of ²⁰⁸Pb/²⁰⁴Pb are 38.222-38.371, with an average of 38.312. The μ values range from 9.46 to 9.62 (average 9.55), most of them are lower than those of normal Earth. On the Pb isotopic discrimination diagram, the Pb isotopic values are located between the crust and mantle Pb isotopic evolution lines, showing the mixing characteristics of crust and mantle. The S and Pb isotopic compositions of Taoyuan Pb-Zn deposit are similar to those of Qingchengzi Pb-Zn-Au-Ag deposit and Indosinian intrusive rocks, indicating that the ore-forming hydrothermal fluid came from deep magma, but obviously different from those of the Liaohe Group surrounding rocks. It is concluded that Taoyuan Pb-Zn deposit is a magmatic hydrothermal type Pb-Zn deposit, which is related to the deep magmatic fluid activity.

Yongxin gold deposit is located in the Heihe-Nenjiang tectonic melange belt in the northeast of the Great Xing'an Range, which is one of the newly discovered altered rock type gold deposit,and is controlled by the tectonic belt in this area. At present, there are few related studies on the genesis of the deposit and ore-prospecting prediction, and many geological problems are still unclear. This study on pyrite thermoelectricity in the deposit is to provide a basis for deep ore-prospecting. A total of 3 200 single crystal grains of pyrite ore samples from 32 drill holes were tested by the BHTE-6 type thermoelectric instrument,and the results show that the pyrite thermal conductance type is N type, which accounts for about 99%,and P type accounts for about 1%. The pyrite thermoelectric coefficient variation ranges from -306. 0 μV/℃ to 296.0 μV/℃. The ore-forming temperature of the Yongxin gold deposit calculated by the thermoelectric coefficient ranges from 190.2 ℃ to 313.5 ℃. The dispersion of pyrite thermoelectric coefficient, the distribution characteristics of conduction type, and the gradient of denudation rate and mapping of thermoelectric coefficient all indicate that the deep northwest part of Yongxin gold deposit still has a good prospecting potential.

Lesser Xing'an Range is located in the eastern section of Xing-Meng orogenic belt, and belongs to Songnen block. The zircon U-Pb geochronology and rock geochemistry of the alkali feldspar granite and syenite granite in Pingdingshan area of Lesser Xing'an Range were studied to determine their formation age, rock genesis, and tectonic setting. The dating data show that the alkali feldspar granite was formed in (189±3) Ma,and the syenite granite was formed in (191±3) Ma, which is the product of the evolution of the Early Jurassic magmatic event. The geochemical results show that the rocks are characterized by high silicon (75.00%-77.60%), rich alkali(7.13%-9.00%), poor magnesium (0.05%-0.45%), poor calcium (0.17%-1.10%), low phosphorus (0.01%-0.07%) and titanium (0.09%-0.23%), and A/CNK (0.94-1.17), belonging to metal aluminous-weak peraluminous high-K calcium-alkaline series. The rocks are poor in high field strength elements Nb, P, Ti, Ta and large ion-lithophile elements Ba, Sr, while rich in Rb, K, Th, Hf and other elements. The total amount of rare earth elements is (38.76-297.13)×10^-6. The REEs distribution curve shows that the light rare earth elements are slightly enriched, and the heavy rare earth elements are gently inclined to the right with obvious negative Eu anomaly. The zircon saturation temperature and geochemical characteristics show that the rocks are highly differentiated Type I granites. Based on the tectonic evolution characteristics of Lesser Xing'an Range, the Early Jurassic granites in the study area are the products the collision and amalgamation of Songnen block and Jiamusi block along the Jiayin-Mudanjiang suture zone, and the magma was originated from the partial melting of igneous material in the lower crust.

