Controlling factors of remaining oil distribution after water flooding and enhanced oil recovery methods for fracture-cavity carbonate reservoirs in Tahe Oilfield

ZHENG Songqing,YANG Min,KANG Zhijiang,LIU Zhongchun,LONG Xibin,LIU Kunyan,LI Xiaobo,ZHANG Shiliang

Table 1 Factors controlling remaining oil distribution in fracture-cavity reservoirs after water flooding.

Category No. Controlling factors Subcategory No. Reservoir type Spatial configuration of reservoir and production well Ⅰ Local high point a Monadnock Located at (or deviating from) the highest point of FCB b Irregular shape FCB Located at (or deviating from) the highest point of FCB c Regular shape FCB Deviating from the highest point of FCB Ⅱ Insufficient well control a FCB segmented by tight matrix Located at the main FCB b FCB segmented by fillings Located at the main FCB c FCB segmented by fractures Located at the main FCB d Blind ends of branch channel in underground river system Located at the main (large branch) channel e Multiple FCBs with small reserves and no bottom water Located at (or deviating from) the highest point of the main FCB Ⅲ Flow channel shielding a FCBs at the upper, lower or lateral part of the connecting channel Located at the connected channel b Poorly connected channel Located at the better connected channel Ⅳ Local low permeability and weak hydrodynamics a Isolated FCB and filled part of underground river FCB Located at the unfilled part of FCB b Fracture-vug FCB Located at the cave reservoir