页岩油压裂用纳米变黏滑溜水的合成及其性能评价

常规滑溜水压裂液已经成功运用于页岩等非常规油气储层压裂中，但其携砂性能差、渗吸采收率低的问题仍然未得到有效解决。针对这一问题，本文合成一种新型纳米变粘滑溜水，该体系不仅具有常规滑溜水优异的减阻特性，还兼具了较强的变粘携砂性能；另外，该体系含有优选的纳米乳液，可将混合润湿或油润湿的页岩油储层改性为水润湿，具有强渗吸置换作用。通过一系列室内实验评价可以发现：碳纳米渗吸（carbon nano imbibtion，CNI ）体系纳米变粘滑溜水为乳液状，可实时在线配制，通过调整其浓度，粘度发生显著变化，达到低浓度时高减阻、高浓度时强携砂的效果，残渣含量及对储层伤害低，实现了一剂多效；同时它还具有常规滑溜水与瓜胶携砂液所没有的改性驱油的效果，从而提高原油采收率。纳米变粘滑溜水同时具备高减阻、高携砂、低伤害和强置换的性能，可作为未来页岩油压裂的主体压裂液。

Synthesis and Performance Evaluation of Nano Variable-Viscosity Slickwater for Shale Oil Fracturing

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, this paper synthesized a new nano variable-viscosity slickwater, which not only has excellent drag reduction characteristics of conventional slickwater, but also has strong variable-viscosity sand-carrying performance; In addition, the system contains the preferred optimized nano-emulsion, which can modify the shale oil reservoir wetted by mixing or oil to be wetted by water, and has 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.