Improved test method for convection heat transfer characteristics of carbonate fractures after acidizing etching

Zhan, Hongyang; Dong, Wenbao; Chen, Sili; Hu, Dawei; Zhou, Haihua; Luo, Jing‐Li

doi:10.46690/ager.2021.04.04

Cited by 13 publications

(1 citation statement)

References 25 publications

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“…It needs to be extracted by horizontal drilling and multi-layer hydraulic fracturing [5] . Therefore, a refined evaluation of ground stress is required to guide the selection of layers for on-site fracturing and the optimal design of horizontal trajectories [6][7] .…”

Section: Introductionmentioning

confidence: 99%

A refined evaluation method for the stress field of the Chang 7₃ shale oil reservoir of northern Shaanxi

Hou

Wang

et al. 2023

IOP Conf. Ser.: Earth Environ. Sci.

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Shale oil resources are abundant in the Chang 73 reservoir in the eastern Ordos Basin. The thin interbeds of shale in the Chang 73 section of the Yanchang Formation in the oil-bearing section are developed with solid interlayer inhomogeneity and unclear longitudinal interlayer stress difference. This has resulted in unpredictable high seam extension heights during hydraulic fracturing. Based on the results of the Kaiser experiments, the lithological variability was finely described by combining with downhole core observations, and the longitudinal interlayer stress difference coefficient in the Chang 73 section was finely interpreted by using logging data to evaluate the regional distribution pattern of ground stress in the Chang 73 shale reservoir in northern Shaanxi. After studying 600 wells in north of Shaanxi, it was found that: the maximum longitudinal ground stress variation in the Chang 73 reservoir with a thickness of 30-50 m was 35-55 MPa, the minimum ground stress variation was 30-50 MPa, and the minimum was 30 MPa. The horizontal stress difference in the Chang 73 reservoir north of Shaanxi was 3.2-8.6 MPa. The maximum horizontal stress was high in the northwest and low in the southeast, with high values distributed in Jiyuan and Dingbian areas and low values distributed in Zhidan. The refined evaluation of the ground stress results guides the selection of the fracturing layer and the optimal design of the horizontal well trajectory in the field.

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Section: Introductionmentioning

confidence: 99%

A refined evaluation method for the stress field of the Chang 7₃ shale oil reservoir of northern Shaanxi

Hou

Wang

et al. 2023

IOP Conf. Ser.: Earth Environ. Sci.

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show abstract

Correlation between the tensile to compressive strength ratio and mechanical parameters of rock based on a nonlinear M-C criterion

Yang

Deng³

et al. 2022

Arab J Geosci

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The effect of cyclic heating and cooling on mechanical and deformation responses of granites under preset angle shearing

Jiang

Yin

et al. 2022

Environ Earth Sci

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The gradual prominence of environmental problems has brought in nite possibilities for the development and utilization of geothermal resources. Due to the discontinues of rock mass widely distributed and the huge earth stress in deep underground, rock failures which induced by compression and shear occur widely in rock mass. The mechanical and deformation responses of hot dry rock (HDR) under the action of compression and shear in Enhanced Geothermal Systems (EGS) are signi cant to investigate. We carried out cyclic heating and water cooling treatment on granite samples at 4 levels of heating temperatures (T = 150 ℃, 300 ℃, 450 ℃, 600 ℃) and 4 levels of cycle times (N = 1, 5, 10, 15). The preset angle shear (PAS) tests were carried out with three preset shear angles (α = 45°, 55°, 65°) for the samples of various T and N. The evolution law of shear strength parameters of granite for various T and N was obtained. Acoustic emission (AE) characteristics, the evolution of strain eld, and brittle-ductile transformation were obtained by using acoustic emission and digital image correlation (DIC) techniques.Then, the microscopic mechanism of thermal damage was revealed by scanning electron microscopy at a microscopic level. It turns out that with the increase of T and N, the thermal damage degree of granite increases, and the peak load shows an accelerating downward trend. The cohesion c of granite declines, and the internal friction angle φ increases gradually as T and N increasing. The energy consumed by the closure of thermal induced cracks and friction between particles leads to a decrease of elastic energy stored, which eventually results in a decrease of accumulative AE events. When N = 1, T increases from 150°C to 600 ℃, the accumulative AE events decreased by 69.3%. When T = 450 ℃, N increased from 1 to 15, the accumulative AE events decreased by 82.4%. AE activities are generally active throughout the loading process, and the granite shows a ductile failure characteristic obviously. Under the action of compression and shear, with the increase of T, the crack initiation area gradually shifts from the two ends of the sample to the middle area. When T = 600 ℃ (N = 1) and N = 15 (T = 450 ℃), it nally shows a complex fracture network distribution of turtle shape and the shearing failure of "Z" shape on the sample surface. The crack density of the nal failure cracks on sample surface also increases with the increase of T and N, and the damage of granite is more serious, showing strong ductile failure characteristics. At the micro level, the intergranular and transgranular cracks connect with each other and form a complex crack network as T and N increases, causing blocky matrix to peel off from the crystal. The continuous heating with high temperature causes minerals to melt and deform, resulting in the decrease of bonding strength between particles. The mechanical properties deteriorate signi cantly, and the ductile failure characteristics are enhanced.

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Improved test method for convection heat transfer characteristics of carbonate fractures after acidizing etching

Cited by 13 publications

References 25 publications

A refined evaluation method for the stress field of the Chang 7₃ shale oil reservoir of northern Shaanxi

A refined evaluation method for the stress field of the Chang 7₃ shale oil reservoir of northern Shaanxi

Correlation between the tensile to compressive strength ratio and mechanical parameters of rock based on a nonlinear M-C criterion

The effect of cyclic heating and cooling on mechanical and deformation responses of granites under preset angle shearing

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Improved test method for convection heat transfer characteristics of carbonate fractures after acidizing etching

Cited by 13 publications

References 25 publications

A refined evaluation method for the stress field of the Chang 73 shale oil reservoir of northern Shaanxi

A refined evaluation method for the stress field of the Chang 73 shale oil reservoir of northern Shaanxi

Correlation between the tensile to compressive strength ratio and mechanical parameters of rock based on a nonlinear M-C criterion

The effect of cyclic heating and cooling on mechanical and deformation responses of granites under preset angle shearing

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Product

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A refined evaluation method for the stress field of the Chang 7₃ shale oil reservoir of northern Shaanxi

A refined evaluation method for the stress field of the Chang 7₃ shale oil reservoir of northern Shaanxi