Streltsov (Str) ore field is a large deposit cluster composed of super-large and large Mo-U deposits, and has been the only source of natural uranium in Russia for a long time after the disintegration of the Soviet Union. Its discovery and exploration in Str ore field is long, tortuous, and legendary. The uranium prospecting began in the region of South Erguna, and stopped completely at the beginning of 1962, as no valuable results had been found. In the autumn of 1962, L P Ishukova, a senior geologist, wrote to the leader suggesting a continue prospecting work in this area, and got the chance to try again. The first super-sized U deposit was discovered by her drilling layout in Str ore field, and caused the big turn of the whole situation. Since then, accelerating the ore field development had become the general principle of all work. The parallel acceleration of exploration and geological research for deposits promoted mutually, and most of the deposits in this ore field were discovered within the following 10 years. By the end of 1966, the preliminary prospecting results of Str and other deposits had become a sufficient basis for the establishment of the largest uranium mine in the Soviet Union in the early 1970s. By the end of 1980s,17 Mo-U deposits had been completely explored. From a technical perspective,the success of Str ore field exploitation has two main reasons:one is that people have had a deep understanding to these deposits and their control conditions in the ore field; the other is that the work methodology adopted has been improved constantly, as almost every deposit in this ore field is a deep-buried blind ore. The new round prospecting strategy was that by the comprehensive use of geology, radioactivity, traditional geophysics, geochemistry, deep survey automatic perforation device, and drilling exploration, three dimensional geological tectonic mapping of different scales was completed. On the basis of these results, drilling was used to discover deposits. The basic fact facing exploration work is that the complexity of deposit composition is the common feature of all the deposits in Str ore field, and each deposit has its own characteristics, which makes every exploration process of these deposits quite different. Drilling was used in early exploration, and the basic mesh ranged from 200 m×100 m to 400m×100 m. In detailed exploration, the combination of underground engineering and drilling was used, and the exploration system combined with horizontal and vertical cross sections was adopted with the basic mesh from 50 m×20 m to 50 m×25 m. The total exploration results of all deposits were fully confirmed thereafter by mining engineering, and the reserves was also increased by 10 percent. The basic experience and lessons of the successful exploration in this field are worthy to learn. The "Str effect" has spread rapidly in China for geological exploration work. It is expected to continue to ferment in China, especially in Hulun Buir, and even in the Mesozoic tectonic-magmatic belt of the Dahingan-Yanshan Mountains with more and greater achievements.

Several slope-breaks are developed on the western slope of the west subsag in Lishui depression, which control the development of distal underwater fans in the lower part of the Paleocene Mingyuefeng Formation. Drilling reveals that the underwater fans are characterized by large sedimentary thickness, good physical properties,and active hydrocarbon-bearing. The description of reservoir characteristics and prediction of distribution range are of great significance to the exploration of lithologic reservoirs in this area. Through analysis of the paleo-geomorphology in the early stage of Mingyuefeng Formation, the effects of slope-breaks on fan development are summarized. Isolated and compound channels are developed in the upthrow block; while the main fan bodies are developed in the downthrow wall of slope break faults. The microfacies of the fan channel is the dominant facies. The main lithology is gray fine sandstone. There are sedimentary structures reflecting collapse, such as water escaping structure and flaming structure. The logging facies are characterized by low gamma and high spontaneous potential anomalies, and the seismic facies are characterized by strong amplitude, low frequency and intermittent reflection. At the same time, the distribution range of three fan stages in this area is identified by using seismic sedimentology technology. From early to late stage, the fans have gradually migrated from north to south, which points out the direction for future exploration in this area.

In order to clarify the reservoir characteristics and its genesis, the factors affecting the development of carbonate reservoirs in different fault zones at the north of Shunbei area were analyzed by means of core and thin section observation, X-ray diffraction, physical property test cathodoluminescence,and Sr isotope testing. The reservoir lithology is mainly composed of bioclastic micrite limestone, micrite sandstone limestone,and micrite limestone. The reservoir space types include caves, fractures, and holes. The main type fillings are calcite, organic asphalt, and siliceous quartz, among which calcite cementation is the most common and widely distributed with 2-3 times of cementation. The difference between the fillings of asphalt and siliceous is obvious in different reservoir spaces. The former fills only in the fracture system, while the latter fills almost entirely in the dissolution cavities. The reservoir body types of Yijianfang and Yingshan Formations are mainly of fracture type and fracture-hole type. The reservoir formation is mainly affected by fault-fracture system, fluid properties, source, and scale. Fault-fracture system directly controls the development of fractured reservoir, which can improve reservoir permeability and contribute to formation through providing a channel for fluid or oil and gas filling, and is a main controlling factor for reservoir development. Under the background of fracture passage, fluid transformation also has some influences on reservoir development. Among them, alkaline calcium-rich fluid has the greatest influence on reservoir development in the study area. The overall scale of acid silicon-rich and hydrocarbon-generating fluids is limited, so only partial reservoir modification is carried out.

