Cambrian carbonate rocks are key targets for regional oil and gas exploration in the northern margin of the North China craton. The study of sedimentary environment and sequence stratigraphic framework is meaningful to stratigraphic correlating and reservoir locating, it can provide clues for the Cambrian oil and gas exploration in North China. Based on outcrop and core observation, thin section analysis, microscope interpretation and geochemical analysis, the lithology, lithofacies and the stack mode of strata were studied, and the sedimentary trend and the division of sequence stratigraphy were discussed. The authors consider that a massive transgression was happened from south to north after Proterozoic in the northern margin of the North China craton, which was controlled by global eustatic sea level changes. Under the double restriction of clastic supply and carbonatite accretion, the North China craton experienced an evolution process of carbonate platform from being built, developed to rimmed. Bordered by Zhangxia Formation, the Lower-Middle Cambrian performed as a gentle slope-shelf environment, while the Upper Cambrian was a rimmed platform. The Cambrian strata in the northern margin of North China can be divided into 7 third-order sequences with different types of boundaries, which are regionally correlated. The most high level system tracts always form a thick-layer carbonate rocks, which are the most important oil and gas reservoirs.

The buried-hill in Wangjiagang-Bamianhe area has a low exploration degree in the south slope of Dongying depression. Its complicated residual stratigraphic structure and unclear development pattern seriously restrict the buried-hill exploration. In this study, the distribution of the residual formation was determined by lithostratigraphic correlation in field, pale-biostratigraphic division, and seismic calibration and trace; meanwhile, based on the technology of tectonic evolution recovery, the control of multiple tectonic movements on formation erosion and residual is clarified. The results show that the study area was affected by many tectonic movements such as the compressional orogenesis of Indo-china movement and extensional rifting of Yanshan movement, the residual strata of buried-hill show a pattern of seesaw type in east-west direction because of the frequent squeezing and stretching; simultaneously, the Mesozoic-Paleozoic formation was controlled by a series of north-west faults. The formation in the uplifted side of north-west faults generally is eroded seriously; while in the downthrown side, the Mesozoic is characterized by the characteristics of "near thick far thin", and the Upper Paleozoic has the characteristics of:"thin or convex bottom", and the formation of Lower Paleozoic is stable.

Based on the investigation of petroleum geology in the northern Mohe basin, we determined the distribution range of hydrocarbon source rocks (including carbonaceous mudstone) closely related to the formation of oil and gas, which provide a target area for the next step to find oil and gas resources. The results show that the source rocks in Mohe basin are black mudstones with total organic carbon w(TOC) of 0.20%-30.30%. We delineated 26 source rock areas of 134.69 km². The pyrolysis T_max (℃) average value of hydrocarbon source rocks is 442℃, indicating that the evolution of source rock is in the mature-over mature stage. Through the analysis of the hydrocarbon geological conditions in the northwest of Mohe basin, the Middle Jurassic sedimentary rocks provide a good space for oil and gas storage; the Mesozoic magmatic activities and ductile shearing provide a suitable temperature for oil and gas formation; the extensional faults, fissures and cataclastic structures provide migration channels and storage space for oil and gas migration and storage.

