Geological controls on artificial fracture networks in continental shale and its fracability evaluation: A case study in the Yanchang Formation, Ordos Basin, China

Fu, Hengzhi; Wang, Xiangzeng; Zhang, Lixia; Gao, Ruimin; Li, Zongtian; Zhu, Xiaolin; Wei, Xu; Li, Qiang; Xu, Ting

doi:10.1016/j.jngse.2015.08.034

Cited by 20 publications

(5 citation statements)

References 29 publications

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“…The 'fracability index (FI)' is a new term that can evaluate the degree to which shale gas and oil reservoirs can be fractured [18]. In recent years, numerous quantification methods for evaluating the fracability of unconventional oil and gas reservoirs have been proposed [43][44][45]. In these methods, apart from BI, other main factors controlling fracability are selected to calculate formation fracability, such as fracture toughness, diagenesis, natural crack density, differential horizontal stress, and so on.…”

Section: Correlation Of Brittleness and Fracabilitymentioning

confidence: 99%

Brittleness Evaluation in Shale Gas Reservoirs and Its Influence on Fracability

Tang

2020

Energies

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The brittleness index (BI) is a key parameter used to identify the desirable fracturing intervals of shale gas reservoirs. Its correlation with fracability is still controversial. There have been a variety of methods proposed that can estimate BI. The brittleness evaluation method based on stress-strain curves according to the energy-balanced law is the most suitable and reliable in this study. Triaxial compression test, optical microscopy and scanning electron microscopy (SEM) observation, and X-ray diffraction analysis (XRD) were performed on nine drill core samples from well SY3 located in the peripheral regions of Sichuan Basin, China. These tests further evaluated several commonly used methods (brittleness indices based on rock elastic parameters, rock mineral compositions) and determined the relationship between brittleness, rock elastic parameters, and the content of minerals. The results obtained indicate that for sedimentary rocks, a higher Young’s modulus reduces the brittleness of rock, and Poisson’s ratio weakly correlates with brittleness. Excessive amounts of quartz or carbonate minerals can increase the cohesiveness of rock, leading to poor brittleness. Furthermore, the most suitable fracturing layers possess a high brittleness index and low minimum horizontal stress.

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Section: Correlation Of Brittleness and Fracabilitymentioning

confidence: 99%

Brittleness Evaluation in Shale Gas Reservoirs and Its Influence on Fracability

Tang

2020

Energies

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“…Fracability is an index that can be used to recognize the intervals in which the chance of success is good and hydraulic fracturing treatment may be proficiently executed. However, as there is no general equation to evaluate the fracability, a fracability index is defined in different situations according to the probable failure mechanism, geological setting, geomechanical background, and also other key parameters that could affect the final operation outcomes (Fang and Amro 2014;Fu et al 2015;Guo et al 2015;Mullen and Christia 2012;F. Zhang et al 2015).…”

Section: Total Fracability Index (Tfi)mentioning

confidence: 99%

Recognizing the best intervals for hydraulic fracturing using a new fracability index

Amiri

Ramezanzadeh

Chamanzad

et al. 2021

J Petrol Explor Prod Technol

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The first phase of any hydraulic fracturing (HF) operation is to select carefully the best layers and wells based on a specific set of criteria. Selecting HF candidates plays a pivotal role in achieving the desired objective such that any attempt to execute this treatment fails without performing comprehensive studies in this regard. In this paper, data from 3 wells in a fractured carbonate reservoir in one of the biggest oilfields of Iran are studied for selecting the best HF candidate. Of these wells, which are comprised of 45 evaluated layers, the best candidate wells/layers are selected from a geomechanical point of view. Initially, a new fracability index appropriate for carbonate reservoirs, namely total fracability index (TFI), is defined. This index integrates mechanical properties and horizontal stresses into an equation. In the next step, four main criteria, namely layer thickness, TFI, natural fractures state (including orientation and density), and fracture confinement, are employed to choose the candidate layers in the wells. Lastly, having used these criteria and analytic hierarchy process, candidate intervals are selected and a hydraulic fracturing simulation model (P3D) is used for evaluation.

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“…Summing up the previous studying achievements (Tang Ying et al, 2012;Fu et al, 2015;Sui et al, 2016), we established the mathematical model for fracability evaluation following these steps. First, we determined the influence factors that should be considered, including brittleness index, fracture toughness, natural fractures and cohesive force.…”

Section: Mathematical Modeling For Fracability Evaluationmentioning

confidence: 99%

“…After normalization, we should determine the impact of each influence factor on fracturing ability, because their influence degrees are different. Refer to Fu et al (2015) and Sui et al (2016), we used analytic hierarchy process to confirm the weight value of each parameter (Table 3). The method for this is to group the parameters into a hierarchical structure and then use judgment matrix criteria to assign values of the parameters according to their degree of importance.…”

Section: Mathematical Modeling For Fracability Evaluationmentioning

confidence: 99%

Fracability Evaluation of Shale of the Wufeng‐Longmaxi Formation in the Changning Area, Sichuan Basin

Huang

et al. 2019

Acta Geologica Sinica (Eng)

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The fracturing technology for shale gas reservoir is the key to the development of shale gas industrialization. It makes much sense to study the mechanical properties and deformation characteristics of shale, due to its close relationship with the fracability of shale gas reservoir. This paper took marine shale in the Changning area, southern Sichuan Basin of China as the research object. Based on field profile and hand specimen observation, we analyzed the development of natural fractures and collected samples from Wufeng Formation and Longmaxi Formation. Combining with the indoor experiment, we investigated the macroscopic and microscopic structural features and the remarkable heterogeneity of shale samples. Then we illustrated the mechanics and deformation characteristics of shale, through uniaxial compression test and direct shear test. The shale has two types of fracture modes, which depend on the angular relation between loading direction and the bedding plane. Besides, the Wufeng shale has a higher value of brittleness index than the Longmaxi shale, which was calculated using two methods, mechanical parameters and mineral composition. Given the above results, we proposed a fracability evaluation model for shale gas reservoir using the analytic hierarchy process. Four influence factors, brittleness index, fracture toughness, natural fractures and cohesive force, are considered. Finally, under the control of normalized value and weight coefficient of each influence factor, the calculations results indicate that the fracability index of the Wufeng Formation is higher than that of the Longmaxi Formation in Changning area, southern Sichuan Basin.

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Geological controls on artificial fracture networks in continental shale and its fracability evaluation: A case study in the Yanchang Formation, Ordos Basin, China

Cited by 20 publications

References 29 publications

Brittleness Evaluation in Shale Gas Reservoirs and Its Influence on Fracability

Brittleness Evaluation in Shale Gas Reservoirs and Its Influence on Fracability

Recognizing the best intervals for hydraulic fracturing using a new fracability index

Fracability Evaluation of Shale of the Wufeng‐Longmaxi Formation in the Changning Area, Sichuan Basin

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