Experimental study on the mechanism of hydraulic fracture growth in a glutenite reservoir

Ma, Xinfang; Zou, Yushi; Li, Ning; Chen, Ming; Zhang, Yinuo; Liu, Zizhong

doi:10.1016/j.jsg.2017.02.012

Cited by 76 publications

(45 citation statements)

References 14 publications

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“…Glutenite is formed by rapid deposition near provenances and therefore contains a large number of randomly distributed coarse gravels (or rock fragments) of various sizes possessing low organic maturity and high heterogeneity (Liu et al, ; Zhang et al, ). A rising tide of evidence implies that the heterogeneity of formations and the horizontal geostress ratio may play important roles in the complex pattern of cracks initiated and propagated during hydrofracturing (Koceir & Tiab, ; Liu et al, ; Ma et al, ; Zhao et al, ). Therefore, understanding and quantifying the role of rock heterogeneities on the propagation and distribution patterns of hydrofracturing cracks are key for enhancing the hydraulic fracturing stimulation of tight gas reservoirs with low permeability.…”

Section: Introductionmentioning

confidence: 99%

CT Identification and Fractal Characterization of 3‐D Propagation and Distribution of Hydrofracturing Cracks in Low‐Permeability Heterogeneous Rocks

Liu

Gao

et al. 2018

JGR Solid Earth

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Understanding and characterization of the three‐dimensional (3‐D) propagation and distribution of hydrofracturing cracks in heterogeneous rock are key for enhancing the stimulation of low‐permeability petroleum reservoirs. In this study, we investigated the propagation and distribution characteristics of hydrofracturing cracks, by conducting true triaxial hydrofracturing tests and computed tomography on artificial heterogeneous rock specimens. Silica sand, Portland cement, and aedelforsite were mixed to create artificial heterogeneous rock specimens using the data of mineral compositions, coarse gravel distribution, and mechanical properties that were measured from the natural heterogeneous glutenite cores. To probe the effects of material heterogeneity on hydrofracturing cracks, the artificial homogenous specimens were created using the identical matrix compositions of the heterogeneous rock specimens and then fractured for comparison. The effects of horizontal geostress ratio on the 3‐D growth and distribution of cracks during hydrofracturing were examined. A fractal‐based method was proposed to characterize the complexity of fractures and the efficiency of hydrofracturing stimulation of heterogeneous media. The material heterogeneity and horizontal geostress ratio were found to significantly influence the 3‐D morphology, growth, and distribution of hydrofracturing cracks. A horizontal geostress ratio of 1.7 appears to be the upper limit for the occurrence of multiple cracks, and higher ratios cause a single crack perpendicular to the minimum horizontal geostress component. The fracturing efficiency is associated with not only the fractured volume but also the complexity of the crack network.

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Section: Introductionmentioning

confidence: 99%

CT Identification and Fractal Characterization of 3‐D Propagation and Distribution of Hydrofracturing Cracks in Low‐Permeability Heterogeneous Rocks

Liu

Gao

et al. 2018

JGR Solid Earth

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“…In order to improve the effectiveness of test results, it is essential to set test conditions as close as possible to field conditions to obtain experimental results approved by field engineers. And many scholars have adopted field parameters as experimental conditions in the hydraulic fracture experiments with triaxial pressure vessels . So the test focuses on the conditions in the design process, such as experimental material, test time, test load, geometric size, kinematic condition, and so on.…”

Section: Methodsmentioning

confidence: 99%

Large‐scale experiments of the borehole instability on shale formation influenced by drill pipe rotation

