Strong Earthquake Model of North China Craton: A Case of 2023 Mw 5.5 Earthquake in Pingyuan County, Shandong Province, China

North China is one of the high-risk areas for destructive strong earthquakes in China's Mainland, with a history of numerous significant seismic events. On August 6, 2023, an Mw5.5 earthquake struck Pingyuan County, Dezhou City, in Shandong Province, China. This earthquake was the largest in the eastern North China Craton(NCC) since the Tangshan earthquake of 1976. Due to the absence of surface ruptures, the fault responsible for the Pingyuan Mw5.5 earthquake remains unclear. To reveal the subsurface geological structure near the earthquake epicenter, this study utilized highresolution two-dimensional seismic reflection profiles to interpret pre-existing faults.

The Distribution of Petroleum Resources and Characteristics of Main Petroliferous Basins along the Silk Road Economic Belt and the 21st-Century Maritime Silk Road

The Silk Road Economic Belt and the 21st-Century Maritime Silk Road Initiative, abbreviated as the Belt and Road Initiative, is a primary development strategy of China＇s future international cooperation. Especially, the energy resource cooperation, including oil and gas resources cooperation, is an important part of this initiative. The Belt and Road has undergone complicated geological evolution, and contains abundant mineral resources such as oil, gas, coal, uranium, iron, copper, gold and manganese ore resources. Among these, Africa holds 7.8% of the world＇s total proven oil reserves. The oil and gas resources in Africa are relatively concentrated, with an overall low exploration degree and small consumption demand. Nigeria and Libya contain the most abundant oil resources in Africa, accounting for 2.2% and 2.9% of the world＇s total reserves, respectively. Nigeria and Algeria hold the richest natural gas resources in Africa, occupying 2.8% and 2.4% of the world＇s total reserves, respectively. Africa＇s oil and gas resources are mainly concentrated in Egypt, Sultan and Western Sahara regions in the northern Africa, and the Gulf of Guinea, Niger River and Congo River area in the western Africa. The Russia--Central Asia area holds rich petroleum resources in Russia, Kazakhstan, Turkmenistan and Uzbekistan. The potential oil and gas areas include the West Siberia Basin, East Siberia Basin and sea continental shelf in Russia, the northern and central Caspian Basin in Kazakhstan, the right bank of the Amu-Darya Basin, the East Karakum uplift and the South Caspian Basin in Turkmenistan, and the Amu-Daria Basin, Fergana Basin, Afghan-Tajik Basin and North Ustyurt Basin in Uzbekistan. The Middle East oil and gas resources are mainly distributed in the Zagros foreland basin and Arabian continental margin basin, and the main oil-producing countries include Saudi Arabia, Iran and Iraq. The Asia Pacific region is a new oil and gas consumption center, with rapid growth of oil and gas demand. In 2012, this region consumed about 33.6% of the world＇s total oil consumption and 18.9% of the world＇s total natural gas consumption, which has been ranked the world＇s largest oil and gas consumption center. The oil and gas resources are concentrated in China, Indosinian, Malaysia, Australia and India. The abundant European proven crude oil reserves are in Norway, Britain and Denmark and also rich natural gas resources in Norway, Holland and Britain. Norway and Britain contain about 77.5% of European proven oil reserves, which accounts for only 0.9% of the world＇s proven reserves. The Europe includes main petroliferous basins of the Voring Basin, Anglo-Dutch Basin, Northwest German Basin, Northeast German-Polish Basin and Carpathian Basin. According to the analysis of source rocks, reservoir rocks, cap rocks and traps for the main petroliferous basins, the potential oil and gas prospecting targets in the Belt and Road are mainly the Zagros Basin and Arabic Platform in the Middle East, the East Barents Sea Basin and the East Siberia Basin in Russia-Central Asia, the Niger Delta Basin, East African rift system and the Australia Northwest Shelf. With the development of oil and gas theory and exploration technology, unconventional petroleum resources will play an increasingly important role in oil and gas industry.

