Accumulation features and mechanisms of high saturation natural gas hydrate in Shenhu Area, northern South China Sea

Zhang, Wei; Liang, Jin; Lu, Jing; Wei, Jiangong; Su, Pibo; Fang, Yuxiao; Guo, Yiqun; Yang, Shengxiong; Zhang, Guangxue

doi:10.1016/s1876-3804(17)30082-4

Cited by 149 publications

(83 citation statements)

References 14 publications

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“…This phenomenon demonstrated that the appearance of gas chimney acoustic fuzzy zones resulted from the intrusion of strata by upward migrating gas-bearing fluids. Moreover, the V-AMP structure and the elevated stacking velocity associated with the gas chimneys are also convincing indicators for the existence of gas hydrate in sediments, which have been confirmed in the Shenhu area (Wan, Xu, Wang, Xia, & Sun, 2017;Zhang, Liang, et al, 2017) and other gas hydrate-bearing basins around the world (Geletti & Busetti, 2011;Scholl et al, 2009).…”

Section: Indicators For the Migration Of Hydrocarbons And Gas Hydramentioning

confidence: 83%

“…The above research in this paper demonstrated that the BSRs in submarine deepwater areas of the QDNB are obvious and are stably distributed in partial regions, which provides basic geophysical evidence of the existence of natural gas hydrate, as well as favourable exploration prospects. The gas hydrate exploration results in the nearby Shenhu area in the PRMB (Figure a) have demonstrated that the occurrence of the BSRs with high amplitude and continuity is the most important and effect indicator for the accumulation of gas hydrate (Su et al, ; Wang, Collett, et al, ; Zhang, Liang, et al, ). Hence, BSRs, distributed around or on top of the mud diapirs and gas chimneys, are direct and powerful evidences of hydrate occurrence in the QDNB, and the central depression belt and the southern uplift areas with widespread BSRs are favourable gas hydrate exploration targets in the QDNB.…”

Section: Discussionmentioning

confidence: 99%

“…The distribution of mud diapirs, gas chimneys, and gas hydrate potential districts throughout the entire QDNB remains unknown, which inhibits the progress of prospecting gas hydrate in the QDNB. Moreover, the well‐known Shenhu gas hydrate‐enriched region in the Pearl River Mouth Basin (PRMB; Figure a), which is near the QDNB, has recently experienced big breakthroughs in the exploration and experimental mining of gas hydrate (Li et al, ; Wang et al, ; Zhang et al, ). This recent exploration has demonstrated that the hydrocarbon migration pathways composed of gas chimneys, mud diapirs, and associated diapiric faults played an important role in gas hydrate accumulation with high saturations (Su et al, ; Su et al, ; Sun, Wu, Dong, Lüdmann, & Gong, ; Zhang et al, ).…”

Section: Introductionmentioning

confidence: 99%

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Distribution and characteristics of mud diapirs, gas chimneys, and bottom simulating reflectors associated with hydrocarbon migration and gas hydrate accumulation in the Qiongdongnan Basin, northern slope of the South China Sea

Zhang

Gong

et al. 2018

Geological Journal

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A comprehensive analysis on high‐resolution seismic data and the geological characteristics of the Qiongdongnan Basin (QDNB) in the northern South China Sea reveals multiple seismic evidence indicative of hydrocarbon migration and gas hydrate accumulation, including mud diapirs, gas chimneys, bottom simulating reflectors (BSRs), acoustic blanking, enhanced reflections, V‐AMP structures, elevated stacking velocity of sediments, and seafloor expressions. Mud diapirs and gas chimneys, which are characterized by acoustic turbidity, fuzziness, and blanking reflections on seismic profiles, with a diversity of structures and scales, are widespread and concentrated in the centres of sags and the transitional zones between sags and uplifts. Five BSR regions, with a total area of approximately 11,000 km2, have been delineated in the QDNB. They have high or medium‐high continuity amplitudes with overlying acoustic blanking on seismic profiles, indicating the occurrence of gas hydrate. Distinct fluid seepage phenomena are common below the BSRs, demonstrating that abundant free gas has migrated and accumulated beneath the gas hydrate. The distribution of BSRs and the developed zones of mud diapirs and gas chimneys presents a spatial superposition feature, and the BSRs are usually located on top of or within the structural highs of the mud diapirs and gas chimneys, indicating a close relationship between them. Mud diapirs, gas chimneys, and associated faults are efficient pathways for migrating hydrocarbons, through which the mature to highly mature thermogenic gas of the Palaeogene strata and the biogenic gas of the Neogene sediments migrate to the gas hydrate stability zones and form gas hydrate. Gas hydrate samples were recovered from the gas chimney area during the remote operated vehicle (ROV) investigation in deepwater QDNB in 2015. Based on the seismic interpretation and geochemical results, we propose two models of gas hydrate accumulation in the deepwater area of the QDNB: (a) near source biogenic gas hydrate with self‐generation and self‐accumulation, and (b) distal source thermogenic gas hydrate with lower generation and upper accumulation. We believe that the areas with a fine spatial coupling configuration between the mud diapirs, gas chimneys, and BSRs are favourable exploration targets for gas hydrate in the QDNB.