Qianshao forest farm is located at the edge of Mohe foreland basin in the northern part of Erguna block in the north of Great Xing'an Range. The authors studied the petrography, geochemistry, and geochronology of intrusive rocks in Qianshao forest farm, and discussed the formation age, petrogenesis, and tectonic environment of the intrusive rocks. The results of LA-ICP-MS zircon U-Pb dating show that the granite was formed in (199.9-199.3) Ma, gabbro was formed at (201.8±2.6) Ma, in Late Triassic-Early Jurassic. The petro-geochemical studies show that the w(SiO₂) of granite is 63.22%-70.10%, w(Al₂O₃) is 12.43%-14.36%, and the Ritman index(σ) is 0.74-1.65, indicating that they belong to cala-alkaline series. They have low Mg^# values (average 39.43), w(TFeO) is 2.80%-4.41%, and w(CaO)is 1.47%-3.38%. The REE is characterized by significant fractionation of light and heavy rare earth elements with enrichment of LREE and depletion of HERR, δEu of 0.48-0.84, enrichment of Rb, Ta, K, La, Nd, Zr, Ti, and depletion of Th, U, Sr, P, Eu. The w(SiO₂) of gabbro is 51.42%-51.98%, w(Al₂O₃) is 17.24%-17.73%, and the Ritman index(σ) is 3.00-3.53, indicating that they belong to cala-alkaline series. They have high Mg^# values (average 51.07), w(TFeO)is 9.06%-9.14%, and w(CaO) is 5.81%-6.69%, light fractionation of light and heavy rare earth elements with δEu of 0.86-0.98, enrichment of Rb, Ta, Nb, Nd, and depletion of Th, U, P, Eu. The above geochemical characteristics show that the granite was the product of crystallization differentiation of gabbro. The original magma was sourced from the mantle and subsequently contaminated by crustal materials. The intrusive rocks in the study area were formed in the compressive environment of the subduction and collision orogenic stage between the Mongolian and Okhotsk Sea.

This study was carried out to analysis the SHRIMP U-Pb zircon dating and geochemistry of the supracrustal enclaves in the Late Neoarchean monzogranite in Lianhuashan area, western Shandong. The supracrustal enclaves are mainly composed of amphibolite, meta-ultramafic rock with some fine-grained (biotite) hornblende gneiss,and fine-grained biotite gneiss. SHRIMP zircon U-Pb dating indicates that the fine-grained hornblende gneiss has a magmatic zircon age of 2 757 Ma, whereas a trondhjemite dyke intruding in the supracrustal enclave has a magmatic zircon age of 2 593 Ma. Some zircon grains separated from meta-ultramafic rock show strong recrystallization and have a large ²⁰⁷Pb/²⁰⁶Pb age variation (2 657-2 397 Ma). The meta-ultramafic rock, amphibolite, and fine-grained hornblende gneiss show LREE-depletion-flat REE pattern, flat REE pattern, and LREE-enrichment REE pattern, respectively, with weak LILE enrichment and insignificant Nb-Ta depletion. Combined with the early work, it is concluded that the rock assemblage, geochemical composition,and formation age of the supracrustal enclaves in the Lianhuashan monzogranite are the same as those of the meta-volcanic series of the typical Early Neoarchean supracrustal rocks (Yanlingguan ‘Formation’) in the adjacent Yanlingguan area, which were formed in ocean environment. The Early Neoarchean supracrustal rocks should be widely distributed in western Shandong more than considered before.

The Mesozoic magmatic rocks are widespread in Wulan area of northern Qaidam, and consist largely of gabbro, diorite, granodiorite and granite. The LA-ICP-MS zircon U-Pb dating of two gabbro samples yield well-constrained ages of (241.9±0.9) Ma and (245.4±1.9) Ma, indicating their formation of the Middle Triassic. Their SiO₂ content of gabbro in northern Wulan area is 47.94% and 52.01%, the total alkali content is low (1.25% and 1.47%), and the Ritman index is 0.33 and 0.26 respectively, belonging to cala-alkaline series. They have high Mg^# (81 and 79), Cr (1 661.00×10^-6 and 1 418.00×10^-6), and Ni (394.00×10^-6 and 280.00×10^-6), similar to those predicted of the original basaltic melts. They have weak LREE/HREE fractionation (3.92 and 3.44) with nearly no Eu anomalies and no obvious magma differentiation. The primitive mantle normalized trace element spider diagrams show enrichment of large ion lithophile elements (e.g., K, Rb) and depletion of high field strength elements (e.g., Nb, Ta, Ti), characteristics considered typical of subduction-related arc magmatic rocks. The large variation of zircon ε_Hf(t) values (from -3.0 to 9.3) implies that the crustal components seem to have been incorporated in the mantle-derived mafic magmas. Combined with regional geological evolution, we suggest that the gabbro formed in the continental marginal arc environment related to the northward subduction of the Paleo-Tethys Oceanic plate. The fluids released from the subducting oceanic slab promote partial melting of the overlying mantle wedge to produce basaltic magma, which was contaminated by crustal materials or mixed with crust-derived magma during magma ascending.