In order to comprehensively characterize the pore structure and storage-seepage capability of multi-type reservoirs in fracture-cavity carbonate gas reservoirs, a series of test techniques were used to study the samples from the Deng 4 Member in Gaoshiti-Moxi block of Sichuan basin. At first, the lithology, physical property, storage space and throat of the reservoirs were qualitatively described by thin section and scanning electron microscope. Then, the reservoirs were classified according to the capillary pressure curves obtained by high pressure mercury injection. Finally, the two and three dimensional pore structure characteristics of three types of samples were quantitatively determined based on multi-scale CT scans. The study results show that:The storage space is composed of intergranular dissolved pores, intra-granular dissolved pores, inter-crystalline dissolved pores, solution cavities, solution fractures, and structural fractures; the throat type mainly contains necking throat, punctual throat, and control shape throat; the reservoirs can be classified to fracture-cavity type, cavity type, and pore type; in fracture-cavity-type reservoirs, large pores and cavities are developed, uniformly distributed, and connected well,and coarse throats are numerous, micro-fractures and dissolution cavities are beaded in series, which are connected with the isolated storage space and has the best storage and seepage capability; in cavity-type reservoirs multi-scale pores and cavities are developed with strong storage capability, throats are coarse but few and poorly connected with limited seepage capability; in pore-type reservoirs, small pores are developed and unevenly distributed, and most of the spaces are occupied by rock skeleton with few throats and poor connectivity, leading to weak storage-seepage capability.

The Upper Paleozoic tight sandstone gas resources are rich in potential in Zijinshan area at the northeast margin of Ordos basin,and are one of the important blocks for unconventional natural gas exploration in China. The petrology, physical properties and gas-bearing characteristics of tight reservoirs were studied through analysis and test of casting thin sections, scanning electron microscope, experiments on porosity,permeability,and pressured-mercury testing,combined with drilling and logging data. The results show that lithic sandstone is the main reservoir rock type at medium degree of composition maturity and textural maturity with high content of quartz,lithic fragment,and low content of feldspar. The dissolved pore is the major type of reservoir space,and its main pore structure is mesoporous fine throat and microporous fine throat. The porosity of the major pores ranges from 2.00% to 12.00%, with an average of 6.96%,and the main permeability is 0.01×10^-3 μm²-1.00×10^-3 μm², with an average of 0.36×10^-3 μm². The correlation of porosity and permeability is good because of the later dissolution. The average thickness of the gas reservoirs with gas saturation of 40.4% is 10.3 m, which accounts for 29% of the tight sandstone reservoirs. The reservoir development is mainly under the control of sedimentation, compaction and dissolution. The material basis and spatial distribution of reservoir formation are controlled by sedimentation. The strength of compaction is directly affected by rock composition in different sedimentary environments. The superimposed development characteristics of sandstone, mudstone, limestone,and coal seam provide a basis for dissolution. Compaction is the main factor that causes reservoir tightness. Dissolution is the decisive factor for the improvement of reservoir properties in the region. The thermal action and eruption of Zijinshan magma enhanced the dissolution.

