Based on statistic analysis of automatic-controlled oil drain device in Shuanghe exploring well, the key causes have been found out of leading to the oil drain device fault.

Reservoir engineering method is adopted to calculate recovery indexes such as the horizontal well's limited recovery factors, well drainage area, reservoir limited recoverable reserves and water cut an.

Compared with vertical wells,horizontal wells has the advantages of shortening distance between wells,extending well drainage area,increasing critical coning flux,controlling the injection fluid and improving oil displacement efficiency.