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On classification of distributive fluvial system
ZHANG Changmin, ZHANG Xianghui, ADRIAN J. Hartley, FENG Wenjie, YIN Taiju, YIN Yanshu, ZHU Rui
2023, Vol.35(4): 1–15
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2123 )
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321
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Hydrocarbon-generating potential of source rocks of Permian lower Urho Formation in western depression，Junggar Basin
TANG Yong, WANG Zhiqiang, PANG Yanqing, DENG Shikun, WANG Chao, HONG Penghui
2023, Vol.35(4): 16–28
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1939 )
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(11179 KB)
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410
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Characteristics and formation mechanism of hydraulic fractures in tight conglomerate reservoirs of Triassic Baikouquan Formation in Mahu Sag
QIN Jianhua, WANG Jianguo, LI Siyuan, LI Sheng, DOU Zhi, PENG Simi
2023, Vol.35(4): 29–36
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2023 )
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(8676 KB)
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227
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Configuration characterization of Triassic Chang 611reservoir in Sai 160 well area of Ansai oilfield，Ordos Basin
YIN Yanshu, DING Wengang, AN Xiaoping, XU Zhenhua
2023, Vol.35(4): 37–49
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1755 )
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(7584 KB)
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334
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Fine characterization of Cenozoic faults and its geological implications in Zhanhua Sag，Bohai Bay Basin
YAO Xiutian, WANG Chao, YAN Sen, WANG Mingpeng, LI Wan
2023, Vol.35(4): 50–60
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1764 )
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(19193 KB)
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298
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A layered velocity modeling method for elastic wave full waveform inversion based on improved conjugate gradient method
WANG Lide, WANG Xiaowei, ZHOU Hui, WU Jie, ZHANG Zhiqiang, WANG Jianle, WANG Deying, FENG Gang
2023, Vol.35(4): 61–69
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1697 )
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(5833 KB)
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293
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A strong seismic energy reduction method under compressed sensing
LI Shengjun, GAO Jianhu, ZHANG Fanchang, HE Dongyang, GUI Jinyong
2023, Vol.35(4): 70–78
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1733 )
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(6130 KB)
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243
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Optimization of 3D first-arrival traveltime tomography inversion
XU Xin, YANG Wuyang, ZHANG Kai, WEI Xinjian, ZHANG Xiangyang, LI Haishan
2023, Vol.35(4): 79–89
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1738 )
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(7192 KB)
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235
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Geological characteristics and exploration potential of shale oil of Permian Lucaogou Formation in hanging wall of Fukang fault zone， Junggar Basin
LIU Hailei, ZHU Yongcai, LIU Longsong, YIN He, WANG Xueyong, DU Xiaodi
2023, Vol.35(4): 90–101
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5341 )
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(10558 KB)
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241
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Development characteristics and sedimentary environment of black shale of Lower Cambrian Niutitang Formation in western Hunan and Hubei
LIANG Xiaocong, NIU Xing, HU Mingyi, LI Yang, HU Zhonggui, CAI Quansheng
2023, Vol.35(4): 102–114
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4360 )
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373
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Natural gas accumulation conditions and main controlling factors of Cretaceous tight volcanic rocks in Yingshan-Shuangcheng fault depression，Songliao Basin
DU Changpeng
2023, Vol.35(4): 115–124
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4056 )
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(7081 KB)
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223
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Prediction of favorable lithofacies and exploration direction of Carboniferous in Fudong slope，Junggar Basin
WU Xiaoning, DENG Yong, LIN Yu, ZHONG Houcai, KANG Xiaoning, WANG Yuting, QU Lin
2023, Vol.35(4): 125–136
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3962 )
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283
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Development characteristics and accumulation model of sublacustrine fans of the first member of Eocene Liushagang Formation in Weixinan Sag，Beibuwan Basin
MAN Xiao, HU Desheng, WU Jie, GONG Liyuan, LIU Zhixuan, JIANG Yingde, ZHAO Ye
2023, Vol.35(4): 137–144
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3689 )
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276
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Sedimentary characteristics of shallow water delta of Middle Jurassic Toutunhe Formation in southern Anjihai river outcrops，Junggar Basin
FU Wenjun, ZHANG Changmin, JI Dongsheng, LOU Lin, LIU Jiale, WANG Xulong
2023, Vol.35(4): 145–160