A device was designed and manufactured to release the crushed gas in shales under vacuum. The gas from this device was geochemically and quantitatively analyzed by the device combined with the enrichment module and gas chromatography. Meanwhile, the comprehensive chemical composition and the stable carbon isotopic composition were obtained through analyzing the gas sealed in the glass tube. With the mixed standard gases calibrating, the correlation coefficient between concentrations of organic and inorganic gases and gas chromatographic response reached 0.999, which indicates that the device is stable for a quantitative analysis of the crushed gas. The result showed a good parallelism between the gas yields and stable carbon isotope values when the different outcrop shales (the Lower Silurian Longmaxi Formation in Xishui County, Guizhou, the Lower Cambrian Niutitang Formation in Mufu Mountain, Nanjing and Upper Triassic Yanchang Formation in Yan'an, Shaanxi) were analyzed, and reported the chemical and stable carbon isotopic compositions of the crushed gases of the core samples from the Lower Silurian Longmaxi Formation, southern Sichuan basin. The results revealed that the crushed gases are mainly inorganic gases (N₂ and CO₂) with a little hydrocarbon gas that are mainly composed of CH₄ and extremely low content of C₂H₆ and C₃H₈. The δ¹³C₁ values of crushed gas range from -38.1‰ to -33.9‰ with a mean value of -35.8‰, which is similar to the value of shale gas in the same area proposed by previous studies. In addition, the crushed gas of shale at low depths of (20-46) m showed a weakly positive relationship between the yield of crushed gas and w(TOC) values/carbonate content, while a negative correlation between the yields of crushed gas with DFT surface area and BJH pore volume. This suggests that the commercial shale gas is possibly originated from the Lower Silurian Longmaxi Formation, corresponding to the strict definition of shale gas. Hence, the crushed gases are neither adsorbed nor dissociated in shale gas reservoir, but sealed up in the enclosed pores in shales.

The orogenic gold deposit is one of the most important gold deposit types in the world. There are a large number of this type of deposits in Southeast Africa, and it is of great significance to study these orogenic gold deposits in this region. On the basis of summarization of the spatial and temporal distribution, metallogenic environment and geological characteristics of the orogenic gold deposits, together with the analysis of the typical orogenic gold deposit in the region, we suggest that the formation of the orogenic gold deposits in the region was closely related to the evolution of the orogenic belt and craton through the three mineralization stages of 3.20-3.00, 2.70-2.55 and 2.10-1.80 Ga. On this basis, four major orogenic gold mineralization potential areas are delineated in Southeast Africa:Kibaran, Ubendian, Pan-Africa and Limpopo.

The Lianzigou gold deposit is located in the west of Xiaoqinling gold mineralization concentrated region, the south margin of the North China craton. The orebodies are hosted in the upper strata of Taihua group and controlled by fault fracture zones or quartz veins. The surficial and zonal potassic alteration is the typical wall rock alteration. The mineral assemblage is quartz-pryite-galena-chalcopyrite±barite±magnetite. For discussion of the ore-forming materials and ore genesis, the S isotopic compositions of pyrites of the gold deposit were measured by using Laser-ablation multi-collector inductively coupled plasma mass spectrometry (LA-MC-ICP-MS). The S isotopic compositions in different ore-forming stages range from -15.27‰ to -11.98‰, with an average of -13.35‰, which is less than the S isotopic value (9.8‰ -12.4‰) of barite. We calculated the total S isotopic value (-5.5‰) of the coexisting barite, which is different from Taihua group and those granites of Yanshanian. Based on the geological characteristics and isotopic compositions, Taihua group had obvious influence on the source of the ore-forming materials than those granites of Yanshanian (Huashan pluton), but not the major source. Deep fluids or pluton is the possible mineralization sources of the Lianzigou gold deposit. The gold deposit is controlled by deep fluids and structure. There is a potential to find structural altered rock type or fine disseminated type of gold deposits in the deep part,but its scale will be limited.

The Shenshan Fe-Cu deposit is the only skarn Fe-Cu deposit discovered in the Middle Great Hinggan Mountains, Inner Mongolia. We focused on the geochemistry features and zircon LA-ICP-MS U-Pb chronology of the intrusions related to the mineralization of the deposit. The Yilite intrusion in Shenshan district is of tonalite, potash rich calc-alkali and magnetite series. The tonalite is characterized by peraluminous, enriched in light rare earth elements, large ion lithophile elements, depleted of high field-strength elements. Its Ce anomalies (δCe) are 0.86-0.92 with no Eu anomalies (δEu of 0.97-1.17). The Zircon LA-ICP-MS U-Pb yields a concordant age of (155.3±1.3) Ma, which reveals that the Yilite intrusion formed in Late Jurassic. The results also show that the Shenshan Fe-Cu deposit was mineralized in Late Jurassic. The geochemistry characteristics of the Yilite intrusion reveal a tectonic setting of thicken crust and tectonic activation in Late Jurassic.

