Micro residual oil description based on high-precision micro nano CT technology

Abstract

In the process of oil and gas field exploitation, high-precision micro nano CT is a highly sophisticated technology widely used to study the occurrence and distribution characteristics of micro residual oil. In order to study the producing degree of micro residual oil by different EOR methods, the micro residual oil is finely described according to the CT scanning results of core pores and internal fluids. The results show that the X-ray emitted by micro nano CT can effectively overcome the image information confusion caused by information overlap in traditional X-ray imaging. Double ray source, high test precision, resolution up to 500nm;Under the condition of not destroying the sample state, scanning from small sample to large sample can be realized, and three-dimensional digitization can intuitively describe the pore structure of the sample, so as to realize micro nano rock imaging; Micro/nano CT scanning technology can be combined with core dynamic displacement experiment unit to quantitatively characterize the micro residual oil saturation after different displacement methods;After polymer flooding, binary composite flooding and heterogeneous composite flooding, the micro remaining oil saturation is 22.3%, 18.4% and 12.0% respectively;After image processing of CT scanning data, the results of solid, oil and water three-phase two-dimensional segmentation can be obtained. According to the two-dimensional data of the core, the pore structure of the core at different layers and the microscopic remaining oil can be reconstructed in three-dimensional space to obtain the visual distribution map of oil, water and rock in three-dimensional space;After chemical flooding, the remaining oil saturation in different pore diameters has decreased, but polymer flooding and binary composite flooding have μ The degree of producing remaining oil in the pores below m is low, and the heterogeneous oil displacement system can be further used less than 5 $\mu$ M residual oil in pores. It is of great guiding significance to reasonably adjust the development mode by elaborately describing the micro residual oil distribution after different displacement modes.