The Jurassic system of Beishan basin group at the junction of Gansu and Inner Mongolia is a new potential field for oil and gas exploration in Northwest China. On the basis of systematic sample collection,the characteristics of organic matter and biomarker of the Jurassic source rocks in Zhongkouzi basin were analyzed in detail by means of testing technology and geochemical analysis. The results show that the kerogen type of the Jurassic source rocks in the middle mouth basin is mainly typeⅡ₁-Ⅱ₂, and the source material of hydrocarbon generation is mainly terrestrial plants, containing a small amount of algae and aquatic organisms. It is mainly formed in a weak oxidation-weak reduction sedimentary environment with moderate oxygen content, such as swamps or transgressive lakes in delta plain. According to the evaluation criteria of hydrocarbon generation potential, most of the Jurassic dark mudstones in Heizhangfang sag belong to the source rocks with poor or medium hydrocarbon generating potential. The hydrocarbon generating potential of the dark mudstones in Nanquan sag is medium or high,better than that in Heizhangfang sag. Based on the analytical data in Zhongkouzi basin and the discussion on sedimentary environment and sources of organic matter, the evaluation criteria for hydrocarbon generation potential of source rocks in coal measures are established. This study can provide a comparative reference for the study of the Jurassic sedimentary paleo-environment and resource potential in Northwest China.

There are skarn iron deposits in Qihe County, Shandong Province. In recent years, a great progress has been made in iron ore exploration and research work in the study area. In order to promote the iron ore exploration in this area, the authors discussed the ore-controlling characteristics and prospecting criteria through statistical analysis of the iron ore exploration and research results in this area. The iron ore-controlling strata are the strata of the Ordovician carbonate rocks and Carboniferous-Permian clastic rocks. The ore-forming geological bodies are the medium-basic intrusive rocks in Late Yanshanian, and the iron ore bodies occur mainly in the contact zone of strata and rock mass, and also in some carbonate strata or the intrusive rocks. The occurrence types of iron ore are various, of which the contact belt is the main type, also including the types of fracture filling, interlayer filling, fissure penetration and xenoliths, etc. The ore bodies are complex in shape, such as layered, cystic, and lenticular. The typical alteration zoning is characterized by diorite-altered diorite-inner skarn-iron ore-outer skarn belt-marble belt-limestone. The mineralization is mainly composed of contact diffusion metasomatism and contact permeation metasomatism, including also some rich ore hydrothermal filling, etc. In this area, the iron ore prospecting criteria mainly include stratigraphic marks (Ordovician carbonate rocks and Carboniferous-Permian clastic rocks strata), intrusive rock marks (medium-basic intrusive rock mass with albitized alteration diorite), structure marks (contact zones between strata and rock mass, structure intersections, interlayer slips, brittle fractures), wall-rock alteration marks (magnetization, skarnization, albitization, serpentinization, phlogopization, etc.), and geophysical marks (obvious high value magnetic anomaly and polarization magnetic anomaly, gradient zone of gravity anomaly, high-low resistivity conversion zone). In iron ore exploration in the future, based on the comprehensive study of the ore-controlling characteristics in this area, a variety of prospecting indicators should be used to cooperate and complement each other so as to achieve the desired exploration goal.

We used graphite furnace atomic absorption section spectroscope to determine the content of five gold chemical phases (soluble phase, free natural gold, carbonate phase, sulfide phase, and silicate phase) in the ores and rocks of the Yangshan Carlin-like deposit in Gansu Province, and identified their distributions in different rocks/ores. According to the results, the major phase in rocks is silicate phase which accounts for 57.6%. In ores, sulfide phase accounts for 56.9%,the highest proportion among the five phases. The proportions of free natural gold, carbonate phase and sulfide phase in ores are much higher than those in rocks. Soluble phase, free natural gold, carbonate phase and sulfide phase are favorable metallogenic phases. The proportions of favorable metallogenic phases in the host strata are obviously higher than those in other strata. This can be used to infer the metallogenic potential of strata and provide a reference for the evaluation of petro-geochemical anomalies.

The widely distributed Early Cretaceous volcanic rocks of Yingcheng Formation in northern Songliao basin are intermediate-felsic rocks, which are mainly rhyolites, characterized by high silicon, aluminum,rich alkali,and low magnesium and iron. The standard curve of rare earth elements reveals the deficiency of heavy rare earth elements,but the enrichment of light rare earth elements, and the rare earth elements are seriously differentiated in different kinds of volcanic rocks. The rhyolites are distinctly enriched in incompatible elements such as Pb, U, Th, Ta, Hf, Zr, and apparently loss of Sr, Ba, Eu, while in neutral andesite, trachyandesite and basic basalt they have no obvious loss, and in the intermediate-acid dacite they are in between. The results show that the magma of Yingcheng Formation originated form depleted mantle. Because the magma was contaminated by crust during evolution under magma plating and crust partial melting, forceful magmatic differentiation occurred before the eruption of acid magma. The volcanoes of Yingcheng Formation may erupt in an extensional background within plate according to the discrimination diagrams, and the volcanic rocks of Yingcheng Formation have the same evolutionary characteristics as those of the volcanic rocks developed in active continental margin or island arc associated with plate subduction. Taking the tectonic environment of Eastern China into consideration, the large-scale volcanic action in the Early Cretaceous may be associated with the lithospheric thinning and mantle upwelling under the subduction of the Pacific plate toward northwest in a high speed.

