Initiation mechanisms of radial drilling‐fracturing considering shale hydration and reservoir dip

Chen, Yuxin; Ding, Yunhong; Liang, Chong; Zhu, Deqing; Bai, Yu; Zou, Chunmei

doi:10.1002/ese3.969

Cited by 4 publications

(4 citation statements)

References 32 publications

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“…The 0.5 g/L copper sulfate solution is selected to simulate the formation with a permeability of 50 mD and the iron wire with a diameter of 2.5 mm and length of 35 cm is selected to simulate the drilling hole with a length of 100 m. It can be seen from Figure 5 that no matter whether the included angle between the two boreholes is 60 • , 90 • , 120 • , or 180 • [27], within the range of the included angle between the two boreholes, the advance distance of the front edge of oil and water displacement is the farthest and the spread is relatively uniform. However, within the two sides of the included angle, the advance distance of the oil-water displacement front is smaller than that of the displacement within the included angle, it is obviously inclined to the radial drilling, and the sweep is not very uniform.…”

Section: Drilling Anglementioning

confidence: 99%

“…Graham [26] introduced the application case of carbonate formation in the North Urtabluk oilfield in the south of Uzbekistan using the radial water jet technology to effectively exploit the remaining oil in the formation. Chen Yuxin [27] developed a model for radial drilling-fracturing in shale reservoirs, which can predict fracture initiation pressure and the failure mode of shale. Compared with published models, this model additionally considers shale hydration and inclinations of boreholes and reservoirs; the influences of seven factors are studied.…”

Section: Introductionmentioning

confidence: 99%

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Study on Stimulation Mechanism and Parameter Optimization of Radial Water Jet Drilling Technique in Low Physical Property Sections of Petroleum Reservoirs

et al. 2023

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Radial drilling-fracturing is an innovative fracturing technology that achieves superior stimulation effects. In order to study the permeability-increasing effect and main influencing factors of radial water jet drilling in the low physical section, this paper uses a fracking electrical simulation experiment, based on the principle of hydropower similarity, to simulate the reservoir conditions and well pattern in the low physical section and, at the same time, establishes the radial fracturing model of the low physical section reservoir, simulates the saturation field, pressure field, and production-change law under different drilling parameters, and studies different influencing factors. The experimental results show that when the number of drilling holes exceeds two, the effect of increasing production gradually becomes less significant as the number of drilling holes increases; Within the range of the angle between the two boreholes, the forward distance of the oil–water displacement front is the farthest and the sweep is relatively uniform. On both sides of the included angle, the forward distance of the oil–water displacement front edge is smaller than the forward distance of the displacement within the included angle range and it is clearly inclined towards the radial drilling with uneven spread. Radial drilling has an impact on the seepage field, causing changes in its streamline. The pressure inside the borehole is lower than the surrounding formation pressure and most of the flow lines change direction near the borehole location, causing deflection. As the borehole length increases, the oil-well production also increases. The optimal effect is for the borehole length to be 100 m. This study provides a reference for the on-site application of radial fracturing in low physical properties sections.

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Section: Drilling Anglementioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Study on Stimulation Mechanism and Parameter Optimization of Radial Water Jet Drilling Technique in Low Physical Property Sections of Petroleum Reservoirs

et al. 2023

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“…In the construction of acid fracturing, acid is injected into the reservoir at pressures higher than the formation breakdown pressure in order to create an artificial fracture or open natural fractures. Unlike the artificial fracture, propped by proppants in conventional hydraulic fracturing [5][6][7], the artificial fracture in acid fracturing is etched by the acid in non-uniform patterns and generates a certain conductivity. These etched fractures can enhance fluid flow from the reservoir into the wellbore and increase the well's production significantly.…”

Section: Introductionmentioning

confidence: 99%

An Integrated Model for Acid Fracturing without Prepad Considering Wormhole Growth