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3904 )
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Experiment on profile control and water plugging of rubber particles in inter-well single fractured-vuggy reservoir
QIAN Zhen, MAO Zhiqiang, ZHENG Wei, HUANG Yuanjun, CHEN Lifeng, ZENG Huiyong, LI Gang, SONG Ai
2023, Vol.35(4): 161–168
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4205 )
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On classification of distributive fluvial system
ZHANG Changmin, ZHANG Xianghui, ADRIAN J. Hartley, FENG Wenjie, YIN Taiju, YIN Yanshu, ZHU Rui
2023, Vol.35(4): 1–15
Abstract
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2123 )
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321
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doi: https://doi.org/10.12108/yxyqc.20230401
Based on the research progress of distributive fluvial system（DFS）， the geomorphic characteristics and main types of DFS were summarized， and the controlling factors of the formation and development of DFS were discussed. The results show that：（1）DFS is not a new or special river channel type，but a regular collection of multiple river channels. The geomorphic characteristics are shown as follows： the river network is radially distributed from one-point，various types of rivers develop together，the geometric shape of the river channel changes greatly，the sedimentary environment includes river channel and interchannel，and the sedimentary system is complex. The main types include alluvial fan，fluvial fan and megafan.（2）Based on DFS radius，area and their surface slope，DFS can be divided into three types as microDFS，macroDFS and megaDFS. The micro DFS，i.e.，alluvial fan，with a radius of less than 30 km，an area of less than 100 km2 and a slope of greater than 1.0°. The macroDFS is called fluvial fan，with radius greater than 30 km but less than 100 km，their area is greater than 100 km2 but less than 1000 km2，and slope is less than 1.0°. The megaDFS is megafan，which has a radius of greater than 100 km，an area of greater than 1 000 km2 and a slope of less than 0.5°. The distribution ranges of the three types have certain overlap and repetition. It is also necessary to distinguish them by combining the hydrodynamic process and sedimentary characteristics of DFS.（3）Tectonic and climate are the most fundamental factors controlling the formation and distribution of DFS. Basin area and provenance may influence the total sediment supply and sediments composition of the depositional system. As an indirect factor，DFS slope may control the channel morphology and the bifurcation and crevasse of the channel together with channel flow and velocity， thus control the sedimentary environment and depositional facies distribution of the DFS.
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Hydrocarbon-generating potential of source rocks of Permian lower Urho Formation in western depression，Junggar Basin
TANG Yong, WANG Zhiqiang, PANG Yanqing, DENG Shikun, WANG Chao, HONG Penghui
2023, Vol.35(4): 16–28
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1939 )
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410
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doi: https://doi.org/10.12108/yxyqc.20230402
The hydrocarbon-generating potential of Permian lower Urho Formation source rocks in western depression of Junggar Basin were systematically studied from lithology，organic matter characteristics，biomarker characteristics and distribution characteristics of large-scale effective hydrocarbon source stoves by means of RockEval pyrolysis，microexamination，thermal evolution analysis，thermal simulation experiment of hydrocarbon generation and basin modeling. The results show that：（1）The source rocks of lower Urho Formation in western depression are mainly mudstone deposits with inconspicuous laminae，and the lithologies include dark grey mudstone， grey silty mudstone，grey argillaceous silty mudstone，and grey carbonaceous silty mudstone.（2）The source rocks of lower Urho Formation have hydrocarbon-generating potential and its differences of samples is obvious， and the organic matters are mainly composed of type Ⅲ kerogen with the Rock-Eval hydrogen index（HI）generally less than 100 mg/g，which indicates a set of gas-prone source rocks. The maturities of organic matters vary widely with the vitrinite reflectance（Ro）ranging from 0.64% to 1.56%（1.06% on average）and the production index （PI）ranging from 0.05 to 0.74（0.33 on average）. At present，the source rocks in Shawan，Pengyijingxi and Mahu sags are in the late oil-generating-peak，condensate/wet-gas-generating stage，and dry-gas-generating stage，respectively. The abundance and hydrocarbon-generating potential vary greatly with the TOC ranging from 0.29% to 9.16%（0.85% on average）and S1+S2 ranging from 0.29 to 3.16 mg/g（0.74 mg/g on average），respectively. Poor and medium-good source rocks account for 50% of the total samples respectively.（3）The source rocks of lower Urho Formation were deposited in fresh-oxidized environment，mainly with terrigenous organic matter input and almost no carbonate input. The lithology and sedimentary environment are different from that of the source rocks of Fengcheng Formation，and the hydrocarbon generation potential is lower.（4）The hydrocarbon generation center of the source rocks of lower Urho Formation is located in western well Pen-1 sag，which has a large development scale. The area of the source rocks with a thickness greater than 100 m is 16 000 km2， and the area of the source rocks with a hydrocarbon generation intensity greater than 500×104 t/km2 is 6 800 km2，showing a favorable potential to form large and medium-sized oil and gas fields.