Located at the junction of Yili block and Siberia plate, the northern Yili block develops a belt of Early Paleozoic intrusive rocks, which are the key to study the northern Yili block tectonic setting and evolution of the old Junggar Ocean. On the basis of a field geological survey and petrographic observation, we present the whole-rock data, U-Pb ages and Hf isotopic data for the Early Paleozoic diorite from Wenquan of northern edge of Yili block. The weighted mean ²⁰⁶Pb/²³⁸U ages of the zircons from quartz diorite are(467.7±5.4)Ma,(457.1±3.9) Ma and(455.4±5.0) Ma, indicating that these diorite bodies crystallized from the Early Ordovician to the Middle Ordovician. The petrological and chemical composition show that these diorites are characterized by low SiO₂ (50.19%-61.91%, average 56.57%) and TiO₂ (0.84%-1.13%, average 1.01%), slightly higher MgO (2.36%-8.17%, average 4.60%), CaO (3.94%-9.45%, average 6.50%), total alkali (Na₂O+K₂O) (3.74%-7.06%, average 5.41%). The ratio of Na₂O/K₂O is high (1.42-4.90, average 2.76), while the ratio of A/CNK is low (0.70-0.95, average 0.84). The geochemical data suggest that these diorite bodies belong to quasia-luminous series. The diorites are enriched in large ion lithophile elements (K,Rb), but depleted of high field strength elements (Ta, Nb, Ti). The REE pattern shows a trend of "left high and right low" with minor negative Eu anomalies (0.67-1.12, average 0.90), and heavy REE content is low, indicating the geochemical characteristics of arc igneous rocks in continental margin. Various binary diagrams reveal fractional crystallization of olivine, clinopyroxene, and hornblende. The existence of stratigraphic xenoliths and the La/Sm value (2.99-8.59, average 5.95) suggest the limited crustal contamination during the magma rise. The zircon Hf isotopic compositions of the quartz diorite are mainly characterized by ε_Hf (t) values of 3.9-7.0, two-stage model ages of 991-1 191 Ma (average 1 083 Ma), which is older than U-Pb age. The petrological, geochemical data and zircon Hf isotopic compositions imply that the primary magma derived from a depleted mantle probably mixed with metasomatic enriched lithospheric mantle components and the early fluid metasomatism of oceanic plate. Based on the regional magmatism and the previous study, the authors infer that the old Junggar Ocean crust subducted southward beneath the northern edge of Yili block during 467.7 Ma-455.4 Ma, and ended in the Late Ordovician-Early Silurian.

The Lower-Middle Jurassic Longshan Formation is located at the south of Tanggai River-Xindie County tectonic melange belt (KSTB) in Taxkorgan area, Xinjiang. The clastic sedimentary rocks are dominated by marls and greywackes, and are a set of steel grey-gray carbonate clastic sediments with low maturity. Their source rocks have not been fully handled and sorted. The REE distribution patterns are uniform and similar to typical post-Archean shales and upper continental crust, with enriched LREE, flat HREE, and negative Eu anomaly. A sedimentary environment analysis shows that the sediments belong to shallow shelf-nearshore-foreshore environment,and are characterized by progradation sedimentation, indicating a regressive sequence. The sedimentary rock formed in tectonic-sedimentary setting of sea level decline and residual sea basin contraction. The tectonic settings of the provenance mainly belong to active continental margin with characteristics of continental island arc. Based on the regional tectonic environment, we conclude that the Middle-Lower Jurassic Longshan Formation is the sediments of residual marginal ocean, formed by completed Qiangtang block and Kunlun block, the source of Longshan Formation comes from the KSTB, the north of Longshan Formation.

