Visualization of adaptive polymer flow and displacement in medium-permeable 3D core-on-a-chip  

作　　者：Yan Zhang Xue-Zhi Zhao Pei-Hui Han Li-Yuan Zhang David A.Weitz Yu-Jun Feng 

机构地区：[1]Polymer Research Institute,State Key Laboratory of Polymer Materials Engineering,Sichuan University,Chengdu,610065,Sichuan,PR China [2]EOR Laboratory,Exploration&Development Research Institute,Daqing Oilfield Limited Company,PetroChina,Daqing,163712,Heilongjiang,PR China [3]School of Engineering and Applied Sciences,Harvard University,Cambridge,02138,United States [4]School of Petroleum Engineering,China University of Petroleum,Qingdao,266580,Shandong,PR China

出　　处：《Petroleum Science》2023年第2期1018-1029,共12页石油科学（英文版）

基　　金：financially supported by the National Natural Science Foundation of China(grant number U1762218).

摘　　要：Polymer flooding has been witnessed an effective technology for enhancing oil recovery from medium-to low-permeability reservoirs;however, direct visualization of polymer solution flow in such reservoir condition is still lacking. In this work, a three-dimensional (3D) core-on-a-chip device with a permeability of around 200 mD was prepared and employed to visualize the pore-scale flow and displacement of a self-adaptive polymer (SAP, 8.7 × 106 g·mol−1)−whose microscopic association structure and macroscopic viscosity can reversibly change in response to shear action−versus partially hydrolyzed polyacrylamide (HPAM), by recording their flow curves, monitoring dynamic transportation process via particle imaging velocimetry, and building 3D structure of remaining oil. The results show that, in single-phase flow, all polymer solutions exhibit flow thinning and then thickening regions as flow rate increases, but the transition between two regimes occurs at a small Weissenberg number (10−3−10−1) in this medium-permeable condition. In contrast to HPAM-1 with close weight-average molecular weight (Mw), the adaptive character not only extends SAP's shear-govern region, allowing SAP to propagate piece by piece and achieve higher accessible pore volume, but it also enhances the elastic resistibility of polymer in the extension-dominated regime, increasing the microscopic displacement efficiency. These two effects result in 1.5–3 times more oil recovery factor for SAP than for HPAM-1. Regarding ultra-high-Mw HPAM-2 (25 × 106 g·mol−1), plugging and chain degradation do occur, thus producing lower oil recovery than SAP. This work provides a direct approach for in-situ assessment of polymer-based displacing system under a more authentic condition of practical reservoirs.

关 键 词：Polymer flooding Medium-permeable transparent media Adaptive polymer In-situ rheology Particle imaging velocimetry 

分 类 号：TE357.6[石油与天然气工程—油气田开发工程]