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Characteristics and formation mechanism of hydraulic fractures in tight conglomerate reservoirs of Triassic Baikouquan Formation in Mahu Sag
QIN Jianhua, WANG Jianguo, LI Siyuan, LI Sheng, DOU Zhi, PENG Simi
2023, Vol.35(4): 29–36
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2023 )
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doi: https://doi.org/10.12108/yxyqc.20230403
The distribution of hydraulic fractures is very important for the efficient development of tight conglomerate reservoirs. Through the observation of fractures in the core from the horizontal coring well MaJ02 in the fractured conglomerate oil area of Mahu Sag，the type，occurrence，formation，opening，density and proppant filling of hydraulic fractures in the tight conglomerate reservoirs of Triassic Baikouquan Formation in Mahu Sag were analyzed，their distribution characteristics were clarified，and the formation mechanism was discussed. The results show that：（1）The hydraulic fractures developed in the cores of Baikouquan Formation in well MaJ02 account for 77.6% of the total number of fractures，with a strike of 90°-110 ° and a dip angle of 70°-90°. （2）The shear fractures formed by strike-slip mechanism in the study area account for 65.8%，followed by tensile fractures formed by tensile stress，accounting for 34.2%. Most of the shear fractures are in groups with small openings and fully filled，and the fracture surface is mainly through gravel，and multiple cracks are superimposed to form a fracture network fracture zone. The tensile fractures are mostly single with relatively large openings and irregular fracture surface，which are fully or half-filled，and the fracture surface is mainly surrounded by gravel.（3）The smaller the distance between the coring well and the fractured well in the study area，the smaller the perforation cluster spacing in the fracturing section，and the greater the hydraulic fracture density. Under the same fracturing engineering conditions，the fractures of argillaceous supported floating conglomerate facies and front sheet sand microfacies are relatively developed. The higher the sand content，the greater the hydraulic fracture density.
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Configuration characterization of Triassic Chang 611reservoir in Sai 160 well area of Ansai oilfield，Ordos Basin
YIN Yanshu, DING Wengang, AN Xiaoping, XU Zhenhua
2023, Vol.35(4): 37–49
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1755 )
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334
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doi: https://doi.org/10.12108/yxyqc.20230404
Sai 160 well area in Ansai oilfield，Ordos Basin，is a shallow water delta deposit，the sand bodies are dominated by channel deposition，with the characteristics of contiguous distribution. However，the injection and production have poor correspondence in the development process，which indicates that the internal configuration and overlapping style of the contiguous sand bodies are complex. Based on modern sedimentation and numerical simulation，combined with core，well logging and dynamic data，the sedimentary facies and sand bodies of Chang 611 reservoir in Sai 160 well area of Ansai oilfield were analyzed，its internal sand body configuration characteristics were defined，and the sand body evolution stages were divided. The results show that：（1）Sai 160 well area is a typical shallow delta sedimentary facies of meandering river，which develops four sedimentary microfacies： underwater distributary channel，mouth bar，sheet sand and intertributary bay.（2）Typical bar finger sand bodies are developed in shallow water deltas on the plane in the study area，and most channels are distributed in the middle of mouth bars，forming a plane distribution pattern of river in the middle and mouth bars on both sides.（3）In the cross provenance direction， distributary channels are more deep but do not cut through the mouth bar， forming a riverbar combination style of “river walking on the bar”. Along the provenance direction，a single mouth bar sand body is deposited forward to form a complex mouth bar sand body.（4）Argillaceous or physical interlayers are developed between different mouth bars，resulting in incomplete connectivity of contiguous sand bodies. The length and width of a single mouth bar are 280-1 400 m and 200-420 m，respectively. The size（ratio of length to width）and forward deposit dip angle of the mouth bar are similar in the same stage，while the along source length and forward deposit dip angle of the mouth bar decrease in different periods， but the width has no obvious change.
