2021 Vol. 27, No. 1

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Experimental study on physical and mechanical characteristics of tight sandstones in the Xujiahe Formation in western Sichuan after high-temperature exposure
YU Xin, LI Gao, CHEN Ze, ZHANG Yi
2021, 27(1): 1-9. doi: 10.12090/j.issn.1006-6616.2021.27.01.001
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This study aims to boost the seepage capacity in the near-well area by the downhole heating so as to improve the production efficiency of low-permeability reservoir while ensuring the sidewall stability. Taking the second member of the Xujiahe Formation in Longchang as the subject, the effect of high temperature on the microstructure, mechanical property and permeability of tight sandstones were studied. The samples underwent thermogravimetric analysis, scanning electron microscopy (SEM), acoustic wave test, physical parameter measurement, uniaxial compression test and permeability test after high-temperature exposure in the range of 26 ℃ to 1000 ℃, and temperature's relevance to the composition, microstructure, mechanical parameter and permeability were analyzed. The test results showed that the internal moisture of the samples was removed continuously with the increase of temperature, and the content of clay minerals decreased by stages in the range of 26 ℃ to 1000 ℃, which led to the decrease of sample mass and apparent density. There was a threshold temperature at about 400 ℃ for the performance of tight sandstone. When the temperature was higher than 400 ℃, the compressive strength and deformation resistance of the samples decreased sharply. With the increase of temperature, more internal fractures emerged and the network size was enlarged, leading to the continuous growing increase of permeability. Therefore, it is considered that keeping the downhole heating temperature above 400 ℃ and expanding the heating range as well are conducive to improving the productivity of single well. The findings of this study are of value for evaluating the wellbore stability and stimulation effect of single well while applying the electric heating technology in tight sandstone reservoirs.
Research on the micro-scale method for testing the mechanical anisotropy of shale
JIA Suogang, WAN Youyu, WANG Qian, LIU Shiduo, LIU Youming, WANG Zhicheng, YE Yu, QI Chunyan
2021, 27(1): 10-18. doi: 10.12090/j.issn.1006-6616.2021.27.01.002
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The mechanical anisotropy of shale is an important basic parameter for the study of in-situ stress, sidewall stability and hydraulic fracture propagation. In view of the limitations and low success rate for sample preparation in macro-scale tests, we chose clastic rocks and fragmentized blocks which were easily found as the subjects for micro-scale tests, and used continuous stiffness measurements to carry out the nano-indentation tests on the shale samples with horizontal bedding and vertical bedding. The test data were analyzed on three main mineral matrices which were identified by the classification rule of hardness. And the hardness and young's modulus of the shale clay matrix were calculated by contact stiffness measurements and the fracture toughness by energy method. The test results proved the reasonability and convenience of the classification rule of hardness in processing nano-indentation data. Shale clay matrix is anisotropic at the nano-scale while the mechanical parameters at the nano-scale are related to the bedding direction. The anisotropy of each mechanical parameter varies in intensity. The anisotropy of young's modulus is weak, while that of fracture toughness is strong. The fracture toughness with horizontal bedding is 80% of that with vertical bedding.
Ancient landform of the Dongying formation in the Shadongnan structural zone, western Bohai Sea area and its control on the sedimentation
KANG Hailiang, LIN Changsong, NIU Chengmin
2021, 27(1): 19-30. doi: 10.12090/j.issn.1006-6616.2021.27.01.003
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The Shadongnan structural zone in the western Bohai Sea area is located in the transitional position from the Shaleitian uplift to the Sha'nan sag. Due to the influence of various factors such as inherited uplift, syn-depositional faults and ancient valleys in different periods, the development of sedimentary facies is relatively complex, restricting the further oil and gas exploration and development. We restored the ancient landform of each three-level sequence in the Dongying formation in the sedimentary period using the strata thickness method, identifying uplifts, slopes, ancient valleys, fault troughs, and shallow and deep sub-sags in the study area. Meanwhile, there are two kinds of ancient landform in the Shadongnan structural zone bounded by the NNE-trending transform fault, with the valley-paleoslope-fault slope-break in the west and the valley-multistage fault slope-break in the east. The former is composed of eroded valleys, buried hill slopes and early syn-depositional faults, while the latter eroded valleys and two or three syn-depositional faults with the same direction and different periods. Our study showed that the valleys located at the edge of the uplifts were the source channels in the early stage and filled with sediments in the late stage. The distribution and filling of the sedimentary system of the valley-paleoslope-fault slope-break were mainly controlled by the ancient slope-fault slopes, and the syn-depositional faults controlling the fault slopes were relatively active in the Shahejie formation and controlled the deposition and filling of the lowstand fans and turbidite fans. By the SQ-Ed3 period, the fault activities gradually weakened, and the fault slope-break distinct the fan delta plain and front in SQ-Ed3 from the deposition of the braided river delta front and shallow lake in SQ-Ed2d and SQ-Ed2u. The Shadongnan No.1 syn-depositional fault with the valley-multistage fault slope-break, which was developed and activated in SQ-Ed3, controlled the formation of the deep sub-sags and the development of the small fan deltas under the first slope break. The Sha'nan syn-depositional fault both formed and activated in SQ-Ed2d was acted as the second slope break separating the bulges and slopes, and controlled the depositional filling of the small fan delta in SQ-Ed2d.