Sun

Meng

Dai

et al. 2019

Energy Science & Engineering

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Wellbore instability happens mostly in the shale formation. Early researches have studied thoroughly on the physicochemical and mechanical mechanism that causes instability. However, only a few works have considered the influence of field drilling operations, such as drill pipe rotation. In this paper, a true triaxial cell is used to simulate the downhole field situations, and a drill pipe rotation device is innovatively designed and implemented into the true triaxial cell. Using this facility, the influence of drill pipe rotation on shale instability has been performed. Different rotation speed, weight on bit, drilling fluid pressure, and microcracks on borehole have been considered. The enlargement of the wellbore is quantitatively plotted and compared.Results show that the drill pipe rotation contributes to a more enlargement of the wellbore, and a higher rotation speed causes a more severe collapse. The drill string weight on bit also contributes to the enlargement of the wellbore, with a larger weight on bit induces a larger diameter of the collapsed wellbore. Compared with the rotation speed and weight on bit, the influence of drilling fluid density is relatively less significant. However, the influence of microcracks caused by hitting of drilling tools is profound. For a cracked shale formation, the wellbore diameter can be enlarged for more than 40%. Then, the variation of borehole collapse with time and depth under drill pipe rotation influence is analyzed. In all of these four factors, the significant sequence is microcracks > weight on bit > rotation speed > drilling fluid pressure.In all the collapse phenomena, the collapse is more severe in the minimum horizontal stress direction. This is explained by the analysis of the stress distribution in the whole circumferential angle (360°) of the wellbore. Overall, this work fills the gap of the influence of drilling operations on wellbore instability. K E Y W O R D Sborehole enlargement, drill pipe rotation, true triaxial cell, wellbore instability 2896 | SUN et al.

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“…For example, Ma et al [8] observed two types of gravels in the glutenite specimens marked by gravel (A) and gravel (B). The brown-red gravel (B) containing a high amount of quartz has more than three times the tensile strength of the caesious gravel (A) containing a high amount of feldspar.…”

Section: Impact Of Gravel Strengthmentioning

confidence: 99%

“…Glutenite reservoirs are typically composed of sandstone and conglomerate gravels which are formed under rapid deposition in nearby provenances [8]. Tight glutenites are among those with low or ultra-low permeability that can range from 0.1 mD to 0.0001 mD [9].…”

Section: Introductionmentioning

confidence: 99%

“…Previous studies on this issue have been conducted through these two approaches. Laboratory experiment has always been a direct and compelling method to conduct such investigations and valuable related findings have been achieved [8,11,12,[17][18][19]. However, similarly, limited by the inner invisibility of a rock specimen and lack of suitable observation methods, in most cases fractured samples after wellbore shut-in are cut open to observe the fracture geometry, which may partly destroy the HF geometry due to the tough manual separation, leave out small HFs or branches, and lead to loss of the emerge of the fracturing process that is quite essential to illuminate problems in some cases.…”

Section: Introductionmentioning

confidence: 99%

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The Fracturing Behavior of Tight Glutenites Subjected to Hydraulic Pressure

Zhang

et al. 2018

Processes

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Tight glutenites are typically composed of heterogeneous sandstone and gravel. Due to low or ultra-low permeability, it is difficult to achieve commercial production in tight glutenites without hydraulic fracturing. Efficient exploitation requires an in-depth understanding of the fracturing behavior of these reservoirs. This paper provides a numerical method that integrates the digital image processing (DIP) technique into a numerical code rock failure process analysis (RFPA). This method could consider the glutenite heterogeneities, including intrarock and interrock heterogeneities, and the practicability is verified through two numerical tests. Two-dimensional (2D) simulations show hydraulic fractures (HFs) can penetrate or deflect to propagate along the gravels, depending on the magnitude of stress anisotropy and gravel strength. Three-dimensional (3D) simulations with the consideration of gravel distribution orientation, gravel size and axial ratio show HFs could propagate past the gravel with no deflection, forming a bypass fracture that is not easy to observe in common laboratory experiments. HFs could also deflect to propagate along the gravels. The impacts of the gravel distribution orientation, gravel size and axial ratio are discussed in detail. The main propagation modes of HFs intersecting the gravels are summarized as: (1) penetrating directly; (2) deflecting to propagate along the gravels to form distorted HFs; (3) propagating to bypass the gravels; (4) a combination of (1) and (2), or (2) and (3).

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Experimental study on the mechanism of hydraulic fracture growth in a glutenite reservoir

Cited by 76 publications

References 14 publications

CT Identification and Fractal Characterization of 3‐D Propagation and Distribution of Hydrofracturing Cracks in Low‐Permeability Heterogeneous Rocks

CT Identification and Fractal Characterization of 3‐D Propagation and Distribution of Hydrofracturing Cracks in Low‐Permeability Heterogeneous Rocks

Large‐scale experiments of the borehole instability on shale formation influenced by drill pipe rotation

The Fracturing Behavior of Tight Glutenites Subjected to Hydraulic Pressure

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