North Dabie terrain (NDT) is located in the core of Dabie orogenic belt, where a large number of migmatites were formed during the collapse of orogen. It is of great significance to understand the formation and evolution of Dabie orogenic belt. The protolith of NDT migmatites are TTG (D) rocks generated from the anatexis induced by dehydration and melting of biotite and amphibolite. The plagioclase-rich leucosome produced in the bedding with Pl+Qtz+Bi±Kfs±Hbl is its major mineral composition. The pegmatite veins or block masses are rich in K-feldspar-rich leucosome with Kfs+Qtz±Pl±Bi±Hbl as its major mineral composition. The melanosome is a crystalloblastic structure with Hbl+Bi+Pl+Qtz±Cpx as its major mineral composition. The amphibolite and biotite in melanosome usually have directional alignment and distinct melting corrosion structures. The main leucocratic minerals in the melanosome are plagioclase and quartzes, indicating the residual products of partial melting. The whole-rock geochemistry shows that alkali metal elements Na, K, large ion lithophile elements Ba, K, La, and LREE etc. have the priority of entering into the acid melt; however, the compatible elements and middle-high rare earth elements remain in the restite minerals. The leucosomes have the same right deviation REE patterns as that of the granitoids, rich in LREE and loss of HREE, but have a large positive Eu anomaly with the ratios of δEu ranging from 2.48 to 6.55; while the granite is on the contrary, the content of the frame structure composed of the large-grain plagioclases is apparently higher than the normal granite melt, which indicates that the leucosomes are more likely the product of the early crystallization of the melts.

For the efficient exploration and development of metamorphic oil fields,it is of great significance to divide the types of metamorphic rock reservoirs and establish the relationship between different types of reservoirs and productivity. Based on the data of core, thin section, physical property, conventional logging, imaging logging,and production logging, the reservoir types,and their logging response characteristics of oil field JZ25-1S in Bohai Bay area were analyzed, and the differences in capacity of different types of reservoirs were discussed. The results show that there are weathering crust type reservoirs, inner-broken reservoirs, and inner-fracture reservoirs developed, and their main space types are dissolution pores-fractures, inter-gravel pores, and structural fractures respectively with different logging response characteristics. The reservoir with capacity greater than 2 m³/d per meter is defined as efficient seepage reservoir. The weathering crust and the inner broken zone are the main effective seepage reservoirs, and the seepage capacity of the inner fractured reservoirs changes greatly. The reservoir type, fracture density and the direction of fracture strike, and the main stress direction control the capacity difference of the metamorphic rock reservoirs

A large number of glutenite fans are developed in the north steep slope of Dongying depression;which is important in oil and gas exploration and development. In this paper, we focus on the sand-bearing conglomerate fan body and its gravity flow sedimentation in the north member of the No. 563 block in the northeast part of Dongying. Through the fine description of the core, the glutenite fan body is divided into eleven facies by lithology, grain size,and structure;then, with the same hydrodynamic conditions as the unit, according to lithology and sedimentary mechanism the lithofacies are combined vertically into eight hydrodynamic types and eight lithofacies combination types. Based on the spatial distribution, scale, contact relationship,and various environments represented by the seven types of mudstone subdivided by the structure and texture of the mudstone in the sediment, five types of sediments are defined for the glutenite fan:thick gravel deposits at the proximal end, restricted water channel deposit, unrestricted tongue deposit, non-channel thin layer deposit, and distal fine grain deposit. Based on a comprehensive analysis of features,six sedimentary microfacies types are identified,including fan root channel, channel, fan-shaped water channel, water channel, fan front edge,and fan end mud. It is believed that the glutenite fan in this area is a near-shore submerged fan. On the basis above, the sedimentary process and sedimentary model of the glutenite fan in this area are finally established.

