Salt Diapir‐Driven Recycling of Gas Hydrate

Burton, Z. F. M.; Dafov, Laura N.

doi:10.1029/2022gc010704

Cited by 18 publications

(16 citation statements)

References 175 publications

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“…Therefore, there must be natural gas migration or a loss in the inorganic pores and bedding fracture systems of this layer. This accumulation mode of self-generation and selfstorage within the siliceous shale layer with bedding migration has certain similarities with conventional natural gas migration and accumulation, even methane hydrate systems [37,38], and is not completely the same as the continuous accumulation mode of Changning-Weiyuan [33] and Barnett shale gas fields [39][40][41]. The latter has basically no bedding migration due to the lack of open bedding fractures [1-3,33], and its "sweet spot area" is widely distributed in the syncline area and is little associated with local structure The above values indicate that, in the Majiatan-Dashuikeng area, the total porosity of the lower Wulalike Formation was similar to that of the Longmaxi Formation, especially with a large number of bed-parallel fractures, providing high-quality reservoir space and flow channels for shale gas accumulation.…”

Section: Discussionmentioning

confidence: 91%

Reservoir Space Characterization of Ordovician Wulalike Formation in Northwestern Ordos Basin, China

Wang,

Zhou,

Liang

et al. 2023

Processes

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The Ordovician Wulalike Formation in the northwestern Ordos Basin is a new prospect for exploring marine shale gas in China, facing prominent problems such as unclear reservoir conditions and the distribution of enrichment areas. The types of reservoir space, fracture development, porosity composition, and physical properties of the lower Wulalike Formation are discussed through the multi-method identification and quantitative evaluation of reservoir space for appraisal wells. The Wulalike Formation in the study area contained fractured shale reservoirs with matrix pores (mainly inorganic pores) and permeable fractures. The fracture system of the lower Wulalike Formation is dominated by open bed-parallel fractures that are intermittent or continuous individually, with a width of 0.1–0.2 mm and spacing of 0.5–14.0 cm. The fracture-developed intervals generally exhibit bimodal or multimodal features on NMR T2 spectra and have a dual-track feature with a positive amplitude difference in deep and shallow resistivity logs. The length and fracture porosity of fracture-developed intervals varied greatly in different parts of the study area. In the Majiatan-Gufengzhuang area in the southern part of the study area, the fracture development degree generally decreased from west to east. In the Shanghaimiao area in the central part of the study area, fractures were extremely developed, the continuous thickness of the fracture-developed interval was generally more than 20 m, and the average fracture porosity was higher than 1.3%. In the Tiekesumiao area in the northern part of the study area, the fracture development degree was generally lower than that in the central and southern parts of the study area and also showed a decreasing trend from west to east. The lower Wulalike Formation had a total porosity of 2.46–7.08% (avg. 4.71%), roughly similar to the Longmaxi Formation in the Sichuan Basin, of which matrix porosity accounts for 34.0–90.0% (avg. 61.1%) and fracture porosity accounts for 10.0–66.0% (avg. 38.9%). From this, it could be inferred that the shale gas accumulation type of the lower Wulalike Formation in the northwest margin of the basin is mainly a fractured shale gas reservoir controlled by structure, and its “sweet spot area” is mainly controlled by tectonic setting and preservation conditions. This indicates that the Wulalike Formation in the northwestern Ordos Basin has good shale gas exploration prospects, and a large number of fault anticlines or fault noses formed by reverse dipping faults have the potential of favorable exploration targets.

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Section: Discussionmentioning

confidence: 91%

Reservoir Space Characterization of Ordovician Wulalike Formation in Northwestern Ordos Basin, China

Wang,

Zhou,

Liang

et al. 2023

Processes

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“…The rock brittleness index and shear/tensile strength factor are proportional to the FI and are positive indicators, which are normalized by Equation ( 14). The fracture toughness and horizontal stress difference factor are negatively related to the FI and are normalized by Equation (15).…”

Section: Parameter Standardizationmentioning

confidence: 99%

“…S n = X max − X X max − X min (15) where S p is the standardization of positive indicators, S n is the standardization of negative indicators, X is the specific assignment of a factor, and X max and X min are the maximum and minimum values of the factor.…”

Section: Parameter Standardizationmentioning

confidence: 99%

Evaluation of Tight Sandstone Mechanical Properties and Fracability: An Experimental Study of Reservoir Sand−Stones from Lufeng Sag, Pearl River Mouth Basin, Northern South China Sea