Chen,

Wang,

et al. 2024

Processes

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Acid fracturing is an effective stimulation technology that is widely applied in carbonate reservoirs. An integrated model for acid fracturing without prepad treatment has been established. Compared with the previous models which use prepad for generating hydraulic fractures, this model can simultaneously simulate the fracture propagation and the acid etching of fracture surfaces, as well as the wormhole growth during acid fracturing. The influences of some essential factors have been studied through a series of numerical simulations, and the main conclusions are as follows. First, increasing the injected acid volume can expand the size of the formed hydraulic fractures and extend the propagation distance of the wormhole. Increasing the injected acid volume can also expand the etched width and extend the effective distance of the injected acid. Second, a high injection rate impels more acid to flow into the depth of a fracture before infiltration and reaction, resulting in the augmentation of a hydraulic fracture’s geometric size and the extension of the effective distance. But the maximum etched width decreases as the injection rate rises. A high injection rate can also enable wormholes to grow in the natural fracture area farther away from the hydraulic fracture inlet, but shorten the length of the original wormhole near the hydraulic fracture inlet. Third, an increase in acid viscosity can enlarge the geometric size of the hydraulic fracture and reduce the propagation distance of wormholes. In addition, an increase in the acid viscosity blocks the acid flow from fracture inlet to tip, reducing the effective distance of acid fracturing. Fourth, the natural fracture is the vital inducement of wormhole growth, and wormholes are apt to grow in the natural fracture area. Moreover, the geometric size of the hydraulic fracture and the effective distance of acid fracturing decrease with an increasing number of natural fractures. This research can provide a reference for field applications of acid fracturing without prepad.

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“…Breakthroughs in the exploration of shale oil and gas have been made, but the complex geological environment, strong heterogeneity, and difficult drilling of shale oil and gas reservoirs pose significant challenges to development efficiency and safety. In order to support the industrialized exploitation of shale oil and gas, it is crucial to study the mechanical properties of the relevant strata (Chen et al., 2021a). Shale is primarily composed of mud and fine sand that formed in a weak hydraulic environment.…”

Section: Introductionmentioning

confidence: 99%

Experimental and damage model study of layered shale under different moisture contents

Xian-yin,

Dian-dong,

Ming-zhe

et al. 2024

International Journal of Damage Mechanics

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To investigate the mechanical properties and damage evolution law of layered shale under varying moisture contents, we conducted triaxial compression experiments on rock samples with different bedding angles and moisture levels. This study analyzed the variations in mechanical properties of layered shale under different conditions, and established a predicted model for elastic modulus based on different bedding angles and moisture content. Additionally, the damage constitutive model of layered shale was improved. The study revealed that shale’s mechanical properties display anisotropy, which is influenced by the bedding angles and moisture contents. The elastic modulus of the rock increases with the rise of bedding angle, exhibiting a ‘U’-shaped change. Conversely, the mechanical properties of rocks deteriorate, and their brittleness weakens with the increase in moisture content. When the confining pressure increased, the overall mechanical properties of shale were enhanced, and the influence of bedding on shale was weakened, but the deteriorating effect of water on rocks was hardly affected. Based on the above experiments, a predicted model of equivalent elastic modulus of shale considering the coupling effect of bedding and different moisture contents was proposed, which could effectively predict the elastic modulus of layered shale with different moisture content under different confining pressures. Furthermore, based on the predicted model of elastic modulus, an improved damage constitutive model of layered shale under triaxial loading was established, and the damage accumulation trend of layered shale was obtained, which showed an “S”-shaped change with strain. Under the coupling effect of bedding and different moisture contents, the damage of shale was advanced, but the accumulation rate of damage slowed down. With the increase of confining pressure, the influence of bedding and moisture content on the damage characteristics of shale decreased, and the damage curves under different conditions gradually tended to isotropy. The developed damage constitutive model for layered shale under different moisture contents provides theoretical support for the study of reservoir fracturing and wellbore stability.

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Initiation mechanisms of radial drilling‐fracturing considering shale hydration and reservoir dip

Abstract: This is an open access article under the terms of the Creat ive Commo ns Attri bution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.

Cited by 4 publications

References 32 publications

Study on Stimulation Mechanism and Parameter Optimization of Radial Water Jet Drilling Technique in Low Physical Property Sections of Petroleum Reservoirs

Study on Stimulation Mechanism and Parameter Optimization of Radial Water Jet Drilling Technique in Low Physical Property Sections of Petroleum Reservoirs

An Integrated Model for Acid Fracturing without Prepad Considering Wormhole Growth

Experimental and damage model study of layered shale under different moisture contents

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