Lanping basin in western Yunnan has attracted wide attention in geological circles because of its large scale resources and great prospecting potential, however,as one of the only three Cenozoic intrusions in the basin, the Zaojiaochang intrusion is rarely reported. To some extent, this not only affects the overall understanding of the basin evolution and metallogenic mechanism, but also is incomplete for the study of alkali-rich porphyry belt in western Yunnan. A study on petrography, zircon U-Pb chronology and elemental geochemistry, shows that the Zaojiaochang intrusion is composed of monzogranite (central facies) and granodiorite porphyry (marginal facies). The LA-ICP-MS zircon U-Pb dating shows that the emplacement age of the Zaojiaochang intrusion is about 34 Ma. The intrusion belongs to high-K calcium-alkali series, with high silicon (w(SiO₂)=71.49%-73.17%), peraluminous (A/CNK=1.12-1.32), and high total alkali (w(K₂O+Na₂O)=7.83%-9.10%). It is rich in LILEs (Rb, Ba, Th, U, K, Hf) and LREEs, relatively depleted of HFSEs (Ta, Nb, Ti and P), with no or weak negative Eu anomalies and special Nb/Ta and Th/U values. Based on the above mentioned data,it is suggested that the magma of the Zaojiaochang intrusion came from deep source, and the parent magmas originated from a metasomatic lithospheric mantle source, and mixed up with crust-source materials later. The comprehensive study shows that the intracontinental subduction of the Tibetan Plateau during the late collision period (40-26 Ma) induced the lateral flow of mantle material,the upwelling of deep asthenosphere, and the forming of the alkali-rich porphyry belt. The Zaojiaochang intrusion was formed in the Late Eocene Lanping basin transformation stage and the mountain intracontinental orogenic extrusion tectonic environment. In the center of the basin, the Lanping-Simao central axis fault with lithospheric fault property reached its peak in this period, and the magma rose along the fault and formed the super hypabyssal alkaline-rich porphyry under a brittle condition near the surface.

In order to solve the problem of short measuring distance of the existing Hall element measuring system, the full stroke measuring system based on the principle of laser triangulation was developed. This system can provide full scale measurement and real-time observation. The SC-86H fluidic hammer was used to carry out the related tests, and the full stroke data were obtained. The displacement-time curve and velocity-time curve of the fluidic hammer were obtained through analyzing the experimental data, which provided vital insights into the working features of the impact body. The results show that the irregular movement occurs in the initial stage of the return stroke. This unstable state improves the cycle time, and accordingly reduces the impact frequency. The actual damping stroke is not sensitive to the pump volume,when the pump volume increases from 80 L/min to 220 L/min, the actual damping stroke varies only from 5.9 mm to 6.8 mm. The actual stroke will slightly increase the actual damping stroke,as demenstrated in the test,the actual damping stroke only increased by 7% when the structure stroke increased by 57% (70-110 mm).The experiment shows that this system can measure the whole stroke of the hammer and record the movement state of the hammer in real time.

In order to study the impact of subway construction on the Baiquan spring group (BSG) in Jinan, on the basis of the comprehensive analysis of the geological and hydrogeological conditions of Baiquan spring area, assuming the location and hydraulic properties of the karst water strong run-off belt in the study area, a numerical model of groundwater flow was established using FEFLOW software. Taking the planned subway Line M1 as the research object, the two construction scenarios of pumping and pumping with artificial recharge were analyzed in Jinan East Station, Liangwang Station, and Liangwang East Station. The impact on the flow of BSG in different construction scenarios was analyzed. The results show that the pumping alone of the subway station of Line M1 decreases the flow of the BSG. The simultaneous construction of the three stations has the greatest impact on the spring flow, and the maximum attenuation is 5.48%. When each of the three station is constructed separately, the Jinan East Station has a greatest impact on the spring flow. The spring flow rate is reduced by 0.043×10⁴ m³/d compared to that without construction. Pumping construction with artificial recharge can effectively mitigate spring flow attenuation. The attenuation of spring flow during the construction of different stationsis reduced from 2.26%-5.48% during the construction of pumping alone to 0.08%-1.21% during the construction of pumping with artificial recharge. The strong run-off belts of karst water will form the preferential run-off of groundwater, promote the recharge of BSG, and alleviate the spring flow attenuation caused by subway construction to a certain extent.

