Effectively　mobilizing　displacement　and　predicting　mobilization　pressure　in　a　porous-type　reservoir　filled　with　bubbles　or　blobs　require　the　knowledge　of　variation　of　contact　angles　and　capillary　pressure.　A　bubble/blob　has　two　interfaces　and　thus　has　two　contact　angles.　It　has　been　found　that　double　interfaces　cause　resistance　to　displacement,　and　the　resisting　pressure　rises　while　one　contact　angle　increasing　and　the　other　decreasing　during　mobilization.　To　quantitatively　explain　how　the　resistance　to　flow　builds　up　according　to　the　contact　angle　variations　during　mobilization,　it　is　assumed　that　(1)　contact　points　remain　unmoved;　(2)　the　volume　of　a　bubble　or　blob　maintains　constant;　(3)　once　the　interface　starts　moving　at　low　capillary　number,　the　contact　angle　remains　to　be　the　advancing　or　receding　angle;　(4)　the　viscous　effect　on　pressure　drop　can　be　ignored;　and　(5)　the　two　angles　of　two　interfaces　are　equal　to　an　equilibrium　angle　at　the　initiation　of　mobilization.　A　theoretical　model　is　developed　based　on　these　assumptions,　and　the　quantitative　relationship　of　the　two　angles　is　expressed　by　an　implicit　function.　Combining　Young-Laplace　equation,　the　capillary　pressure　induced　by　double　interfaces　is　obtained.　The　model＇s　prediction　is　in　good　agreement　with　experiments　in　studies.　The　equilibrium　angle　has　strong　influence　on　the　variation　of　the　two　angles.　When　the　equilibrium　angle　is　less　than　90　degrees,　a　relatively　greater　change　in　the　contact　angle　at　the　advancing　interface　leads　to　a　smaller　change　in　the　other　one.　Otherwise,　the　opposite　is　true.　The　changes　of　the　two　angles　are　equal　when　the　equilibrium　angle　is　90　degrees.　Moreover,　a　linear　trend　proposed　by　a　previous　investigation　is　incorporated　into　the　model,　to　predict　the　ending　of　mobilization　stage　and　to　predict　the　maximum　mobilization　pressure　on　a　given　solid　surface.