The Sertengshan Group is an important component of the Early Precambrian metamorphic basement in the mid-west of the North China craton. It is of significance to study the tectonic evolution of the Early Precambrian North China craton. The formation age of the Sertengshan Group is one of the current research hotspots. In this paper, through the study of petrology and zircon SHRIMP U-Pb dating, the rock composition and chronological characteristics of Dongwufenzi Formation of the Sertengshan Group in the Chaganhada area of Urad Zhongqi were identified. The Dongwufenzi Formation suffered severe destruction of magmatism and tectonism in the later period, and has no an intact top and bottom. It is mainly composed of medium-fine amphibolites, fine-grained biotite plagioclase gneisses, augen fine-grained biotite plagioclase gneisses, banded fine-grained biotite plagioclase gneisses, and fine-grained biotite hornblende schists. The mineral assemblage characteristics indicate that it experienced low green schist facies-low amphibolite facies metamorphism. Most automorphic and semi-automorphic zircons with oscillatory zoning indicate its magmatic origin from the fine-bearing biotite plagioclase gneiss. The zircon SHRIMP U-Pb dating results (1 930.7±9.6 Ma) represent the formation age of basal rock, suggesting that the metamorphic age of the Dongwufenzi Formation should be later than 1 930 Ma.

In order to clarify the mechanism of rainfall-induced landslides and to determine the basis of prevention and control, the Dongmen Qishan landslide was fully studied. The landslide occurred in Yongtai County, Fujian Province. Based on detailed geological survey and monitored displacement during rainfall period, the mechanism of landslide activation was studied from the perspectives of geological condition and influencing factors. The evolution of the landslide was investigated by using Geostudio, and on which landslide control can be divided into two main steps. The first step is emergency mitigation, in which drainage is designed to decrease groundwater level in the landslide. Based on the analysis of the relationship between rainfall and landslide deformation velocity, the drainage is to be installed in the lower part of landslide. The second step is to install stabilizing piles. Based on numerical and theoretical analyses, the stabilizing piles should be installed in the lower part of the landslide. The diameter, net spacing and center-to-center spacing are 1.0 m, 2.0 m and 3.0 m, respectively.

In order to study mechanical characteristics of heterogeneous soils under different conditions, the authors conducted a series of ring shear tests, and compared the differences of shear mechanical characteristics between loess, sand, and heterogeneous soils composed of sand and loess. A comparative analysis was carried out on the differences and their generation mechanisms. The study results showed that under different drainage conditions, the change form of shear stress and shear strength of heterogeneous soil composed of sand and loess were significant different from those of loess or sand during the mutual shearing process. At the same shearing rate, when compared with those of single loess and single sand, the shear strength of sand-loess under different drainage conditions was decreased by 71% and 51%, respectively. During the shearing process, the heterogeneous soil composed of sand and loess presented the shearing mechanical characteristics of cohesive soil. The mechanical characteristic differences between heterogeneous soils and single loess or single sand under different drainage conditions are mainly related to the interaction between sand and loess on the shearing surface and pore water state inside soil body.

To research the failure mechanism of the south slope of Fushun West open-pit mine and restrain the deformation and damage,the slipping profile of the South slope was studied by using micro-seismic monitoring technology and satellite monitoring technology. The failure mechanism of slope at the final state of mining was studied and the two-stage internal dumping control measure was put forward and analyzed based on the principle of RFPA strength reduction method. The results show:1) The failure mechanism of South slope is that the damage occurred first in the upper part of the slope, then moved along the weak layer to the middle of the slope, and then was restrained by the surface of unconformity in the lower part of the slope, and finally cut out the bottom of the pit along the middle of the weak layer. 2) The two-stage internal dumping foot-pressing scheme control measure can significantly restrain the movement of weak layer. When the dumping stacked to -262 m level, the movement of weak layer was partially restrained,and the phenomenon of bottom bulging was disappeared; when the dumping stacked to -212 m level, the movement of weak layer was completely restrained, at that moment the slope safety factor was 1.324, which meets the safety requirements.

