Effect of polymer on gas flow behavior in microfractures of unconventional gas reservoirs

Song, Zhaojie; Liu, Lingbo; Hou, Jirui; Bai, Baojun; Su, Wei

doi:10.1016/j.jngse.2015.01.021

Cited by 13 publications

(5 citation statements)

References 28 publications

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“…When comparing the surface tension of the slick water gel breaker with the same concentration of the drag-reducing agent, it can be found that the surface tension is much higher than the interfacial tension. This is because when measuring the surface tension, the upper layer of the testing medium is air, the density is 0 g/cm 3 , and when measuring the interfacial tension, it is kerosene, the density difference with the slick water gel breaker becomes smaller. Li, 42 Xu, 43 and others think that low interfacial tension is one of the main driving forces to promote imbibition.…”

Section: Resultsmentioning

confidence: 99%

“…At present, a considerable part of conventional oil and gas deposits has been extracted. In comparison, the output of unconventional oil and gas deposits is negligible. − According to research, unconventional oil and gas reservoirs are widely distributed in the world and it is necessary to enhance the exploitation of unconventional oil and gas reservoirs because it is the most potential oil and gas reservoirs in the world. However, from conventional oil and gas to unconventional oil and gas development, the technical requirements increase, the cost increases, and the development difficulty increases.…”

Section: Introductionmentioning

confidence: 99%

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Performance Evaluation of the Multifunctional Variable-Viscosity Slick Water for Fracturing in Unconventional Reservoirs

et al. 2021

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The traditional guar gum fracturing fluid system has the drawbacks of the fracturing process of unconventional oil and gas deposits, such as high drag resistance and large residuum harm, which is gradually replaced by the system of the slick water fracturing fluid. The conventional slick water system, however, still has the features of low sand-carrying capability. Therefore, high-viscosity slick water is often used in fracturing operations, but most of the high-viscosity slick water is difficult to prepare, dissolve, and break gels, which needs to be improved. Based on the abovementioned problems, a new type of multifunctional variable-viscosity slick water is proposed in this paper. The self-made loop drag test unit, a dynamic crack sand-carrying model, a multifunctional core flow device, and other equipment were used for testing, and a set of systematic evaluation methods for the performance of multifunctional variable-viscosity slick water are established. In addition, the mechanism of improving sand-carrying capacity and increasing viscosity and solubilization was explained through the macroevaluation experiment of polymer properties and the analysis of the polymer microstructure. The experimental results show that compared with high-viscosity slick water, the multifunctional variable-viscosity slick water has good drag-reducing performance, the drag-reducing rate can reach more than 75%; the intersection value of viscoelastic modulus is about 0.01 Hz, the sand carrying capacity is higher; the gel-breaking time is faster, the residue content is lower, 38.5 ppm; it has the characteristics of low harm, the harm rate to the core is 18.30%; and it also has the performance of enhancing oil recovery.

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Performance Evaluation of the Multifunctional Variable-Viscosity Slick Water for Fracturing in Unconventional Reservoirs

et al. 2021

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“…Then, other researchers represented by Barrat further demonstrated that adsorption properties of surfactants are the main reason leading to drag reduction effect. They believe that the surfactants adsorbed on the wall of reservoir microchannels weaken the interaction between water molecules and therefore reduce the flow drag [25][26][27][28]. Generally, previous research studies the drag reduction mechanism in microscale, and the drag reduction agents used in the research are mainly surfactants.…”

Section: Introductionmentioning

confidence: 99%

Drag Reduction Mechanism of Viscoelastic Slick-Water Fracturing Fluid in Tortuous and Rough Fractures