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Fine characterization of Cenozoic faults and its geological implications in Zhanhua Sag，Bohai Bay Basin
YAO Xiutian, WANG Chao, YAN Sen, WANG Mingpeng, LI Wan
2023, Vol.35(4): 50–60
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1764 )
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298
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doi: https://doi.org/10.12108/yxyqc.20230405
The fine characterization of faults is of great significance for the potential exploration of remaining oil in complex fault block oilfields with ultra-high water cut. The fine characterization of faults in Cenozoic complex fault block oilfield in Zhanhua Sag of Bohai Bay Basin was studied through comprehensive analysis of correlation of well-seismic marker layer，identification of seismic event variation and validation of fault overlap model. The results show that：（1）The jointing relationship of rock formation on both sides of complex fault block reservoirs in Zhanhua Sag is complicated，the pattern of fault assemblage is varied and inherited small and micro faults are developed. The multi-technology fault interpretation method based on breakpoint identification，fault section interpretation，fault plane combination verification and fault space modeling have realized the fine identification，positioning and characterization of the faults，especially small and micro faults.（2）In the seismic profile of complex fault block reservoir in Zhanhua Sag，the variation phenomena of the events such as distortion，bifurcation and merging are important characteristics of the development of small and micro faults. The micro-twist， micro-distortion and micro-misalignment of the events are important basis for the fine identification and location of small and micro-faults.（3）The fine fault characterization can transform “blind area” and “fuzzy area” of the fault edge in the study area into potential area of remaining oil enrichment，which realized the expansion of new geological reserves on both sides of the fault. The fine fault characterization can optimize and improve the well pattern，increase the effectiveness of tapping potential and development，and also provided a scientific basis for further defining the remaining oil enrichment and distribution， adjusting the development well pattern and implementing precise development.
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A layered velocity modeling method for elastic wave full waveform inversion based on improved conjugate gradient method
WANG Lide, WANG Xiaowei, ZHOU Hui, WU Jie, ZHANG Zhiqiang, WANG Jianle, WANG Deying, FENG Gang
2023, Vol.35(4): 61–69
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1697 )
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doi: https://doi.org/10.12108/yxyqc.20230406
Due to the lack of low-frequency information and complex wave field of land seismic data， the nonlinearity of elastic wave full waveform inversion is aggravated. A layered inversion strategy of time-domain multiscale inversion was proposed to reconstruct the P-wave and S-wave velocity based on the improved conjugate gradient method. The results show that： （1）Time window was used to screen the early arrival wave information and to constrain the offset size to reconstruct the velocity field in the shallow area from low frequency to high frequency， which can reduce the strong nonlinear effects caused by the reflected waves and noises in the middle and deep layers. The shallow velocity was fixed，and the full offset data of full wave field was used to conduct multi-scale inversion for the middle and deep layer velocity.（2）The whole inversion process used the improved conjugate gradient method based on moving weighted average to update the P-wave and S-wave velocity iteratively. The improved conjugate gradient method can enhance the stability of inversion， improve the quality of deep velocity modeling，and increase the convergence speed. The layered inversion strategy can reduce the amount of calculation and ensure the accuracy of wave field simulation by using staggered grid finite difference method with different mesh size， and improve the calculation efficiency of inversion. The layered inversion strategy based on the improved conjugate gradient can effectively reduce the nonlinear impact of the onshore actual data，making the common imaging point gathers flattened better and the velocity reconstructed more precise.
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A strong seismic energy reduction method under compressed sensing
LI Shengjun, GAO Jianhu, ZHANG Fanchang, HE Dongyang, GUI Jinyong
2023, Vol.35(4): 70–78
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1733 )
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243
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doi: https://doi.org/10.12108/yxyqc.20230407
Based on the compressive sensing（CS）theory and the wavelet interference mechanism between strong and weak reflections，a dynamic dictionary strong reflection decomposition method by approximating arbitrary strong reflection waveforms and a strong reflection reduction method based on shielding function were proposed. The validity of the methods was verified using numerical models and physical models with large lateral variations of strongly reflected waveforms. The methods have been practically applied in the second member of Permian Maokou Formation in the central uplift tectonic zone of central Sichuan Basin. The results show that：（1）Compared with the conventional de-strong reflection method，the strong reflection reduction method based on shielding function has better lateral continuity of the seismic event，the strong reflection event is more thoroughly reduced， and the weak reflection of the blocky sand body shielded by the strong reflection is revealed. At the same time， the method has low dependence on the horizon and can process the strong reflection within the time window at one time without accurate strong reflection horizon data.（2）The strong reflection reduction method based on shielding function has a better elimination effect when the distance between the sand body and the strong reflection layer is less than λ（wavelength）and greater than λ/4. The strong reflection can be completely removed and the weak reflection is completely revealed. When the distance between the sand body and the strong reflection layer is less than λ/4，the elimination effect is poor. When the distance between the sand body and the strong reflection layer is less than λ/8，the elimination effect is worse.（3）This method is better applied in the second member of Permian Maokou Formation in the central uplift tectonic zone of central Sichuan Basin. The weak reflection of the reservoir is revealed when the distance between the reservoir and the strong reflection layer is less than λ/4. The reservoir response is enhanced when the distance between the reservoir and the strong reflection layer is greater than λ/4.
