scholarly journals Characterization of a Volcanic Gas Reservoir Using Seismic Dispersion and Fluid Mobility Attributes

Lithosphere ◽  
2021 ◽  
Vol 2021 (Special 3) ◽  
Author(s):  
Zhiqi Guo ◽  
Yuedong Li ◽  
Cai Liu ◽  
Da Zhang ◽  
Anbang Li
Keyword(s):  
Bulk Modulus ◽  
Velocity Dispersion ◽  
P Wave ◽  
Inversion Method ◽  
High Porosity ◽  
Gas Reservoirs ◽  
Volcanic Gas ◽  
Gas Reservoir ◽  
Gas Saturation

Abstract Seismic dispersion and fluid mobility attributes are used to characterize a volcanic gas reservoir in the Songliao Basin of China. A rock physics model is constructed to describe poroelastic behaviors associated with heterogeneous fluids saturation within the volcanic gas reservoirs, where velocity dispersion and attenuation of propagating waves are attributed to the wave-induced fluid flow described by the patchy saturation theory. Modeling results indicate that the frequency-dependent bulk modulus at the seismic frequency is more sensitive to gas saturation than the P-wave velocity dispersion. Accordingly, a new inversion method is developed to compute bulk-modulus-related dispersion attribute DK for improved characterization of volcanic gas reservoirs. Synthetic tests indicate that DK is more sensitive than traditional P-wave dispersion attribute DP to the variations of reservoir properties. The high value of dispersion attribute DK indicates the volcanic gas reservoirs with high porosity and gas saturation. At the same time, fluid mobility attribute FM can discriminate the volcanic gas reservoir as DK. Field data applications illustrate that DK and FM exhibit anomalies to the gas zones in the volcanic gas reservoir on the cross-well section. However, DK is more robust than FM to identify favorable zones on horizontal slices for specific target layers. Overall, rock physical modeling provides insights into the poroelastic behaviors of volcanic gas reservoirs, and inversion for seismic dispersion attribute DK improves hydrocarbon detection in the volcanic gas reservoir.

Characterization of Microstructures of Volcanic Gas Reservoirs

2014 ◽  
pp. 457-541 ◽  
Author(s):  
Qiquan Ran ◽  
Yongjun Wang ◽  
Yuanhui Sun ◽  
Lin Yan ◽  
Min Tong
Keyword(s):  
Gas Reservoirs ◽  
Volcanic Gas

scholarly journals Prediction of sweet spots in tight sandstone reservoirs based on anisotropic frequency-dependent AVO inversion

2021 ◽  
Vol 18 (5) ◽  
pp. 664-680
Author(s):  
Xilin Qin ◽  
Zhixian Gui ◽  
Fei Yang ◽  
Yuanyuan Liu ◽  
Wei Jin ◽  
...  
Keyword(s):  
Velocity Dispersion ◽  
Fractured Reservoirs ◽  
P Wave ◽  
Inversion Method ◽  
Tight Sandstone ◽  
Anisotropic Parameter ◽  
Frequency Dependent ◽  
Anisotropy Parameters ◽  
Fluid Detection ◽  
Parameter Dispersion

Abstract The frequency-dependent amplitude-versus-offset (FAVO) method has become a practical method for fluid detection in sand reservoirs. At present, most FAVO inversions are based on the assumption that reservoirs are isotropy, but the application effect is not satisfactory for fractured reservoirs. Hence, we analyse the frequency variation characteristics of anisotropy parameters in tight sandstone reservoirs based on a new petrophysical model, and propose a stepwise anisotropic FAVO inversion method to extract frequency-dependent attributes from prestack seismic field data. First, we combine the improved Brie's law with the fine-fracture model to analyse frequency-dependent characteristics of velocities and Thomsen anisotropy parameters at different gas saturations and fracture densities. Then, we derive an anisotropic FAVO inversion algorithm based on Rüger's approximation formula and propose a stepwise anisotropic FAVO inversion method to obtain the dispersions of anisotropy parameters. Finally, we propose a method that combines the inversion spectral decomposition with the stepwise anisotropy FAVO inversion and apply it to tight sand reservoirs in the Xinchang area. We use P-wave velocity dispersion and anisotropy parameter ε dispersion to optimise favourable areas. Numerical analysis results show that velocity dispersion of the P-wave is sensitive to fracture density, which can be used for fracture prediction in fractured reservoirs. In contrast, anisotropic parameter dispersion is sensitive to gas saturation and can be used for fluid detection. The seismic data inversion results show that velocity dispersion of the P-wave and anisotropic parameter dispersion are sensitive to fractured reservoirs in the second member of Xujiahe Group, which is consistent with logging interpretation results.