Distribution characteristics of the present-day in-situ stress in the Chang 6 tight sandstone reservoirs of the Yanchang Formation in the Heshui Area, Ordos Basin, China and suggestions for development
LIU Jian, HUI Chen, FAN Jianming, LYU Wenya, WANG Jiwei, YIN Chen, WANG Haonan
2021, 27(1): 31-39. doi: 10.12090/j.issn.1006-6616.2021.27.01.004
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Tight reservoirs feature poor physical properties and strong heterogeneity. The distribution of present-day in-situ stress affects tight reservoirs in the drilling operation, well pattern deployment, fracturing transformation and water injection management. The microseismic monitoring method and the hydraulic fracturing data were used respectively to analyze the direction of present in-situ stress of single well in the Chang 6 reservoirs and the magnitude of present-day in-situ stress of single well in the study area. Combining the analysis with the characteristics of structure, sedimentation and lithofacies in the study area, we built a three-dimensional heterogeneous geological model. Based on the triaxial rock mechanics test and operation data, we identified the physical parameters of different facies, and built a three-dimensional mechanical model. Also the Ansys finite element numerical simulation was applied to build a three-dimensional present-day in-situ stress distribution model of the Chang 6 reservoirs. The simulation results showed that the maximum horizontal principal stress ranged from 34 MPa to 42 MPa, the minimum from 25 MPa to 36 MPa, and the horizontal differential stress from 3 MPa to 10 MPa. The simulation results of the wellpoint stress had a less than 10% margin of error compared with the actual measurement, proving the simulation results are reliable. It was inferred from the simulation results that the present-day in-situ stress distribution in the study area was mainly affected by the difference in rock physical and mechanical properties, but less by the tectonic framework. On the basis of the result analysis, it is suggested that natural fracture should also be considered as an influencing factor when wells are deployed in the study area. Meanwhile, in order to reduce development cost as much as possible, industrial wells should be generally deployed in the place with low stress as for the area with equal differential stress.
Land surface temperature retrieval and geothermal resources prediction by remote sensing image: A case study in the Shijiazhuang area, Hebei province
XIN Lei, LIU Xinxing, ZHANG Bin
2021, 27(1): 40-51. doi: 10.12090/j.issn.1006-6616.2021.27.01.005
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Thermal infrared remote sensing technology can retrieve land surface temperature information, which has played an important role in the prediction of geothermal resources. Based on the geothermal accumulation theory of the North China Plain, the mono-window algorithm was used to retrieve the land surface temperature of the Shijiazhuang area on March 6, 2015. Combined with the night thermal infrared images, remote sensing structure interpretation results and residual gravity anomaly data, through the comprehensive analysis and mutual demonstration, one upland convection-type and two sedimentary basin-type prospective areas were delineated, whose formation modes were convection and conduction respectively. In Sigou Village of Pingshan County, the land surface temperature is higher than that of the surrounding land features day and night, and the residual gravity anomaly data confirm the presence of NE faults in this area. Therefore, it is inferred that this area is a geothermal field formed by faults as water and heat conduction channels connecting the surface and the deep crustal heat source. The Gaocheng-Wuji area and Mayu-Huanmadian area are interpreted as deep uplift structures base on the residual gravity anomaly data, and there are hidden faults passing through, suggesting that this area is a geothermal field formed by the heat transfer and collection from the hidden faults to the uplift. This study is a geothermal resource prediction that based on the geothermal accumulation theory and the comprehensive analysis of remote sensing technology and geological and geophysical data. The prediction of target area is geologically interpretable and more in line with the understanding of geothermal accumulation.