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Optimization of 3D first-arrival traveltime tomography inversion
XU Xin, YANG Wuyang, ZHANG Kai, WEI Xinjian, ZHANG Xiangyang, LI Haishan
2023, Vol.35(4): 79–89
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235
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doi: https://doi.org/10.12108/yxyqc.20230408
The 3D first-arrival traveltime tomography inversion was optimized by picking up the first-arrival wave using machine learning，establishing the initial velocity constrained by micro logs，obtaining the global traveltime by multi-stencils fast marching method and narrow-band continuation algorithm，gaining the ray propagation path by ray tracing technology，and restricting the target inversion equation by apparent slowness and regularization. The results show that： （1）The machine learning based on image segmentation was used to divide the seismic records into three categories，including the early，the later and the narrow band of first arrival. The classification was weighted to pick up 576 000 channels of seismic data. The accuracy of picking up was greater than 99%，and the efficiency of picking up was more than 80 times higher than that of manual pick up.（2）Using the multi-stencils fast marching method which includes six difference templates can cover the traveltime calculation of 26 nodes around the grid，which can improve the traveltime calculation accuracy of grid diagonal direction. The 3D narrowband extension technique could be used to calculate the forward traveltime of global grid nodes. The 3D ray tracing technique based on Runge-Kutta algorithm could obtain the ray path.（3）Using micro logs information to construct the initial velocity and using apparent slowness information and regularization technology to constrain the tomography inversion equation can effectively improve the accuracy of velocity inversion within 1 000 m underground.（4）The optimized tomography inversion technology has been used to process the actual seismic data of Fusha 4 wiring bundle and Yingmai block in Tarim Oilfield，which could eliminate the “bull's eye” illusion and boundary artifact. The velocity curve of well point is highly consistent with the actual logs data.
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Geological characteristics and exploration potential of shale oil of Permian Lucaogou Formation in hanging wall of Fukang fault zone， Junggar Basin
LIU Hailei, ZHU Yongcai, LIU Longsong, YIN He, WANG Xueyong, DU Xiaodi
2023, Vol.35(4): 90–101
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241
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doi: https://doi.org/10.12108/yxyqc.20230409
Based on outcrops，cores and geochemistry analytical data，the lithologies，sedimentary paleoenvironment，the evaluation and distribution characteristics of source rocks of Permian Lucaogou Formation in the hanging wall of Fukang fault zone in Junggar Basin were analyzed，and the hydrocarbon accumulation model was discussed. The results show that： （1）There were sandstone，shale and carbonate rocks developed in Lucaogou Formation in Fukang fault zone，and they were dominated by gray-black and black oil shale with thickness of 200- 600 m. The carbonate rocks and shale were interbedded，and asphalt and oil traces can be seen in carbonate interbeds.（2）The Lucaogou Formation in the study area was deposited during the semi-deep lake to deep lake facies，the climate was mainly dry and hot，with intermittent warm and wet climate，and the ancient water body was brackish-saline water. The northern foot of Bogda Mountain was the center of the sedimentary lake basin， which has better deposition and preservation conditions.（3）It was a high mature and high-quality hydrocarbon source rock with abundance of organic matter in the study area，with outcrops Ro of 0.74%-1.28% and drilling core TOC of 0.92%-4.48%. They are mainly typeⅠ and Ⅱ1 and have high hydrocarbon potential，with S1+S2 greater than 20 mg/g. The hydrocarbon source rocks at the northern foot of Bogda Mountain has a larger scale of development and higher maturity than that in the western side，and the chloroform asphalt “A” content is greater than 1 200× 10-6.（4）The reservoirs of Lucaogou Formation in the study area are controlled by traps and faults. The reservoirs in the northern high steep zone are mostly exposed on the surface，damaged，and dominated by thick oil. The central nasal ridge zone is tectonically stable，with eight traps developed. The reservoirs in the central nasal ridge zone are characterized by self-generation and multi-phase filling. The southeastern part can be designated as the sweet spot area for shale oil exploration.