Based on fractal theory, the pore structures of tight sandstone of Yanchang Formation in Ordos basin were characterized by high pressure mercury intrusion (HPMI) and nuclear magnetic resonance (NMR). The fractal dimension from mercury intrusion capillary pressure was calculated by 3D capillary tube model and wetting phase model, the fractal dimensions of macropores, mesopores, micropores and total pores from NMR T₂ spectra were calculated by NMR model, and the correlations between the calculated fractal dimension and petrophysical properties were analyzed. The research results show that the fractal dimensions calculated by mercury capillary pressure and capillary tube model have a better correlation with the petrophysical properties than those by wetting phase model. With the increase of fractal dimension, the median pore radius decreases, the pore structure heterogeneity increases, and the petrophysical properties of tight sandstone become worse; the fractal dimensions of total pores are poorly correlated to tight sandstone petrophysical properties. After the pore size ranges are divided into macropores, mesopores,and micropores, the calculated fractal dimensions of macropores and mesopores are strongly correlated to tight sandstone petrophysical properties compared to micropores, and the petrophysical properties become worse with the increase of the fractal dimensions of macropores and mesopores. It shows that tight sandstone petrophysical properties are mainly dominated by macropores and mesopores, and the fractal dimension can effectively characterize the influence of micropores, mesopores, and macropores on the tight sandstone petrophysical properties.

The research of solid bitumen can provide the information about hydrocarbon formation and evolution,which can guide for hydrocarbon exploration and development. Based on the analyses at home and abroad, the definition, origin and classification of solid bitumen, influence of solid bitumen on reservoir properties,and identification of solid bitumen logging are comprehensively expounded. There are various genetic types of solid asphalt, which can be divided into two categories:thermal and cold metamorphism. Solid bitumen reflectance can be used as an index to judge maturity, but transformation relationship should be determined based on the actual geological situation. Solid bitumen can fill up reservoir pores, and pore throats can be blocked. This can result in reservoirs destructed and uneven distributed, however, solid bitumen can be favorable sealing belts for preservation and formation of subtle reservoirs. Solid bitumen has special response characters in nuclear magnetic resonance, and can be identified by NMR T₁/T₂ index, neutron-density cross plot, difference between density porosity and gas porosity, and longitudinal wave slowness-resistivity cross plot. Further analyses on solid bitumen should concentrate on the relationship between its structure and reflectance. The way to calibrate solid bitumen with logging parameters quantitatively will be the difficult and hot spot in the future solid bitumen analyses.

There are abundant oil shale resources accompanied with coal in Tanshan area. Oil shale are mainly existed in coal-bearing strata of the middle and lower part of Yan'an Formation in Middle Jurassic. Based on the oil shale samples of Yan'an Formation obtained from boreholes, the characteristics and sedimentary environments were studied, and the identification basis of oil shale logging was defined in Tanshan area by low-temperature dry distillation, main element measurement,and drilling logging. The research shows that the oil shale in Tanshan area is mainly black, grayish black and dark gray, with light texture, low density,and low hardness. The oil shale has the characteristics of staggered, shell-like fracture, grease, asphalt luster, and block layer development. The oil-bearing ratio is 3.60%-9.00%, the ash is 42.50%-79.05%, the total sulfur is 0.07%-1.37%, and the calorific value is 11.01 kJ/g (average value), which belongs to medium quality because it is siliceous ash, low sulfur, and associated with coal. The content of SiO₂ in oil shale varies greatly from 53.89% to 65.55%, Al₂O₃ is 17.45%-23.29%, K₂O is significantly higher than Na₂O, and Fe₂O₃+MgO value is 12.75%-21.98%, containing many potassium-bearing minerals and magnesium iron components. The Al₂O₃/(CaO+Na₂O) value is 3.09-21.12, which reveals that the stable components in oil shale are high. The logging curves characteristics of oil shale are obviously different from the coal seams and mudstones. The data of gamma, sonic and density of oil shale are between the coal seam and the mudstone, and the resistivity is significantly lower than the coal seam and mudstone. The chemical alteration index of oil shale is 74.87-84.35, Sr/Ba value is 0.33-0.83 with average of 0.61, and Th/U value is 1.00-3.50, indicating that the oil shale sedimentary environment in Tanshan area was a warm, anoxic, and oxygen-poor terrestrial freshwater lake environment.

In order to investigate the potential of oil and gas resources of Upper Permian Leping Formation in Pingle depression, the well GFD1 was deployed to prospect shale gas, coal bed gas, and tight sandstone gas in Qujiang syncline in Fengcheng area, in central Jiangxi Province. The shale gas enrichment model was studied based on the data of drilling, organic geochemistry, petrological parameter, and gas-bearing characteristics, etc. The type of organic matter is mainly type Ⅱ₂-Ⅲ. The total organic carbon (TOC) content in Wangpanli Member and Laoshan Member is sufficient with high-maturity. The average brittle mineral mass percent is 34.84%, which is prone to later fracturing. The high logging of total hydrocarbon indicates that the gas is rich in this syncline. The field desorption shows that the coal bed gas is more than 1.00 m³/t, with an average of 3.54 m³/t, the shale gas content varies between 0.10 and 1.50 m³/t, with an average of 0.54 m³/t, and the tight sandstone gas is lower than 0.30 m³/t. The structure of the north side of Qujiang syncline is normal, while the south side is a reverse fault, which is benefitial for oil and gas sealing.