Located in the south section of the Daxing'anling metallogenic belt, the Baiyinnuoer Pb-Zn deposit is a typical skarn deposit. In order to determine the mineralization age of the deposit, LA-ICP-MS U-Pb dating of zircons in the granodiorite porphyry and rhyolite porphyry associated with the mineralization was studied. The results suggest that the granodiorite and rhyolite porphyry were crystallized in (253.4±0.9) Ma and (133.6±0.7) Ma. The rock geochemistry indicates that the granodiorite is quasi-aluminous,and the rhyolite porphyry is excessive-aluminous. Both of them are characterized by fractionation of HREE and LREE, enrichment of large ion lithophile elements (LILE) and relative depletion of high field strength elements (HFSE). Combined with the geological characteristics and the previous research in this region, we conclude that two mineralization events occurred in the deposit with the early mineralization at about 253.4 Ma and the late one at about 133.6 Ma. The early mineralization may be related to the closure of the Paleo-Asian Ocean and the late mineralization was influenced by the subduction of the Mongolia-Okhotsk Ocean. The Baiyinnuoer Pb-Zn deposit was formed in the post-collisional extension.

The authors discussed the petrogenesis and sedimentary environment of the Permian cherts from the Maihanhada Formation in Haobiru and Hangwula sections of Alxa Right Banner according to the study of the petrologic characteristics,major and rare earth elements. The geochemical test results show that the SiO₂ content of the cherts from Haobiru Section is 89.83%-94.16%,with an average of 92.01%;Al/(Al+Fe+Mn) ratio is 0.49-0.65,with an average of 0.56;δCe value is 0.87-0.92,with an average of 0.89. The SiO₂ content of the cherts from Hangwula Section is 75.93%-90.14%,with an average of 86.70%;Al/(Al+Fe+Mn) ratio is 0.68-0.78, with an average of 0.73; δCe value is 0.89-0.94, with an average of 0.90. In the Al-Fe-Mn triangular graph, the dots fall into the biochemically deposited area,which indicates its biochemical origin. On the other hand,Al₂O₃/(Al₂O₃+Fe₂O₃)value from Haobiru Section is 0.59-0.78,with an average of 0.71;MnO/TiO₂ value is 0.17-0.88,with an average of 0.41;(La/Ce)_N value is 1.07-1.25,with an average of 1.16; Ceanom value is -0.059——0.026,with an average of -0.043; Al₂O₃/(Al₂O₃+Fe₂O₃) value from Hangwula Section is 0.78-0.86,with an average of 0.83;MnO/TiO₂ value is 0.04-0.40,with an average of 0.16;(La/Ce)_N value is 1.02-1.15, with an average of 1.10;Ceanom value is -0.041——0.001, with an average of -0.029. In the discrimination plot of sedimentary environment of cherts,the rocks fall in the continental margin,indicating that the cherts in the study area were deposited in an oxygen-deficient environment. Based on the comprehensive analysis,it can be inferred that the sediments in the study area had been deposited in a coastal shallow marine environment in the continental margin during Early Permian.

To constrain the characteristics of sedimentary provenance and sedimentary tectonic setting of the Early Paleozoic Chenming Formation located in the eastern Heilongjiang Province, its geochemical characteristics were studied. The results show that the I_CA and I_PA values measured from the rock samples of Chenming Formation are relatively low, while their I_CV values are moderate, indicating that the sediments of Chenming Formation came from an immature source, and experienced weak chemical weathering and initial circulation in an active tectonic environment. The enriched LREE, flat HREE pattern and obvious negative Eu-anomaly are suggestive to the obvious upper crustal characteristics of the materials in sedimentary provenance, and the source rocks of the sediments might be felsic igneous rocks.The geochemical analyses on major, trace elements as well as rare earth elements demonstrate that Chenming Formation might be deposited in an active continental margin or continental island arc environment. Combined with the previous literatures, the source rocks of Chenming Formation might be the Early Paleozoic granite, which were altered by weak to moderate weathering, and the sedimentary tectonic setting might be an active continental margin that was adjacent to island arcs.

