Mechanistic Modeling of Clay Swelling in Hydraulic Fractures Network

Sanaei, Alireza; Shakiba, Mahmood; Varavei, Abdoljalil; Sepehrnoori, Kamy

doi:10.2118/180372-ms

Cited by 4 publications

(2 citation statements)

References 37 publications

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“…Swell. Experimental and simulation works have shown that clay minerals could expand in volume up to 20 times through adsorption of water [27], which lead to fracture permeability decrease 10% to 90% based on different kinds of clay minerals and clay content in shale samples [28]. Hence, the swelling effect is considered when analyzing fracture aperture evolution in our experiments.…”

Section: Effective Hydraulic Aperture Decrease Induced By Claymentioning

confidence: 98%

Mechanical-Chemical-Mineralogical Controls on Permeability Evolution of Shale Fractures

Jia

Tang

et al. 2018

Geofluids

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We report experimental observations of permeation of CO2-rich aqueous fluids of varied acidic potential (pH) on three different shales to investigate mechanical, chemical, and mineralogical effects on fracture permeability evolution. Surface profilometry and SEM-EDS (scanning electron microscopy with energy-dispersive X-ray spectroscopy) methods are employed to quantify the evolution in both roughness on and chemical constituents within the fracture surface. Results indicate that, after 12 hours of fluid flow, fracture effective hydraulic apertures evolve distinctly under different combinations of shale mineralogy, effective stress, and fluid acidity. The evolution of roughness and transformation of chemical elements on the fracture surface are in accordance with the evolution of permeability. The experimental observations imply that (1) CO2-rich aqueous fluids have significant impact on the evolution of fracture permeability and may influence (and increase) shale gas production; (2) shale mineralogy, especially calcite mineral, decides the chemical reaction and permeability increasing when CO2-rich aqueous fluids flow through fractures by free-face dissolution effect; (3) clay mineral swelling reduces fracture aperture and additively calcite pressure solution removes the bridging asperities, which are the main reasons for fracture permeability decrease; (4) competition roles among clay mineral swelling, mineral pressure solution, and free-face dissolution determine how fracture permeability changes. Furthermore, a multiple parameter model is built to analyze effective hydraulic aperture evolution in considering above three mechanisms, which provide a reference to forecast fracture permeability evolution in shale formations.

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Section: Effective Hydraulic Aperture Decrease Induced By Claymentioning

confidence: 98%

Mechanical-Chemical-Mineralogical Controls on Permeability Evolution of Shale Fractures

Jia

Tang

et al. 2018

Geofluids

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“…caused the expansion of a double diffusive layer of clay minerals [32]. Consequently, the clay swelling may lead to the increase of clay mineral content of carbonate-poor and carbonate-rich shale.…”

Section: Geofluidsmentioning

confidence: 99%

Pore Structure Alteration Characteristics of Different Mineralogical Composition Shale during Shale-Fracturing Fluid Physical-Chemical Interactions

et al. 2019

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Hydraulic fracturing is widely applied to economic gas production from shale reservoirs, but the effect of the shale mineral composition on the physical-chemical reactions during hydraulic fracturing is still poorly understood. To develop a foundational understanding of chemical interactions occurring on shale with different mineralogical compositions, two different types of mineral composition marine shale (carbonate-poor and carbonate-rich) from the Niutitang Formation were reacted with slick water fracturing fluid in a laboratory reactor at 100°C and 50 MPa for three days. To identify the changes of the pore structure characteristics during hydraulic fracturing, the field emission scanning electron microscopy (FE-SEM), X-ray diffraction (XRD), low-temperature nitrogen adsorption, and porosity measurement were performed on the original and treated shale samples. After the slick water treatment, the dissolution of pyrite in carbonate-poor shale (obtained from Youyang County, labeled as YY) was observed by FE-SEM and XRD analyses, while in carbonate-rich shale (obtained from Guzhang County, labeled as GZ), the carbonate dissolution was observed. Results from the low-temperature N2 adsorption and porosity measurement demonstrated that the variation trend of pore structure characteristics for the YY and GZ shale samples was quite different after reacting with slick water fracturing fluid. For YY shale, the specific surface area, total pore volume, and porosity increased after the reaction, whereas an opposite trend was observed in the GZ shale. Moreover, the fractal dimension analysis illustrated that the pore surface became less rough and the pore structure became more complex in the YY shale, whereas the degree of pore surface roughness and pore structure complexity of the GZ shale was reduced. The results demonstrated that the initial mineralogical composition of shale played an important role in pore structure alteration during hydraulic fracturing.

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Aspects of Scale Deposition in a Compositional Coupled Wellbore/Reservoir Simulator

Abouie

Korrani²,

Sepehrnoori

2017

SPE International Conference on Oilfield Chemistry

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Scale deposition in surface and subsurface production equipment is one of the major operational problems encountered during oil production, which results in equipment corrosion, wellbore plugging, production rate decline, and requires frequent squeeze treatments. Oil field scales mainly result from changes in the physicochemical properties (pH, temperature, and pressure), mixing with incompatible brine compositions, and mixing with inhibitors. Meanwhile, comprehensive modeling and prediction of scale formation has remained challenging due to the complexity of the geochemical reactions that occurs in real fields. For the first time and to overcome the lack of comprehensive geochemical-based tools, a robust, accurate, and flexible coupled reservoir and wellbore model is developed, and then, integrated with a geochemical tool (i.e. IPhreeqc) to predict scale formation from injection wells through the reservoir to production wells. IPhreeqc, the United States Geological Survey (USGS) geochemical tool, has the capability of modeling homogenous and heterogeneous, reversible and irreversible, and ion-exchange reactions under non-isothermal, non-isobaric, and local equilibrium or kinetic conditions. In this work, by integrating IPhreeqc with the compositional reservoir (UTCOMP) and wellbore simulator (UTWELL), the geochemical capabilities of IPhreeqc is used in a multi-physics reservoir/wellbore models for comprehensive prediction of carbonates and sulfates scales deposition. Moreover, the effects of weak acids and hydrocarbon phase dissolution in the aqueous phase were included to accurately predict the carbonate scale profile. To the best of our knowledge, there is no comprehensive simulator available in the industry through which scale deposition in the reservoir and wellbore can be predicted accurately. In this paper, scale deposition profile in the field is estimated by including 1) the interaction of the hydrocarbon and aqueous phases and its effect on the aqueous-scale geochemistry 2) effects of parameters that vary greatly in the field (i.e. pressure, temperature, and pH) and 3) comprehensive geochemistry simulation (provided through coupling of the simulators with IPhreeqc). The outcome of this study yields a comprehensive tool for prediction of scale deposition profile and will help scale deposition risk management and mitigation plans.

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Mechanistic Modeling of Clay Swelling in Hydraulic Fractures Network

Cited by 4 publications

References 37 publications

Mechanical-Chemical-Mineralogical Controls on Permeability Evolution of Shale Fractures

Mechanical-Chemical-Mineralogical Controls on Permeability Evolution of Shale Fractures

Pore Structure Alteration Characteristics of Different Mineralogical Composition Shale during Shale-Fracturing Fluid Physical-Chemical Interactions

Aspects of Scale Deposition in a Compositional Coupled Wellbore/Reservoir Simulator

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