Nianzigou molybdenum deposit is located in the western part of the Xilamulun molybdenum metallogenic belt at the north margin of North China Craton, which is a medium-sized typical quartz vein type deposit. The ore veins mainly occur in the NNW, NW trending faults developed in the monzonitic granite-moyite intrusions of Early Yanshanian. The hydrothermal mineralization can be divided into four stages:pyrite ±molybdenite+quartz(Ⅰ), molybdenite+pyrite ±chalcapyrite+quartz (Ⅱ), chalcopyrite+pyrite ±sphalerite+quartz (Ⅲ), and quartz ±calcite (Ⅳ). The systematic study on petrography of fluid inclusions, fluid inclusion assemblages,and micro-thermometry shows that the primary ore forming fluids are of high temperature (490-550℃),low-medium salinity NaCl-H₂O type solutions (10%-18%); their δ¹⁸O_H2O-SMOW(2.21‰)and δD_H2O-SMOW(-68.9‰)imply that they were originally from magmatic activities, and continuously up-rose and gathered into ore-controlling faults; later with the gradual decrease of temperature and pressure(380-460℃, 26-40 MPa→360-420℃, 25-30 MPa), the state of immiscible two-phase appeared, and the fluid began to boil, which resulted in the deposition of large amounts of Mo; at the late stage of the fluid evolution, the residual solution mixed with meteoric water. Nianzigou Mo deposit is a medium-high temperature magmatic hydro thermal deposit in Early Yanshanian.

Biliya Valley Ag-Pb-Zn deposit is located in the Derbugan metallogenic belt on the western slope of Great Xing'an Range, which was discovered in recent years. The orebody types are vein, veinlet disseminated, and breccia. The ore bodies occur mainly in the Middle Jurassic intermediate-basic volcanic rocks of Tamulangou Formation and the felsic volcanic rocks of Manketouebo Formation, and are controlled by the NW-extending faults. According to the mineral association, ore fabric, and vein body interpenetration, the ore formed in four stages:silicified quartz + pyrite stage (Ⅰ),quartz + pyrite + sphalerite stage (Ⅱ),quartz+pyrite+sphalerite+galena+argentite+chalcopyrite±tetrahedrite stage (Ⅲ), and quartz + pyrite + calcite + fluorite ±opal stage (Ⅳ). The study on the fluid inclusions(FIs) of quartz and sphalerite shows that the FIs in quartz of the early stages (Ⅰ and Ⅱ) are composed of liquid-rich (WL type) and CO₂-H₂O (C type) types. Their homogenization temperature, salincty, and density vary from 188 to 254℃, 1.83% to 4.79%, and 0.81 to 0.94 g/cm³ respectively, and the fluid in this stage belongs to H₂O-NaCl-CO₂ system with low temper ature and medium-low salinity. The FIs in quartz and sphalerite of the main stage (Ⅲ) are composed of liquid-rich (WL type) type, their homogenization temperature, salincty, and density vary from 160 to 188℃, 3.69% to 7.15%, and 0.92 to 0.96 g/cm³ respectively, and the fluid in this stage generally belongs to H₂O-NaCl-CH₄ system with medium-low temperature and low salinity. The FIs in quartz of the late stage (Ⅳ) are composed of liquid-rich (WL type) and liquid (L type) types, their homogenization temperature, salincty, and density vary from 130 to 165℃, 1.22% to 3.53%, and 0.93 to 0.95 g/cm³ respectively, and the fluid in this stage generally belongs to H₂O-NaCl system with low temperature and low salinity. The hydrogen-oxygen isotope geochemical characteristics of fluid inclusions reveal that the δ¹⁸O_H2O-SMOW and δD_H2O-SMOW values of ore-forming fluids in the early stages vary from -6.3‰ to -5.9‰ and -163.4‰ to -162.7‰, respectively. The δ¹⁸O_H2O-SMOW value of ore-forming fluids in the main stage is -14.4‰, and δD_H2O-SMOW values of ore-forming fluids in the main stage vary from -165.4‰ to -162.0‰. The δ¹⁸O_H2O-SMOW and δD_H2O-SMOW values of ore-forming fluids in the late stage are -19.1‰ and -150.7‰, respectively. The ²⁰⁶Pb/²⁰⁴Pb, ²⁰⁷Pb/²⁰⁴Pb, and ²⁰⁸Pb/²⁰⁴Pb ratios of the lead isotope composition of metal sulfides vary from 18.435 to 18.513, 15.579 to 15.675, and 38.283 to 38.603, respectively. These features reveal that the ore-forming fluids of the deposit belong to H₂O-NaCl-CH₄ system with low temperature and low salinity; and the initial ore-forming fluid was mainly derived from the magmatic water, which was then mixed with meteoric water during mineralization; the ore-forming materials came from a mixed crustal and mantle source. Biliya Valley deposit is a low-sulfidation epithermal Ag-Pb-Zn polymetallic deposit, which is related to the volcanic-subvolcanic activity similar to the same type of deposits in the region. The mineralization occurred in Early Cretaceous (131.3 Ma), in a back-arc extension related subduction of the Paleo-Pacific plate.