Peng¹,

Zhou²,

Wu³

et al. 2023

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Reservoir rocks of the Pearl River Mouth Basin’s Lufeng Sag have low porosity (average porosity 12.6%) and low permeability (average permeability 16.5 mD), requiring hydraulic fracturing to obtain economic production of oil and gas. To contribute to the understanding of these reservoirs, and to promote successful production in the region, we analyzed the mechanical properties of tight sandstone. Moreover, we introduced the shear/tensile strength factor, in combination with the fracture toughness and horizontal stress difference coefficient, as an innovative approach to characterize the ease of forming a complex fracture network after reservoir fracturing. Based on this, we established a fracability evaluation model suitable for offshore low-permeability sandstone reservoirs by an analytic hierarchy process from the perspective of whether the reservoir can form an effective transformation volume and complex fracture network after fracturing. The results indicate that the primary minerals of the target reservoir are quartz and clay minerals, and the natural fractures are not developed. The mechanical properties exhibit a high Young’s modulus (ranging from 30.4 to 34.4 GPa) and high compressive strength (with cohesion between 41 and 45 MPa and an angle of internal friction between 31.0 and 33.5°). The relatively low tensile strength and fracture toughness values are conducive to fracture initiation and extension during the fracturing process. Through the fracability evaluation model constructed in this paper, the depth interval at 4155.1–4172.1 m is identified as a high-quality fractured layer. The results of this study not only provide theoretical guidance for target well and formation selection in the Lufeng Sag, but also have important practical implications for increasing oil and gas production from tight sandstone reservoirs.

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“…Furthermore, understanding mudslides and mass movements has broader implications, extending to marine environments and the geological record of sediment transport on land and in the oceans [9,10]. This knowledge is relevant for modeling marine instability and landslide processes as well [11][12][13][14]. Several studies have employed numerical simulations to investigate mudslides.…”

Section: Introductionmentioning

confidence: 99%

Simulation and Management Impact Evaluation of Debris Flow in Dashiling Gully Based on FLO-2D Modeling

Jia,

Lv,

Luo

2024

Applied Sciences

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Dashiling Gully, located in Miyun District, Beijing, exhibits a high susceptibility to debris flow due to its unique geological and topographical characteristics. The area is characterized by well-developed rock joints and fissures, intense weathering, a steep gradient, and a constricted gully morphology. These factors contribute to the accumulation of surface water and loose sediment, significantly increasing the risk of debris flow events. Following a comprehensive field geological investigation of Dashiling Gully, key parameters for simulation were obtained, including fluid weight, volume concentration, and rainfall. The formation and development conditions of potential mudslides were analyzed, and numerical simulations were conducted using FLO-2D software (version 2009) to assess scenarios with rainfall probabilities of 1 in 30, 50, and 100 years. The simulations accurately reconstructed the movement velocity, deposition depth, and other critical movement characteristics of mudslides under each rainfall scenario. Using ArcGIS, pre- and post-treatment hazard zoning maps were generated for Dashiling Gully. Furthermore, the efficacy of implementing a retaining wall as a mitigation measure was evaluated through additional numerical simulations. The results indicated that mudslide velocities ranged from 0 to 3 m/s, with deposition depths primarily between 0 and 3 m. The maximum recorded velocity reached 3.5 m/s, corresponding to a peak deposition depth of 4.31 m. Following the implementation of the retaining wall, the maximum deposition depth significantly decreased to 1.9 m, and high-risk zones were eliminated, demonstrating the intervention’s effectiveness. This study provides a rigorous evaluation of mudslide movement characteristics and the impact of mitigation measures within Dashiling Gully. The findings offer valuable insights and serve as a reference for forecasting and mitigating similar mudslide events triggered by heavy rainfall in gully mudslides.

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Salt Diapir‐Driven Recycling of Gas Hydrate

Cited by 18 publications

References 175 publications

Reservoir Space Characterization of Ordovician Wulalike Formation in Northwestern Ordos Basin, China

Reservoir Space Characterization of Ordovician Wulalike Formation in Northwestern Ordos Basin, China

Evaluation of Tight Sandstone Mechanical Properties and Fracability: An Experimental Study of Reservoir Sand−Stones from Lufeng Sag, Pearl River Mouth Basin, Northern South China Sea

Simulation and Management Impact Evaluation of Debris Flow in Dashiling Gully Based on FLO-2D Modeling

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