Types and evolution of faults in the east area of the Wushi Sag, Beibuwan Basin
WU Kongyou, LIU Yulei, HU Desheng, LIU Yin, ZHANG Shuai, CUI Lijie
2021, 27(1): 52-62. doi: 10.12090/j.issn.1006-6616.2021.27.01.006
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Affected by multiple stages of tectonic movements, the Wushi Sag in the Beibuwan Basin has formed complex internal structures. Accurately identifying the structural development characteristics of different stages has a great significance for oil and gas exploration. In this paper, we used the high-precision 3D seismic and drilling data to analyze the fault type, combination pattern, evolution rule and dynamic mechanism in the east area of the Wushi sag. The results show that under the influence of the regional stress of extension-strike-slip and weak compression caused by the interaction between the Pacific plate, the Indian plate and the Eurasian plate, three sets of extension-strike-slip-compression fault systems were developed in the east area of the Wushi sag, and 13 types of plane and profile fault combinations are identified. The formation and evolution of the fault system endured five main stages, including the initial weak rifting stage in the Paleocene, the main extension stage in the Eocene, the strike-slip and weak extension stage in the Early and Middle Oligocene, the strike-slip and weak compression stage in the late Oligocene, and the final stage since the Neogene.
Using terrestrial LiDAR to accurately measure the microgeomorphologic geometry of active fault: A case study of fault scarp on the Maoyaba fault zone
ZHANG Di, LI Jiacun, WU Zhonghai, LIU Shaotang, LU Yan
2021, 27(1): 63-72. doi: 10.12090/j.issn.1006-6616.2021.27.01.007
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The micro-geomorphologic geometry of active fault is often complex due to the natural dynamics, such as high degree of sedimentation and erosion, and man-made activities. It is difficult for traditional measurement methods to quickly and efficiently obtain the high-precision geomorphological geometry of fault scarp and to acquire fault displacement in a large scale. Light Detection And Ranging (LiDAR) provides a new technology for the quantitative study of the micro-geomorphologic geometry of active fault. In this study, the high-precision point cloud data of micro-geomorphologic geometry of the fault scarp are obtained by the terrestrial LiDAR on the Maoyaba fault. After the registration, filter, resample and irregular triangular mesh modeling processing of the point cloud data, the 0.05 m high-resolution DEM and the true color three-dimensional model are generated. On this basis, the geomorphic features of the fault scarp are analyzed, and the vertical displacements of two landforms produced by the latest two periods of normal faulting are obtained. The results show that the terrestrial LiDAR technology is an effective method to accurately measure the micro-geomorphic morphology of active fault and to quantify the relevant geomorphic characteristic parameters, which improves the precision and understanding level of the micro-geomorphologic geometry of active fault.
Centrifuge model tests on the near-horizontal slide of hard soil-soft rock landslides
HU Le, XIN Peng, WANG Tao, LIANG Changyu, LI Congan
2021, 27(1): 73-82. doi: 10.12090/j.issn.1006-6616.2021.27.01.008
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In order to study the deformation characteristics of the Neogene hard soil-soft rock landslides in northwest China, two sets of centrifuge model tests were conducted to simulate the deformation process under the degraded state of shear zones, and the soil pressure and displacement-time curve during the deformation process of the landslides were obtained. The test results reveal that when the strength of the soft zone decreases, the main body of the hard soil-soft rock landslide is block-like. In the process of fast slide, the slip mass presents an overall translational slide, without complete liquefaction and disintegration. The attenuation of the dynamic friction strength of the slide zone is the main controlling factor in the distance and time of the movement. Moreover, the slide zones of hard soil-soft rock landslides with high stress underwent plastic flow deformations, which caused the horizontal stress concentration in the front part of the landslide, resulting in the horizontal movement of the overlying slip mass in the front part of the landslide and the extension to the back edge of the landslide, and multi-level horizontal slides occurred at the end.
