Numerical simulation of hydraulic fracture propagation in laminated shale reservoirs

Zhou, Taofa; Wang, Haibo; Li, Fengxia; Li, Yuanzhao; Zou, Yushi; Zhang, Chi

doi:10.1016/s1876-3804(20)60122-7

Cited by 50 publications

(16 citation statements)

References 23 publications

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“…A continuous decline in conventional oil reserves has led to increasing attention to unconventional oil resources (Awan et al, 2021), especially shale oil, due to its vast number of resources and considerable production rate after fracturing (Zhou et al, 2020a;Zhou et al, 2020b). The output of shale oil in the United States has reached 60% of the total output of crude oil (Dong et al, 2011).…”

Section: Introductionmentioning

confidence: 99%

Oil Occurrence States in Shale Mixed Inorganic Matter Nanopores

et al. 2022

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In present paper, the mineral and fluid compositions of shale oil from the Songliao Basin are analyzed systematically using core samples, X-ray diffractometer (XRD), and gas chromatography (GC). The effects of shale mineral composition, pore size, temperature, and pressure on the mass density of the adsorbed layers are then studied utilizing molecular dynamics simulation. The results show that illite and quartz are predominant in the micro petrological components of the shale, and nC19 is the main carbon peak. The fluid consists primarily of n-alkane molecules, and nC19 is found to be representative of the shale oil composition. Moreover, the adsorbing effect of quartz-illite mixed wall is between that of a pure mineral wall (illite and quartz), indicating that the selection of a mixed wall is similar to the actual shale composition. If the pores are inorganic, the minimum pore size of only adsorption oil is smaller than the organic pores. The critical adsorption point of shale oil in inorganic pores is less than 3.2 nm. Furthermore, compared to pressure, the temperature has a more significant effect on fluid adsorption due to the correlation with the kinetic energy of alkane molecules. This research shows the oil occurrence status in inorganic matter nanopore with a mixed solid wall, and provides theoretical support for shale oil exploration.

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Section: Introductionmentioning

confidence: 99%

Oil Occurrence States in Shale Mixed Inorganic Matter Nanopores

et al. 2022

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“…Total organic carbon (TOC) has been used to determine gas generation in the organic shale of the Longmaxi Formation (Zou et al 2015;He et al 2017;Zhang et al 2020a). Horizontal bedding fractures, accounting for most natural fractures in the Longmaxi shale, provide storage spaces and migration channels for gas enrichment (Zhang et al 2020b;Xu et al 2021) and are favorable for hydraulic fracturing (Zhou et al 2020). Using seismic methods to identify hydrocarbon enrichment and predict bedding fractures can provide valuable information for locating promising shale gas reservoirs.…”

Section: Introductionmentioning

confidence: 99%

Hydrocarbon Identification and Bedding Fracture Detection in Shale Gas Reservoirs Based on a Novel Seismic Dispersion Attribute Inversion Method

et al. 2022

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Prediction of hydrocarbon enrichment and natural fractures is significant for sweet spot characterization in shale gas reservoirs. However, it is difficult to estimate reservoir properties using conventional seismic techniques based on elastic and isotropic assumptions. Considering that the viscoelastic anisotropic model better represents organic shale, we propose a new seismic inversion method to improve shale gas characterization by incorporating the anisotropic reflectivity theory in the frequency-dependent inversion scheme. The computed P-wave velocity dispersion attribute DP evaluates the hydrocarbon enrichment by estimating the inelastic properties of shale associated with organic materials. The inverted anisotropic dispersion attribute Dε detects the development intensity of bedding fractures using frequency-dependent anisotropy owing to wave-induced fluid flow in parallel fractures. Synthetic tests indicate that DP can robustly estimate shale attenuation and Dε is sensitive to the frequency-dependent anisotropy of shale. The results are validated by reservoir properties measured in gas-producing boreholes and rock physical modeling analysis, supporting the applicability of the dispersion attributes for hydrocarbon identification and bedding fracture detection. The predicted hydrocarbon enrichment and the development of bedding fractures correlate with the structural characteristics of the shale formation. The depth-related shale properties can be described by improving the geological understanding of the study area. Finally, favorable areas with high hydrocarbon enrichment and extensive development of bedding fractures are identified by simultaneously considering high DP and Dε anomalies, providing essential information for predicting potential shale gas reservoirs. Article Highlights A novel seismic inversion method for anisotropy dispersion attributes is proposed P-wave velocity dispersion attribute is used to identify hydrocarbon enrichment in shale Anisotropic dispersion attribute is used to detect bedding fractures in shale

