scholarly journals Brittleness Evaluation in Shale Gas Reservoirs and Its Influence on Fracability

Energies ◽  
2020 ◽  
Vol 13 (2) ◽  
pp. 388 ◽  
Author(s):  
Yapei Ye ◽  
Shuheng Tang ◽  
Zhaodong Xi
Keyword(s):  
Shale Gas ◽  
Evaluation Method ◽  
Triaxial Compression ◽  
Horizontal Stress ◽  
Brittleness Index ◽  
X Ray Diffraction ◽  
Elastic Parameters ◽  
Gas Reservoirs ◽  
Shale Gas Reservoirs ◽  
Minimum Horizontal Stress

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.

Brittleness index prediction in shale gas reservoirs based on efficient network models

2016 ◽  
Vol 35 ◽  
pp. 673-685 ◽  
Author(s):  
Xian Shi ◽  
Gang Liu ◽  
Yuanfang Cheng ◽  
Liu Yang ◽  
Hailong Jiang ◽  
...  
Keyword(s):  
Shale Gas ◽  
Network Models ◽  
Brittleness Index ◽  
Gas Reservoirs ◽  
Shale Gas Reservoirs

A Novel Model of Brittleness Index for Shale Gas Reservoirs: Confining Pressure Effect

2015 ◽  
Author(s):  
Yuan Hu ◽  
M. E. Gonzalez Perdomo ◽  
Keliu Wu ◽  
Zhangxin Chen ◽  
Kai Zhang ◽  
...  
Keyword(s):  
Shale Gas ◽  
Pressure Effect ◽  
Confining Pressure ◽  
Brittleness Index ◽  
Gas Reservoirs ◽  
Shale Gas Reservoirs ◽  
Confining Pressure Effect ◽  
Novel Model

New Models of Brittleness Index for Shale Gas Reservoirs: Weights of Brittle Minerals and Rock Mechanics Parameters

2015 ◽  
Author(s):  
Yuan Hu ◽  
M. E. Gonzalez Perdomo ◽  
Keliu Wu ◽  
Zhangxin Chen ◽  
Kai Zhang ◽  
...  
Keyword(s):  
Rock Mechanics ◽  
Shale Gas ◽  
Brittleness Index ◽  
Gas Reservoirs ◽  
Shale Gas Reservoirs ◽  
New Models

scholarly journals Sedimentary Facies of the Longmaxi Formation Shale Gas Reservoir in the Weiyuan Area Based on Elemental Characteristics

Geofluids ◽  
2021 ◽  
Vol 2021 ◽  
pp. 1-17
Author(s):  
Yijia Wu ◽  
Hongming Tang ◽  
Ying Wang ◽  
Jing Li ◽  
Yanxiang Zeng ◽  
...  
Keyword(s):  
Shallow Water ◽  
Shale Gas ◽  
Evaluation Method ◽  
Sedimentary Environment ◽  
Sedimentary Facies ◽  
Gas Reservoirs ◽  
Longmaxi Formation ◽  
Shale Gas Reservoirs ◽  
Carbonaceous Shales ◽  
Sedimentary Microfacies

The Lower Silurian Longmaxi Formation in the southern Sichuan Basin is composed of a series of dark carbonaceous shales deposited in a hydrostatic shelf reduction environment. In this study, the ratio of uranium to thorium (U/Th), the total organic carbon (TOC), and the biological silicon content (SiBio) were selected as the characteristic parameters to precisely analyze the sedimentary environment and its impact on reservoir quality. The results show that the Weiyuan area in the Early Silurian Longmaxi period experienced two transgression-regression cycles, forming two third-class sequences, SSQ1 and SSQ2, which can be divided into six sedimentary microfacies: organic-rich siliceous argillaceous shelf, organic-rich silicon-containing argillaceous shelf, organic-rich silty argillaceous shelf, deep-water silty argillaceous shelf, shallow-water silty argillaceous shelf, and shallow-water argillaceous silty shelf microfacies. The organic-rich siliceous argillaceous shelf and organic-rich silicon-containing argillaceous shelf microfacies developed in the deepest transgressive system tract (TST1), with high U/Th, high TOC, and high SiBio, which are identified as the main control facies for reservoir development. These two microfacies are located in the middle of the study area, while a transition occurs in the east affected by the Neijiang Uplift. According to the classification criteria proposed in this article, the favourable shale gas reservoirs in Weiyuan area are characterized with high U/Th (>1.25), high TOC (>3%), and high SiBio (>15%). This paper proposed an evaluation method for shale sedimentary facies based on elemental and electrical logging characteristics, avoiding the limitations of core samples, which makes the quantitative division of shale sediments and the efficient recognition of high-quality reservoirs available. It is of great significance for delineating the potential production areas in the study area and beneficial for the scaled development of shale gas reservoirs.

scholarly journals Logging Evaluation Method for Pore Pressure of Shale Gas Reservoirs- Taking Fuling Area, Sichuan Basin as an Example

2015 ◽  
Vol 8 (1) ◽  
pp. 350-353
Author(s):  
Hao Shibo ◽  
Jin Wujun
Keyword(s):  
Pore Pressure ◽  
Shale Gas ◽  
Evaluation Method ◽  
Oil And Gas ◽  
Gas Reservoirs ◽  
Shale Gas Reservoirs ◽  
Oil And Gas Resources ◽  
Pore Pressure Prediction ◽  
Formation Pore Pressure ◽  
Exploration And Development

Unconventional oil and gas resources, especially shale gas resources have great potential for exploration and development in China. In Shale gas exploration and development process, reservoir pore pressure is a very important parameter, and the pore pressure prediction can improve the appraisal accuracy of project dessert. This paper analyzes several formation pore pressure calculation methods based on logging data, and optimized the “Equivalent depth method”. The preliminary results show that this method can carry out the accurate evaluation on the abnormal high pressure of the shale gas reservoirs of Fuling area with high calculation precision and application potential.

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