Jinan iron deposit is one of the BIF-type of deposits discovered early in the Northeast China, which is located in the north part of Longgang massif, at the joint of the North China craton and the Xing'an-Mongolia orogenic belt. The layered, stratified, and lenticular iron orebodies are mainly hosted within the metamorphic rocks of Jinan Formation, Anshan Group. The ore-bearing rocks mainly include biotite plagioclase gneiss, amphibole biotite plagioclase gneiss, biotite amphibole plagioclase gneiss, and amphibolite, which experienced amphibolite facies regional metamorphism. The ore types are mainly comprised of BIF-type and massive magnetite amphibolite type. To determine the tectonic setting of ore-bearing formation of Jinan deposit, the geochemical analysis and LA-ICP-MS were conducted for the intermediate-basic rocks. The geological and geochemical features, together with the protolith re-constrution diagrams, indicate that the protolith of the amphibolite is sub-alkaline basalt (tholeiite) formed in the back arc basin. The LA-ICP-MS zircon U-Pb dating of the amphibolite shows that the ages of two old metamorphic zircons are (2 468±15) and (2 469±9) Ma, representing the peak metamorphism age in this area (~2 460 Ma). The concentrated ages of 26 metamorphic zircons were (2 275±25) Ma, representing the retrograde metamorphic age in the area. A comprehensive comparison with the typical BIFs both at home and abroad indicates that Jinan and Guandi iron deposit in Helong area belongs to Algoma-type.

Dahu-Qinnan molybdenum deposit in Xiaoqinling is within the Xiong'ershan-Waifangshan metallogenic subzone, which is located at the margin of North China platform. Its mineralization types are divided into Mo-bearing secondary quartzite and vein disseminated associated with granitoid mineralization types. The textures are characterized by breccia,lump,porous,stockwork, and massive. The alterations are dominated by disseminated and stockwork of potassic + sillific + carbonated + argillic + anhydrited. The vein and stockwork with disseminated mineralization is closely associated with the granitoid,occasionally occurs within gneiss nearby the Mo-bearing secondary quartzite. The alterations in vein and stockwork ores are mainly characterized by feldspar + quartz + sericite,with minor pyrite + kaolin + carbonate. The Mo-bearing secondary quartzite ores usually contain granitoid breccia associated with veins. The field evidences show that the Mo-bearing granitoid is disintegrated near its contacted zone to small breccias,and finally disappeared inside of the Mo-bearing secondary quartzite; on the contrary, the Mo-bearing secondary quartzite thickens with the increase of intensive argillic and anhydrite alteration. The results suggest that the Mo-bearing secondary quartzite is derived from the Mo-bearing granitoids.12 samples of molybdenite were taken from the Mo-bearing secondary quartzite and the Mo-bearing granitoids in Dahu-Qinnan molybdenum deposit. The age of Re-Os molybdenite of Dahu-Qinnan molybdenum deposit is (223.6±4.1) Ma to (196.1±3.0) Ma and(197.8±3.2)Ma to(196.1±3.3)Ma. The Re-Os isochron age is (199 + 14/-25) Ma. This result suggests that the molybdenum mineralization of Dahu-Qinnan deposit took place in Indosinian, or early Yanshanian. The excellent correlation between the Re-Os ages from molybdenite and the ages of granitoids in the area indicate a direct genetic relation between the granitic porphyry and syenite porphyry. The similarity of the Mo-bearing granitoids in Dahu-Qinnan deposit and the classic porphyry deposit in mineralization and alteration pattern implies that this area has the porphyry molybdenum deposit potential for the exploration of porphyry molybdenum deposits. The Re content in molybdenite is 0.894×10^-6-2.964×10^-6,indicating that the molybdenum materials come from the crust. Alkaline rocks are dominated during Indosinian,suggesting that the molybdenum mineralization occurred in continental extension tectonics. It is suggested that exploration of molybdenum porphyry should be carried out in Indosinian granitoids.

