裂缝性油藏多段塞凝胶调剖技术研究及应用

Research and Application of Multi-Slug Gel Profile Control Technology in Fractured Reservoirs

为了研究多段塞调剖剂对裂缝性低渗透油藏调剖机理及效果,通过室内可视化裂缝模型,研究了多段塞调剖剂对单一裂缝封堵及对复合裂缝系统调剖物理过程,阐述了裂缝性低渗透油藏多段塞调剖机理,并在延长东部油田进行了多段塞深部调剖矿场试验。室内实验及矿场试验表明:对于单一裂缝,多段塞调剖封堵过程分为两个阶段:凝胶充填阶段和凝胶压实阶段,小段塞多轮次注入调剖剂比大段塞连续注入的后水驱压力梯度提高2倍以上;对于复合裂缝系统,多段塞调剖封堵过程则包含三个阶段:调剖剂选择性进入阶段、凝胶充填阶段和凝胶压实阶段,最终使裂缝系统吸水剖面得到最大改善。延长东部油田试验区经过多段塞深部调剖后,注水井都已正常注水,注水压力由0.25 MPa上升到8.5 MPa,注水量由2.0 m3/d上升到8.0 m3/d,油井日增油量为2.52 t,油井平均含水率由90%以上降至71.7%,多段塞深部调剖技术获得了较好的矿场试验效果,可作为裂缝性低渗透油藏增油降水措施的优选技术之一。

In order to study the mechanism and effect of multi-slug agent profile control in fractured reservoirs, the multi-slug agent flow control process of single and multiple fractures system was researched by indoor visual fracture model, and the mechanism of multi-slug agent profile control in fractured reservoirs was analyzed. The field tests of multi-slug agent profile control were conducted in Yanchang eastern oilfield. Experiments and field tests showed that the multi-slug agent profile control process in single fracture has two stages： gel filling stage and gel compaction stage, the water flooding pressure gradient after multi-cycle with small slug agent injection increases more than 2 times than that of large slug agent continuous injection; the multi-slug agent profile control processed in multiple fractures system had three stages： agent selective entrance stage, gel filling stage and gel compaction stage, eventually the profile control of fractures was improved. After multi-slug agent profile control, the injection wells of Yanchang eastern oilfield returned to normal, water injection pressure rose from 0.25 MPa to 8.5 MPa, water injection rate rose from 2.0 m3/d up to 8 m3/d, the daily oil increment was 2.52 t, the average water cut decreased from more than 90% to 71.7%. The multi-slug gel profile control technology obtained good effect in oilfield, which could be used as one of the increasing oil and decreasing water technology for fractured low permeability reservoirs.