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Development characteristics and sedimentary environment of black shale of Lower Cambrian Niutitang Formation in western Hunan and Hubei
LIANG Xiaocong, NIU Xing, HU Mingyi, LI Yang, HU Zhonggui, CAI Quansheng
2023, Vol.35(4): 102–114
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373
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doi: https://doi.org/10.12108/yxyqc.20230410
The Lower Cambrian Niutitang Formation in the western Hunan and Hubei is an important target for shale gas exploration in southern China. Two profiles，Guchengcun in western Hubei and Yanwutan in western Hunan，were selected to carry out petrological and geochemical analysis of the black shale series of Lower Cambrian Niutitang Formation，so as to find out the provenance and tectonic background of the black shale，and analyze the sedimentary environment. The results show that：（1）The black shale deposits of Niutitang Formation in the two profiles are obviously different. The shale of Niutitang Formation in Guchengcun profile is mainly argillaceous shale with small thickness，and a small amount of siliceous shale is developed at the bottom，while the shale of Niutitang Formation in Yanwutan profile is mainly siliceous shale with large thickness，and the bottom is rich in silicophosphorous nodules，nickel，cobalt，vanadium and other metals. The quartz content of Yanwutan profile is much higher than that of Guchengcun profile，and pyrite is also more abundant.（2）There are obvious differences in the sedimentary environment，provenance background and tectonic background between the black rock series in the two profiles. The provenance of Guchengcun profile is mainly felsic igneous rocks and quartz sedimentary rocks，which were deposited in a weak reduction and weak oxidation environment on the continental shelf of the passive continental margin. The provenance of Yanwutan profile is mainly felsic igneous rocks， quartzitic sedimentary rocks and continental tholeiites， and with the input of hydrothermal provenance， it was deposited in a reducing environment on the continental slope of the passive continental margin.（3）In the Early Cambrian，the sediments of Hefeng Guchengcun in western Hubei were mainly black carbonaceous shale and limestone，with low contents of organic matters and silica，the water body was relatively shallow，and it was obviously affected by sea level fluctuations，so it was a shelf environment. However，the sedimentary thickness in western Hunan was large，with high content of organic matters，and it was close to deep faults，the source of hydrothermal silicon was abundant， which is a continental slope environment.
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Natural gas accumulation conditions and main controlling factors of Cretaceous tight volcanic rocks in Yingshan-Shuangcheng fault depression，Songliao Basin
DU Changpeng
2023, Vol.35(4): 115–124
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4056 )
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223
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doi: https://doi.org/10.12108/yxyqc.20230411
Based on the analysis of structural characteristics，reservoir accumulation stages and conditions，the distribution characteristics and main controlling factors of Cretaceous tight volcanic reservoirs in Yingshan-Shuangcheng fault depression of Soliao Basin were determined by using the data of seismic，inclusions，source rocks and production test. The results show that：（1）Yingshan-Shuangcheng fault depression has experienced threestage extension and compression tectonic activities. During the late sedimentary period of Qingshankou Formation（84-88 Ma）which was the main reservoir accumulation stage，the study area was in a stable depression period with weak tectonic activities，which was conducive to the formation and preservation of gas reservoirs.（2）The volcanic reservoirs in the study area are dominated by pyroclastic rocks and lava，with porosity and permeability of 9.6% and 0.93 mD. The source rocks of Shahezi Formation have high organic abundance，TOC（total organic carbon content）and S1+ S2（hydrocarbon generation potential）are 2.61% and 0.62 mg/g respectively，and the average vitrinite reflectance Ro is 3.26%，which is in an over-mature stage. The gas migrated into volcanic rocks of the first member of Yingcheng Formation through faults and unconformities.（3）The natural gas accumulation in Yingshan-Shuangcheng fault depression is controlled by hydrocarbon source rocks，faults，unconformities，volcanic bodies and their coupling relations. The differential activities of faults control the development and superposition of the first member of Yingcheng Formation and Shahezi Formation. The source rocks of Shahezi Formation are developed locally in the northern Yingshan fault depression，while the source rocks of the first member of Yingcheng Formation are mainly developed Sizhan-Taipingzhuang fault. The gas reservoirs are concentrated near the high-over mature source rocks with Ro greater than 3.0%，and the high yield gas wells are distributed circularly around the hydrocarbon generation center. The reservoirs of explosive facies and overflow facies near faults and unconformities that connected source have good physical properties and are important gas enrichment areas.（4）There are two accumulation models of natural gas reservoirs in the study area： “lower generation and upper reservoir， fault matching，near source and vertical migration” in Yingshan fault depression and “lateral generation and lateral reservoir，fault associated with unconformity，far source lateral migration and accumulation” in Shuangcheng fault depression. The structural-lithologic gas reservoirs in Yingshan fault depression are the most favorable exploration area in the study area.