The western Hunan and eastern Guizhou are located in the southeast margin of the Yangtze craton,where more than 200 Pb-Zn deposits/occurrences are developed. It is one of the important successive strategic bases of Pb-Zn resources in China. In this district, a systematic study is conducted on ore controlling factors and prospecting indicators of Pb-Zn deposits. The Pb-Zn deposits are jointly controlled by stratum, lithofacies, and structures, specifically the lithology assemblages, middle shallow ramp facies, regional faults, anticline, secondary faults,and fractures. The important prospecting indicators of Pb-Zn deposits in this district mainly include oxidation outcrop containing limonite or smithsonite, hydrothermal alterations of calcilization, pyritization, baratization,and bituminization, Pb, Zn, Cd, CaO, Hg geochemical anomalies, and Pb-Zn-Cd combination geochemical anomaly. On the basis of the comprehensive analyses of controlling factors and prospecting indicators, the authors build a geological-geochemical regional prospecting model, which is helpful to conduct comprehensive quantitative prediction by using characteristic analysis method on the GIS platform. According to the prospecting probability contour map of Pb-Zn deposits, two first-class ore prospective areas and two second-class ore prospective areas are delineated. The authors suggest that Songtao, Zhenyuan-Tongren and Duyun-Kaili are the most potential areas for further exploration.

In order to reveal the distribution of Early Yanshanian magmatism and its petrogenetic and metallogenic significance in South China,the authors studied the mineral composition and LA-ICP-MS zircon U-Pb geochronological characteristics of Guposhan pluton, which intruded in Huashan-Guposhan belt in northeast Guangxi. The geochronological analyses show two crystallized ages of (162±3) and (163±2) Ma, which are consistent with the time of Mesozoic large scale magmatism and mineralization in South China. The result of electron microprobe analyzer (EMPA) suggests that the biotite from Guposhan pluton has high TFeO and low MgO contents with Fe/(Fe+Mg) values of 0.68-0.84, resembling those of siderophyllite. The negative correlation between TFeO and MgO shows that the replacement between Fe²⁺ and Mg²⁺ occurred during crystallization of biotite. The data of biotite thermometers show high crystallization temperature of 680-705℃ and low oxygen fugacity of -17.0--15.5. The results of Al-in-biotite barometer indicate the biotite crystallization pressure is 69-179 MPa, suggesting a crystallization depth of 2 621-6 755 m. Integrated with regional geological data, it could be inferred that the Early Yanshanian (~162 Ma) granitic magmatism is a common geological process, and a large scale of lithospheric extension and thinning might be the key mechanism to drive the Mesozoic magmatism and the corresponding mineralization in South China. Relatively high temperature, low oxygen fugacity, and shallow environment are favorable for Sn mineralization.

