In view of the ineffective cycling issue of injected water through the high permeability zones during water flooding process in positive rhythm reservoirs,the gel dam in-depth fluid diversion technique is proposed.The technique first promoted the injection of gel by horizontal or sidetracking wells drilled in the more permeable and strongly swept zones of thick positive rhythm reservoirs.The injected water then will bypass the "gel dams" and be diverted into the upper unswept or poorly swept low permeability zones.As a result,the swept efficiency and oil recovery of the upper low permeability zones can be both increased. Gel dam placement method can be enhanced the oil recovery both in the laboratory experiments and numerical simulation technology, but the use of new drilling horizontal wells for gel dam placement accompany with certain technical and economic risks;In order to reduce risk, to explore the law of horizontal well gel dam placement, we proposed the use of the crossing straight well set to place the gel dam for Daqing Oilfield, which is consistent with the current research status.Straight and horizontal wells gel dam placement have the similar principles, but there are some differences, how to use a crossing well to place the gel dam should be further study to improve the development effectiveness. The physical modeling experiments of gel dams in a positive rhythm formation and in a point bar sand body are conducted in the 3D physical model. The results of the experiments indicated that,with one or two gel dams, the sweep volume and ultimate oil recovery were both increased greatly,and the water cut ascending velocity was decreased. Compared with the physical model with horizontal gel dam,the ultimate oil recoveries of those with gel dams decrease by 8.1,but the oil recvoery is still 7.6% higher than water flood .By vertical well "gel dam" in-depth fluid diversion technique, the difficulties in the in-depth placement of plugging agents will be solved, risk has been reduced and the swept efficiency of positive rhythm reservoir can be increased significantly.


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