Identifying Wettability Preference of Dolomite Rock Based on Pore/ Grain Contact Angle Using the SEM-BSE Technique

Abstract An accurate technique was used to evaluate the wettability preference of Dolomite fresh core plugs from a native Kuwaiti tight carbonate reservoir. The evaluation was based on the classification of the rock wettability through the measurements of contact angles at pore area and pore/ grain-wall boundary system by 2D technology digitally captured images of available fresh cores using Scattered Electron Microscope (SEM) with Backscattered Electron (BSE) detector segmentations. The generated data were used to estimate the wettability distribution through the investigation of information at three different magnifications of X40 (mm), X400 (μm), and X4000 (nm), where big data statistical wettability contact angles at the pore/ grain boundary distinct morphological features were closely examined. The pore counting method and big data were used to count all pores and pore/ grain wettability contact angle (θ°) measurements. The 2D contact angle classifications were set equally, spanned between 0° to 360° degrees over ten clusters, and the group class average was technically calculated. The Al-Bazzaz classification has been relied upon to evaluate the wettability of the dolomite reservoir rocks and to provide suggestions for optimal oil recovery methods. The degree of wettability preference of the dolomite reservoir rocks has been thoroughly examined, and a detailed evaluation of the rock's preference for wettability in each contact angle cluster has been performed. The results show that the overall pore/ grain-wall wettability preference is 78.85% towards general water wet, and the remaining wettability preference tends toward 21.15% for general oil wet. With its 78.85% preference towards general water wet, this dolomite rock system is an excellent candidate for secondary water displacement developments, offering significant practical implications for petroleum engineering and geology.