Research On Microscopic Remaining Oil Distribution And Flow Characteristics Based On CT Imaging Technology

As a kind of strategic energy,oil plays a key role on the stability and development of a country.Now most of the oil fields in the eastern part of our country have entered high water production period with the characteristics of low oil production,high water cut and low recovery efficiency.How to efficiently exploit the remaining oil is one of the core aims in present study.Research on micro-residual oil distribution and flow characteristics is the key basic problem to develop remaining oil and improve ultimate recovery,which will provide theoretical guidance for residual oil exploration and recovery solution scheme.In recent years,with the rapid development of micro CT imaging technology,it has been widely used in petrophysical analysis and microscopic seepage field.It provides a new path to research microscopic remaining oil distribution because it can obtain high resolution images fast and nondestrcutively.This paper conducts multiphase fluids imaging experiments using Micro XCT-400 scanner,on the basis of which to study the pore scale residual oil distribution and flow characteristics.The main work are as followings:(1)A new type of CT core holder is designed.As a modular external component,it can be connected to CT imaging equipment and displacement device to finish the multiphase fluid distribution experiment and obtain high resolution images.(2)The obtained images are processed using nonlocal means filter and watershed segmentation algorithm so as to intuitively display the distribution states of multiphase fluids and extract pore unit for building up the network model.(3)Residual oil distribution studying mainly includs:1)Combining image information,the occurrence states of fluids under different displacement periods are concluded,and the endowment is quantitatively characterized using marking and summing algorithm;2)The influence of core microscopic parameters and wettability on remaining oil distribution is studied based on pore network model and automatic polynomial fitting method;3)Extract the single oil phase and establish the network model so as to analysis the change rule of oil’s morphology.(4)conbining unequal-diameter capillary model,the micro seepage model of water flooding remaining oil is established,and then the influence rule of pore radius,droplet size and fluid viscosity on the relative permeability curve are analyzed.This paper makes a deep analysis of the distribution characteristics and migration mechanism from pore scale based on the microscopic distribution images,providing theoretical support for efficiently developing remaining oil and improving recovery.