Characterization of Accumulation-Permeation Units in Volcanic Gas Reservoirs

2014 ◽  
pp. 393-455
Author(s):  
Qiquan Ran ◽  
Yongjun Wang ◽  
Yuanhui Sun ◽  
Lin Yan ◽  
Min Tong
Keyword(s):  
Gas Reservoirs ◽  
Volcanic Gas

scholarly journals High-Order AVO Inversion for Effective Pore-Fluid Bulk Modulus Based on Series Reversion and Bayesian Theory

Energies ◽  
2020 ◽  
Vol 13 (6) ◽  
pp. 1313
Author(s):  
Lei Shi ◽  
Yuhang Sun ◽  
Yang Liu ◽  
David Cova ◽  
Junzhou Liu
Keyword(s):  
Bulk Modulus ◽  
Seismic Data ◽  
Pore Fluid ◽  
High Order ◽  
Bayesian Theory ◽  
P Wave ◽  
Seismic Exploration ◽  
Inversion Method ◽  
Fluid Identification ◽  
Avo Inversion

Pore-fluid identification is one of the key technologies in seismic exploration. Fluid indicators play important roles in pore-fluid identification. For sandstone reservoirs, the effective pore-fluid bulk modulus is more susceptible to pore-fluid than other fluid indicators. AVO (amplitude variation with offset) inversion is an effective way to obtain fluid indicators from seismic data directly. Nevertheless, current methods lack a high-order AVO equation for a direct, effective pore-fluid bulk modulus inversion. Therefore, based on the Zoeppritz equations and Biot–Gassmann theory, we derived a high-order P-wave AVO approximation for an effective pore-fluid bulk modulus. Series reversion and Bayesian theory were introduced to establish a direct non-linear P-wave AVO inversion method. By adopting this method, the effective pore-fluid bulk modulus, porosity, and density can be inverted directly from seismic data. Numerical simulation results demonstrate the precision of our proposed method. Model and field data evaluations show that our method is stable and feasible.

scholarly journals Application of Dipole Array Acoustic Logging in the Evaluation of Shale Gas Reservoirs

Energies ◽  
2019 ◽  
Vol 12 (20) ◽  
pp. 3882
Author(s):  
Wenrui Shi ◽  
Xingzhi Wang ◽  
Yuanhui Shi ◽  
Aiguo Feng ◽  
Yu Zou ◽  
...  
Keyword(s):  
Shale Gas ◽  
Total Porosity ◽  
P Wave ◽  
S Wave ◽  
Gas Reservoirs ◽  
Acoustic Logging ◽  
Gas Saturation ◽  
Shale Gas Reservoirs ◽  
Gas Potential ◽  
The Relationship

In order to effectively evaluate shale gas reservoirs with low porosity, extra-low permeability, and no natural productivity, dipole array acoustic logging, which can provide various types of information including P-wave slowness (DTC) and S-wave slowness (DTS), is widely used. As the dipole array acoustic logging tool has a larger investigation depth and is suitable for complex borehole environments, such as those with a high wellbore temperature, high drilling fluid column pressure, or irregular borehole wall, it has been mainly applied to the evaluation of lithology, gas potential, fractures, and stimulation potential in shale gas reservoirs. The findings from a case study of the Sichuan Basin in China reveal that the acoustic slowness, S-P wave slowness ratio (RMSC), and S-wave anisotropy of the dipole array acoustic logging can be used to qualitatively identify reservoir lithology, gas potential, and fractures. Using the relationship between DTC and the total porosity of shale gas reservoirs, and combined with the compensated neutron (CNL) and shale content (Vsh) of the reservoir, a mathematical model for accurately calculating the total porosity of the shale gas reservoir can be established. By using the relationship between the RMSC and gas saturation in shale gas reservoirs and tied with density log (DEN), a mathematical model of gas saturation can be established, and the determination of gas saturation by the non-resistivity method can be achieved, delivering a solution to the issue that the electric model is not applicable under low resistivity conditions. The DTS, DTC, and DEN of shale can be used to calculate rock mechanic parameters such as the Poisson’s ratio (POIS) and Young’s modulus (YMOD), which can be used to evaluate the shale stimulation potential.

Analysis of the Accumulation Conditions for Volcanic Gas Reservoirs: A Case from Deep Yingcheng Formation, Southern Part of Songliao Basin

2013 ◽  
Vol 848 ◽  
pp. 273-278
Author(s):  
Yi Wu ◽  
Wei Chao Tian
Keyword(s):  
Large Scale ◽  
Volcanic Rocks ◽  
Songliao Basin ◽  
Gas Reservoirs ◽  
Volcanic Gas ◽  
Gas Reservoir ◽  
Rock Types ◽  
Yingcheng Formation ◽  
Study Results ◽  
Reservoir Conditions