Origin of dolomites in the Permian dolomitic reservoirs of Fengcheng Formation in Mahu Sag,Junggar Basin, NW China

Origin of authigenic dolomites in the dolomitic reservoir of the Permian Fengcheng Formation in the Mahu Sag of Junggar Basin is unclear.Occurrence and genetic evolution of the authigenic dolomites in dolomitic rock reservoir of the Fengcheng Formation in the Mahu Sag were analyzed by polarized and fluorescence thin sections,scanning electron microscope(SEM),electron microprobe(EMP),C,O and Sr isotopes analysis,and other techniques.(1)Dolomites were mainly precipitated in three stages:penecontemporaneous-shallow burial stage(early stage of the Middle Permian),middle burial stage(middle stage of the Middle Permian),and middle-deep burial stage,with the former two stages in dominance.(2)Dolomitization fluid was high-salinity brine originating from alkaline lake.In the penecontemporaneous-shallow burial stage,Mg^(2+)was mainly supplied by alkaline-lake fluid and devitrification of volcanic glass.In the middle burial stage,Mg^(2+)mainly came from the transformation of clay minerals,devitrification of volcanic glass and dissolution of aluminosilicates such as feldspar.(3)Regular changes of Mg,Mn,Fe,Sr,Si and other elements during the growth of dolomite were mainly related to the alkaline-lake fluid,and to different influences of devitrification and diagenetic alteration of volcanic materials during the burial.(4)In the penecontemporaneous stage,induced by alkaline-lake microorganisms,the micritic-microcrystalline dolomites were formed by primary precipitation,replacement of aragonite and high-Mg calcite,and other processes;in the shallow burial stage,the silt-sized dolomites were formed by continuous growth of micritic-microcrystalline dolomite and replacement of calcites,tuffs and other substances;in the middle burial stage,the dolomites,mainly silt-and fine-sized,were formed by replacement of volcanic materials.The research results are referential for investigating the formation mechanism and distribution patterns of tight dolomitic reservoirs in the Mahu Sag and other similar oil and gas bearing areas.

Time-dependent model for two-phase flow in ultra-high water-cut reservoirs:Time-varying permeability and relative permeability

For the ultra-high water-cut reservoirs,after long-term water injection exploitation,the physical properties of the reservoir change and the heterogeneity of the reservoir becomes increasingly severe,which further aggravates the spatial difference of the flow field.In this study,the displacement experiments were employed to investigate the variations in core permeability,porosity,and relative permeability after a large amount of water injection.A relative permeability endpoint model was proposed by utilizing the alternating conditional expectation(ACE)transformation to describe the variation in relative permeability based on the experimental data.Based on the time dependent models for permeability and relative permeability,the traditional oil-water two-phase model was improved and discretized using the mimetic finite difference method(MFD).The two cases were launched to confirm the validation of the proposed model.The impact of time-varying physical features on reservoir production performance was studied in a real water flooding reservoir.The experimental results indicate that the overall relative permeability curve shifts to the right as water injection increases.This shift corresponds to a transition towards a more hydrophilic wettability and a decrease in residual oil saturation.The endpoint model demonstrates excellent accuracy and can be applied to time-varying simulations of reservoir physics.The impact of variations in permeability and relative permeability on the reservoir production performance yields two distinct outcomes.The time-varying permeability of the reservoir results in intensified water channeling and poor development effects.On the other hand,the time-varying relative permeability enhances the oil phase seepage capacity,facilitating oil displacement.The comprehensive time-varying behavior is the result of the combined influence of these two parameters,which closely resemble the actual conditions observed in oil field exploitation.The time-varying simulation technique of reservoir physical properties proposed in this paper can continuously and stably characterize the dynamic changes of reservoir physical properties during water drive development.This approach ensures the reliability of the simulation results regarding residual oil distribution.