It is necessary to select an optimal scheme of cutoff wall for earth-rock cofferdams, because the structure of the cutoff wall in the earth-rock cofferdam has an important influence on the seepage flow and the stability of cofferdam. In this paper, the optimal design of the thickness and depth of cutoff wall is studied by finite element method (FEM) taking as an example of a certain earth-rock cofferdam for construction, which is located in the Pearl River basin. The seepage fields based on 33 types of cutoff wall scheme which is composed of no concrete cutoff wall and 32 types of concrete cutoff wall about its thickness and its embedded depth within the weakly weathered rock were simulated. Then the control index, such as the seepage per unit width of cofferdam, the water head behind the cutoff wall, the hydraulic gradient at the bottom of cutoff wall and the cofferdam foot, were calculated and compared with the allowable value. Finally, the optimized anti-seepage scheme of cutoff wall was obtained. The conclusions made are as follows:1) Comparing with the thickness of cutoff wall, increasing the embedded depth within the rock can control more effectively the seepage per unit width of cofferdam and the height of the water head behind cutoff wall. 2) The change of hydraulic gradient at the bottom of cutoff wall is related to the depth of cutoff wall within the weakly weathered rock. Increasing the depth of cutoff wall from 0 to 8 m, the hydraulic gradient will decrease and will change from fast to slow. When the depth increases from 8 to 12 m, the hydraulic gradient will increase with the embedded depth and there is a significant increase after 10 m. 3) The cutoff wall with 0.8 m in thickness and 2 m in embedded depth within weakly weathered rock is regarded as the optimal anti-seepage scheme for this project after considering the project input and construction convenience. The results not only provide a basis for the design of the earth-rock cofferdam, but also provide a reference for the anti-seepage system of proposed earth-rock cofferdam projects under the same geological conditions.

Traditional field survey of mine geological environment is easily affected by traffic and terrain,and labor intensity, the working efficiency is low, and the cost is high. In this paper, the application of unmanned aerial vehicle (UAV) photogrammetry technology in mine geological environment survey is studied. By taking Changchun Jingyue Dongsheng quarry as the study area, the ground control point coordinates were determined by using the RTK(real-time kinematic), and the geometric information related to the mining environment in the study area was obtained by using DJI Phantom 4 UAV for aerial photography, such as slope orientation, length, height, volume, surface area, landslides, collapsed deposits, and faults. After measurement and interpretation, the 3D model of the study area was established by using Pix4Dmapper, topographic maps, DOM,and DSM of the study area were made,meanwhile,a lot of trace and orientation information of random discontinuities were interpreted. The results show that the mine geological environment survey based on UAV photogrammetry technology can quickly obtain the information of mine geological environment, and the discontinuity dip and dip angle errors obtained are within 5° and 4° respectively, which meet the precision requirement of mine geological environment survey.

The heavy metal elements in soil under natural conditions is a core concern in the solidification remediation of heavy metal pollution. Taking the common heavy metal Pb²⁺ as an example, the authors calculated the binding stability of heavy metals with ion groups in soil through applying the first principle to the analysis. The free energy, energy band,and density of states of PbCO₃, PbSO₄, PbCl₂, Pb₃(PO₄)₂, PbAl₂O_4, and Pb₃Fe₂(PO₄)₄ were calculated. The binding stability of Pb²⁺ with anions in soil such as CO₃^2-, SO₄^2-, Cl^- and PO₄^3- was deduced firstly, and then the influence of adding metal cations of Al³⁺ and Fe³⁺on the stability. The results show that the trend of free energy of lead compounds is Pb₃Fe₂(PO₄)₄ < Pb₃(PO₄)₂ < PbSO₄ < PbCO₃ < PbAl₂O₄ < PbCl₂, and the corresponding order of structural stability is PbCl₂ < PbAl₂O₄ < PbCO₃ < PbSO₄ < Pb₃(PO₄)₂ < Pb₃Fe₂(PO₄)₄. Through the analysis of energy band and density of states, it is considered that the introduction of SO₄^2- and PO₄^3- can enhance the stability of the lead-containing system, and further addition of the metal cation Fe³⁺ will make the system more stable. It is suggested that SO₄^2- and PO₄^3- are suitable functional groups for the treatment of Pb²⁺ pollution, and the substances easily to release SO₄^2- and PO₄^3- should be selected as the appropriate passivator.In future work, sodium dihydrogen phosphate,sodium sulfate and desulfurized gypsum can be used as passivators in field experiments.

The self-gradient effect produced by the vehicle is a serious disturbance to the ultra-high precision of the gravity gradiometer in an airborne gravity gradient survey. Due to the complexity of the vehicle structure, it is difficult to remove these interferences by using conventional modeling and forward calculation accurately. In this article, a multiple linear regression algorithm is used to deal with its own gradient effect, which corrects the interference from the gradient in a pure data-driven way,without making any assumptions or approximations to the vehicle model. Through regression diagnosis and model simulation, this correction method has high accuracy and predictive ability when the actual corner is within the ground calibration range.