In order to quantitatively calculate the release flux of radionuclides to marine environment through groundwater under the situation of drainage pipeline leakage in hilly area, an offshore nuclear power station was taken as an example. Firstly, a three-dimensional topographic geological model was established by using GOCAD software to describe the distribution, denudation,and tendency of strata; Secondly, a three-dimensional hydrogeological model was built with FEFLOW to generalize the characteristics of recharge, runoff,and discharge of groundwater system in hilly area; Finally, the distribution coefficients of ⁹⁰Sr、¹³⁷Cs in different groundwater rock and soil media were measured experimentally. After that, the concentration distribution of radionuclides in groundwater after continuous leakage of drainage pipes for 60 a was simulated and calculated. The result shows that the migration velocity of ³H is basically the same as that of groundwater. The maximum concentration of ³H in groundwater is 0.285 0 Bq/L, and the maximum release flux to the receiving water reaches about 526 Bq/d on the 20 000th day. The maximum migration of ⁹⁰Sr is about 80 m, and the maximum radioactive concentration in groundwater is 0.032 1 Bq/L. ¹³⁷Cs is retained near the pipeline for a long time because of its strong adsorption capacity, its maximum radioactive concentration in groundwater is 6.840×10^-3 Bq/L, and the release flux is 0 Bq/d. Based on the analysis of dispersion uncertainty, the greater the dispersion is, the smaller the maximum radioactive concentration of ³H is in groundwater, and the greater the release flux is to marine environment.

With the acceleration of urbanization, urban flood and waterlogging disasters are frequent. In order to accurately analyze the impact of flood disasters on the current flood control system and make corresponding measures for flood control and disaster reduction, the lower reach of Ling River along the southeast coast is taken as the research area in this paper. We construct a hydrodynamic coupling model based on Saint-Venant equation, and simulates the process of river burst flood in real time. Considering the factors of the study area such as topography, meteorology, hydrological data, hydraulic engineering, underlying surface conditions and so on, in the coupling connection of one-dimensional river network model and two-dimensional hydrodynamic model, the interactive inundation of water flow inside and outside the river channel in real terrain can be restored to the greatest extent. With the help of typhoon and rainstorm data in the study area, the one-dimensional and two-dimensional coupled hydrodynamic models established are calibrated and validated. The tested models can be used to simulate the real-time submergence of design flood and historical flood in Coastal cities along the lower reaches of Ling River. The results show that the model has good accuracy in simulating the real-time flood routing process under complex terrain conditions, and the error between the calculated value and the measured value of typical section water level along the river system is less than 0.1 m.

The traditional water quality prediction model is complicated in calculation and will cause errors in the case of large convection, so it is not applicable to intelligent water quality prediction in the era of big data. Based on the data of San Francisco Bay surface water quality research area, the authors studied the water quality of the research area by using data analysis, statistical testing, deep learning time series models,and other technical methods. Based on the principal component information, a long short term memory(LSTM) circulation neural network model was constructed, and further,the water quality of 5 surface water sampling sites was predicted. The results show that the long short term memory cyclic neural network model can effectively control the loop and memory unit structure through gates and the input characteristics of the incoming model, thereby reducing the complexity of the model. Moreover, the prediction accuracy of the two-layer long and short-term memory cyclic neural network model is 5.3 % higher than that of the single-layer long and short-term memory cyclic neural network model.

