Structural Diagenesis in Carbonate Rocks as Identified in Fault Damage Zones in the Northern Tarim Basin, NW China

Wu, Guanghui; Xie, Erqing; Zhang, Yunfeng; Qing, Hairuo; Luo, Xiaofeng; Sun, Chi‐Lu

doi:10.3390/min9060360

Cited by 15 publications

(6 citation statements)

References 43 publications

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“…This agrees with the fact that high oil/gas production wells in the reef-shoal facies are much more than that in the carbonate intraplatform [8,16]. However, more than 90% of primary pores are absent in the long diagenetic history [16,17,19,25]. The residual primary porosity is less than 0.5% in the reef-shoal reservoirs.…”

Section: Discussion 41 the Production In Different Reservoirssupporting

confidence: 84%

An Overview of the Differential Carbonate Reservoir Characteristic and Exploitation Challenge in the Tarim Basin (NW China)

et al. 2023

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The largest marine carbonate oilfield and gas condensate field in China have been found in the Ordovician limestones in the central Tarim Basin. They are defined as large “layered” reef-shoal and karstic reservoirs. However, low and/or unstable oil/gas production has been a big challenge for effective exploitation in ultra-deep (>6000 m) reservoirs for more than 20 years. Together with the static and dynamic reservoir data, we have a review of the unconventional characteristics of the oil/gas fields in that: (1) the large area tight matrix reservoir (porosity less than 5%, permeability less than 0.2 mD) superimposed with localized fracture-cave reservoir (porosity > 5%, permeability > 2 mD); (2) complicated fluid distribution and unstable production without uniform oil/gas/water interface in an oil/gas field; (3) about 30% wells in fractured reservoirs support more than 80% production; (4) high production decline rate is over 20% per year with low recovery ratio. These data suggest that the “sweet spot” of the fractured reservoir rather than the matrix reservoir is the major drilling target for ultra-deep reservoir development. In the ultra-deep pre-Mesozoic reservoirs, further advances in horizontal drilling and large multiple fracturing techniques are needed for the economic exploitation of the matrix reservoirs, and seismic quantitative descriptions and horizontal drilling techniques across the fault zones are needed for oil/gas efficient development from the deeply fractured reservoirs.

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Section: Discussion 41 the Production In Different Reservoirssupporting

confidence: 84%

An Overview of the Differential Carbonate Reservoir Characteristic and Exploitation Challenge in the Tarim Basin (NW China)

et al. 2023

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“…Several previous works have highlighted the importance of studying deformational structures and chemical changes, known as structural diagenesis (e.g., Eichhubl et al, 2004;Laubach and Ward, 2006;Eichhubl et al, 2009;Laubach et al, 2010;Wu et al, 2019), in unraveling how fractures and fluid flow interact along fracture systems. Despite numerous studies, understanding structural diagenesis, that is, the relationship between fluid flow and structural elements, remains challenging.…”

Section: Introductionmentioning

confidence: 99%

Structural diagenesis and dolomitization of Cenozoic post-rift carbonates in the Red Sea rift basin: A multiproxy approach

Herlambang

Koeshidayatullah²,

Amao³

et al. 2022

Front. Earth Sci.

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Middle Miocene post-rift sediments are considered prolific subsurface reservoirs, representing one of the thickest sequences in the Red Sea rift basin. In the Umm Luj Basin of the eastern Red Sea, post-rift sediments are well exposed and represented by a carbonate-dominated system of the Raghama Formation. This formation was intensely fractured, following the rifting trend of the Red Sea. Such fractures and their associated diagenetic products could provide a significant archive of past tectonic fluid evolution. However, little is known about the origin and timing of the different fluid flows and diagenetic processes in the area. This study aims to resolve this issue by integrating fracture and multiproxy geochemical analyses of calcite precipitated in veins, fault breccia, and dolomitized host rock. The δ18O and δ13C isotopic compositions of calcite veins show tight clustering, varying between −10.6 and −9.5‰ and between −7.9 and −7.2‰, respectively. Meanwhile, the precipitated calcite along the fault breccia exhibited a closer to host rock isotopic composition (δ18O = −6.8‰; δ13C = −4.8‰). The δ18OVPDB of the dolomitized host rock shows a heavier average value, closer to the expected range of Miocene seawater. X-ray diffraction analysis shows that the veins have a high magnesium calcite content (up to 79.5%). In contrast, all the host rock samples, except samples 1-1BH, have dolomite contents of up to 94.3%, as well as breccia fragments. Thus, we argue that the structural diagenesis history of the study area comprises two distinct fluid members and tectonic events. The first member is the deposition of heavier isotopic composition related to dolomitization at slightly higher temperatures of up to 42.2°C. The second fluid flow member corresponded to a depleted isotopic calcite member with a temperature of 33°C. Compared with the Midyan Peninsula, the study area shares the same regional tectonic events, but the local tectonic and depositional settings could act as the determining factors of the dolomitization mechanism and meteoric alteration in each location. Hence, our results provide a new understanding of paleo-fluid circulation related to the evolution of tectonic events and highlights the value of integrating fracture and multiproxy geochemical analysis for structural diagenetic studies.

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“…In addition, the dominant gas-bearing Lower Cretaceous Bashijiqike Formation is buried to an ultra-deep depth of 5500-8000 m (Lai et al, 2019a). 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 and diagenesis of Bashijiqike Formation in the 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, 2019a).…”

Section: Introductionmentioning

confidence: 99%

“…Previous studies have individually unraveled the structural evolution, in situ stress, fracture and diagenesis of Bashijiqike Formation in the 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, 2019a). Despite the extensive researches on diagenesis and structure, few researches have been conducted on the structural diagenesis by interacting structure with dia-Structural diagenesis, a cross-disciplinary approach investigating relationships between structures (deformation, fractures, etc) and diagenesis (Laubach et al, 2010), helps us to better understand the changes in reservoir petrophysical properties and subsurface fluid flow (Vandeginste et al, 2012;Matonti et al, 2017;Ferraro et al, 2019;Wu et al, 2019;Rodrigues et al, 2021). Foreland fold-and-thrust belts are challenging for hydrocarbon exploration due to their structural complexity and heterogeneous reservoir quality distribution (Vandeginste et al, 2012).…”

Section: Introductionmentioning

confidence: 99%

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

Lai

Dong

et al. 2022

Solid Earth

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Abstract. The Lower Cretaceous Bashijiqike Formation of the Kuqa Depression is made up of ultra-deeply buried sandstones in fold-and-thrust belts. Few researches have linked 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, but 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 attention is paid on the dissolution associated with the fracture planes. Large numbers of natural fractures are cemented by carbonate cements, which limit fluid flow. In addition, the presence of fracture enhances 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 these contain preserved intergranular pores. Natural fractures are mainly related to the low Δσ layers. The presence of intergranular and intragranular dissolution pores is 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 the Kuqa Depression.

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Structural Diagenesis in Carbonate Rocks as Identified in Fault Damage Zones in the Northern Tarim Basin, NW China

Cited by 15 publications

References 43 publications

An Overview of the Differential Carbonate Reservoir Characteristic and Exploitation Challenge in the Tarim Basin (NW China)

An Overview of the Differential Carbonate Reservoir Characteristic and Exploitation Challenge in the Tarim Basin (NW China)

Structural diagenesis and dolomitization of Cenozoic post-rift carbonates in the Red Sea rift basin: A multiproxy approach

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

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