A quantification method for shale fracability based on analytic hierarchy process

Sui, Lili; Ju, Yang; Yang, Yongming; Yang, Yue-Tzu; Li, Aishan

doi:10.1016/j.energy.2016.09.035

Cited by 59 publications

(36 citation statements)

References 11 publications

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“…Although the Analytic Hierarchy Process is considered to be a subjective weighting approach, it should be noted that only evaluating a pairwise comparison matrix needs subjective analysis according to experience, 28 and the matrix tends to be achieved through comparison between two parameters in the same level with one another. 28 indicate the calculation results pass a consistency check of rationality and reliability ( Table 5).…”

Section: Index Weight Determinationmentioning

confidence: 99%

“…Indicators with weight values exceeding 0.03 include R o , organic matter type, burial depth, porosity, structural characteristics, fracture development, permeability, reservoir pressure, and mineral composition; in contrast, other factors, for example, the economic conditions, have lower weight values. 28 However, EWM, EDM, and GRA are based on objective data, and the calculation of the relevant parameters depends little on the subjective or sensory components. However, the results using λ GRA that show poor importance differentiation of each parameter are almost around the average of 0.004, and the gas content as the mother factor has the largest weight value.…”

Section: Index Weight Determinationmentioning

confidence: 99%

“…23 Integrated evaluation maps prepared by the stacking method are widely used in delineating the distribution of favorable areas in a specific region. [25][26][27][28] Actually, the selection of favorable shale gas areas can be abstracted mathematically as the multi-index decision, and these approaches, in principle, can be used to serve for the target. [25][26][27][28] Actually, the selection of favorable shale gas areas can be abstracted mathematically as the multi-index decision, and these approaches, in principle, can be used to serve for the target.…”

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confidence: 99%

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Approaches for the evaluation of favorable shale gas areas and applications: Implications for China's exploration strategy

Zhang

Tang

et al. 2019

Energy Science & Engineering

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To explore practical approaches for the evaluation of favorable shale gas areas, a structural decomposition analysis with respect to the index system, evaluation criteria, weight determination, and evaluation methods was carried out. Five types of indexes were determined from 25 subindexes that formed the index system, and improved whitenization weight functions are proposed to establish evaluation criteria. The index weights calculated using entropy weight and Euclidean distance methods are consistent, whereas the weights determined by gray relational analysis are significantly affected by the relative number of indexes and evaluation objects, selected mother factor, and resolution coefficient. The significant linear positive correlation between the relative approach degree values calculated using TOPSIS and the scores obtained using fuzzy comprehensive evaluation (FCE) is indicative of a consistent evaluation result, but it should be noted that extreme indicator values can have strong effects on the evaluation using the fuzzy similarity method. Finally, an exploration strategy for China's shale gas is suggested: Areas with weak reformation and relatively low maturity are expected to be favorable for marine shale production in South China, and continental and transitional shale‐bearing basins are promising for the prospecting multiple‐origin shale gas and coal measure gas, respectively.

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Section: Index Weight Determinationmentioning

confidence: 99%

Section: Index Weight Determinationmentioning

confidence: 99%

mentioning

confidence: 99%

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Approaches for the evaluation of favorable shale gas areas and applications: Implications for China's exploration strategy

Zhang

Tang

et al. 2019

Energy Science & Engineering

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“…Various brittleness evaluation equations were established, and the most popular among them was proposed by Rickman et al 7 According to his viewpoint, brittleness combines the Young's modulus and Poisson's ratio and can represent the level of fracability. Sui et al 19 creatively used analytic hierarchy process (AHP) method to establish a quantification model for fracability evaluation of shale gas reservoirs. The fracability level increases with increased content of brittle minerals.…”

Section: Introductionmentioning

confidence: 99%

“…In this paper, inspired by the study in the reference, 19 the AHP was used to establish a comprehensive fracability evaluation model for naturally fractured sandstone reservoir. However, some important factors such as natural fracture was not included, which may lead to bias for fracability evaluation of naturally fractured reservoirs.…”

Section: Introductionmentioning

confidence: 99%

A comprehensive approach for fracability evaluation in naturally fractured sandstone reservoirs based on analytical hierarchy process method

Yang

et al. 2019

Energy Science & Engineering

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The tight sandstone gas reservoir in southern Songliao Basin is naturally fractured and is characterized by its low porosity and permeability. Large‐scale hydraulic fracturing is the most effective way to develop this tight gas reservoir. Quantitative evaluation of fracability is essential for optimizing a fracturing reservoir. In this study, nine fracability‐related factors, particularly mechanical brittleness, unconfined compressive strength (UCS), mineral brittleness, cohesion, internal friction angle (IFA), natural fracture, fracture toughness, horizontal stress difference, and fracture barrier were obtained based on a series of petrophysical and geomechanical experiments. Taking above factors into consideration, a modified comprehensive evaluation model is proposed based on analytic hierarchy process (AHP) method. The UCS and IFA were removed from the AHP model based on the results of factor correlation analysis. The transfer matrix in the weighting procedure was applied to improve the consistency of judgment matrix, and the fuzzy matrix was employed to promote the objectiveness of final decision. The fracability evaluation of four reservoir intervals in Jinshan gas field was analyzed. Field fracturing tests were conducted to verify the feasibility of the proposed evaluation model. Results showed that the tubing pressure curve is more fluctuated in the reservoir interval with more developed natural fractures, and gas production is higher in the reservoir interval with greater fracability coefficient. The field test data coincide with the results of the proposed evaluation model.

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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

Self Cite

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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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A quantification method for shale fracability based on analytic hierarchy process

Cited by 59 publications

References 11 publications

Approaches for the evaluation of favorable shale gas areas and applications: Implications for China's exploration strategy

Approaches for the evaluation of favorable shale gas areas and applications: Implications for China's exploration strategy

A comprehensive approach for fracability evaluation in naturally fractured sandstone reservoirs based on analytical hierarchy process method

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

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