Studies on the Inversion Phenomenon of Physical Properties Observed in the Huagang Formation Reservoir in the Xihu Sag Based on the Water-Rock Reaction Experiments

Huang, Siqin; Xu, Fanghao; Xu, Guoce; Cui, Hengyuan; Zhang, Wu

doi:10.1007/s11802-021-4565-y

Cited by 3 publications

(2 citation statements)

References 13 publications

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“…According to the tuning effect of the thin bed, in Figure 15a, the high frequencies indicate thin sandstones, and the low frequencies indicate thick sandstones (Tian, Gao, et al., 2022). In the target area, large porosity corresponds to thick sandstone, and small porosity corresponds to thin sandstone, generally (Gao et al., 2021; Huang et al., 2021). So, comparing Figure 15a,c, they match well in most areas, such as high value areas indicated by red ellipses and low value areas indicated by blue ellipses, which illustrates the reliability of the proposed workflow.…”

Section: Field Applicationsmentioning

confidence: 99%

Tight sandstone gas reservoir characterization via amplitude‐versus‐offset attributes

Tian

Stovas

Gao

et al. 2023

Geophysical Prospecting

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The low porosity and low permeability of tight sandstone pose considerable challenges on characterizing the reservoir fluid. Moreover, the geophysical characteristics of the tight sandstone are usually similar to the surrounding rocks, leading to small impedance contrast, compounding the difficulty of reservoir parameters inversion. Amplitude‐versus‐offset technology is an important tool to invert the reservoir parameters from seismic data. The existing amplitude‐versus‐offset inversion methods are challenged to predict the tight sandstone reservoir parameters for the reasons above. In this paper, we propose a new workflow based on amplitude‐versus‐offset attributes to characterize the tight sandstone gas reservoirs in the Xihu Depression, East China Sea. The proposed workflow utilizes the Backus average method and Gassmann's equation to construct the rock physics model. Based on the analysis of the anisotropic model, we introduce Rüger's anisotropic equation for amplitude‐versus‐offset forward modelling. We compare the amplitude‐versus‐offset gathers with the real data and adjust the reservoir parameters. Through the sensitivity analysis, we select the gas saturation and porosity as the inversion parameters. The relationship between the reservoir parameters and amplitude‐versus‐offset attributes is established by fitting the fifth‐order polynomials. We use Shuey's equation and the least squares inversion method to calculate the amplitude‐versus‐offset attributes (intercept and gradient). For real data, we introduce the Toeplitz‐sparse matrix factorization method to calculate the reflectivity of the amplitude‐versus‐offset gathers. Finally, we proposed a multi‐well joint inversion approach to invert the gas saturation and porosity. The application results demonstrate the effectiveness of the proposed workflow for the characterization of the gas reservoir in tight sandstone for the describedcase.

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Section: Field Applicationsmentioning

confidence: 99%

Tight sandstone gas reservoir characterization via amplitude‐versus‐offset attributes

Tian

Stovas

Gao

et al. 2023

Geophysical Prospecting

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“…If the creep effect is ignored, it may cause major accidents of instability and failure of these projects [5][6][7][8][9][10][11]. The wetting-drying cycle refers to the process in which the rock mass is continuously subjected to repeated cycles of soaking, dewatering, soaking, and dewatering under rainfall or groundwater conditions [12][13][14][15][16][17][18][19]. In this process, the physical and mechanical parameters of the rock mass are continuously weakened, the strength is continuously reduced, and the creep aging effect is continuously intensified [20][21][22][23][24][25][26], with the increase of time, under certain conditions, it may even cause accidents such as engineering instability and failure.…”

Section: Introductionmentioning

confidence: 99%

Study on creep mechanical properties of carbonaceous shale under dry-wet cycle

Wei¹,

et al. 2023

Phys. Scr.

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The creep mechanical properties of rock under dry-wet cycles are of great significance for studying the long-term aging stability of engineering rock and soil. In the past, there were few studies in this area, and most of the dry-wet cycle tests on rock samples did not conform to the actual stress state of the rock. In view of the shortcomings of these studies, this paper innovatively carried out the dry-wet cycle test of the rock under the continuous state of the stress field, and studied its mechanical properties. The specific method is to take carbonaceous shale as the research object, and use the soft rock shear rheological test system independently developed by our research group to carry out the shear creep test of carbonaceous shale under the action of dry-wet cycle. The test results show that the creep full-time curves of carbonaceous shale under different dry-wet cycles show a step-shaped curve shape. The dry-wet cycle has a significant effect on the deformation characteristics of carbonaceous shale. With the increase of the number of dry-wet cycles, the instantaneous strain of the rock gradually increases, the instantaneous shear modulus decreases from 596.650 MPa at 0 times to 365.199 MPa at 12 times, and the attenuation rate reaches 38.79 %. The creep strain and cumulative creep strain become larger, the stress required for accelerated creep decreases from 3.29 MPa to 2.75 MPa, and the accelerated creep time in the third stage increases from 11.892 h to 5.316 h, and the creep effect is more significant. The long-term strength of carbonaceous shale decreases from 3.05 MPa to 2.49 MPa, and the decrease increases with the increase of dry-wet cycles. The more the number of dry-wet cycles, the smaller the undulation of the shear failure section of the carbonaceous shale, and the smoother the surface. The research results have important guiding significance for the long-term aging stability analysis of engineering rock and soil mass subjected to repeated dry-wet cycles.

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Characteristics and Controlling Factors of Tight Marl Reservoirs with an Eyelid-Shaped Structure of the First Member of the Deep Maokou Formation in Eastern Sichuan

2023

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Tight marl is a special type of unconventional oil and gas resource, and the study on its reservoir characteristics and controlling factors is of immense scientific significance. In this paper, 113 core samples of marl from Gouxi Area, Eastern Sichuan were selected. Based on organic carbon, pyrolysis, X-ray diffraction of whole rock, and X-ray diffraction of clay analysis, the reservoir evaluation of eyelid-shaped limestone in the first member of Maokou Formation was carried out. The results show that there are obvious differences between eyelid-shaped limestone reservoirs and eyeball-shaped limestone reservoirs in the target stratum. Eyelid-shaped limestone is mainly distributed in the lower members a and c of the first member of Maokou Formation. It could be the main reservoir of low porosity and permeability tight marl, as its developed apertures, micro-fractures, and pore throat structure are obviously better than that of the eyeball-shaped limestone. As eyelid-shaped limestone features obvious self-generation and self-storage characteristics, the deep-water and low-energy sedimentary environment provides it with a large amount of highly brittle minerals and clay minerals as well as a favorable reservoir-forming background for diagenetic evolution and organic matter adsorption of clay minerals in the later period. The transformation of sepiolite into talc through diagenesis provides a large number of shrinkage joints for the reservoir, which are an effective space for tight gas accumulation.

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Studies on the Inversion Phenomenon of Physical Properties Observed in the Huagang Formation Reservoir in the Xihu Sag Based on the Water-Rock Reaction Experiments

Cited by 3 publications

References 13 publications

Tight sandstone gas reservoir characterization via amplitude‐versus‐offset attributes

Tight sandstone gas reservoir characterization via amplitude‐versus‐offset attributes

Study on creep mechanical properties of carbonaceous shale under dry-wet cycle

Characteristics and Controlling Factors of Tight Marl Reservoirs with an Eyelid-Shaped Structure of the First Member of the Deep Maokou Formation in Eastern Sichuan

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