Quantitative characterization of vertical zonation of Mesozoic granite weathering reservoirs in the coastal area of eastern Fujian Province, China

Hu, Jingsong; Jiang, Yiming; Tang, Huafeng; Ma, Wei; Peng, Tao; Sun, Ning

doi:10.1016/j.petsci.2023.05.011

Cited by 2 publications

(3 citation statements)

References 35 publications

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“…In addition, 26 Jurassic-Cretaceous granite samples for porosity and permeability testing along with 4 NMR samples were collected from the Xiapu area in eastern Fujian for analysis and comparison. The NMR sample information of well L1 is shown in Table 1, and the specific information of field samples can be found in reference [31]. Weathering fracture and dissolution micropore…”

Section: Samplesmentioning

confidence: 99%

“…The degree of chemical weathering is based on the classification method of reference [31] and the classification scheme summarized by wells in the study area. Overall, the soil zone and the weathering and dissolution zone of the basement weathering crust in the Lingfeng buried hill and Xianqiao structural belt in Lishui Sag were thin and difficult to distinguish, indicating weak chemical weathering.…”

Section: Jurassic Granite In the Xianqiao Structural Zonementioning

confidence: 99%

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Characteristics of Weathering Reservoirs and Differences in Fracture Formation in the Weathering Crust of the Pre-Cenozoic Basement of Lishui Sag, East China Sea Basin, China

Liu,

Tang

2024

Minerals

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Fractures are the main reservoir space in basement weathering crusts and control the development of dissolution/alteration pores. A clear understanding of the main factors controlling fracture formation is needed to accurately predict reservoir characteristics. In this study, the reservoir characteristics along with the vertical zonation and thermal history of basement weathering crust were studied through lithology, mineral identification, porosity and permeability tests, nuclear magnetic resonance (T2), whole-rock analysis, and fission-track dating based on core samples, cuttings, and imaging logging data. Under the constraints of the Anderson model, the formation stages and timing of fractures were analyzed according to the regional stress field, fracture strike, fracture filling characteristics, and rock mechanical properties. The results revealed tensile structural fractures, shear structural fractures, weathering micro-fractures, alteration fractures, and intracrystalline alteration pores in the weathering crust of the Pre-Cenozoic basement in Lishui Sag. The reservoirs were characterized by low porosity, low permeability, and small pore diameter. The reservoir quality of granite was better than that of gneiss. The weathering crust could be divided into four zones: the soil layer, weathering dissolution zone, weathering fracture zone, and bedrock zone. The thickness of the soil layer and weathering dissolution zone were small. Four stages of fractures were identified: Yandang movement shear fractures, Paleocene tension structural fractures, Huagang movement shear fractures, and Longjing movement shear fractures. The main stage of basement fracture formation differed between the Lingfeng buried hill zone and Xianqiao structural zone. Considering the influence of the temperature and pressure environment on the rock’s mechanical properties, the differential fracture formation is related to the lithology, the coupling between the uplifted and exposed basement histories, and the tectonic stress field. Combined with the thermal histories of the Lingfeng buried hill zone and Xianqiao structural zone, the results suggest that the Lingfeng buried hill granite is favorable for basement fractures in Lishui Sag. Overall, this paper provides a novel method for analyzing the stages of fracture formation.

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Section: Samplesmentioning

confidence: 99%

Section: Jurassic Granite In the Xianqiao Structural Zonementioning

confidence: 99%

Characteristics of Weathering Reservoirs and Differences in Fracture Formation in the Weathering Crust of the Pre-Cenozoic Basement of Lishui Sag, East China Sea Basin, China

Liu,

Tang

2024

Minerals

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“…To date, many scientists have carried out extensive works on granite weathering crust reservoirs. Vertical zonation of the weathering crust is determined based on weathering intensity indices such as granite color, rock structure, mineral composition, logging characteristics, reservoir space types and geochemical indicators [8][9][10][12][13][14][15][16][17][18][19]. There are also various geological models of weathering crust established in previous studies [9,10,16,[20][21][22].…”

Section: Introductionmentioning

confidence: 99%

Characteristics and Genetic Mechanism of Granite Weathering Crust of Songnan Low Uplift, Qiongdongnan Basin, South China Sea

Li,

Guo,

2024

Minerals

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Recently, a large-scale gas reservoir was discovered in granitic buried hills of the Songnan Low Uplift in the Qiongdongnan Basin. However, the strong heterogeneity of granite reservoirs limits further exploration and evaluation. Based on observations of sixty core samples and sixty thin sections, mineral composition, zircon dating, apatite fission tracks, physical properties, image logs, outcrop surveys and seismic interpretations, the characteristics of granite weathering crust of the Songnan Low Uplift are analyzed, and its controlling factors and evolution process are evaluated. The results show that weathered granite in the study area can be divided into several zones, from top to bottom: eluvium–slope zone, sandy zone, weathered fracture zone and horizontal undercurrent vuggy zone. The reservoirs in the eluvium–slope zone are dominated by microfissures and intergranular dissolution pores and have an average porosity of 4.68% and permeability of 2.34 md; the reservoirs in the sandy zone are composed of intergranular and intragranular dissolution pores and have an average porosity of 11.46% and permeability of 4.99 md; the reservoirs in the weathered fracture zone consist of various fractures and have an average porosity of 3.91% and permeability of 2.5 md; the reservoirs in the horizontal undercurrent vuggy zone are subhorizontal fractures and vugs and have an average porosity of 2.7% and permeability of 0.23 md. The development of granite reservoirs is jointly influenced by petrology and minerals, long-term exposure in a warm humid paleoclimate, faults, diverse topographies and shallow buried depth. Based on the above, our study establishes a development model of weathering crust and suggests that only the gentle slope and platform remain strongly weathered zones. After undergoing a complex evolution process of formation–destruction/denudation–regeneration–preservation, the current weathering crust of the Songnan Low Uplift is finally established. The results of this study have important theoretical and application value for the hydrocarbon exploration of buried hills in the Qiongdongnan Basin and provide a reference example for other granite reservoirs worldwide.

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Quantitative characterization of vertical zonation of Mesozoic granite weathering reservoirs in the coastal area of eastern Fujian Province, China

Cited by 2 publications

References 35 publications

Characteristics of Weathering Reservoirs and Differences in Fracture Formation in the Weathering Crust of the Pre-Cenozoic Basement of Lishui Sag, East China Sea Basin, China

Characteristics of Weathering Reservoirs and Differences in Fracture Formation in the Weathering Crust of the Pre-Cenozoic Basement of Lishui Sag, East China Sea Basin, China

Characteristics and Genetic Mechanism of Granite Weathering Crust of Songnan Low Uplift, Qiongdongnan Basin, South China Sea

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