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Prediction of favorable lithofacies and exploration direction of Carboniferous in Fudong slope，Junggar Basin
WU Xiaoning, DENG Yong, LIN Yu, ZHONG Houcai, KANG Xiaoning, WANG Yuting, QU Lin
2023, Vol.35(4): 125–136
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283
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doi: https://doi.org/10.12108/yxyqc.20230412
Based on the analysis of cores，logging and seismic facies，the lithofacies of Carboniferous in Fudong slope of Junggar Basin was divided and the distribution of volcanic rocks was predicted，and the favorable exploration direction was pointed out. The results show that： （1）There are five lithofacies of Carboniferous developed in Fudong slope： volcanic vent facies，explosive facies，overflow facies，argillaceous tuff facies，sedimentary pyroclastic facies，among which the explosive facies and overflow facies are favorable reservoir facies.（2）The volcanic vent facies in the study area is characterized by medium-low frequency，medium-strong amplitude，disordered funnel-shaped or columnar reflection， the explosive facies is characterized by medium-low frequency， mediumweak amplitude and disordered mound reflection，the overflow facies is characterized by low frequency，strong amplitude and continuous reflection，the argillaceous tuff facies is characterized by low frequency，mediumstrong amplitude and continuous reflection，and the sedimentary pyroclastic facies is characterized by medium frequency，medium-strong amplitude and continuous reflection.（3）The overflow facies of section b of Songkaersu Formation is mainly distributed in the southeast of the study area，the north of well XQ11 and the west of well XQ17 to XQ11，and the explosive facies of section a of Songkaersu Formation is mainly distributed in the main part of Xiquan nose-uplift.（4）Explosive facies and overflow facies are developed on a large scale in Xiquan nose-uplift of the study area，and they are close to hydrocarbon generation center of Carboniferous，with developed fractures and superior reservoir accumulation conditions， so it is a favorable area for natural gas exploration.
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Development characteristics and accumulation model of sublacustrine fans of the first member of Eocene Liushagang Formation in Weixinan Sag，Beibuwan Basin
MAN Xiao, HU Desheng, WU Jie, GONG Liyuan, LIU Zhixuan, JIANG Yingde, ZHAO Ye
2023, Vol.35(4): 137–144
Abstract
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doi: https://doi.org/10.12108/yxyqc.20230413
Based on the data of 3D seismic，mud-logging，wire-logging and core observation，the sedimentary characteristics and main controlling factors of the sublacustrine fan of the first member of Eocene Liushagang Formation in Weixinan Sag of Beibuwan Basin were studied，and the lithologic trap development model and hydrocarbon accumulation model were determined. The results show that： （1） The sublacustrine fans are developed in lowstand systems tract（LST）and transgressive systems tract （TST）of the first member of Liushagang Formation in subsag A of Weixinan Sag. The sublacustrine fans in LST are developed near the No. 1 fault，which is characterized by continuous and strong seismic reflection，while the sublacustrine fans in TST are distributed in the sag，and have obvious mound reflection.（2）Controlled by two major factors of source supply and paleogeomorphology，the first member of Liushagang Formation in subsag A developed two stages of sublacustrine fans. During the period of LST，there was little source supply in short axis direction，the footwall of No. 1 fault was the accumulation center of the sag，small scale nearshore submarine fans that directly enter the lake were developed，and lithologic traps that dip upward and pinch out toward the source area were formed. During the period of TST，the source supply gradually increased，the activity of No. 1 fault weakened，and the accumulation center of subsag A gradually migrated to the sag. The loose sediments in the fan delta front transported again into the middle of the sag and developed sublacustrine fans. Lithologic traps that dip and pinch out toward the south slope，and structurallithologic traps shielded by No. 2 fault were formed.（3）Vertical migration conditions are the key factors for lithologic reservoir accumulation in the study area. Microfractures controlled by early faults and late structural differential settlement developed in the upper part of the hydrocarbon source layer of subsag A，providing a good migration path for oil and gas to vertically migrate through mudstone caprocks to the lithologic trap above the source and accumulate to form reservoirs. This area has a reservoir accumulation model of “overpressure driving，microfractures provide migration path， and accumulation in low potential areas”.
