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Copyright of Natural Gas Geoscience is the property of Natural Gas Geoscience and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of International Economy & Management is the property of Omniscient Pte. Ltd. and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Journal of Shaanxi University of Science & Technology is the property of Journal of Shaanxi University of Science & Technology Editorial Department and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Conventional slickwater fracturing fluid has been successfully used in the fracturing of unconventional oil and gas reservoirs such as shale, but the problems of poor sand-carrying performance and low imbibition recovery have not been effectively solved. To solve this problem, a new nano variable-viscosity slickwater was synthesized, which not only had excellent drag reduction characteristics of conventional slickwater, but also had strong variable-viscosity sand-carrying performance. In addition, the system contained the preferred optimized nano-emulsion, which can modify the shale oil reservoir wetted by mixing or oil to be wetted by water, and had the effect of strong imbibition displacement. Through a series of laboratory experimental evaluation, it can be found that the carbon nano imbibtion (CNI) system nano variable-viscosity slickwater is in the form of emulsion, which can be prepared online in real time. By adjusting its concentration, the viscosity changes significantly, reaching the effect of high drag reduction at low concentration and strong sand carrying at high concentration, and the residue content and damage to the reservoir are low, realizing multiple effects in one dose. At the same time, it has the effect of modified oil displacement that conventional slickwater and guar sand-carrying fluid do not have, to improve crude oil recovery. Nano variable-viscosity slickwater has the properties of high drag reduction, high sand carrying, low damage and strong replacement at the same time, and can be used as the main fracturing fluid for shale oil fracturing in the future. [ABSTRACT FROM AUTHOR]

As a new fracturing fluid system with good sand-carrying performance and imbibition displacement, nano variableviscosity slickwater has been successfully applied to shale oil volume fracturing in Changqing Oilfield. The field test results show that it has good sand-carrying performance and stimulation effect. Under the condition of 40 % sand ratio, the pressure of sand adding process is stable, and the daily oil production of a single well can reach 11.31 tons after fracturing construction, but its sandcarrying mechanism and imbibition performance are not clear. In this paper, the laboratory experimental study on the field concentration of nano variable-viscosity slickwater and the conventional EM30S crosslinkable slickwater system is carried out. Through the experimental methods of dynamic sand-carrying migration, transmission electron microscope (TEM), rheological property evaluation, and pressurized imbibition under the condition of reservoir temperature and pressure, the sand-carrying mechanism of nano variable-viscosity slickwater is revealed and its imbibition performance is evaluated. The experimental results show that the intersection value of elastic modulus and viscous modulus of slickwater reflects the sand-carrying capacity of slickwater solution. The smaller the intersection value is, the stronger the elastic sand-carrying capacity is; Under the same viscosity, the intersection value of viscoelastic modulus of nano variable-viscosity slickwater CNI system is only 0.0741 Hz, which is far lower than 0.181 Hz of field slickwater EM30S, resulting in its static and dynamic elastic sand-carrying performance much higher than EM30S; TEM results show that the strengthening association structure between nano emulsion and variable-viscosity slickwater is the main reason for the enhancement of elastic sand-carrying performance of slickwater. In addition, the results of pressure imbibition experiment show that the nano variable-viscosity slickwater has good imbibition displacement performance, and can replace the crude oil in the nano pores of shale, and the overall recovery can reach 36%. Among them, the order of recovery efficiency of different pore types is: mesopore > micropore > macropore. [ABSTRACT FROM AUTHOR]

Copyright of Clean Coal Technology is the property of Clean Coal Technology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Journal of Shaanxi University of Science & Technology is the property of Journal of Shaanxi University of Science & Technology Editorial Department and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Clean Coal Technology is the property of Clean Coal Technology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Clean Coal Technology is the property of Clean Coal Technology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)