Liu

Fan²,

Zhang

et al. 2021

Geofluids

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Slick-water can effectively reduce the flow drag of fracturing fluid. Many studies have focused on the drag reduction performance of slick-water in wellbore and perforation, but there has been little research on drag reduction characteristics in fracture flow. In this paper, a new visualization experiment system is used to simulate real fracture. The fracture surface is produced through actual triaxial hydraulic fracturing and is copied by a three-dimensional printer using resin material to maintain its shape feature. In comparing the experimental results, it was found that the main factors affecting drag reduction in a fracture are the relative molecular weight and the added concentration. Unlike the flow rule of the drag reducer in a pipeline, when the concentration is greater than 0.10%, a negative DR effect begins to appear. The influence of molecular weight is related to the flow stage; the increasing of molecular weight causes a reduction in DR effect when the flow rate is 0.24 m/s. However, the flow rate exceeds 0.5 m/s; drag reducers with higher molecular weight demonstrate better drag reduction performance. The drag reduction mechanism analysis in fractures was obtained from visualization observations, and the flow characteristics of fluid were characterized by using tracking particles. Drag reduction effect occurs mainly on the surface of the fractures in contrast to near the centre of the flow channel. This research can provide a reference for the experimental study on drag reduction in fractures and is of great significance to the optimization and improvement of drag reducing agent.

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“…Fracturing fluid is one of the most important components of hydraulic stimulation and plays a key role in creating complex conductive fracture networks for gas to flow into the wellbore (Barati and Liang, 2014). Furthermore, in order to achieve an economically reasonable and continuous gas flow, some chemical additives are added to the fracturing fluid (Aminto and Olson, 2012;Song et al, 2015;Xu et al, 2016). Slick water hydraulic fracturing is the common form of well stimulation in shale reservoirs, which can create fractures with smaller widths and greater lengths, thereby increasing the complexity of the creature fracture (Palisch et al, 2010).…”

Section: Introductionmentioning

confidence: 99%

Experimental investigation of the effects of different types of fracturing fluids on the pore structure characteristics of Shale Reservoir Rocks

Sun

Wang

et al. 2019

Energy Exploration & Exploitation

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The chemical and physical capabilities of shale can be altered by the interactions between fracturing fluid and shale formation, affecting the long-term reservoir productivity. To obtain information regarding how fracturing fluids with different components impact the pore structure, porosity and mineral compositions of shale reservoir rocks over time, two different types of commercial fracturing fluids (slick water and crosslinked gel) were used to react with the shales from Longmaxi Formation of Lower Silurian in the Sichuan Basin of South China. Experiments were conducted with various time intervals (1, 4 and 10 days) in a reactor at 50 MPa and 100°C, and then analytical methods including X-ray diffraction, low pressure nitrogen adsorption, field emission scanning electron microscopy and porosity measurement were used to examine the changes of mineralogical compositions, pore structure and porosity. The results demonstrated that the mineral compositions of shale samples were significantly changed after treatment with two different fracturing fluids for 4 days. The analysis of field emission scanning electron microscopy revealed that the carbonate minerals were dissolved and developed many dissolution pores after slick water treatment, while the crosslinked gel mainly caused the precipitation of carbonate minerals. After exposure to different fracturing fluids, the total pore volume and specific surface area decreased over time. Moreover, the fractal dimensions (D1 and D2) of shale showed an apparent decrease trend after treatment with two different fracturing fluids, indicating that the pore surface and structure become smooth and regular. The porosity of shale significantly decreased by 15.9% and 17.8%, respectively, after 10 days of slick water and crosslinked gel treatment. These results indicated that the injection of the two different types of fracturing fluids may negatively impact the shale gas production through reducing the nanopore structure and porosity of shale reservoir rocks.

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Effect of polymer on gas flow behavior in microfractures of unconventional gas reservoirs

Cited by 13 publications

References 28 publications

Performance Evaluation of the Multifunctional Variable-Viscosity Slick Water for Fracturing in Unconventional Reservoirs

Performance Evaluation of the Multifunctional Variable-Viscosity Slick Water for Fracturing in Unconventional Reservoirs

Drag Reduction Mechanism of Viscoelastic Slick-Water Fracturing Fluid in Tortuous and Rough Fractures

Experimental investigation of the effects of different types of fracturing fluids on the pore structure characteristics of Shale Reservoir Rocks

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