Characterization of braided river-delta facies in the Tarim Basin Lower Cretaceous: Application of borehole image logs with comparative outcrops and cores

Nian, Tao; Jiang, Zaixing; Wang, Guiwen; Xiao, Chengwen; He, Wenjun; Fei, Liyin; He, Zhibo

doi:10.1016/j.marpetgeo.2018.06.024

Cited by 36 publications

(14 citation statements)

References 23 publications

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“…Among them, the Lower Cretaceous Kapushaliang Group (K 1 kp) and Bashijiqike Formation (K 1 bs) are the dominant reservoir intervals, and many giant gas fields including Kela 2, Awa, Bozi, Dina, Dabei, Keshen gas fields have been discovered in this gas bearing formation (Fig. 1C) (Jin et al, 2008;Shen et al, 2017;Nian et al, 2018).…”

Section: Geological Settingsmentioning

confidence: 99%

“…Depositional facies of the Bashijiqike Formation are recognized as fan-braided deltaic environments (Jia and Li, 2008). The lithologies include a wide range from siltstone, fine-medium grained sandstone, to conglomerate and pebby sandstones, and intergranular, intragranular pores as well as fracture constitute the main reservoir pore spaces (Nian et al, 2018;Lai et al, 2019;Nian et al, 2021). The depositional subfacies evolved from fan delta plain in K 1 bs 3 to braided delta front subfacies in K 1 bs 2 and K 1 bs 1 members, and the main depositional microfacies https://doi.org/10.5194/se-2021-85 Preprint.…”

Section: Geological Settingsmentioning

confidence: 99%

“…The ultra-deep burial depths, complex structure patterns and concentrated stress will result in complex diagenetic modifications and pore evolution histories (Laubach et al, 2010;Wu et al, 2019;Del Sole et al, 2020). Previous studies have individually unraveled the structural evolution, in situ stress, fracture as well as diagenesis of Bashijiqike Formation in Kuqa depression (Jia and Li, 2008;Lai et al, 2017a;Shen et al, 2017;Nian et al, 2018;Ju and Wang, 2018;Lai et al, 2019).…”

Section: Introductionmentioning

confidence: 99%

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Structural diagenesis in ultra-deep tight sandstones in Kuqa depression, Tarim Basin, China

Lai

Liu

et al. 2021

Preprint

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Abstract. The Lower Cretaceous Bashijiqike Formation of Kuqa depression is ultra-deeply buried sandstone in fold-and-thrust belts. Few researches link diagenetic processes with structure. To fill this gap, a comprehensive analysis integrating diagenesis with structure pattern, fracture and in situ stress is performed following a structural diagenetic approach. The results show that the pore spaces include residual intergranular pores, intergranular and intragranular dissolution pores, and micro-fractures. The sandstones experienced a high degree of mechanical compaction, and compaction is limited in well-sorted rocks or abundant in rigid quartz grains. The most volumetrically important diagenetic minerals are calcites. The framework grains experienced a varied degree of dissolution, and intergranular and intragranular dissolution pores are formed. Special aims are paid on the dissolution associated with the fracture planes. Most natural fractures are cemented by carbonate cements, which limit fluid flow. In addition, presences of fracture enhance dissolution, and the fracture planes are enlarged by dissolution. Cementation and dissolution can occur simultaneously in fracture surfaces, and the enlarged fracture surfaces can be cemented by late-stage cements. The in situ stress magnitudes are calculated using well logs. The horizontal stress difference (Δσ) determines the degree of mechanical compaction, and rocks associated with low Δσ experienced a low degree of compaction, and there contain preserved intergranular pores. Natural fractures are mainly related to the low Δσ layers. The presences of intergranular and intragranular dissolution pores are mainly associated with the fractured zones. The high quality reservoirs with intergranular pores or fractures are related to low Δσ layers. The structural diagenesis researches above help the prediction of reservoir quality in ultra-deep sandstones, and reduce the uncertainty in deep natural gas exploration in Kuqa depression.