The study area is located in the northeastern part of the Xing'an block in DaXing'anling. The main types of rocks focused on are alkali feldspar granite and granite porphyry, and their formation age, geochemical characteristics, genesis and tectonic setting were studied in depth. The results show that SiO₂ has a high mass fraction, with high A1₂O₃, TFeO/MgO, poor MgO, TiO₂, P₂O₅, etc.. A/NK-A/CNK and w(K₂O)-w(SiO₂) diagrams show that the samples are mainly of peraluminous, high potassium calc alkaline granites. All the (Na₂O+K₂O)/CaO-w(Zr+Nb+Ce+Y), TFeO/MgO-w(Zr+Nb+Ce+Y) and zircon saturation temperatures show that the rocks are of highly fractionated I-type granites. The emplacement age of the rock mass obtained from zircon LA-ICP-MS U-Pb dating is 128-124 Ma. It is concluded that the tectonic setting of the geotectonic background was the crustal extension in the late stage of continental collision orogeny after the extinction of the Mongolia-Okhotsk Ocean. The magma was originated from the partial melting of igneous source rocks.

In order to deeply understand the geological features of loess, the super high-rise and thick loess foundation was selected as the study object in Qingyang, to investigate the physical and mechanical properties of Longdong loess. Mainly through in-situ and indoor experiments, all sides of loess engineering performance were comprehensively analyzed and evaluated, including the under structure, depth of distribution, liquid limit, plastic limit, index of plasticity, void ratio, collapsible deformation, shear wave velocity, bearing capacity of foundation, shear strength, and so on. The results showed that:Malan loess within 5.0 m had strong collapsibility, small cohesive force, and large compressibility; with the gradual increase of loess thickness, the cohesive force of Lishi loess and Wucheng loess increased, while the compressibility decreased, showing a slight to moderate collapsibility;when the pressure of Malan loess exceeded 400 kPa, the pressure of Lishi loess was greater than 600 kPa, and that of Wucheng loess was greater than 200 kPa, with no collapsibility; the maximum dry density was 1.67-1.76 g/cm³, and the optimal water content was between 16.6% and 17.7% within 15.0 m; the high water content was relatively concentrated in the region below 62.0 m of groundwater level and above 90.0% of saturation.

In order to solve the problem of cutting slope instability caused by reactivation of old landslides,taking a instable cutting slope along with expressway as an example, the cutting excavation and the effect of advance support was studied with the help of numerical analysis. The main conclusions and suggestions are as follows:1) The overall stability of the slope can be improved by the wide platform excavation mode. However, the wide platform excavation mode is not conducive to the stability of the old traction landslide with the existence of weak structural plane, weak interlayer and sliding zone with expansion properties. Advance support must be adopted, such as anchor rope, anti-slide pile and so on, and unloading measures also should be taken urgently when necessary. 2) Anchor cable pre support can effectively restrain the cutting deformation, so effective measures should be taken to improve the tensile strength of anchor, which is arranged at slope toe or to apply pre-stressing force. 3) In advance anti-slide pile supporting, attention should be paid to the design optimization of pile position, pile length and pile spacing. Anti-slide pile should be anchored by bolts, and the sliding zone in front of the pile should be used for pre grouting; and it is necessary to arrange multi row anti-slide piles along the main sliding direction of the old landslide, or to adopt the h-type pile design.

The beam centrifuge pile-jacking system of the University of Western Australia was employed to carry out the penetration mechanism of jacked pile in clay. A series of T-bar tests, sinking pile tests, pile tensile tests and pile compression tests were made in two-layered kaolin clay. The comparison and analysis were conducted to the applications of T-bar in homogeneous soft clay and in two-layered clay by measuring the undrained shear strength with different penetration depth. The profiles of penetration resistance, end resistance and shaft resistance during the pile installation as well as the changing of pile radial stresses during the pile installation were investigated. The different relationships between pile final pressure and pile bearing capacity were revealed. The results show that shaft resistance plays a major role in the whole pile penetration resistance in clay; for the same soil layer, the pile end resistance is not affected by the properties of adjacent soil layers when the pile end exceeds a certain range of influence below the soil interface; in addition, the time effect of pile shaft friction on bearing capacity is greater than that of end resistance.

