Hydrothermal Dolomite Paleokarst Reservoir Development in Wolonghe Gasfield, Sichuan Basin, Revealed by Seismic Characterization

Gao, Bole; Tian, Fei; Pan, Renfang; Zheng, Wenhao; Li, Rong; Huang, Tianjun; Liu, Yisheng

doi:10.3390/w12020579

Cited by 6 publications

(6 citation statements)

References 25 publications

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“…Previous studies indicate that the main causes of hydrothermal dolomite formation originated from a transformation that the limestone reshaped by Mgrich hydrothermal fluid seepage, leading to a considerable difference between thickness and dolomite degree (Gao et al, 2020). The researchers' focuses were always put on reservoir porosity and thickness characteristics when conducting a traditional investigation of seismic response characteristics of dolomite, the main factors of hydrothermal dolomite are mainly reflected in thickness and dolomitization development degree.…”

Section: Introductionmentioning

confidence: 99%

RETRACTED ARTICLE: A research on seismic forward modeling of hydrothermal dolomite：An example from Maokou formation in Wolonghe structure, eastern Sichuan Basin, SW China

Zhu

Gao²,

Pan

et al. 2020

European Journal of Remote Sensing

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To solve the problem of multi-resulted in seismic responses brought by dual impacts of the thickness and the lithologic association for further research of seismic response characteristics of hydrothermal dolomite, significant efforts have been made, which were based on the study of dolomite, the Maokou formation in the eastern Sichuan Basin, to conduct an analysis of mineral composition, strata distribution and dolomitization in its area, to develop layered medium models in accordance with different dolomitization degrees and thicknesses, and to build standardized wedge models for the full display of that in binary changes. Moreover, an essential application of the pre-stack and post-stack seismic forward modeling have been performed for analyzing how different dolomitization degrees and thicknesses had influences on the seismic response characteristics of hydrothermal dolomite. Given this, the sensitive seismic attributes of the target interval in the study area have been selected preferentially by analyzing the seismic response characteristics of hydrothermal dolomite, which plays a critical role in the entire process. The results show that?1. The response characteristic of amplitude is greatly influenced by the dolomitization degree and bed thickness?2. The dolomitization degree constitutes a transformation of AVO response characteristics from II to IV, while the variation of thickness leads to a transformation of AVO response characteristics from IV to II. 3. The actual results indicate that the relative fluid factor FF is one of the most sensitive AVO attributes, and the predicted results are in par with the actual results.

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Section: Introductionmentioning

confidence: 99%

RETRACTED ARTICLE: A research on seismic forward modeling of hydrothermal dolomite：An example from Maokou formation in Wolonghe structure, eastern Sichuan Basin, SW China

Zhu

Gao²,

Pan

et al. 2020

European Journal of Remote Sensing

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“…The best-known examples of hydrocarbon fields closely associated with karst reservoirs come from China. Reservoirs of this type have been identified there within a few large petroleum basins, including the Tarim Basin [6,7,30,[39][40][41][42][43], the Ordos Basin [44,45] or the Sichuan Basin [4,46], among others. The issue of identifying zones of paleokarst development in carbonate formations based on seismic and borehole data has been addressed by various authors, e.g., [8,10,12,47,48].…”

Section: Discussionmentioning

confidence: 99%

Examples of Paleokarst in Mesozoic Carbonate Formations in the Carpathian Foreland Area

Łaba-Biel,

Filipowska-Jeziorek,

Urbaniec

et al. 2024

Energies

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A paleokarst system developed in the Upper Jurassic–Lower Cretaceous carbonate complex has been recognized in the Carpathian Foreland area. Well logs testing and core data as well as an acoustic imager, a microresistivity scanner and six-arm dipmeter images were used to identify and analyze the character of the paleokarst features. A detailed interpretation of microresistivity and acoustic image logs allowed for the identification of different types of karst forms, such as caverns; multidirectional fractures, including fractures widened by dissolution; and the type of sediments filling them. The analysis of the seismic survey was conducted by linking the paleokarst characteristic features recognized in the seismic image to the karst intervals determined from borehole data. The set of seismic attributes calculated from the analyzed 3D seismic data, including the RMS amplitude, instantaneous frequency, consistent dip, variance, sweetness and relative acoustic impedance, helped to delineate the zones of the paleokarst distribution. Within the interpreted paleokarst surface developed in the carbonate formations in the study area, there are sinkholes, limestone pavements and valleys. Furthermore, in the northwestern part of the analyzed area, the development of paleokarst forms is related to the presence of a relatively deep branch of a paleovalley formed in the Paleogene, as well as to numerous discontinuities developed in carbonate formations. The development of this type of larger karst form was probably controlled primarily by tectonic faults. The research conducted by the authors of this paper showed the widespread presence of paleokarst features in Upper Jurassic–Lower Cretaceous carbonate formations in the study area. A good spatial identification of the paleokarst surface can be important in a regional context, since the highest part of the profile of carbonate formations is the most important reservoir for geothermal or hydrocarbon resources in this region.

