Quantitative investigation on the characteristics of ions transport into water in gas shale: Marine and continental shale as comparative study

Liu, Yang; Shi, Xian; Ge, Hongkui; Liu, Dunqing; Qu, Xiangmei; Gao, Junfeng; Li, Lingdong; Xu, Peng; Tan, Xiqun

doi:10.1016/j.jngse.2017.07.020

Cited by 14 publications

(4 citation statements)

References 21 publications

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“…Clay minerals also affect the release and transport of ions in shale. Many exchangeable ions attach to the surface of clay minerals, and when in contact with fluid, they are separated and diffused into water, which therefore influences the release of ions [18]. Previous studies also have revealed that under acidic conditions clay minerals like illite release more Si and Al than under neutral and alkaline conditions [37], which could also contribute to the different results of the S1(3) and S2(4) experiments.…”

Section: Evolution Of Ph and Fluid Compositionmentioning

confidence: 99%

“…However, due to the ultra-low porosity and permeability of unconventional reservoirs (e.g., shale and coal-bed methane reservoirs), horizontal drilling and hydraulic fracturing techniques are needed for effective extraction of these unconventional resources [15,16]. During the hydraulic fracturing process, from 7500 to 15,000 cubic metres of water along with specific chemical additives, which are acidic and oxidative, are injected into subsurface shale formations for one typical shale gas well [17,18]. From 5 to 85% of the injected fluid (generally 30-50%) flows back to the near surface and has a salinity three times greater than that of the initial water [19,20].…”

Section: Introductionmentioning

confidence: 99%

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Experimental Investigation of the Impacts of Fracturing Fluid on the Evolution of Fluid Composition and Shale Characteristics: A Case Study of the Niutitang Shale in Hunan Province, South China

Tan

et al. 2020

Energies

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Hydraulic fracturing is a widely used technique for oil and gas extraction from ultra-low porosity and permeability shale reservoirs. During the hydraulic fracturing process, large amounts of water along with specific chemical additives are injected into the shale reservoirs, causing a series of reactions the influence the fluid composition and shale characteristics. This paper is focused on the investigation of the geochemical reactions between shale and fracturing fluid by conducting comparative experiments on different samples at different time scales. By tracking the temporal changes of fluid composition and shale characteristics, we identify the key geochemical reactions during the experiments. The preliminary results show that the dissolution of the relatively unstable minerals in shale, including feldspar, pyrite and carbonate minerals, occurred quickly. During the process of mineral dissolution, a large number of metal elements, such as U, Pb, Ba, Sr, etc., are released, which makes the fluid highly polluted. The fluid–rock reactions also generate many pores, which are mainly caused by dissolution of feldspar and calcite, and potentially can enhance the extraction of shale gas. However, precipitation of secondary minerals like Fe-(oxy) hydroxides and CaSO4 were also observed in our experiments, which on the one hand can restrict the migration of metal elements by adsorption or co-precipitation and on the other hand can occlude the pores, therefore influencing the recovery of hydrocarbon. The different results between the experiments of different samples revealed that mineralogical texture and composition strongly affect the fluid-rock reactions. Therefore, the identification of the shale mineralogical characteristics is essential to formulate fracturing fluid with the lowest chemical reactivity to avoid the contamination released by flowback waters.

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Section: Evolution Of Ph and Fluid Compositionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Experimental Investigation of the Impacts of Fracturing Fluid on the Evolution of Fluid Composition and Shale Characteristics: A Case Study of the Niutitang Shale in Hunan Province, South China

Tan

et al. 2020

Energies

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“…According to the calculation results of Yang et al (2017b), the porosity is positively related to the specific surface area.…”

Section: Factors Influencing Ion Diffusion 331 Effects Of Permeability and Porositymentioning

confidence: 99%

“…As the clay content increases, the ion diffusion rate increases. Clay minerals have a large specific surface area and are rich in soluble salt minerals (Yang et al, 2017b). Water enters into the clay crystal layers, causing the clay minerals to swell and releasing large amounts of salt ions.…”

Section: Effects Of Clay Mineralsmentioning

confidence: 99%

A comparative study of ion diffusion during water imbibition in shale, sandstone and volcanic rock

et al. 2020

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The recovered fracturing fluid is generally high in salinity (close to 200 kppm), which is related to the diffusion of salt ions from shale reservoir to the fracturing fluid. However, it is not clear about the diffusion capacity of salt ions in different types. In this paper, the shale, tight volcanic and sandstone are selected as comparative study and a series of tests are carried out for the porosity, permeability and mineral composition. The results show that the shale immersing in fracturing fluid will cause ions dissolution and diffusion, which will increase the salinity of the fracturing fluid. The solution salinity increases rapidly in the early stage and gradually slows down in the later stage. The salinity of the fracturing fluid has a linear relationship with the square root of time, so the slope of the curve can be used as a characteristic parameter to evaluate the ion diffusion rate. The process of dissolution and diffusion of salt ions will induce the expansion of micro-cracks, increasing the contact area between the fracturing fluid and shale and enhancing the solution salinity. The ion diffusion rate is positively related with the content of clay minerals and carbonate. The soluble ions include mainly SO 2− 4 , Ca 2+ , Na + and K + . The Na + /Cl − ratio is closely related to the content of clay minerals and carbonate minerals. It has a positive correlation with content of illite and chlorite, and a negative correlation with carbonate minerals, suggesting NaCl source from illite and chlorite. This study is significant for understanding the salinity characteristics of recovered fracturing fluid and evaluating the fracture network shape.

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Characteristics and significance of heterogeneity of sea-land transitional facies shale gas reservoir in North Guizhou, China

et al. 2018

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Quantitative investigation on the characteristics of ions transport into water in gas shale: Marine and continental shale as comparative study

Cited by 14 publications

References 21 publications

Experimental Investigation of the Impacts of Fracturing Fluid on the Evolution of Fluid Composition and Shale Characteristics: A Case Study of the Niutitang Shale in Hunan Province, South China

Experimental Investigation of the Impacts of Fracturing Fluid on the Evolution of Fluid Composition and Shale Characteristics: A Case Study of the Niutitang Shale in Hunan Province, South China

A comparative study of ion diffusion during water imbibition in shale, sandstone and volcanic rock

Characteristics and significance of heterogeneity of sea-land transitional facies shale gas reservoir in North Guizhou, China

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