Assessment of geological disaster susceptibility in the Hehuang Valley of Qinghai Province
ZHAO Dongliang, LANCUO Zhuoma, HOU Guangliang, XU Changjun, LI Wanzhi
2021, 27(1): 83-95. doi: 10.12090/j.issn.1006-6616.2021.27.01.009
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The Yellow River and Huangshui Valley, located at the northeast margin of the Qinghai-Tibet Plateau, are prone to geological disasters due to violent geological activities, large elevation difference and strong hydraulic power. In order to clarify the zoning of susceptibility of geological disasters in this area, an assessment index system is built by selecting factors such as geomorphology, slope, slope height, vegetation, lithology, rainfall, distance from faults, rivers and roads, using the information model to calculate the susceptibility index of collapse, landslide, debris flow and comprehensive geological disasters. The susceptibility of geological disasters in the study area can be divided into five grades: extremely high, high, medium, low and extremely low. The result shows that the extremely high susceptible areas are mainly in the valley areas, accounting for 2.03%, including the middle and lower reaches of the Yellow River and the Huangshui River in Guide county, Huangzhong county and Ledu county. The high susceptible areas are mainly in the areas on small and moderately undulating mountain basins, accounting for 21.2%. The medium susceptible area are mainly in the moderately undulating mountain areas, accounting for 23.45%, which belong to the transition areas of high and low susceptible areas. The low susceptible areas are mainly in moderately and sharply undulating mountain areas, accounting for 42.1%. The extremely low susceptible areas are mainly on the mountains such as the Lenglong mountain, Laji mountain and Xiqing mountain, accounting for 11.23%. The research result is of great significance to the disaster prevention and reduction in the Hehuang Valley and to the sustainable development of society.
Analysis of three-dimensional movement characteristics of rockfall: A case study at a railway tunnel entrance in the southwestern mountainous area, China
WANG Dong, WANG Jianfeng, LI Tianbin, ZENG Peng, MA Junjie, CHEN Wei
2021, 27(1): 96-104. doi: 10.12090/j.issn.1006-6616.2021.27.01.010
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High unstable rock masses are widely distributed in the upper part of a railway tunnel entrance in the southwestern mountainous area, which causes serious hazards to the construction of the lower tunnel. The Rockfall Analyst software was used to simulate the three-dimensional movement track of five kinds of high unstable rock masses in the upper part of the tunnel, and it shows that the rockfalls in the study area have the characteristics of high bounce height, fast speed and high impact energy. There is no relation between the bounce height, the movement speed and the mass of rockfall, while the impact energy is proportional to the mass of rockfall. The analysis shows that multiple and comprehensive protective measures should be recommended for the protection of unstable rock masses in this area instead of single protective measure.
Characteristics and evolution process of the ridge-groove sequence of the Jiulongtan glacial accumulation in Mengshan, Shandong: with the discussion on the difference of accumulation sequence of glacier and debris flow
WANG Zhaobo, WANG Jiangyue, HE Lelong, ZHANG Jian, ZHAO Xiangyang, LI Baojie
2021, 27(1): 105-116. doi: 10.12090/j.issn.1006-6616.2021.27.01.011
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The existence of Quaternary glaciers in the medium-low mountainous areas in the east of China has been disputed for a century. As an important evidence for glacial accumulation in the east, "mud-gravel" (moraine) has long been referred to as debris flow sediments by those who hold a non-glacial view. However, due to the essential difference of the accumulation process between glacier and debris flow, it would inevitably show specific differences in the characteristics of the accumulation body. Therefore, in the cause analysis of moraine and restoration of moraine accumulation process, it is of great significance to identifying and summarizing the specific differences between glacier and debris flow in accumulation characteristics and accumulation process. Based on the comparative analysis, it reveals that, the glacial moraine forms a specific ridge-groove sequence on the plane, and on the section it shows a state of unstratified and mixed accumulation; Debris flow forms an accumulation fan. The fan surface presents a radial ridge accumulation, and the section shows a prosodic sequence. This is what distinguishes glacier from debris flow deposit. On this basis, the diamictons in the Jiulongtan area were investigated and reconstructed. It is found that they have the typical ridge-groove sequence of glacial origin, and meanwhile they present a state of unstratified and mixed accumulation on the section, which proves they are the results of Quaternary glaciation. The ridge-groove sequence is not only the specific feature to judge whether the diamictons are the results of glaciation, but also the theoretical basis to restore the basic geomorphological features and accumulation process of moraine deposits.