The role of provenance in the diagenesis of siliciclastic reservoirs in the Upper Triassic Yanchang Formation,Ordos Basin,China

A better understanding of the controls on reservoir quality has become essential in the petroleum exploration in recent years. Determining the original composition of tile sediment framework is important not only for paleogeographic reconstructions, but it is also vital tbr predicting the nature of physical and chemical diagenesis of the potential reservoirs. Depositional setting and diagenesis are important factors in controlling the type and quality of most siliciclastic reservoirs. We studied the Upper Triassic Chang 8 and 6 members, where the relationship between sediment provenance and diagenesis was examined. The study attempts to clarify sediment provenance and post-depositional diagenetic modifications of the sandstones through systematic analytical methods including petrographic macro- and microscopic analysis of grain and heavy mineral types, and measurements of the palaeocurrent direction of the Yanchang Formation sediments in the outcrops in order to determine the provenance of the studied sediments. Furthermore, the relationship between framework grains, pore types and diagenesis of the sediments was analyzed by thin section petrographic characterization using a polarizing microscope. Additionally, a JEOL JSM-T330 scanning electron microscope （SEM） equipped with a digital imaging system was used to investigate the habits and textural relationships of diagenetic minerals. On the basis of our results, we believe that sediment provenance is a significant factor which controls the type and degree of diagenesis which may be expected in sandstones. In the Chang 8 and 6 members, tile formation of chlorite rims and laumontite cement was observed where volcanic rock fragments constitute a large part of the framework grains. Furthermore, high biotite content provides abundant iron and magnesium and enables the tbnnation of chlorite rims due to biotite hydrolysis. In addition, ductile deformation of biotite leads to strong mechanical compaction of the sediments. Conversely, high feldspar content diminishes the degree of mechanical compaction, however the dissolution of feldspar minerals in sandstones is commonly observed. Apart from feldspars, quartz and other rigid fi＇amework grains highly control the degree of mechanical compaction during the initial stage of burial （0-2 km）.

Present Geothermal Fields of the Dongpu Sag in the Bohai Bay Basin

The Dongpu sag is located in the south of the Bohai Bay basin,China,and has abundant oil and gas reserves.To date,there has been no systematic documentation of its geothermal fields.This study measured the rock thermal conductivity of 324 cores from 47 wells,and calculated rock thermal conductivity for different formations.The geothermal gradient and terrestrial heat flow were calculated for 192 wells on basis of 892 formation-testing data from 523 wells.The results show that the Dongpu sag is characterized by a medium-temperature geothermal field between stable and active tectonic areas,with an average geothermal gradient of 32.0℃/km and terrestrial heat flow of 65.6 mW/m2.The geothermal fields in the Dongpu sag is significantly controlled by the Changyuan,Yellow River,and Lanliao basement faults.They developed in the Paleogene and the Dongying movement occurred at the Dongying Formation depositional period.The geothermal fields distribution has a similar characteristic to the tectonic framework of the Dongpu sag,namely two subsags,one uplift,one steep slope and one gentle slope.The oil and gas distribution is closely associated with the present geothermal fields.The work may provide constraints for reconstructing the thermal history and modeling source rock maturation evolution in the Dongpu sag.

The Seismogenic Structure of the 2010 Suining Ms 5.0 Earthquake and its Geometry,Kinematics and Dynamics Analysis

In January 2010, the Suining Ms5.0 earthquake occurred in central Sichuan Basin, with the epicenter in Moxi-Longnvsi structural belt and a focal depth of 10 km. Based on structural interpretations of seismic profiles in this area, we recognized a regional detachment fault located at a depth of 9-10 km in the Presinian basement of the Suining area, transferring its slipping from NW to SE orientation. This detachment fault slipped from NW to SE, and underwent several shears and bends, which caused the basement to be rolled in and the overlaying strata fold deformation. It formed a fault-bend fold in the Moxi area with an approximate slip of 4 km. Correspondingly, the formation of the Moxi anticline is related to the detachment fault. With the earthquake＇s epicenter on the ramp of the detachment fault, there is a new point of view that the Suining earthquake was caused by re-activation of this basement detachment fault. Since the Late Jurassic period, under the influence of regional tectonic stress, the detachment fault transfered its slip from the Longmen Mountains （LMS） thrust belt to the hinterland of the Sichuan Basin, and finally to the piedmont zone of southwest Huayingshan （HYS）, which indicates that HYS might be the final front area of the LMS thrust belt.