The blended acquisition of seismic data is widely used in the industry area; however, the seismic data acquired by such a method contain overlapping shot records of multiple sources, which is not conducive to the subsequent seismic data processing. A modified separation and primary estimation method for blended data based on 3D sparse inversion is proposed in this paper. We introduce the L1 norm bi-convex optimization into the solution process of estimating primary impulse responses by conventional EPSI and SPGL1 algorithm to get the global minima, so that the inversion process is stable. Besides, 2D curvelet transform and 1D wavelet transform are combined into a 3D sparse constraint to improve the calculation speed while ensuring the inversion accuracy. Compared to the conventional EPSI for blended data in the standard industry workflow, the effectiveness and superiority of this proposed method is verified in the application in synthetic data and marine field data.

The existing t₀ method to determine the normal depth of refractive surface has the following problems:firstly, the calculation process is complicated by using the idea of elementary mathematics and introducing the process function into the calculation process; secondly, there are two approximations in the solution, which increases the error of results; finally, when the normal depth curve is smoothed by using the existing method, the manual offset processing is not only time-consuming and laborious, but also causes manual errors. An improved method to determine the normal depth of refractive surface is therefore proposed. This method adopts advanced mathematics without process function, which makes the calculation more accurate through eliminating the approximation problem and reducing the calculation error; and the method smooths the normal depth curve by using the adjacent average method, which improves work efficiency, cuts labor cost, and realizes the whole process of computer processing. In comparison with the results by the existing one, the results by the improved method are more in accord with the changes of true refracted wave depth, therefore it can accurately determine the refractue surface tilt angle.

The regular Pickett plot is derived from Archie formula, which is not suitable for the evaluation of argillaceous formation in the west of the South China Sea. The authors modified the regular Pickett plot based on the Indonesian formula, developed a new Pickett plot for argillaceous formations, and proposed a method for calculating water resistivity and geoelectric parameters accurately by iteration. The study shows that the formation water resistivity calculated by the improved Pickett plot of argillaceous sandstone is consistent with that calculated by pure water layer. In comparison with the empirical value, water resistivity and geoelectric parameters obtained by the iterative method are more consistent with the actual situation.

One of the key techniques for logging evaluation of water-flooded reservoir is to determine the resistivity of the mixed liquid of water-flooded reservoir. At present, the method of calculating the resistivity of the mixed liquid of water-flooded reservoir needs to be improved. In this paper,a dimensional dynamic material balance method is proposed to accurately calculate the resistivity of formation mixed fluid. The method makes the water flooding process microelement and takes into account the variable exchange ratio of original water and the injected water ions in the water flooding process. In theory, the variable gradually changes from 0 to 1 with the increase of flooding degree. The comparison results show that the average relative errors of the rock resistivity calculated by the first derivative method, the variable magnification material balance method, and the improved micro-element dynamic material balance method are 0.192, 0.169, and 0.124 respectively. The improved micro-element dynamic material balance method is more accurate when measuring the mixed solution resistivity in different flooding types. The residual oil saturation can be calculated more accurately in well evaluation. The method has been applied to the well logging evaluation of different flooding types in major oil fields. The calculated water saturation of water-flooded reservoir is the closest to the saturation data of the closed coring. The comprehensive interpretation coincidence rate of the flooded reservoir logging reaches more than 87%.

In order to study the relationship between porosity, permeability and clay content and sandstone-type uranium mineralization, the authors analyzed the sandstone at the bottom of Sifangtai Formation in a block south of Daqing Placanticline in the central depression of Songliao basin. The uranium-bearing ore sandstone has high radioactivity, which makes the density value of the logging curve decrease and the natural gamma value rise abnormally. Through the research, this paper summarizes the method of correcting the density by using the increased natural gamma, and the method of reconstructing natural gamma by using other curves unaffected by radioactivity. Through the comparative analysis with the core, it is proved that the corrected density and the reconstructed natural gamma are more accurate. The problem that the parameters of porosity and permeability of uranium-bearing sandstone are calculated by logging curve is solved by the correction of density and the reconstruction of natural gamma. Based on the accurate calculation of the logging parameters, the spatial distribution and mapping analysis of the physical properties are obtained, which can show the characteristics of heterogeneity in sand body. It is concluded that the sand bodies producing uranium ore are not in the place with the best or the worst porosity and permeability, but in the place with the transition from high porosity and permeability to low porosity and permeability.