In order to solve the problem of exfoliation and collapse of pyroclastic rocks during drilling, the authors studied the effect of drilling fluid performance on the disintegration of pyroclastic rocks. The samples of pyroclastic rocks in the Akechukesai mining area of Qinghai were taken to analyze the mineral composition of rocks, and the sample drying and soaking cycle experiments were carried out. The relationship between the main parameters of the original 1^# and 2^# drilling fluids and the slake durability index was analyzed by multiple linear regression analysis. It shows that the correlation between the dynamic performance ratio, static shear force, water loss, funnel viscosity of the drilling fluid and the disintegration of pyroclastic rocks can reach 83.37%. The effect of dynamic plastic ratio on the collapsing of pyroclastic rocks is particularly significant. By adjusting the mass fraction of hydrolyzed polyacrylamide and lignite resin to improve the dynamic fluid ratio and stability of the drilling fluid, the drilling fluid formulation is optimized as:water +4% bentonite +3% sodium carbonate +0.1% sodium hydroxide +0.15% medium viscosity sodium carboxymethyl cellulose +0.5% low viscosity sodium carboxymethyl cellulose +2% lignite resin + 0.08% hydrolyzed polyacrylamide. The field application results show that when drilling to the depth of 429.00 m, the thickness of residual cuttings at the bottom of the hole with the optimized drilling fluid is 89.7% lower than that with the 1^# drilling fluid, and 80.3% lower than that with the 2^# drilling fluid.

In order to obtain the migration and output laws of low permeability coalbed methane in mining of well group combined with thermal injection, a coupled thermal-solid-fluid mathematical model of coalbed methane was developed based on the theory of heat transfer, elastic mechanics, seepage mechanics, and rock mechanics. Combined with the geological parameters of 3# coal seam of Shanxi Formation in Lu'an mining area, the finite software was utilized to simulate seepage rules in the mining process. Under different well pattern, 10 d thermal stimulation and 100 d mining were carried out respectively, and the curves of related parameters, temperature, and stress and gas pressure variation were drawn. The results show that the average velocity of heat transfer of coal seam is 1.57 m/d after 10 d steam injection in the 35 m effective area of thermal stimulation. With the increase of well number and the decrease of well spacing, along the radial direction of well,the well group interference is strengthened, the reservoir pressure drops more quickly, the gas desorption area increases, and the production of well is promoted significantly. The production of cumulative coalbed methane of seven wells heat injection with 20 m well-bore spacing is 2.01 times of that of five wells with 30 m well-bore spacing without heat injection. The simulation results show the advantages of heat injection and inter-well interference,and provide a theoretical basis for coalbed methane mining technology of multi-well combined with thermal injection in low permeability reservoirs.

The Sino-Singapore Tianjin Eco-city is a typical coastal city. Its complex hydrogeological conditions restrict the construction of underground space. In order to find out the vertical distribution of underground water quality, soil samples were collected from 40 m boreholes. The pore water in the core was obtained through gas squeezing. pH, total hardness, TDS, K ⁺, Na ⁺, Ca^{2 +}, CO₃^2-, HCO₃^-, SO₄^2-, Cl^-, Sr, Br, Cl/Br,γNa/γCl and ⁸⁷Sr/⁸⁶Sr were used to discuss the chemical characteristics and influence factors of pore-water. The results show that the vertical mass concentration is significantly different in chemical composition of pore water, the highest value is four times of the lowest one. In the northern area, affected by brines formed by seawater evaporation on coastal beach, the ion maximum concentration (except HCO₃^-) appears in the depth of 5.0 m underground; while in the central and southern area, affected by surface water, the maximum of Cl^-appears in the depth of about 15.0 m, and those of other ions are similar. The pore water within 20.0 m shows the obvious characteristics of modern seawater. The pore water chemistry below 20.0 m is controlled by water and rock interactions, and is significantly affected by paleo-sedimentary seawater.

Nano-FeS was modified by sodium carboxymethyl cellulose (CMC) and guar gum to improve its performance of stability and migration. The sedimentation properties, migration properties, and deposition rates of three kinds of ferrous sulfide (CMC-FeS, GG-FeS, and Nano-FeS) were studied experimentally. According to the theory of colloid filtration, the maximum migration distances of the three kinds of FeS in different media were calculated. The results showed that the anti-settling property was CMC-FeS > GG-FeS >> Nano-FeS, and the polymer improved the suspending stability of FeS. The penetration curves showed that the penetrating ability (the ratio of outflow concentration ρ_i to injection concentration ρ₀) of the three kinds of FeS in three media was CMC-FeS > GG-FeS > Nano-FeS, and the penetration ability of CMC-FeS was higher than that of GG-FeS in coarse and medium sand, but was similar to that of GG-FeS in fine sand. It shows that the shear thinning property of guar gum is more conducive to the migration of GG-FeS in fine granular media. With the increase of FeS concentration,more FeS will be deposited in the medium, but polymer modification can significantly reduce the deposition rate:GG-FeS References | Related Articles | Metrics