Formation and evolution of Sinian oil and gas pools in typical structures, Sichuan Basin, China

The only major breakthrough in the exploration of the Sinian of the Sichuan Basin has been the Weiyuan gas field. Taking the typical structures in the Sichuan Basin as examples, an apatite fission track simulation was applied to constrain the thermal evolutionary history of the source rocks in this study. Combined with trap formation and evolution, the formation, destruction, and accumulation history of the Sinian reservoirs were analyzed from a dynamic perspective. The Sinian reservoirs underwent several primary stages： the paleo-reservoir formation and destruction in the late Silurian, hydrocarbon recharge in the Permian-Triassic, the cracking of oil to gas and dissolved-gas in the late Triassic-Mid-Late Jurassic, and the exsolution and accumulation of dissolved-gas as a result of episodic uplift since the Late Cretaceous. The exsolution process of dissolved-gas is of great significance to the accumulation of natural gas. The formation of the Weiyuan gas field is also related to this process. The Sinian in the Sichuan Basin has a broad exploration prospect, and exploration targets focused on the Leshan-Longnüsi Paleo-uplift tectonic zone with weak influences on potential hydrocarbon reservoirs from the late tectonism and transformation.

Explosive limits of mixed gases containing CH_4,CO and C_2H_4 in the goaf area

The explosive gases CO and C2H4, released mainly flammable gases during the process of coal self-ignition, are of the most important ingredients of the multi-component gases in goal areas, along with CH4. We have determined some of the parame- ters of explosive properties of the one-component gases CH4, CO and C2H4 using an explosive trial device of polybasic explosive gas mixtures and emphasized particularly the effect on the limits of explosive concentration of the binary explosive mixed gases CH4＋CO, CH4＋C2H4, as a function of the amount of CO, C2H4 and inert flame resisting gases （N2, CO2）. The experimental results show that the effect of inert gases on the explosive limits of mixed gases, given the property of explosive gas, is obvious： the inert gases （N2, CO2） possess some inhibitory effects on the explosion of the multi-component explosive gas mixtures. The results will provide some experimental support to suppress the occurrence of the gas explosions in goaf areas and provide some directions for designing explosion-proof electric equipment and fire arresters.

Features and genesis of Paleogene high-quality reservoirs in lacustrine mixed siliciclastic–carbonate sediments, central Bohai Sea, China

The characteristics and formation mechanisms of the mixed siliciclastic-carbonate reservoirs of the Paleogene Shahejie Formation in the central Bohai Sea were examined based on polarized light microscopy and scanning electron microscopy observations, X-ray diffrac- tometry, carbon and oxygen stable isotope geochemistry, and integrated fluid inclusion analysis. High-quality reservoirs are mainly distributed in Type I and Type II mixed siliciclastic-carbonate sediments, and the dominant pore types include residual primary intergranular pores and intrafossil pores, feldspar dissolution pores mainly devel- oped in Type II sediments. Type I mixed sediments are characterized by precipitation of early pore-lining dolo- mite, relatively weak mechanical compaction during deep burial, and the occurrence of abundant oil inclusions in high-quality reservoirs. Microfacies played a critical role in the formation of the mixed reservoirs, and high-quality reservoirs are commonly found in high-energy environ- ments, such as fan delta underwater distributary channels, mouth bars, and submarine uplift beach bars. Abundant intrafossil pores were formed by bioclastic decay, and secondary pores due to feldspar dissolution further enhance reservoir porosity. Mechanical compaction was inhibited by the precipitation of pore-lining dolomite formed during early stage, and oil emplacement has further led to the preservation of good reservoir quality.

