Influence of Typical Core Minerals on Tight Oil Recovery during CO2 Flooding Using the Nuclear Magnetic Resonance Technique

Abstract

CO2 flooding is widely recognized as an efficient way of developing tight reservoirs. Multiple types of minerals in tight rocks may interact with introduced CO2, resulting in more complex mechanisms of tight reserve recovery from tight reservoirs. It is necessary to reveal the impact of core minerals on tight oil recovery, which is critical in understanding the fundamental mechanisms of CO2 flooding for enhanced tight reserve recovery. In this work, 18 tight core samples, retrieved from the Changqing oilfield, are characterized to obtain their mineral compositions. Three typical core samples are then selected to conduct CO2 flooding and investigate how the minerals contained in these tight cores affect the tight oil recovery during CO2 flooding using the nuclear magnetic resonance technique. On the basis of the characterization results, Changqing tight cores mainly contain three typical minerals, i.e., illite, montmorillonite, and quartz. With regard to illite-dominated cores, CO2 is not efficient in extr...