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Section: Geological Settingsmentioning

confidence: 99%

Section: Geological Settingsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Structural diagenesis in ultra-deep tight sandstones in Kuqa depression, Tarim Basin, China

Lai

Liu

et al. 2021

Preprint

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“…Movahed Zohreh et al [29] evaluated the drilling risk of wells, especially the borehole failure, through imaging logging, but the borehole morphology was not observed with enough accuracy. Facing the lack of data on outcrops, cores or thin sections, Nian et al [30] elaborated the sedimentary features of a braided delta, and deduced the paleocurrent direction through high-quality imaging logging. Nonetheless, the paleocurrent direction cannot be determined accurately without considering the regional tectonic setting.…”

Section: Literature Reviewmentioning

confidence: 99%

A Statistical Method for Lithic Content Based on Core Measurement, Image Analysis and Microscopic Statistics in Sand-conglomerate Reservoir

Chen¹,

Qu²,

Qiu³

et al. 2019

I2M

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The type and content of lithics are of great importance to reservoir research. The existing statistical methods for lithic content mainly focus on sand-level lithics, failing to consider gravel-level lithics. Thus, these methods are not applicable to sand-conglomerate reservoirs, where sand-level and gravel-level lithics coexist. To solve the defects, this paper proposes a hybrid strategy for lithic content in sand-conglomerate reservoirs. Firstly, the type and content of gravel-level lithics were determined through full-bore formation microimager (FMI) imaging logging and core analysis. Next, the type and content of sand-level lithics were obtained by thin-section observation. On this basis, the data on the two levels of lithics were integrated to yield the total content of each type of lithics in the sand-conglomerate reservoir. The hybrid strategy was applied to analyze the lithics features and physical properties of a sand-conglomerate reservoir in the upper part of the fourth member of the Shahejie Formation (upper Es4), north zone, Dongying Depression, China. The results show that the hybrid strategy output greater upper and lower limits of the total lithic contents than the existing methods, and outshined the traditional thin-section observation in accuracy. In the study area, the sand-conglomerate reservoirs in the upper Es4 of the two blocks have different physical properties. The difference is mainly attributable to the different types and contents of lithics of the two blocks. The proposed strategy boasts a strong application potential in oil and gas exploration.

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“…The borehole electrical images provide a wealth of geologic data obtainable only from cores previously. Even though spatial resolution of features visible on the images (down to 0.2 inch) is lower than that on a core, borehole images can offer major geologic information where core is absent [1][2][3][4][5]. However, the generated image essentially provides numerical data in the form of log curves which may be useful to quantify the images and classify grain size of rocks [6].…”

Section: Introductionmentioning

confidence: 99%

A grain size auto-classification of Baikouquan Formation, Mahu Depression, Junggar Basin, China

et al. 2020

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The borehole electrical imaging log offers general visual borehole wall, leaving no doubt that the conductivity contrast is sufficient to obtain a qualitative gain-size distribution of rocks. In this study, an automatic grain-size classification method is proposed using gray values of borehole electrical images from Baikouquan Formation in Mahu Depression. The first stage is comparing electrical images with cores. Gravels, sands, silts and clays are all discovered in the cores. The gravels are “mottled” in electrical images, and the bigger the spots, the coarser the gravels. The images of sands are homogeneous bright colored, and the coarser the sandy grains, the brighter the images. The electrical images of silts and clays are homogeneous brown and dark-brown colored. The second stage is auto-discriminating four categories of grain sizes roughly using averages and variances of gray values. The variances of gray values of gravels are high, whereas those of sands are medium. The gray averages of silts are between 160 and 220, whereas those of clays are larger than 200. The third stage is auto-classifying three kinds of gravels or sands finely using frequency distribution of gray values. The gray values of frequency peaks of cobbles are less than 50 and frequencies are larger than 15%, whereas those of pebbles are less than 50 or larger than 200 and frequencies are between 10% and 20%; almost gray frequencies of granules are less than 10%. The dominated gray values of coarse sandstones, medium sandstones and fine sandstones are less than 50, between 50 and 160 and ranged from 160 to 240, respectively. The proposed method is demonstrated to be useful and fast to auto-classify grain size of various rocks in conglomeratic environments.

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Characterization of braided river-delta facies in the Tarim Basin Lower Cretaceous: Application of borehole image logs with comparative outcrops and cores

Cited by 36 publications

References 23 publications

Structural diagenesis in ultra-deep tight sandstones in Kuqa depression, Tarim Basin, China

Structural diagenesis in ultra-deep tight sandstones in Kuqa depression, Tarim Basin, China

A Statistical Method for Lithic Content Based on Core Measurement, Image Analysis and Microscopic Statistics in Sand-conglomerate Reservoir

A grain size auto-classification of Baikouquan Formation, Mahu Depression, Junggar Basin, China

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