Near-wellbore fracture initiation and propagation induced by drilling fluid invasion during solid fluidization mining of submarine nature gas hydrate sediments

Zhu, Hehua; Dang, Yike; Wang, Guorong; Zhou, Shouwei; Fu, Qiang

doi:10.1016/j.petsci.2021.09.026

Cited by 18 publications

(11 citation statements)

References 44 publications

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“…Recently, these two methods have been widely used in hydraulic fracturing. Zhu et al 41 combined the DEM and computational fluid dynamics to study fracture propagation and found that the existence of an in situ stress difference is important. The higher the pumping pressure, the more microfractures are formed in the hydrate and the higher is the speed, which is relatively favorable for the extension of fractures.…”

Section: Fracture Formation and Developmentmentioning

confidence: 99%

“…At great depth, the fractures were mainly concentrated around the wellbore and did not extend into the formation. The shallower the formation depth, the longer the fracture length and the larger the drilling fluid invasion area . Sun et al found that the higher the drilling fluid temperature and density, the more obvious the drilling fluid invasion and hydrate dissociation, resulting in wellbore instability.…”

Section: Properties Of Nghrsmentioning

confidence: 99%

See 1 more Smart Citation

Reservoir Stimulation Technologies for Natural Gas Hydrate: Research Progress, Challenges, and Perspectives

Liang

2023

Energy Fuels

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The energy crisis has intensified in recent years. The current global economic environment and increasing cost of mining necessitate additional energy access channels. Previous studies have shown that natural gas hydrate reservoirs (NGHRs) contain a large number of natural gas resources. However, several problems are associated with the safe and efficient exploitation of the NGHRs. Reservoir stimulation technology is expected to address these issues. This study introduces the properties and mining difficulties of NGHRs and reviews their stimulation scheme and related research progress based on three perspectives: hydraulic fracturing, burden sealing, and near-well reconstruction. The principles, advantages, and limitations of the three schemes are compared. In addition to the stimulation effects of the three aforementioned methods, this study focused on the fracability of NGHRs, the factors influencing fracture initiation and development, and the fracturing fluid, proppant, completion fluid, and slurry suitable for NGHR stimulation. In addition, the principles, current challenges, and future research prospects for reservoir stimulation are summarized to provide a reference for the commercial exploitation of natural gas hydrates in the future.

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Section: Fracture Formation and Developmentmentioning

confidence: 99%

Section: Properties Of Nghrsmentioning

confidence: 99%

Reservoir Stimulation Technologies for Natural Gas Hydrate: Research Progress, Challenges, and Perspectives

Liang

2023

Energy Fuels

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“…The flow equation of the drilling fluid with the change of the opening of the bedding fracture from the borehole wall to the bedding fracture at the finite length fracture is obtained as follows (Zhu et al, 2021):…”

Section: Physical Modelmentioning

confidence: 99%

The invasion law of drilling fluid along bedding fractures of shale

Wang²,

Zhang³

et al. 2023

Front. Earth Sci.

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In the process of drilling, the drilling fluid will invade into the bedding plane of shale under the action of pressure difference that will cause hydration collapse and wellbore instability. In order to ensure the wellbore stability during shale oil and gas drilling, it is necessary to clarify the invasion law of drilling fluid along bedding fractures during the drilling process. The immersion experiment method is often used to study the invasion law of drilling fluid, which is quite different from the actual invasion process of drilling fluid underground. In this paper, the depth of drilling fluid invasion into shale under different confining pressures and displacement times is intuitively and accurately determined by the displacement experiment and NMR scanning first. Also, then the mathematical relationships between drilling fluid invasion depth and invasion time, invasion pressure difference, confining pressure, bedding angle, and drilling fluid viscosity were established. The errors between the calculated values of the drilling fluid invasion depth and the experimental values were less than 15%, and the calculation accuracy was high. In addition to the influence of invasion time, formation pressure difference and confining pressure on invasion depth were researched through the method of numerical simulation. The results showed that the liquid invasion depth increased logarithmically with the increase of invasion time and formation pressure difference, but it grew slowly in the later period and tended to be stable; the invasion depth decreased exponentially with the increase of confining pressure, bedding plane angle, and drilling fluid viscosity. The results in the paper provide a basis for the subsequent determination of the collapse pressure and collapse period of bedding shale.

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“…It mainly exists under low temperature and high pressure. − It is estimated that the amount of natural gas hydrate resources is twice that of global fossil energy, which is potential alternative energy. − Hydrate dissociation can easily lead to geological engineering disasters, such as submarine landslides, wellbore instability, formation deformation, etc. − Due to the increasing global resource consumption, it is imperative to realize the commercial exploitation of natural gas hydrate. However, hydrate extraction should meet the production efficiency and ensure formation stability. , …”

Section: Introductionmentioning

confidence: 99%

“…However, hydrate extraction should meet the production efficiency and ensure formation stability. 16,17 The hydrate dissociation front is essential for distinguishing whether the hydrate exists stably. The reservoir can be divided into a hydrate dissociation zone and an undissociated area based on the location of the dissociation front.…”

Section: ■ Introductionmentioning

confidence: 99%

Hydrate Dissociation Evaluation and Stratum Subsidence Response Induced by Depressurization in Hydrate-Bearing Permafrost

Huang

et al. 2022

Energy Fuels

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Ensuring formation stability is vital to realizing the commercial development of hydrate reservoirs. Therefore, studying the formation subsidence in the hydrate mining process is essential. This study proposes a method for predicting the maximum surface subsidence using the hydrate dissociation front. Firstly, to more realistically evaluate the hydrate dissociation characteristics and reservoir deformation during the hydrate mining process in permafrost, soil permeability experiments under different hydrate saturations were conducted, and the dynamic permeability model was established. On this basis, combined with the multifield coupling model, the depressurization process of the hydrate reservoir is simulated. The hydrate dissociation property and stratum subsidence response under different parameters are analyzed. In addition, the parameter sensitivity is evaluated, and the corresponding relationship between the hydrate dissociation front and the maximum surface subsidence is established. According to the research results, assuming that the safety limit of surface subsidence is set to 0.3 m, the safe hydrate dissociation range within soil permeability K = [20 mD, 120 mD] is about [0 m, 77.7 m]. For every 20% decrease in wellhead pressure, the hydrate dissociation range increases by 30%. It is worth noting that the three points A, B, and C (located at the upper, middle, and lower positions next to the well perforation end) show completely different deformation trends during the mining process.

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Near-wellbore fracture initiation and propagation induced by drilling fluid invasion during solid fluidization mining of submarine nature gas hydrate sediments

Cited by 18 publications

References 44 publications

Reservoir Stimulation Technologies for Natural Gas Hydrate: Research Progress, Challenges, and Perspectives

Reservoir Stimulation Technologies for Natural Gas Hydrate: Research Progress, Challenges, and Perspectives

The invasion law of drilling fluid along bedding fractures of shale

Hydrate Dissociation Evaluation and Stratum Subsidence Response Induced by Depressurization in Hydrate-Bearing Permafrost

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