In order to study the ecological response law and characteristics of Typha angustifolia in different water depth environments on 2018-06-30, 2018-07-30, 2018-08-29, and 2018-09-28, the changes of growth indexes, water quality factors,and sediment factors of Typha angustifolia under different flooding depths were discussed through field sampling survey and indoor chemical analysis. The results showed that the growth indexes of Typha orientalis Presl were different at different flooding depths. At the water depth of 50 cm, the growth state of Typha orientalis Presl was the best. The water samples of Shifosi reservoir were weakly alkaline over 4 sampling days, and sediment types were acidic neutral sediment. With the increase of the water depth, the mass concentration of dissolved oxygen (DO), nitrate nitrogen (NO₃^-),and nitrite nitrogen (NO₂^-) in the water samples gradually decreased, and the mass concentration of total nitrogen (TN) and ammonia nitrogen (NH₄⁺) increased. With the increase of water depth, the overall quality score of ammonia nitrogen (NH₄⁺) and organic carbon (SOC) increased, the quality score of total nitrogen (TN), nitrate nitrogen (NO₃^-) and nitrite nitrogen (NO₂^-) decreased gradually, the overall conductivity decreased gradually, and the quality score of the total phosphorus (TP) and available phosphorus (AP) fluctuated substantially. The content of nitrogen in sediment and water had a great influence on the growth of Typha orientalis Presl.

In order to find a highly effective remediation agent for soils contaminated by multiple heavy metals, the modified Mg (OH)₂ with OH^- sustained release function was studied. Through the experiment of stabilization and remediation of heavy metals contaminated soil,the modified Mg(OH)₂ stabilization efficiency for multiple heavy metals (lead, cadmium, copper, zinc) in polluted soil and its influence on the form distribution of the multiple heavy metals were studied. The results show that the addition of modified Mg(OH)₂ has a stabilizing effect on various heavy metals in soil, and the stabilizing efficiencies for lead, cadmium, copper and zinc are 72.42%, 34.53%, 87.64%,and 97.65%, respectively. Moreover, the modified Mg (OH)₂ can significantly reduce the content of exchanged heavy metal states and increase the content of residue states, which can further improve the stability of heavy metals and reduce the bioavailability of heavy metals. In addition, the modified Mg(OH)₂ has the characteristics of sustained-release of OH^-, which can keep the soil alkaline for a long time,thus the modified Mg(OH)₂ is a long-term effective soil remediation agent.

Biochar is usually used in Cr(Ⅵ) removal due to its micro porous structure and huge specific surface area, but different biochar has different removal efficiency. Choosing poplar, willow, peach,and pine as feedstocks, twenty types of biochar were prepared through pyrolysis of the FeCl₃-modified and unmodified biomass with different particle sizes at 300 ℃ or 600 ℃, respectively. A batch of experiments were performed to evaluate the efficiency of different biochar in removing hexavalent chromium from the simulated groundwater. The mechanism of Cr(Ⅵ) removal by biochar was investigated using Fourier transform infrared (FTIR) spectroscopy and X-ray absorption near edge spectrum (XANES). The results showed that the removal efficiency of the modified biochar by pyrolysis at 300 ℃ was over 99.0% of Cr(Ⅵ); The biochar (<0.5 mm) showed better removal efficiency than the biochar with a particle size of 2 mm; The Cr (Ⅵ) removal process by FeCl3BC300Y could be well described by the pseudo-first-order equation; XANES analysis suggested that the chromium on FeCl3BC300Y was in a trivalent state, and FTIR analysis indicated that hydroxyl and carboxylate groups contributed to Cr(Ⅵ) removal. The mechanism of Cr(Ⅵ) removal by biochar included reduction and complexation. The biochar modified by iron is expected as a filler material of permeable reactive barriers, and will become a new material to repair groundwater contaminated by hexavalent chromium.

According to the real time geo-steering and evaluation mapping requirements of logging while drilling in horizontal and high-angle wells, in view of the disadvantages of traditional borehole information displaying methods, a high efficient two-dimensional decomposition drawing method is proposed for real time logging information, well trajectory and strata. Aiming at the high time and space complexity of the two-dimensional decomposition drawing method, this paper provides local real time calculation and screen copy redrawing algorithms driven by different events, which control the consumption of CPU and memory, improve the drawing efficiency, and eliminate flicker and lag in real-time drawing. The application shows that the two-dimensional decomposition real-time drawing method can realize smooth, non-stuttering real time drawing of large-scale logging while drilling and mud logging geo-steering graphics, also it can improve the accuracy and timeliness of the evaluation of highly inclined and horizontal well reservoir models.