This study is to explore the applicability of the response displacement method to the seismic analysis of underground utility tunnels as well as the determination and modeling of foundation spring stiffness. SAP2000 software for finite element structural analysis was adopted to analyze the seismic response of underground structures and probe into the influence of different calculation methods of modulus of subgrade reaction and shear stress of soil on the seismic response of structures. The results were compared with those derived from dynamic time-history analysis in PLAXIS. According to the research, the response displacement method is clearly preferable in the preliminary seismic calculation of underground utility tunnels. In the calculation of foundation spring stiffness, the Japanese empirical formula and the conventional static finite element methods are advisable; meanwhile, the layering of soil should be considered as much as possible, because the obsessive equivalent linearization may result in a larger shear modulus of soil, and the deviation of the internal force of the structure can reach -400%—-250% compared with the results of the dynamic time history method. When applying foundation springs to the seismic response calculation model, it is recommended that two-node compression-only gap elements in SAP2000 be adopted to simulate normal foundation springs by combining distally fixed hinge supports, and the conventional soil spring elements be adopted to simulate tangential foundation elements.

Unsymmetrical load tunnel is a common type encountered in highway and railway construction. Because of its stress features, it is difficult to design and construct unsymmetrical load tunnel. Many researches focus mainly on stress distribution of unsymmetrical load tunnel, the causes of unsymmetrical load tunnel, surrounding rock stability, stress and strain distribution and construction affection etc. Seldom study focus on unsymmetrical load stress ratio and on conditions of unsymmetrical load stress ratio under the condition given of highway and railway design code. In this paper, based on the critical grade and coverage depth corresponding to the condition of the design code of double track railway tunnels, the stress ratios of the symmetrical position of the tunnel were calculated by means of numerical simulation. The results show that:under the premise of safety,when the stress ratio at arch shouldesr of grade Ⅲ surrounding rock is greater than 7.45,the stress ratio of grade Ⅳ(soil)surrounding rock is greater than 2.23,the stress ratio of grade Ⅳ(rock)surrounding rock is greater than 3.34,and the stress ratio of grade Ⅴ surrounding rock is greater than 1.06,the tunnel can be considered as an unsymmetrical load tunnel. The quantitative analysis results under the condition of railway tunnel design code provide a theoretical basis for the quantitative identification of the unsymmetrical load tunnel.

Hot dry rock has the characteristics of high hardness, poor abrasiveness, poor drill-ability, difficult drilling and so on; in drilling, a conventional impregnated diamond bit is easy to slip or quickly wear out. Aiming at these technical problems, we developed a bionic abnormal shape bit to improve its wear-resistance, and the bit was made with referring to a pangolin claw toe as a bionic prototype and combining with the structure and manufacturing techniques of impregnated diamond bit. In field drilling tests of the hot dry rocks in Gonghe County of Qinghai Province, no slip occurred with the bionic abnormal shape bit. Compared to the conventional impregnated diamond bit, the drilling speed of the bionic abnormal shape bit increased by 97.5%, and the life span (bionic drill life is calculated life) increased by 1.268 times. It is proved that the bionic abnormal shape bit can improve drilling efficiency, shorten drilling cycle and save drilling cost in a hard and slippery hot dry rock formation.

