Reservoir classification and log prediction of gas hydrate occurrence in the Qiongdongnan Basin, South China Sea

Zhu, Linqi; Zhou, Xueqing; Sun, Jie; Liu, Yan‐Rui; Wang, J. Y.; Wu, Shiguo

doi:10.3389/fmars.2023.1055843

Cited by 5 publications

(2 citation statements)

References 65 publications

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“…The basin exhibits widespread development of mud diapirs, gas chimneys, and other fluid activities. 29,30 These fluid leakage channels manifest in diverse forms, scales, and exhibit complex genetic and evolutionary processes. As a result, the Qiongdongnan Basin has become a focal point in current research on fluid leakage systems.…”

Section: Reservoir Model Of Three Gas Reservoirs Geological Settingmentioning

confidence: 99%

Potential on joint development of three-gas reservoirs in the Qiongdongnan Basin

Wu,

Sun,

et al. 2024

TIG

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<p>Gas hydrates are typically found in the fine-grained sediments with low abundance and strong heterogeneity in the northern South China Sea. To date, although numerous gas hydrate reservoirs have been discovered, commercial exploitation remains highly challenging. Previous studies show that the Qiongdongnan Basin exhibits coexistence of gas hydrates, shallow gas and deep gas reservoirs. The hydrate-bound gases are a mixture of thermogenic and biogenic gas, mainly sourced from the granite buried hill reservoir, central canyon channel of the Lingshui Depression and the Yacheng Formation. In this study, we described a new development concept termed ��Three-gas Joint Development�� (TJD), to elucidate the simultaneous exploitation of these three gas reservoirs. Based on the distribution of three-gas reservoirs, three different TJD plans are proposed. If the relative distance between three-gas reservoirs does not exceeds the extension limit, a single production platform is capable of exploiting all three-gas reservoirs. A vertical well is suggested if the deep gas reservoir lies directly below the gas hydrates and shallow gas. Otherwise, multilateral well should be used to exploit different gas reservoirs with various branches in a main wellbore. However, several key issues remain unsolved. Numerical simulation of TJD should be conducted to evaluate interlayer interference and productivity. Efficient sand control and wellbore stability techniques, such as frac-packing and high-performance drilling fluids, are recommended when drilling unconsolidated sediments. Once these key technologies are overcome, TJD can provide a feasible approach for the commercial development of gas hydrates.</p>

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Section: Reservoir Model Of Three Gas Reservoirs Geological Settingmentioning

confidence: 99%

Potential on joint development of three-gas reservoirs in the Qiongdongnan Basin

Wu,

Sun,

et al. 2024

TIG

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“…These reservoir models need to account for multiphase fluid flow, heat transfer, and thermodynamics of hydrate formation and dissociation, in addition to the changing porosity and permeability of the reservoirs. − Therefore, coupled mass and energy balance equations are solved in the simulations, which consider the equilibrium kinetics of hydrate formation and dissociation. ,, Generally, homogeneous reservoirs have been used in simulation studies and only a few studies describe the dynamics of heterogeneous reservoir behavior. , However, the flow properties and initial conditions that are used in the reservoir simulations are not deterministic. − This is because we use small samples of the reservoir rocks from the well to determine these properties from laboratory tests . During the drilling process of a well, a compact core sample is extracted, and subsequently, the laboratory conducts direct measurements of both porosity and permeability. , The flow properties of a reservoir can be estimated by field tests at wells, using indirect methods such as logging, however, this gives information for the areas around the well only. − This technique samples a greater, although still extremely limited volume. It is also possible to use multiple wells to reduce the uncertainty in the log data collected, but that will increase the cost of the testing.…”

Section: Introductionmentioning

confidence: 99%

Uncertainty Propagation in Predicting Recovery from Gas Hydrate Reservoirs: From Reservoir Characteristics to Performance Analysis

Choudhary,

Phirani

2024

Energy Fuels

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The necessity of forecasting recovery from the gas hydrate reservoirs is restricted due to the limiting data availability for reservoir properties, such as porosity and hydrate saturation, used in reservoir models. Predicting recovery becomes essential to determine the feasibility and viability of a reservoir. Therefore, it is paramount to understand uncertainty propagation from reservoir characteristics to reservoir performance by using reservoir simulations. In this work, we explore the uncertainty in reservoir performance due to the uncertainty in reservoir characterization of porosity and saturation. We employ the Monte Carlo method to analyze the impact of uncertainty on gas and water production from a class 2, confined, oceanic methane hydrate reservoirs. We observe that uncertainty in porosity leads to a substantial uncertainty in our prediction of gas recovery until a critical porosity value. If the porosity is higher than the critical porosity value, then the gas production using depressurization does not change significantly. This is attributable to the thermal nature of gas hydrate dissociation in which high porosity means less heat content from the sediments for hydrate dissociation. For the same reason, at the same porosity, variation in hydrate saturation does not lead to a high variation in gas recovery. The uncertainty in porosity leads to a 24% coefficient of variation in cumulative gas production, uncertainty in initial hydrate saturation leads to 3% and their combined uncertainty leads to 20% coefficient of variation in cumulative gas production. Using the cumulative density function of the gas production, we show that our P 90 , P 50 , and P 10 estimates will vary depending on the production time considered for estimation.

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A novel reservoir classification method for sandstone reservoir evaluation using multi-scale digital rock method

Chen,

Gao,

Wang

et al. 2024

J Petrol Explor Prod Technol

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The formulation of an effective development plan, optimizing exploitation efficiency, relies heavily on accurate reservoir characterization. However, existing reservoir classification methodologies, which rely on macroscopic geological observations and well-logging data, have limitations in data availability and fail to capture micro-scale pore structure characteristics accurately. The emerging technology of digital rock, widely employed in the petroleum industry, also faces challenges in accurately capturing reservoir heterogeneity due to its single-scale nature and limited application for reservoir classification. To overcome these challenges, this study presents an innovative reservoir classification approach based on the multi-scale digital rock method. This approach integrates qualitative assessment of micro-CT images for particle contact relationships and pore types with quantitative evaluation of multi-scale characteristic parameters, obtained from micro-CT and scanning electron microscopy (SEM) images. The proposed classification method demonstrates excellent agreement with the prioritization of development and production data for offshore sandstone reservoirs. By establishing a robust evaluation methodology, this classification method facilitates exploration potential assessment and development strategy optimization within the field.

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Reservoir classification and log prediction of gas hydrate occurrence in the Qiongdongnan Basin, South China Sea

Cited by 5 publications

References 65 publications

Potential on joint development of three-gas reservoirs in the Qiongdongnan Basin

Potential on joint development of three-gas reservoirs in the Qiongdongnan Basin

Uncertainty Propagation in Predicting Recovery from Gas Hydrate Reservoirs: From Reservoir Characteristics to Performance Analysis

A novel reservoir classification method for sandstone reservoir evaluation using multi-scale digital rock method

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