For naturally fractured low permeable limestone reservoirs, the oil displacing function by spontaneous imbibition of water is weak when the matrixrock surfaces are mixed wet or oil wetted.
裂缝发育的低渗灰岩储层，当基质岩块为混湿及油湿时，毛细渗吸驱油作用很弱。
2
It is situated in a fragile rockmatrix that has already collapsed some time in the past.
它位于一个脆弱的岩石基体上，该岩石基体曾在过去倒塌过。
3
Rock fragments including volcanics are common and the matrix consists largely of kaolin and illite.