Fluid evolution and hydrocarbon accumulation model of ultra-deep gas reservoirs in Permian Qixia Formation of northwest Sichuan Basin,SW China

The fluid evolution and reservoir formation model of the ultra-deep gas reservoirs in the Permian Qixia Formation of the northwestern Sichuan Basin are investigated by using thin section,cathodoluminescence,inclusion temperature and U-Pb isotopic dating,combined with gas source identification plates and reservoir formation evolution profiles established based on burial history,thermal history,reservoir formation history and diagenetic evolution sequence.The fluid evolution of the marine ultra-deep gas reservoirs in the Qixia Formation has undergone two stages of dolomitization and one phase of hydrothermal action,two stages of oil and gas charging and two stages of associated burial dissolution.The diagenetic fluids include ancient seawater,atmospheric freshwater,deep hydrothermal fluid and hydrocarbon fluids.The two stages of hydrocarbon charging happened in the Late Triassic and Late Jurassic–Early Cretaceous respectively,and the Middle to Late Cretaceous is the period when the crude oil cracked massively into gas.The gas reservoirs in deep marine Permian strata of northwest Sichuan feature multiple source rocks,composite transportation,differential accumulation and late finalization.The natural gas in the Permian is mainly cracked gas from Permian marine mixed hydrocarbon source rocks,with cracked gas from crude oil in the deeper Sinian strata in local parts.The scale development of paleo-hydrocarbon reservoirs and the stable and good preservation conditions are the keys to the forming large-scale gas reservoirs.

Petroleum Distribution Characteristics of the Americas and the Exploration Prospect Analysis

The world＇s present demand for oil and gas is still in a rapid growth period, and traditional oil and gas resources account for more than 60% of the global oil and gas supply. The Americas is the world＇s second largest production and consumption center of liquid fuel, and is also the world＇s largest natural gas producer. In 2016, the Americas had 85.3 billion tons of proven oil reserves and 18.7 trillion m3 of proven natural gas reserves, which account for 35.4% and 10.0% of world＇s total reserves, respectively. It produced 1267.1 Mt of oil and 1125.4 billion m3 of natural gas, which account for 28.9% and 31.7% of the world＇s total production, respectively. The crude oil and natural gas reserves are mainly distributed in the U.S., Canada and Venezuela. The U.S. is the earliest and most successful country in shale gas exploration and development, and its shale gas is concentrated in the southern, central and eastern U.S., including the Marcellcus shale, Barnett shale, EagleFord shale, Bakken shale, Fayettevis shale, Haynsvill shale, Woodford shale and Monterey/Santos shale. The potential oil and gas resources in the Americas are mainly concentrated in the anticline and stratigraphic traps in the Middle- Upper Jurassic slope deposition of the North Slope Basin, the Paleozoic Madsion group dolomite and limestone in the Williston Basin, dominant stratigraphic traps and few structural traps in the Western Canada Sedimentary Basin, the Eocene structural-stratigraphic hydrocarbon combination, structural- unconformity traps and structural hydrocarbon combination, and the Upper Miocene stratigraphic- structural hydrocarbon combination in the Maracaibo Basin of Venezuela, the stratigraphic-structural traps and fault horst, tilting faulted blocks and anticlines related to subsalt structure and basement activity in the Campos Basin, the subsalt central low-uplift belt and supra-salt central low-uplift belt in the Santos Basin of Brazil, and the structural-stratigraphic traps in the Neuquen Basin of Argentina. In addition, the breakthrough of seismic subsalt imaging technology makes the subsalt deepwater sea area of eastern Barzil an important oil and gas potential area.