At present, the P-wave anisotropy-based fracture prediction method is widely-used with relatively satisfactory performance. However, the accuracy of the conventional ellipse fitting method is affected by a series of factors, which leads to inaccurate inversion results of fracture density. In this study, the calculation method of reservoir fracture density in anisotropic media is derived according to the exact formula of Ruger equation. Firstly, the reflection coefficient of P-wave is calculated by using the functions of incidence angle, azimuth angle, Thomsen anisotropy and medium elastic parameters; then the tangential anisotropy coefficient of fractures in the reservoir to be measured is calculated according to the reflection coefficient of P-wave; finally, according to the anisotropy coefficient, the fracture density of the reservoir to be measured is calculated. The fracture density of Zhengbanan area in the Sichuan basin was calculated by using the fracture inversion results obtained from the actual P-wave AVOA data, and the results are consistent with the drilling data. It shows that this method can be used to determine the fracture development status and the fractured reservoir identification.

Because of the complicated shape of the actual geological bodies, it may be quite different from the real situation when using the cuboid grid to establish the forward model, and the reliability of the calculation results is poor. In this paper, a constrained Delaunay meshing method is proposed to discretize the geological bodies and perform gravity modeling. The grid adaptive cryptography is used in the complex region such as a model boundary to discretize a three-dimensional geological body into a finite tetrahedron;then, the gravity forward formula of the tetrahedral mesh is derived in detail;and finally,the three-dimensional gravity numerical simulation based on the constrained Delaunay meshing technique is realized. For a composite data model, the calculated solution is compared to the analytical solution. And the simulation results of fine mesh are better than that of coarse mesh, and meet the accuracy requirements of numerical simulation. The method was applied to the actual geological body modeling in Jinchuan mining area. According to the local needs, a three-dimensional model with uneven mesh density was built, the surface gravity field of the model was calculated, and the simulation data was compared with the measured data. The results show that the unstructured mesh modeling method is strongly applicable and can simulate the gravity anomalies of complex geological bodies.

Based on the geometric features and spatial distribution of the major active faults in Liaoning Province, the earthquakes with frequency of M_L≥2.0 in Liaoning since 1980 and the earthquakes with annual occurrence rate of M_s≥5.0 since 1900 were studied,their relationship with the tectonic settings of the active faults were analyzed, and the preliminary evaluation results of the seismicity and seismic risk of the main faults and tectonic zones were obtained. The main tectonic faults with high activity are Haicheng River fault, Jiuzhai-Gaizhou north section of Jinzhou fault, Chaoyang-Beipiao fault, etc.; the faults with relatively high risk of M_s≥5.0 earthquake in the next 3 years are Haicheng River fault, Xiongyue fault, Jiuzhai-Zhuanghe fault, Yalu River fault, the intersection of Chifeng-Kaiyuan fault, and Liuhe fault, etc. It is suggested that not only the spatial distribution of the precursory anomalies, but also the activity and seismic risk of the main structures in the region should be fully considered in the regional earthquake risk and hazard assessment.

In view of the complexity, heavy workload,and low degree of automation in current survey of land resource change detection, a building change detection method of high-resolution remote sensing image based on deep learning model is proposed, and the idea of semantic segmentation is applied to change detection. Based on the better extraction performance of the residual structure than convolution layers and the characteristics of multi-scale prediction of feature pyramid networks, the residual structure and FPN are fused into Unet model to establish FPN Res-Unet. The model is based on Unet with ResNet residual structure as its feature extraction layer. After each convolution, padding is used to keep the size of the input image and the output image consistent. In the process of sampling at each level of the decoding path, the branch path is expanded to fuse FPN into the network trunk of the model. It fully combines the advantages of residual structure, Unet and FPN, which makes it pay attention to details while obtaining deep semantic information, and improves the detection accuracy of building change. Experiments show that the accuracy rate, recall rate and F₁ of the method in the data set used reach more than 90%.