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Sedimentary characteristics of shallow water delta of Middle Jurassic Toutunhe Formation in southern Anjihai river outcrops，Junggar Basin
FU Wenjun, ZHANG Changmin, JI Dongsheng, LOU Lin, LIU Jiale, WANG Xulong
2023, Vol.35(4): 145–160
Abstract
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doi: https://doi.org/10.12108/yxyqc.20230414
The Middle Jurassic Toutunhe Formation is an important exploration target zone in the southern margin of Junggar Basin. Based on the field survey of southern Anjihai river outcrops in the southern margin of Junggar Basin，combined with thin section identification of rock samples and geochemical analysis data，the lithologies and sedimentary structure of Toutunhe Formation were descried，and the sedimentary environment，sedimentary facies types and depositional evolution were analyzed. The results show that：（1）The Middle Jurassic Toutunhe Formation in the study area experienced a semi-arid，arid and humid climate evolution during the sedimentary period. The lacustrine basin was shallow，the lake bottom was gentle，and shallow delta deposits were developed.（2）Six types of sedimentary microfacies were developed in the study area，including distributary channel，inter-distributary depression，underwater distributary channel，inter-distributary bay，sheet sand and beach bar. The shallow water delta of Toutunhe Formation was affected by rivers and lake waves，forming a river-dominated shallow water delta in the stable period of lacustrine basin，and wave-dominated shallow water delta was developed.（3）From the early stage to the late stage of Toutunhe Formation，the lake level generally decreased and then increased. Riverdominated shallow water delta was developed in the first member of Toutunhe Formation，the distributary channel had strong hydrodynamic force. The river was frequently diverted and bifurcated，and continuously accumulated towards the lacustrine basin. The multi-stage channels were spliced. At that time，it was dominated by distributary channel and underwater distributary channel. Subsequently，the climate was further dry，wave-controlled shallow water delta was developed in the second member of Toutunhe Formation. The river action was weakened，and the wave action was enhanced. The delta plain was dominated by the development of a folded distributary channel. The sand bodies of underwater distributary channel of the delta front were transformed by wave scouring，forming strip-shaped sheet sand. During the deposition of the third member of Toutunhe Formation， due to the continuous subsidence of the Junggar Basin and the lateral migration of delta lobes，the surface of delta lobes in the shallow lacustrine basin was covered by lake water，and part of the clastic materials in the front of the shallow delta were reconstructed by lake waves， forming beach bar deposits parallel to the lake shore.
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Experiment on profile control and water plugging of rubber particles in inter-well single fractured-vuggy reservoir
QIAN Zhen, MAO Zhiqiang, ZHENG Wei, HUANG Yuanjun, CHEN Lifeng, ZENG Huiyong, LI Gang, SONG Ai
2023, Vol.35(4): 161–168
Abstract
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doi: https://doi.org/10.12108/yxyqc.20230415
Based on the model of a single-seam fractured-vuggy reservoir between wells in Tahe Oilfield，a physical simulation and displacement experiment of water plugging by rubber particle flow regulating agent was designed， the law of water flooding was analyzed，and the effects of different blocking locations，rubber particle dosage， particle size，density and injection rate on the displacement effect were discussed. The results show that：（1）The model length is 40 cm， the width is 30 cm， the thickness is 5 cm， the crack opening to is 4-20 mm， the cave diameter is 2-4 cm，the width of the wellbore is 10 mm，the crack volume of the model is 175 mL. At a temperature of 25 ℃ and atmospheric pressure，and at a water injection rate of 10 mL / min，the final degree of recovery is 43.83% when the water content of the production well reaches 98% by water injection at the rate of 10 mL/min. Due to gravity differentiation， there is a large amount of attic oil and bypass oil after water flooding， attic oil is mainly concentrated in the transverse top channel，bypass oil is mainly concentrated in the high position of the transverse middle channel and the transverse bottom channel，and the oil-water interface is flush with the high seam of the transverse middle channel.（2）In the simulation experiment，the transverse bottom channel and the transverse middle channel were blocked at the same time. The rubber particles were mixed in particle size，and the particle density is consistent with the density of the simulated formation water. The larger the amount，the greater the injection rate，and the better the flow regulation effect. When the amount of rubber particles was 0.04 PV，the particle size was less than 1 mm and 2-4 mm， and the injection rate was 15 mL/min， the recovery rate increased by 18.45%. Rubber particles with the same density as formation water can be carried and transported to the desired blocking position by injecting water，and the water blocking effect is better.（3）In the field experiment of rubber particle profile control and water plugging in well TH25X，The rubber particle size of the front section plug is 2-4 mm，the rubber particle size of the rear section plug is less than 1 mm，and the particle density is 1.13 g/cm3. Water and rubber particles were injected simultaneously at the rate of 50 m3/d， and the total amount is 920 m3. After water plugging， the cumulative oil increase is 1 200 t， and the water content decreases by 15%， achieving good plugging effect.