Analysis and Modeling of Wangqing Oil Shale Drying Characteristics in a Novel Fluidized Bed Dryer with Asynchronous Rotating Air Distributor

In order to replace the conventional distributor, a novel asynchronous rotating air distributor, which can optimize the drying ability of fluidized bed and strengthen the drying performance of oil shale particles, is creatively designed in this study. The rotating speed of the asynchronous rotating air distributor with an embedded center disk and an encircling disk is regulated to achieve the different air supply conditions. The impacts of different drying conditions on the drying characteristic of Wangqing oil shale particles are studied with the help of electronic scales. The dynamics of experimental data is analyzed with 9 common drying models. The results indicate that the particles distribution in fluidized bed can be improved and the drying time can be reduced by decreasing the rotating speed of the embedded center disk and increasing the rotating speed of the encircling disk. The drying process of oil shale particles involves a rising drying rate period, a constant drying rate period and a falling drying rate period. Regulating the air distributor rotating speed reasonably will accelerate the shift of particles from the rising drying rate period to the falling drying rate period directly. The two-term model fits properly the oil shale particles drying simulation among 9 drying models at different air supply conditions. Yet the air absorbed in the particles' pores is diffused along with the moisture evaporation, and a small amount of moisture remains on the wall of fluidized bed in each experiment, thus, the values of drying simulation are less than the experimental values.

Orbital cyclicity in sedimentary sequence and climatic indications of C-O isotopes from Lower Cretaceous in Qingxi Sag, Jiuquan Basin, NW China

Sedimentary deposits of the Lower Cretaceous Xiagou Formation form the most significant potential hydrocarbon reservoirs in the Qingxi Sag, Jiuquan Basin(NW China). Zircon U-Pb ages of the dated basalts at the top of the Xiagou Formation give an isochron age of 115.6 Ma, and the sedimentation interval of the Xiagou Formation was speculated to range from about 125/124 Ma to 115 Ma based on paleontological research and stratigraphic correlation analysis. Here we use GR logging data as a palaeoenvironmental and palaeoclimatic proxy to conduct a detailed cyclostratigraphic study of five selected wells. Power spectra, evolutionary fast Fourier transformation and wavelet analysis all reveal significant sedimentary cycles in the Xiagou Formation. The ratios of cycle wavelengths in these stratigraphic units are 33.82 m : 7.91 m : 3.06 m : 1.79 m, which is similar to the ratio of orbital targets of 20 : 5 : 2 : 1. The ratio of 20 : 5 : 2 : 1 is interpreted as Milankovitch cycles of 405 kyr long eccentricity,100 kyr short eccentricity, 37 kyr obliquity, and 22 kyr precession cycles respectively. A high-resolution astronomical time scale is constructed by tuning the stratigraphy into target curves of orbital cycles respectively. Based on the astronomical time scale, the absolute ages of 55 samples were estimated,which are used for subsequent stable carbon and oxygen isotope stratigraphy analysis. The analysis results of the five studied wells in the Qingxi Sag indicate:(1) a negative trend of δ^(13)C values upwards in the Xiagou Formation, and(2) negative δ^(18)O values with a positive trend upwards. Both relatively heavy values and pronounced covariances of δ^(13)C values and δ^(18)O values indicate an arid-evaporationcontrolled climate during the sedimentary period of the Lower Cretaceous Xiagou Formation, Qingxi Sag, Jiuquan Basin. Moreover, positive covariances of SQK_1g_(2+3) indicate extremely high temperature, and negative covariances of SQK_1g_1 indicate a relatively low temperature.

