STUDY ON PORE STRUCTURE CHARACTERISTICS OF CORAL SKELETON LIMESTONE BASED ON CT SCANS

This paper aims to explore the microscopic pore structure characteristics and qualitative and quantitative analysis of coral skeleton limestone distributed on a certain island reef. We established the three-dimensional digital models for six representative coral skeleton limestone samples through CT scans and studied the pore structure characteristics. The results show that the overall average porosity of the six rock samples is only 3.30%,which indicates a small degree of pore development. The porosity of the rock samples fluctuates greatly from layer to layer. The porosity is small,but its standard deviation is large,which reflects the heterogeneity of the rock sample. We marked and screened the pores extracted from the 3D model of the rock sample,and carried out statistical analysis of the pore volume and quantity. The data shows that although the number of macropores in coral skeleton limestone is small,the volume of macropores accounts for a large proportion. There are some super large pores. Through the ball-and-stick model analysis,it can be found that the main distribution range of coordination numbers is 0~2,indicating that the pore connectivity of coral skeleton limestone is poor. The pores are mainly independent pores and single connected pores. The pores have no connectivity in the x/y/z direction,which means that there is no potential fluid migration channel.