Surface irrigation and other agricultural activities cause the input of exogenous materials, such as nitrate, organic matter and so on, which will lead to seasonal fluctuations in the shallow sedimentary aquifers. In this study, the iodine-rich sediments were selected to explore the influence of irrigation practice on iodine mobilization and accumulation in shallow groundwater system. The results show that under the anaerobic conditions, the reduction of iron mineral phase will be promoted by microbes using organic matter as electron donor because of the input of exogenous organic matter. This process can lead to iodine release into the liquid phase from iron oxide/hydroxide surface, mainly in the form of iodine ion in groundwater. With extra NO₃^- input, Fe(Ⅲ) will be reduced to Fe(Ⅱ) until nitrate is consumed completely by microbes using NO₃^- as electron acceptor. The input of exogenous substances by human activities is favorable for the iodine release from solid into shallow groundwater. Iron phase adsorbed by Illite may be the main carrier of solid iodine in shallow aquifers. Under the action of microorganisms, the reductive dissolution of solid Fe is the main controlling factor for release of solid iodine, thereby forming high iodine groundwater in shallow aquifers.

Sulfidated nanoscale zerovalent iron (S-nZVI) is a new nZVI modified material with core-shell structure, and exhibits a higher reactivity towards various contaminants than nZVI. In this study, S-nZVI was synthesized by a two-step method. S-nZVI and nZVI were investigated by transmission electron microscope-energy dispersive X-ray spectroscopy (TEM-EDX), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). The effects of n(S)/n(Fe), initial pH, reagent dosage and groundwater chemical composition on Cr(Ⅵ) removal by nZVI and S-nZVI were evaluated. The results showed that S-nZVI has obvious core-shell structure, and the core of Fe⁰ is coated with amorphous ferrous sulfide and polysulfide. The optimum n(S)/n(Fe) was 0.14 for the reaction between S-nZVI and Cr(Ⅵ). The increased dosage of S-nZVI enhanced Cr(Ⅵ) removal efficiency. With the same dosage, the Cr (VI) removal efficiency by S-nZVI was significantly higher than that by nZVI. When pH increased, the Cr(Ⅵ) removal efficiency by both S-nZVI and nZVI decreased gradually. But the efficiency and removal rate by S-nZVI were always higher than by nZVI under the same pH. Especially at pH=5, S-nZVI removed 100% of Cr(Ⅵ), whereas nZVI removed 85%. K⁺, Na⁺, Ca²⁺, Mg²⁺, SO₄^2-, NO₃^-, and Cl^- promoted Cr(Ⅵ) removal by both S-nZVI and nZVI, but more effectively in S-nZVI system. The presence of HCO₃^- increased the solution pH, and thus inhibited Cr(Ⅵ) removal more stronger in nZVI than S-nZVI systems. S-nZVI shows a higher efficiency of Cr(Ⅵ) removal than nZVI under the influence of various pH and groundwater chemical components, so it has a broader application prospect.

Ultrasound enhanced zero-valent iron (ZVI) activated persulfate process to degrade 1,4-dioxane in groundwater was studied, and the effects of ultrasound, ZVI dosage, concentration of persulfate and carbonate ions were also investigated. ZVI was characterized by X-ray photo electron spectroscopy (XPS) and scanning electron microscope (SEM). The results show that ultrasound can accelerate the generation of sulfate radicals and Fe²⁺, and enhance the degradation of 1,4-dioxane. The degradation efficiency can be increased through increasing ZVI dosage and persulfate concentration;however, the final degradation efficiency of 1,4-dioxane decreases when Fe⁰ dosage is much more than persulfate. The presence of carbonate ions in groundwater reduces the concentration of sulfate radicals, thus the efficiency of 1,4-dioxane degradation decreases with the increase of carbonate concentration. In conclusion, ultrasound enhanced ZVI-activated persulfate process can effectively degrade 1,4-dioxane, is a promising method in the treatment of 1,4-dioxane in groundwater.

After entering underground, light non-aqueous phase liquid (LNAPL) will firstly migrate vertically in unsaturated zone, and then form a saturated lens above the water table when reaching the capillary zone. Precisely predicting the lens thickness in the capillary fringe is of great significance for the restoration of polluted aquifer. The authors measured the initial drainage curve and initial wetting curve of the water-oil phase through laboratory experiment, and then fitted the entry pressure with the saturation-pressure curve. According to the relationship between the drainage entry and wetting entry pressures when the lens become stable, a method to predict the thickness of the lens was established. A case study of medium sand and coarse sand shows that the predicted thickness of the lenses are 4.61 and 1.29 cm,respectively;while by laboratory experiments, the measured lens thickness are 5.30, 1.50 cm, respectively. The relative errors between the predicted and measured results are 13.0%, 14.0%, respectively. We can hardly get the absolute drainage or wetting curves in laboratory, therefore the lens thickness predicted is smaller than measured in laboratory.