By using high-surface-area activated carbon as adsorbent manufacturing electrode, the authors studied the effects of capacitive deionization for cadmium removal from groundwater, and discussed the influences of initial concentration, supply voltage and common cation in groundwater on capacitive deionization for cadmium removal. The results show that the adsorption of cadmium by CDI is monolayer adsorption,which conforms to quasi-second order adsorption kinetics, and satisfies Langmuir isothermal adsorption equation. The adsorption capacity increases with the increase of the initial concentration; at lower concentration, higher voltage increases the adsorption rate at initial stage, but has no significant effect on the final adsorption capacity of the electrode; the main cations in underground water increase conductivity of solution and improve cadmium adsorption rate and removal rate.

In order to establish a simple, rapid and specific method for detecting 17β-estradiol in complex environmental water, we prepared a novel fluorescence probe by using graphite nanoparticles(GN) as excellent quencher, aptamers as recognition elements,and 1-pyrenebutyric acid N-hydroxysuccinimide ester as heterobifunctional crosslinking reagent. We studied the effects of initial concentration of aptamer on the construction of aptamer probe, the change of aptamer probe's concentration on fluorescence signals, and the optimal conditions for 17β-estradiol detection. The results showed that the aptamers were successfully anchored on the surface of GN, and the fluorescence aptamer probe was well synthesized. The optimum initial concentration of aptamer for the preparation of fluorescence probe was 1.0 μmol/L; the optimum concentration of the fluorescent probe for analysis was 4 μg/mL. Under the optimal condition, the relative fluorescence intensity was proportional to the concentration of 17β-estradiol ranging from 50 to 800 ng/mL, and the limit of detection was 34.5 ng/mL. This method is simple, quick and specific for the detection of 17β-estradiol.

With the continuous depletion of conventional oil and gas resources, the exploration and development of unconventional oil and gas reservoirs have gradually become an inevitable trend, which makes micro-seismic monitoring technology develop rapidly. The duration of microseismic events is relatively short,and the frequency of sound waves is relatively high, which result in a low signal-to-noise ratio of the microseismic data collected by actual acquisition. Firstly, the authors briefly introduce in this paper the possibility of guaranteeing high productivity in unconventional oil and gas development by microseismic monitoring technology, and the importance of microseismic noise suppression in data processing, as it directly affects the accuracy and reliability of subsequent microseismic research. Then, the noise sources and several common noise types in the ground microseismic monitoring data are summarized,such as strong pulse interference, 50 Hz industrial alternating current interference, drilling interference, acoustic interference, regular interference, and their basic characteristics are analyzed. The results of denoising methods in the ground microseismic data are classified according to the characteristics of frequency, direction of propagation,and spatial distribution area,also the noise types and the influences of various denoising methods on effective signals are discussed. Finally, based on the stronger representation abilities of deep learning complex functions, the structure and characteristics of three typical deep learning models are analyzed. In combination with the successful application of data denoising in other related fields,deep learning can solve the problem of noise suppression of current microseismic data, and can be used as a new method for microseismic data denoising. Considering that the current number of microseismic data samples may affect the large-scale application of deep learning in microseismic monitoring, the authors propose to build a microseismic data sample library by generating countermeasure network to solve this problem,and which can be used in model training in the subsequent deep learning processe.

Full-wave seismic inversion is a trend of geological structure interpretation. Seismic first-arrival travel time is an important parameter in processes of providing initial models like tomography. An efficient, accurate and stable method for travel time computation is very important for anisotropic modeling. Firstly, we use the perturbation theory and Taylor's theorem to expand the eikonal equation of the VTI media, by which we achieve the analytical solution of the homogeneous media (Alkhalifa2012); next, we introduce a fast marching method of isotropic media, and use the upwind difference to obtain the single point travel time. Combining with narrowband propulsion technique, we set a new travel-time computation method in VTI media based on the fast matching method. The calculated result is evaluated by comparing with the analytical values of the weak anisotropic homogenous model. The effectiveness and stability of the method is verified through calculating the travel time of the reflected waves in the layered medium model. The theoretical analysis and model trial show that this method is efficient and precise, and can be applied to anisotropic tomography and full wave field migration.