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Section: Indicators For the Migration Of Hydrocarbons And Gas Hydramentioning

confidence: 83%

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Distribution and characteristics of mud diapirs, gas chimneys, and bottom simulating reflectors associated with hydrocarbon migration and gas hydrate accumulation in the Qiongdongnan Basin, northern slope of the South China Sea

Zhang

Gong

et al. 2018

Geological Journal

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“…The drilling results showed that the top of the hydrate-bearing layers (HBL) are located at 115-229 m below the ocean floor [14,15]. In 2015, a total of 23 wells across 19 sites, were drilled in GMGS-3 research area in the Shenhu area in the northern South China Sea ( Figure 1) [15,20,21].…”

Section: Hydrates In the Shenhu Areamentioning

confidence: 99%

“…The NGH saturation varies from 13% to 53% in these wells. High saturations of up to 75% were observed sporadically in some of these wells [15,20]. The exploration results of GMGS-1 and GMGS-3 showed that the NGH enrichment area in the Shenhu area holds large NGH reserves; however, NGH saturations and permeability of reservoirs show clear differences both in horizontal and vertical directions, and strong heterogeneity [20].…”

Section: Hydrates In the Shenhu Areamentioning

confidence: 99%

Influence of Reservoir Stimulation on Marine Gas Hydrate Conversion Efficiency in Different Accumulation Conditions

et al. 2018

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Abstract:In this paper, we used a method of combining reservoir stimulation technique (RST) with depressurization to investigate the conversion efficiency of marine natural gas hydrate (NGH) reservoirs in the Shenhu area, on the northern slope of the South China Sea, which differ in intrinsic permeability and initial NGH saturation conditions. We also analyzed the influence of the variable-stimulation effect on marine NGH conversion efficiency in different accumulation conditions, providing a reference scheme for improving the NGH conversion efficiency in the Shenhu area. In this work, we performed calculations for the variations in CH 4 production rate and cumulative volume of CH 4 in different initial NGH saturation, intrinsic permeability, and stimulation effect conditions. Variance analysis and range analysis methods were used to analyze the significance of these key factors and their interaction. Furthermore, we investigated the sensitivity of stimulation effect on NGH conversion efficiency. The simulation results showed that the stimulation effect has a significant influence on NGH conversion efficiency, and the influence of interaction between these three factors was not obvious. Possibly most importantly, we clarified that the sparsely fractured networks (N = 3) had a better effect for higher NGH conversion efficiency under higher saturation conditions. For lower permeability cases, the influence between sparsely (N = 3) and densely (N = 5) fractured networks were similar.

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Application of X‐Ray Computed Tomography Technology in Gas Hydrate

Zheng

Tang

et al. 2019

Energy Tech

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Clathrate hydrates are formed by water molecules and natural gas molecules under a certain temperature and pressure. Natural gas hydrates are mainly distributed in the marine sediments and the permafrost in nature. As a kind of potential clean energy, determining the structural characteristics of hydrates in sediments is the prerequisite for the safe and economic exploitation of natural gas hydrate. X‐ray computed tomography (CT) is a potential method to nondestructively detect the occurrence of natural gas hydrate. The basic physical properties such as porosity, hydrate saturation, and sediment permeability of the hydrate‐bearing sediments are analyzed by calculating the CT numbers or combining with the network model. Therefore, the X‐ray CT is used to study the hydrates produced in the laboratory and the hydrates formed in the nature by scientists all over the world. By summarizing the previous research, this article focuses on the important role of X‐ray CT in the hydrate research from the following three aspects: analyzing the basic physical properties of hydrate sediment, identifying the occurrence mode of hydrate in sediments, and measuring the hydrate formation and decomposition process. In response to the research progress and future research directions, relevant suggestions had been put forward.

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Accumulation features and mechanisms of high saturation natural gas hydrate in Shenhu Area, northern South China Sea

Cited by 149 publications

References 14 publications

Distribution and characteristics of mud diapirs, gas chimneys, and bottom simulating reflectors associated with hydrocarbon migration and gas hydrate accumulation in the Qiongdongnan Basin, northern slope of the South China Sea

Distribution and characteristics of mud diapirs, gas chimneys, and bottom simulating reflectors associated with hydrocarbon migration and gas hydrate accumulation in the Qiongdongnan Basin, northern slope of the South China Sea

Influence of Reservoir Stimulation on Marine Gas Hydrate Conversion Efficiency in Different Accumulation Conditions

Application of X‐Ray Computed Tomography Technology in Gas Hydrate

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