Deep-sea exploration with high precision is one of the research focuses in marine exploration. The traditional exploration by using a towed transmitter in seawater while positioning receiver at seafloor has the defects that the receivers can easily get lost, the data are instable, and the survey electrodes are influenced by ocean topography. In order to solve these problems, we designed an exploration technique with high working efficiency,reliability and low exploration cost, and developed a 3D DC forward modelling algorithm for accurately recognizing the electric characteristics of the sediment and mineral sources. Based on the previous researches, we put forwarded a towed marine DC resistivity method, and presented a 3D anisotropic forward modelling algorithm for deep-sea DC resistivity method by using finite-elements on unstructured grids for a fully towed DC system with considering the anisotropy of sea sediments at the ocean bottom. We checked the accuracy of our algorithm against 1D semi-analytical solutions for an arbitrarily anisotropic sea bottom. Through the numerical experiment analyses on typical anisotropic models, we demonstrated the high resolution of DC resistivity to the anisotropy of seafloor sediments and minerals. Based on these simulations, we summarized the characteristics of the apparent resistivity when the axis of the anisotropic conductivity rotted around the Descartes coordinate axis, and discussed the influence of the submarine topography on the anisotropic explorations.

In order to effectively detect methane leakage of a sedimentary layer, we designed an in situ electricity monitoring system used in sea floor. The Shenhu gas hydrate production area in South China Sea was selected as the target area, and the corresponding geological models and resistivity models were established to evaluate the detection the capability of the system for methane leakage. The resistivity profiles with different acquisition parameters were calculated and analyzed by simulating and monitoring them with the designed electrical system. The simulation results indicate that the seawater forms a low-resistance stripe concomitant anomaly in a depth range of the detection profile, which suppress electrical signals in corresponding to its position. The top position of the concomitant anomaly can be defined as the effective monitoring depth. The effective monitoring depth is directly affected by the electrode distance, and the effective monitoring depth of the 10 m dipole-dipole array is about 50 m. Within the effective monitoring depth, the detection profile has a good reflection in a layered, agglomerate methane gathering area and a slow methane leaking area. The relative resistivity profiles obtained from the data processing can better reflect the boundaries of methane accumulation zones than electrical profiles. This in situ electricity monitoring system can effectively monitor the spatial variation of a methane leakage area in real time.

An unusual M 5.5 earthquake occurred on October 31st, 2013 in Songyuan City(44.60°N, 124.18°E),Northeastern China, and about 700 shocks were recorded in the following 40 days (5 times earthquakes above M 5.0). In the Songyuan area, earthquake activities have been frequent in recent years. Since January 2014, there have been nine times earthquakes with magnitude above 4.0 and one time with magnitude above 5.0. The epicenter is located in the oil-gas exploration area of Songliao basin, and the seismic sequence is very special. In order to reveal the earthquake mechanism, earthquake model and the relationship between deep geological processes and earthquakes, the magnetotelluric (MT) depth sounder was used to record a NW-SE 25-km-long profile with 23 MT survey points across the epicenter. On the basis of the MT profile, geothermal gradient, gas-phase hydrocarbons yield, ³He/⁴He ratio, carbon isotope analyses of CO₂ gas and the seismic sequence, two low-resistance bodies were recognized at different depths in the epicentral area. The earthquakes are related to the deep mantle magmatism. We propose a new model that the earthquakes are triggered by "magma bubble" bursting. A "magma bubble" is a magma body formed by gradual accumulation of melts at a certain depth below the surface and rises at a certain speed. Magma gathers into magma bubble near the brittle-ductile transition zone. The energy stores in the magma-bubbles, and the strain energy stores in the overlying strata. Earthquakes occur as a result of the sudden energy release from the magma bubble bursting and the consequent overlying strata fracturing. Deep reservoirs of mantle-derived CO₂ can be formed as a result of such long-term seismic activity. This model can explain the occurrence mechanism of many intraplate and deep-seated earthquakes.