In order to establish a flexible, stable and accurate ray tracing method for complex seabed geological conditions such as rugged seabed, steep slope seabed, submarine volcano, and to analyze the kinematic characteristics of different types of seismic waves, we put forward a fast marching upwind interpolation method through taking the advantages of many kinds of algorithms together. Firstly, a complex seabed model is built by using hybrid grids. Secondly, through incorporating the idea of upwind differences, the linear interpolation scheme is adapted to construct high precision,unconditionally stable, and flexible local computational formulas for travel-time and ray-path. Then, by using these formulas and the flexibility of the fast marching method, the travel-time information of various types of seismic waves in the whole model are calculated, and by using reverse tracing, the ray-path is calculated. Finally, the accuracy of this method is analyzed. It is found that the computational accuracy is relatively high by using this method for travel-time and ray-path, and the computational accuracy of reflected waves is much higher than that of incident waves. Furthermore, based on some computational examples, the kinematic characteristics of seismic waves can be obtained, for example, refracted waves are abundant in the first-arrival wave, reflected wave caused by steep structures can be received at large offsets, and the ray paths of various waves are complicated in rugged seabed, etc. Finally, based on the above kinematic characteristics, we suggest to use the travel-time of direct wave for replacing the one of first-arrival wave and increase the length of acquisition array to improve imaging quality of steep dip structures.

Land subsidence occurs often in the plain of the northern Henan Province.It is very important to rapidly and effectively grasp the information of land subsidence and settlement to the construction of central plains urban agglomeration.Using high and medium resolution data of RADARSAT-2 radar and SBAS-InSAR technology,the land subsidence monitoring records of north Henan Plain from 2014 to 2016 were obtained.The records show that in the two years the whole land subsided in Henan Province,of which eight areas were more seriou swith about 3 006 km² subsidence, and the settlement rate of each area was approximately 25.00-114.85 mm/a. Among them, except the maximum settlement rate of Baibi Town-Neihuang County and Hui County was 95.36 and 114.85 mm/a respectively, the maximum settlement rate of the other six subsidence areas was less than 73.58 mm/a.According to the field investigation and comprehensive analysis of the settlement areas, the land subsidence in north Henan Plain is mainly caused by active faults, soft rock, groundwater overdraft, urban construction activities, and oil and geothermal mining.The authors suggests that the prevention and control of ground subsidence in north Henan Plain should be focused on the excess exploitation of groundwater and overloading of soft rock soil layer caused by city construction.

In the application of digital close-range photogrammetry, a certain number of control points should be set up to quickly obtain the geometric information of rock mass discontinuities;however the rock structure surface in a special area (tunnel, chamber, and quarry) is relatively fragmented, the characteristic points are extremely insignificant. Under the influence of construction schedule, the control points cannot be placed. To solve this problem, a self-designed portable controller framework was used, on which 28 control points were placed, and the rock mass discontinuities were photographed and interpreted by using VZ workstation to determine the spatial coordinates of the feature points. After this the information of structural planes was obtained according to the given formula. Taking the rock slope of Jingyue No.2 Quarry as the research object, the portable controller frame was installed and inspected, the collection of the external data and the processing of the internal data were carried out. Through point accuracy evaluation based on error theory, the control point coordinates of interpretation and the orientation of rock mass discontinuity were compared with the measured and the accuracy was analyzed. The results show that this method is feasible,and it opens up a new way to rapidly obtain the geometric information of rock mass discontinuities in special areas where it is inconvenient to place control points.

In the process of 3D geological modeling, interpolation algorithm has a significant influence on the accuracy of the model. In order to evaluate the influence of different interpolation algorithms on 3D modeling, the inverse distance weight interpolation and the natural neighborhood interpolation methods were selected to make a comparative study. Through theoretical analyses and case studies, these two methods were analyzed and compared in aspects of statistics, interpolation errors,and visualization. The results show that the inverse distance weight interpolation method has higher accuracy and wider adaptation area in modeling. Compared to the natural neighborhood interpolation method, the inverse distance weight interpolation method is, at first, more applicable to the area where some strata lack seriously, and can better retain characteristics of the lacked strata. Next,the method is able to handle fault structures and perform better for the fault fluctuation of strata. Finally, its result has a smaller error in sedimentary strata, and is closer to the actual situation.