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“…The Indosinian movement at the end of the Late Triassic resulted in the collision of the Yangtze plate with the North China plate. The Longmenshan island chain along the western edge of the Sichuan Basin gradually evolved into a strong thrust nappe orogenic belt and entered the stage of foreland basin evolution, and the coal-bearing clastic rocks of the Xujiahe Formation were deposited [17,18,[22][23][24].…”

Section: Methodsmentioning

confidence: 99%

“…The Q2 quartz cement was mainly formed from 95 to 125 °C, and the calculated paleofluid δ 18 O(water) value ranges from −6.63 to −0.09‰ VSMOW (Figure 8). Since the oxygen isotope composition of the formation waters generally evolves to more positive values with increasing burial as a result of water-rock reactions, the recrystallization reactions of the clay minerals and hydrocarbon emplacement tend to result in δ 18 O(water) enhancement [4,[30][31][32], and it is inferred that the pore fluid maybe the complex hightemperature mixed fluid remaining after hydrocarbon emplacement and water-rock reactions. The Q3 quartz cement primarily formed from 130 to 170 °C, and the calculated paleofluid δ 18 O(water) value ranges from −4.68to 1.54‰ VSMOW (Figure 8).…”

Section: Electron Probe Analysis Of the Quartz Cementsmentioning

confidence: 99%

“…The δ18 O Data of the Quartz Cements and Quartz GrainsThe δ18 O(Vienna Standard Mean Ocean Water (VSMOW)) values of the quartz cements in the Xu2 sandstones range from 6.56 to 18.91‰ (n = 23) (average 14.33‰) and are higher than those of the detrital quartz grains, which range from 6.56 to 8.21‰ (n = 7). The δ 18 O(VSMOW) value of the Q1 quartz cement ranges from 18.3 to 19.05‰ (n = 6), with an average of 18.61‰, and that of the Q2 quartz cement ranges from 15 to 17.99‰ (n = 7), with an average of 16.76‰, while that of the Q3 quartz cement ranges from 12.79 to 15.47‰ (n = 10), with an average of 14.22‰.…”

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The Origin of Quartz Cement in the Upper Triassic Second Member of the Xujiahe Formation Sandstones, Western Sichuan Basin, China

Ren

Wang

et al. 2021

Water

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High-precision in situ δ18O values obtained using secondary ion mass spectrometry (SIMS) for μm-size quartz cement are applied to constrain the origin of the silica in the deep-buried Upper Triassic second member of Xujiahe Formation tight sandstones, western Sichuan Basin, China. Petrographic, cathodoluminescence (CL), and fluid inclusion data from the quartz cements in the Xu2 sandstones indicate three distinct, separate quartz precipitation phases (referred to as Q1, Q2, and Q3). The Q1 quartz cement was formed at temperatures of approximately 56–85 °C and attained the highest δ18O values (ranging from 18.3 to 19.05‰ Vienna Standard Mean Ocean Water (VSMOW)). The Q2 quartz cement was generated at temperatures of approximately 90–125 °C, accompanying the main phase of hydrocarbon fluid inclusions, with the highest Al2O3 content and high δ18O values (ranging from 15 to 17.99‰ VSMOW). The Q3 quartz cement was formed at temperatures of approximately 130–175 °C, with the lowest δ18O values (ranging from 12.79 to 15.47‰ VSMOW). A portion of the Q2 and Q3 quartz cement has a relatively high K2O content. The dissolution of feldspar and volcanic rock fragments was likely the most important source of silica for the Q1 quartz cement. The variations in δ18O(water) and trace element composition from the Q2 quartz cement to the Q3 quartz cement suggest that hydrocarbon emplacement and water-rock interactions greatly altered the chemistry of the pore fluid. Feldspar dissolution by organic acids, clay mineral reactions (illitization and chloritization of smectite), and pressure dissolution were the main sources of silica for the Q2 and Q3 quartz cements, while transformation of the clay minerals in the external shale unit was a limited silica source.

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Hydrothermal Dolomite Paleokarst Reservoir Development in Wolonghe Gasfield, Sichuan Basin, Revealed by Seismic Characterization

Cited by 6 publications

References 25 publications

RETRACTED ARTICLE: A research on seismic forward modeling of hydrothermal dolomite：An example from Maokou formation in Wolonghe structure, eastern Sichuan Basin, SW China

RETRACTED ARTICLE: A research on seismic forward modeling of hydrothermal dolomite：An example from Maokou formation in Wolonghe structure, eastern Sichuan Basin, SW China

Examples of Paleokarst in Mesozoic Carbonate Formations in the Carpathian Foreland Area

The Origin of Quartz Cement in the Upper Triassic Second Member of the Xujiahe Formation Sandstones, Western Sichuan Basin, China

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