Characteristics and Natural Gas Origin of Middle-Late Triassic Marine Source Rocks of the Western Sichuan Depression, SW China

A scientific exploration well(CK1) was drilled to expand the oil/gas production in the western Sichuan depression, SW, China. Seventy-three core samples and four natural gas samples from the Middle–Late Triassic strata were analyzed to determine the paleo-depositional setting and the abundance of organic matter(OM) and to evaluate the hydrocarbon-generation process and potential. This information was then used to identify the origin of the natural gas. The OM is characterized by medium n-alkanes(n C15–n C19), low pristane/phytane and terrigenous aquatic ratios(TAR), a carbon preference index(CPI) of ~1, regular steranes with C29 > C27 > C28, gammacerane/C30 hopane ratios of 0.15–0.32, and δDorg of-132‰ to-58‰, suggesting a marine algal/phytoplankton source with terrestrial input deposited in a reducing–transitional saline/marine sedimentary environment. Based on the TOC, HI index, and chloroform bitumen "A" the algalrich dolomites of the Leikoupo Formation are fair–good source rocks;the grey limestones of the Maantang Formation are fair source rocks;and the shales of the Xiaotangzi Formation are moderately good source rocks. In addition, maceral and carbon isotopes indicate that the kerogen of the Leikoupo and Maantang formations is type Ⅱ and that of the Xiaotangzi Formation is type Ⅱ–Ⅲ. The maturity parameters and the hopane and sterane isomerization suggest that the OM was advanced mature and produced wet–dry gases. One-dimensional modeling of the thermal-burial history suggests that hydrocarbon-generation occurred at 220–60 Ma. The gas components and C–H–He–Ar–Ne isotopes indicate that the oilassociated gases were generated in the Leikoupo and Maantang formations, and then, they mixed with gases from the Xiaotangzi Formation, which were probably contributed by the underlying Permian marine source rocks. Therefore, the deeply-buried Middle–Late Triassic marine source rocks in the western Sichuan depression and in similar basins have a great significant hydrocarbon potential.

Moisture Distribution of Heterogeneous Agglomerates in Fluidized Bed

Agglomerates formed in the fluidized bed were studied in this paper using the TEB atomization nozzle. The multi-sieving method was adopted to distinguish the size of original particles, nucleation agglomerates, coherence agglomerates, and paste agglomerates in order to successfully identify the different growth stages and select the region for coexistence of most stable heterogeneous agglomerates as the research object. A multi-channel conductance electrical circuit experimental device was developed in this study to measure the conductance signal, which was found to have a liner relationship with the moisture content inside the fluidized bed. By adjusting the sieve mesh openings to achieve the layered isolation of heterogeneous agglomerates, the conductance signal recovered slowly as a result of the agglomerates' fracture during the continuous fluidization process, so that particles and agglomerates moisture distribution measurements could be implemented. The device was used to measure the particles and agglomerates moisture distribution state in the heterogeneous coexistence region, when they were injected with liquid mass within the range of w i=2.8 kg to 4.4 kg. The results indicated that with the increase of liquid mass flow, the moisture content of coherence agglomerates also increased, but the moisture content of nucleation agglomerates was decreased, and that of the original particles was maintained at a relatively low level. When the experimental injection amount reached 4.4 kg, the moisture contained in coherence agglomerates could amount to 87.3%, accounting for a big percentage of moisture in the fluidized bed.

Research on application of rockmass breaking and inversion stress distribution by MS monitoring in Iongwall face

Brought forward the conception of conventional MS monitoring, and described the different monitoring ranges of frequencies and magnitude about earthquake and conventional MS monitoring and MS monitoring in detail. The monitoring results received by the Polish ARAMIS M/E monitoring system and the monitodng instrument designed by the author＇s research group in the same colliery show that the events amount received by conventional MS monitoring instrument which is only about 1/20 of the MS monitoring events, and it can only describe violent activity in larger range and be only applied to monitor hard and thick surrounding rock under mine. Meanwhile the small scale and high precision MS monitoring instrument can receive a lot of low rock fracturing signals, which can actualize the rock movement inversion and precisely descdbe 4-D changes of stress fields, and depend on the observed results we can determine the upper limits of mining and describe S-shaped strata spatial structure and high stress field in Iongwall face surrounded by two sides mined areas.