Nowadays, fractured reservoirs have attracted more and more attention, and how to effectively identify and evaluate a fractured formation has also been widely discussed. Wave-field separation and HHT were applied to the array acoustic logging data of the gas bearing fractured porous formation in Liaohe basin. The following conclusions are obtained:the presence of fractures and oil/gas causes attenuation of Stoneley wave energy (occurred mainly in high frequency section), basic frequency decrease and time lag, and they are correlated. The Stoneley wave energy and the reflection coefficient become larger along with the increase of the fractures. The ratio of high frequency and low frequency of Stoneley wave is called energy ratio. When the energy ratio is close to zero, it corresponds to the permeable fractured formation; while the energy ratio is relatively small, it may correspond to the permeable porous formation. The IMF retains the inherent physical properties of the raw array acoustic data, and the HHT spectrum contains abundant information, which can highlight the dynamic characteristics of array acoustic waves from time and frequency. Fourier transform and HHT can be used to evaluate the reservoir properties. HHT can magnify the sensitivity of array acoustic signals to formation properties and is easy to analyze and compare.

The topography of tidal flat has the characteristics of rapid change. In the tidal flat area covered by salt marsh vegetation, acquiring topography data by terrestrial laser scanning (TLS) is affected by surface salt marsh. In order to study the precision of TLS on topography of salt marsh covered area and the relationship between its accuracy and vegetation coverage, we took the Phragmites australis, Imperata cylindrica, and Spartina alterniflora communities and Scirpus mariqueter as the research objects. The vegetation filter algorithm,based on the moving window method supplemented by cluster analysis, was used to recover the terrain and topography features from point cloud data. The results showed that:1) the higher the vegetation coverage,the lower the accuracy of TLS topography retrieval was, a negative correlation; 2) the penetration of TLS was different with the type of vegetation:when the vegetation coverage was greater than 50%, the original coverage that laser could not penetrate was 70%, 65% and 65% of Imperata cylindrica, Spartina alterniflora,and Scirpus mariqueter communities respectively, and the root-mean-square error (RMSE) was 22.0, 22.0 and 8.6 cm, respectively; when coverage equaled to 50%, RMSE of topography retrieval was 16.0 cm of Imperata cylindrica community, 6.6 cm of Scirpus mariqueter community, 4.5 and 5.7 cm respectively of Phragmites australis and Spartina alterniflora communities; when coverage was less than 50%, with the decrease of the coverage, the accuracy of topography retrieval of the Phragmites australis, Spartina alterniflora and Scirpus mariqueter communities increased slightly, while that of the Imperata cylindrica community was improved more obviously. 3) When using TLS recover topography in the salt marsh area, the higher and the more of the TLS setting direction in the same area, the better the accuracy of the topography retrieval was.

The uncertainty and complexity of rock discontinuities such as trace length, occurrence and spatial combination form make it difficult to study the whole geometry of structural plane. The discontinuous surfaces with large number of random distributions in rock mass are statistically similar. Using statistical methods to describe the structural plane parameters is the basis for 3D network simulation of rock random discontinuities, and it can also provide a reliable basis for stability evaluation of rock mass. Based on the digital close-range photogrammetry technology, the slope of Dongsheng quarry in Jingyue Development Zone of Changchun City was investigated and studied, and a lot of high precision rock mass structure details were obtained such as long trace occurrence, spacing, aperture geometry parameters. We compiled the Kolmogorov-Smirnov (K-S) test program by Matlab to test the probability distribution of the structure parameters, analyzed the structure parameter types of probability distribution, used SPSS software to test the correctness of the program, and introduced and selected the optimal fitting probability model which accords with a variety of probability distribution parameters. The results show that the length and spacing of the structural surfaces in the study area obey the lognormal distribution, and the shape of the structure obeys the Gamma distribution.