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“…The distribution of hydraulic fractures under different bedding densities, mechanical properties and fracturing engineering parameters (e.g. perforation clusters, injected flow rate, and fracturing fluid viscosity) were analysed (Zhou et al, 2020). The finite difference method and numerical solution of a single element were used to determine the direction of the formation of hydraulic fractures.…”

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Dual bilinear cohesive zone model-based fluid-driven propagation of multiscale tensile and shear fractures in tight reservoir

Wang

Zhang

2022

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PurposeHydrofracturing technology has been widely used in tight oil and gas reservoir exploitation, and the fracture network formed by fracturing is crucial to determining the resources recovery rate. Due to the complexity of fracture network induced by the random morphology and type of fluid-driven fractures, controlling and optimising its mechanisms is challenging. This paper aims to study the types of multiscale mode I/II fractures, the fluid-driven propagation of multiscale tensile and shear fractures need to be studied.Design/methodology/approachA dual bilinear cohesive zone model (CZM) based on energy evolution was introduced to detect the initiation and propagation of fluid-driven tensile and shear fractures. The model overcomes the limitations of classical linear fracture mechanics, such as the stress singularity at the fracture tip, and considers the important role of fracture surface behaviour in the shear activation. The bilinear cohesive criterion based on the energy evolution criterion can reflect the formation mechanism of complex fracture networks objectively and accurately. Considering the hydro-mechanical (HM) coupling and leak-off effects, the combined finite element-discrete element-finite volume approach was introduced and implemented successfully, and the results showed that the models considering HM coupling and leak-off effects could form a more complex fracture network. The multiscale (laboratory- and engineering-scale) Mode I/II fractures can be simulated in hydrofracturing process.FindingsBased on the proposed method, the accuracy and applicability of the algorithm were verified by comparing the analytical solution of KGD and PKN models. The effects of different in situ stresses and flow rates on the dynamic propagation of hydraulic fractures at laboratory and engineering scales were investigated. when the ratio of in situ stress is small, the fracture propagation direction is not affected, and the fracture morphology is a cross-type fracture. When the ratio of in situ stress is relatively large, the propagation direction of the fracture is affected by the maximum in situ stress, and it is more inclined to propagate along the direction of the maximum in situ stress, forming double wing-type fractures. Hydrofracturing tensile and shear fractures were identified, and the distribution and number of each type were obtained. There are fewer hydraulic shear fractures than tensile fractures, and shear fractures appear in the initial stage of fracture propagation and then propagate and distribute around the perforation.Originality/valueThe proposed dual bilinear CZM is effective for simulating the types of Mode I/II fractures and seizing the fluid-driven propagation of multiscale tensile and shear fractures. Practical fracturing process involves the multi-type and multiscale fluid-driven fracture propagation. This study introduces general fluid-driven fracture propagation, which can be extended to the fracture propagation analysis of potential fluid fracturing, such as other liquids or supercritical gases.

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Numerical simulation of hydraulic fracture propagation in laminated shale reservoirs

Cited by 50 publications

References 23 publications

Oil Occurrence States in Shale Mixed Inorganic Matter Nanopores

Oil Occurrence States in Shale Mixed Inorganic Matter Nanopores

Hydrocarbon Identification and Bedding Fracture Detection in Shale Gas Reservoirs Based on a Novel Seismic Dispersion Attribute Inversion Method

Dual bilinear cohesive zone model-based fluid-driven propagation of multiscale tensile and shear fractures in tight reservoir

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