The effect of thermal fluid derived from mud diapir on sandstone reservoirs in the Yinggehai Basin, South China Sea

The underground thermal fluid is one of the significant factors controlling the formation and quality of reservoirs.The Huangliu Formation(N_(1)h)in YF1 area of the central depression belt in the Yinggehai Basin,South China Sea,is characterized by intense thermal fluid activities related to mud diapir and large-scale shallow-water gravity flow deposits.The multi-episodic invasion of high-temperature and CO_(2)-rich thermal fluid into the formation induces complex water-rock reaction during diagenetic pro-cess,providing a preferable investigation opportunity for revealing how thermal fluid affects reservoir quality.This study characterizes the reservoirs in the formation through core and thin section analyses as well as physical property test.The reservoirs are dominated by fine-grained sandstone characterized by medium porosity(15.2-21.3%)and lower permeability(0.56-15.75mD).Based on an analysis of casting thin section,cathode luminescence(CL),scanning electron microscope(SEM),carbon and oxygen isotope,inclusion test,and electron-probe microanalysis(EPMA),we systematically investigate the diagenetic patterns and pore evolution process for the reservoirs in the formation.The episodic invasion of thermal fluid occurred approximately 0.4 Ma ago plays an important role in controlling reservoir development:The CO_(2)-rich formation water induces massive late-stage dissolution,resulting in a higher proportion of dissolved pores(38.7-46.4%),which improves the porosity of reservoirs at a depth of 2600-3100 m.Nevertheless,the late dissolution together with carbonate cementation occurred in closed diagenetic system blocks most seepage channels.Furthermore,the relatively high level clay mineral transformation in the YF1 area leads to a higher content of authigenic illite(44-62%)in the formation.Massive authigenic illite severely blocks the pore throats in fine sandstone,reducing permeability.This study offers an insight to the understanding of mud diapir-derived thermal fluid affecting and controlling the quality of reservoirs in some areas of the Yinggehai Basin.

The Brittleness Evaluation of Sand and Shale based on the Stress-Strain Curve in Fifth Member of Xujiahe Formation,Xinchang Gas Field,Sichuan Province

Brittleness index is a very important parameter for horizontal well drilling, hydraulic fracturing and production prediction of gas shale.

Tertiary hydrothermal activity and its effect on reservoir properties in the Xihu Depression, East China Sea

Three large-scale episodes of volcanic activity occurred during the Tertiary in the Xihu Depression, located in the East China Sea. Intermediate-felsic magmas intruded along faults and the associated hydrothermal fluids resulted in the hydrothermal alteration of the clastic country rock. To better describe reservoir characteristics, reservoir samples were subjected to the following investigations: thin section examination, scanning electron microscope-energy dispersive spectrometer analysis(SEM–EDS), fluid inclusion homogenization temperature tests, vitrinite reflectance measurements, and X-ray di raction. The results of this study provide evidence of the following hydrothermal alteration phenomena: brittle fracturing, clastic particle alteration, precipitation of unique hydrothermal minerals(celestite, zircon, apatite, barite, and cerous phosphate). The presence of abnormally high temperatures is indicated by fluid inclusion analysis, the precipitation of high-temperature authigenic minerals such as quartz, illite alteration, and anomalous vitrinite reflectance. Two aspects related to hydrothermal effects on reservoir properties have been investigated in this study:(1) Deep magmatic hydrothermal fluids carry large amounts of dissolved carbon dioxide and sulfur dioxide gas. These fluids percolate into the country rocks along fault zones, resulting in dissolution within the sandstone reservoirs and the development of significant secondary porosity.(2) Magma intrusions increase the temperature of the surrounding rocks and accelerate the thermal evolution of hydrocarbon source rocks. This results in the release of large amounts of organic acids and carbon dioxide, leading the dissolution of the aluminosilicate minerals and volcanic fragments in the reservoirs, and the generation of significant secondary porosity.