Discovery of the ancient Ordovician oil-bearing karst cave in Liuhuanggou, North Tarim Basin, and its significance

Zhong, Jun; Cui, Mao; Li, Yong; Li, Yang; Yuan, Xiangchun; Niu, Yongbin; Chen, Xin; Huang, ZhiJuan; Shao, Zhufu; Wang, Peijun; Li, Jia; Zhang, Danfeng

doi:10.1007/s11430-012-4467-3

Cited by 16 publications

(4 citation statements)

References 8 publications

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“…When Z = 120, the environment of the carbonate is then of the uncertain type. This conclusion has been confirmed by many subsequent research results (Zhong et al, 2012). Table 1 shows that the δ 13 C values of the 49 tested samples are distributed within the range of −2.63%-2.48%, while the distribution range of their Z values is 117.48-130.24.…”

Section: Relationship Between Paleosalinity Levels and Carbon/oxygen ...supporting

confidence: 78%

“…In Epstein and Mayeda, 1953 further realized Urey's theory; they established the basic principles for using δ 18 O values to calculate paleosalinity levels and determined that the δ 18 O value increased with increases in salinity. For a long time, experts and scholars have made great progress in studying the sedimentary environment and diagenesis of carbonate rocks in the Tarim Basin by using the stable carbon and oxygen isotopic composition of carbonate rocks (Zhang et al, 2015;Zhang et al, 2016a;Zhang et al, 2016b;Zhong et al, 2012;Gao et al, 2011;Zhao et al, 2012). Furthermore, much research has been performed using the carbon and oxygen isotope compositions of karst cave-filling stalagmites and stalactites to reconstruct paleoclimates and paleoenvironments since the Permian period (Liu et al, 1997;Zhang et al, 2015;Huang et al, 2016).…”

Section: Introductionmentioning

confidence: 99%

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Isotopic characteristics of carbon and oxygen within ordovician carbonate paleokarst in the tazhong region and their paleoenvironmental significance

Liu¹,

Ji²,

Li³

2023

Front. Earth Sci.

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The Tazhong region is a key area for oil and gas exploration and development within the Tarim basin. In this region, development of Ordovician carbonate paleokarsts has been found to be extremely heterogeneous. To investigate the developmental stages of these Ordovician carbonate karsts and their corresponding paleoenvironmental conditions, oxygen and carbon isotopic characteristics of calcite paleokarst fissure fillings were examined in conjunction with rock-structure analyses. Results show that δ18O (PDB) values tend towards negative values in general, ranging from −3.97% to −12.7% (average value −7.64%), which is indicative of the presence of paleokarstification via dissolution by atmospheric freshwater. Values of δ13C (PDB) span a relatively large range, from 2.48% to −2.13% (average value of 0.23%). This shows that the paleokarst in this area has gone through two stages of supergene and burial diagenesis, and the process of paleokarst is complex. The paleotemperature at which the karst fissure-filling deposits were formed ranged from 6.5 to 47.1°C (average value of 21.8°C), and the salinity of the medium has Z values from 117.48 to 130.24 (average value of 123.94). Four different paleokarsification settings were thus revealed: a marine depositional environment, an atmospheric freshwater karst-filling environment, a shallow-burial paleokarsification environment and a deep-burial high-temperature environment. It has thus been shown that the karst pores, fissures and caves formed by paleokarstification over multiple stages are the main reservoir spaces in this region. This study will serves as a basis for karst reservoir predictions, and exploration and development in this region.

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Section: Relationship Between Paleosalinity Levels and Carbon/oxygen ...supporting

confidence: 78%

Section: Introductionmentioning

confidence: 99%

Isotopic characteristics of carbon and oxygen within ordovician carbonate paleokarst in the tazhong region and their paleoenvironmental significance

Liu¹,

Ji²,

Li³

2023

Front. Earth Sci.

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“…The total exposed thickness could reach 500 m, primarily carbonate. Emphatically, Penglaiba group, Yingshan group, Yijianfang group, and Dawangou group were the significant formations [27][28][29]. Respectively, Penglaiba group is mainly off-white fine-meso crystalline dolomite, Yingshan group consists of gray and light gray microcrystalline limestone.…”

Section: Geological Settingmentioning

confidence: 99%

“…During the Indo-Yanshanian period, the subduction collision of the Indosinian plate towards the Eurasian continent produced a strong far-source collision effect in the northern Tarim region, which caused a strong horizontal compression and tectonic uplift in the Aksu area. Current north-south thrust nappe structure was finally formed [29]. In the Himalayan period, the stratum at the southern edge of the Kepingtag structural belt has undergone strong uplift and bending deformation, and suffered some degree of erosion.…”