Volcanic gas reservoir in deep Southern Songliao Basin has became source for incremental oil and reserves. Due to the low degree of exploration, study on the accumulation condition for volcanic gas reservoir is insufficient, to some extent, influencing the effectiveness of exploration. In this paper, the accumulation conditions for volcanic gas reservoir have been analyzed systematically including the source rock conditions, reservoir conditions, sealing conditions, conducting conditions and trap conditions. The study results show that large-scale coal-bearing strata in Shahezi Formation can provide sufficient gas for volcanic gas reservoir: the fracture systems in deep volcanic rocks can communicate with the earlier developed pores, fractures and caves, forming good reservoir and flow space; It contains multiple rock types with good preservation condition, the mudstone in first member of Quan Formation is better regional seal. Mudstone in third and fourth member of Denglouku Formation and Shahezi Formation are favorable local seals, with good seal capability for volcanic rocks gas accumulation in Yingcheng Formation. ontains three types of transporting pathways: permeable formation, unconformity and fault.

Initial Ensemble Design Scheme for Effective Characterization of Three-Dimensional Channel Gas Reservoirs With an Aquifer

2017 ◽  
Vol 139 (2) ◽  
Author(s):  
Sungil Kim ◽  
Hyungsik Jung ◽  
Kyungbook Lee ◽  
Jonggeun Choe
Keyword(s):  
Reservoir Characterization ◽  
Three Dimensional ◽  
Grid System ◽  
Gas Reservoirs ◽  
Gas Reservoir ◽  
Design Scheme ◽  
Initial Ensemble ◽  
The Mean ◽  
Grid Points

Reservoir characterization is a process of making models, which reliably predict reservoir behaviors. Ensemble Kalman filter (EnKF) is one of the fine methods for reservoir characterization with many advantages. However, it is hard to get trustworthy results in discrete grid system ensuring preservation of channel properties. There have been many schemes such as discrete cosine transform (DCT) and preservation of facies ratio (PFR) for improvement of channel reservoirs characterization. These schemes are mostly applied to 2D cases, but cannot present satisfactory results in 3D channel gas reservoirs with an aquifer because of complex production behaviors and high uncertainty of them. For a complicated 3D channel reservoir, we need reliable initial ensemble members to reduce uncertainty and stably characterize reservoir models due to the assumption of EnKF, which regards the mean of ensemble as true. In this study, initial ensemble design scheme is suggested for EnKF. The reference 3D channel gas reservoir system has 200 × 200 × 5 grid system (250 × 250 × 100 ft for x, y, and z, respectively), 15% porosity, and two facies of 100 md sand and 1 md shale. As the first step, it samples initial ensemble members, which show similar water production behaviors with the reference. Then, grid points are randomly selected for high and low 5% from the mean of sampled members. As a final step, initial ensemble members are remade using the selected data, which are assumed as additional known data. This proposed method reliably characterizes 3D channel reservoirs with an aquifer.

scholarly journals ntegration of Petrophysical Analysis and Elastic Log Properties as an Input to Optimize the Development Wells Target in Unique Globigerina Limestone Gas Reservoir in Madura Strait

2021 ◽  
Vol 1 (2) ◽  
pp. 55-70
Author(s):  
Hendra Himawan ◽  
◽  
Indra Sumantri ◽  
Okky Yuditya Pahlevi
Keyword(s):  
Elastic Properties ◽  
Water Saturation ◽  
Velocity Ratio ◽  
Reservoir Rock ◽  
High Porosity ◽  
Gas Reservoir ◽  
Petrophysical Analysis ◽  
Gas Saturation ◽  
Rock Quality ◽  
Volume Porosity

The Madura Strait PSC is located in the southern part of North East Java Basin with biogenic gas from Globigerina limestone Pliocene Mundu and Selorejo sequence as main target. At early stage of field development,understanding and knowledge about petrophysical and elastic properties of reservoir rock quality is required and very important. The petrophysical analysis provide properties such as clay volume, porosity, permeability, water saturation and mineral volume to separate reservoir and non-reservoir zone. The elastic rock properties such as acoustic impedance (AI), shear impedance (SI), velocity ratio (Vp/Vs), and Poisson’s ratio (σ) were generated to identify clay zone, gas and non-gas also focused to distinguish reservoir rock quality inside gas zone as an effective reservoir characterization. This research is done by utilize core data, quad combo logs from eleven wells and shear velocity from eight wells. The purpose of this research is to optimize development well target in Globigerina limestone gas reservoir, which have good to best reservoir rock quality shown with high porosity and permeability,low clay volume and water saturation. Results from this research indicate that lime mud matrix have significant impact in the reservoir rock quality. Meanwhile, gas saturation can affect the elastic properties due to this high gas saturation can decrease compressional velocity (Vp) value. Finally, the integration of petrophysical result and combination of elastic properties implementation can help in distinguishing the best reservoir rock quality, which contains gas that should be penetrated by the development wells

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