Hydrogeological characteristics and water yield pattern of the Paleogene Zhujiagou formation in south-central Shandong Province
LI Bo, SONG Yixin, GAO Han, WU Xuan, GUAN Qin, LIU Chunwei
2021, 27(1): 117-126. doi: 10.12090/j.issn.1006-6616.2021.27.01.012
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The Zhujiagou formation, a set of calcareous conglomerates of terrigenous clastic deposition, is mainly distributed along the edge of the depression basins in south-central Shandong. Taking the Zhujiagou formation in the Wenkou basin and the Xinwen basin as the study area, the hydrogeological characteristics are analyzed through 1:50000 hydrogeological survey, hydrogeological drilling, geophysical exploration, pumping test, water quality analysis and other technical methods. The results show that the karst morphology of the Zhujiagou formation is dominated by corrosion fissure, karst hole and karst cave, which are mainly developed in the shallow layer of 150 m. The water yield property is obviously controlled by the fracture, and the water inflow of a single well in the fracture karst development area can be more than 300 m3/d, indicating practical water supply significance. The water yield pattern of the Zhujiagou formation features fracture-karst water storage structure of fractured calcareous conglomerate and fracture structure is the main controlling factor. This pattern has universality and applicability in south-central Shandong Province, which is of guiding significance for new water supply aquifers exploration and site selection and layout for wells.
Research progress of factors affecting apatite fission track annealing
CHENG Luyao, TANG Xiaoyin, LI Yi
2021, 27(1): 127-134. doi: 10.12090/j.issn.1006-6616.2021.27.01.013
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Apatite fission track annealing is a complicated chemical kinetic process. It is crucial for the application of fission track thermochronology to clearly understand the factors affecting annealing. In the article, the development of apatite fission track annealing model is summarized, and the research progress on factors influencing annealing is reviewed. Generally, the factors can be divided into internal and external ones. The internal factors include chemical composition, crystal structure, track length and radius, and crystallographic orientation, among which, chemical composition plays a leading role. Among the external factors, temperature is the dominant one, and pressure and etching conditions can also affect annealing. The research results are conducive to improving the apatite fission track annealing model and increase its accuracy as a thermal history recorder.
Geological and chronological characteristics of the Baiyin'gaolao Formation in Gaoyaowula, Inner Mongolia
DONG Peipei, LI Yingjie, WANG Genhou, XIN Houtian, WANG Jinfang, LI Hongyang
2021, 27(1): 135-152. doi: 10.12090/j.issn.1006-6616.2021.27.01.014
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Based on a regional geological survey at a scale of 1:50000, it reveals that the volcanic rocks from the Baiyin'gaolao Formation of Gaoyaowula in Inner Mongolia could be divided into three lithologic segments by the triple mapping method of "volcanic structure-lithology and lithofacies-volcanic formation". The first lithologic segment is composed of pyroclastic sedimentary rocks, the second intermediate volcanic rocks and the third acidic volcanic rocks. The three lithologic segments constitute a complete depositonal-eruptive cycle, and the early to late magma is characterized by a transition from neutral to acid. The Baiyin'gaolao Formation can be classified into eruptive facies, intrusive facies, overflow facies, volcanic vent facies, eruption-deposition facies and subvolcanic facies, etc. Twelve V-grade volcanic apparatuses are delineated. The Zircon U-Pb LA-ICP-MS dating of the trachyandesite from the second lithologic segment of the Baiyin'gaolao Formation of Gaoyaowula and the rhyolite from the third are 128.2±0.9 Ma and 125.5±0.5 Ma respectively, indicating that the formation age is early-Cretaceous.
2021, 27(1): 153-155. doi: 10.12090/j.issn.1006-6616.2021.27.01.015
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2021, 27(1): 156-157. doi: 10.12090/j.issn.1006-6616.2021.27.01.016
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2021, 27(1): 158-158.
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