Section: Geological Settingmentioning

confidence: 99%

Filling Provenance in Fracture Cavity Formation within Aksu Area, Tarim Basin, NW China: Indicators from Major and Trace Element, Carbon-Oxygen, and Strontium Isotope Compositions

Ren

et al. 2021

Lithosphere

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With an aim to increase the understanding about sedimentary environment and isotopic and chemical characteristics of fillings in fracture cavities with multiple compositions, we conducted scanning electron microscope (SEM), fluid inclusion testing (FIT), common and trace element chemistry, full analysis testing, isotopic compositions (δ13C, δ18O, 87Sr/86Sr), and apatite fission track testing to study the formation environment of Aksu area, Tarim Basin. According to outfield and microscope observations, combined with SEM results, three textural and compositional type fractures and cavities were distinguished. Through fine analysis of geochemistry characteristics on fractures, cavities, multiple filling periods, and environments were interpreted. Constrained by rare earth element (REE) pattern diagram, relationships between carbon and oxygen isotopes, strontium isotope, the compositional patterns, and generation environment of the fracture and cavities were determined. The results show that (1) cavity, fracture filling, and wall rock primarily consist of calcite, with a proportion of 56.85%, 80.48%, and 81.00%, respectively. (2) Four fracture sets have been distinguished in the Ordovician limestone of the karst cave, Middle-Late Caledonian (Set 1), Early Hercynian (Set 2), Indo-Yanshanian (Set 3), and Himalayan orogeny (Set 4). Two stages of cave filling deposition are distinguished. Stage I was coeval with the Middle-Late Caledonian Set 1 fractures and is attributable to the circulation of freshwater fluid. Stage II was coeval with the Early Hercynian Set 2 fractures and is attributable to deep hydrothermal fluid circulation. (3) Cavity, fracture filling, and wall rock in Ordovician strata are slightly influenced by diagenesis alteration and territorial supply. Three significant filling stages were distinguished, freshwater fluid with strong oxidizing environment (Middle-Late Caledonian), hydrothermal fluid with authigenic abnormal enrichment (indicating obvious hypoxic sedimentary water, Early Hercynian), and high-temperature hydrothermal fluid from deep earth (primarily influenced by magmatism, Indo-Yanshanian, and Himalayan).

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A Connected Domain Identification Method and Its Application in Quantitative Pickup of Cave Information Using Electric Imaging Logging

Yan

Qiang

Zun-Zhi

et al. 2016

Chinese J of Geophysics

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Solution caves are important fluid reservoir space in carbonate reservoir, and researching FMI images' caves connected domain labeling and extracting their information are meaningful. A high resolution color image can be obtained after data processing of FMI. After a series of processes which include image graying, median filtering and threshold segmentation for the color image, a binary image will be obtained which can reflect the characteristic of solution caves on the wall of a well. And on the image, caves are black spots which are labeled by same number. The labeling algorithm for image connected domain based on equivalence pair processing has the advantages of fast and no‐repeat labeling, which can eliminate equivalent pairs while labeling connected domain. The solution caves in the binary image can be marked from small to large number accurately by this arithmetic, in addition, the information of every connected domain including holes' size, grading factor, area of connected domains (areal porosity) and roundness can be extracted and processed. Using the labeled binary image can calculate porosity curve which reflects development degree of caves, and based on this curve the image can be divided into several layers. On this basis, the information distribution of areal porosity, holes' size, roundness and grading factor of every layer can be calculated easily. At last, all of these informations will be used to quantitatively evaluate the carbonate reservoir which has strong heterogeneity and lots of solution caves. And this work is also a helpful exploration for quantitative extracting of cave information from FMI images.

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Discovery of the ancient Ordovician oil-bearing karst cave in Liuhuanggou, North Tarim Basin, and its significance

Cited by 16 publications

References 8 publications

Isotopic characteristics of carbon and oxygen within ordovician carbonate paleokarst in the tazhong region and their paleoenvironmental significance

Isotopic characteristics of carbon and oxygen within ordovician carbonate paleokarst in the tazhong region and their paleoenvironmental significance

Filling Provenance in Fracture Cavity Formation within Aksu Area, Tarim Basin, NW China: Indicators from Major and Trace Element, Carbon-Oxygen, and Strontium Isotope Compositions

A Connected Domain Identification Method and Its Application in Quantitative Pickup of Cave Information Using Electric Imaging Logging

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