水平井连续油管酸化及效果评价

HORIZONTAL WELL COILED TUBING ACIDIZING AND ITS EFFECT EVALUATION

针对磨溪气田水平井段长度大、有效储层分散及非均质的特点 ,提出了水平井连续油管拖动解堵及大型空井酸化工艺技术 ,即先将连续油管下到水平段末端 ,根据水平井段储层分布规律 ,在连续油管注酸的同时按设计的速度提升连续油管 ,直到酸液覆盖整个水平储层段。采用这种方法 ,可以让每个射孔段都能接触到地面原始浓度的鲜酸 ,解决了由于水平井段长 ,部分射孔段难以接触到鲜酸的难题。此外 ,还可以将水平井段中的压井液替出井底和进行酸后液氮排液 ,提高了残酸的返排效率 ,减少了增产作业中的二次损害。大型空井酸化对连续油管酸化后的井进行彻底解堵和改造。该工艺技术在M75—H、M 38H及M 5 0井实施了水平井连续油管酸化工艺试验。 3口先导试验水平井累计增加井口产能 37.86× 10 4m3 /d ,是该地区同类直井平均产量的 4～ 7倍 ,获得了显著的增产效果和经济效益。

In view of the characteristics of Moxi gas field, as long horizontal intervals, dispersed effective reservoirs and strong hetergeneity, the horizontal well coided tubing towed plug removal and large-sized empty well acidizing technology are proposed in the paper. By way of tripping in the coiled tubing to the end of the horizontal interval firstly and according to the distribution of the reservoirs in the horizontal interval, while injecting acidizing fluid through the coiled tubing, we must elevate the tubing at a designed speed so as to cause all the reservoirs in the horizontal interval to be covered by the fresh acidizing fluid. So each perforated interval can contact with the fresh acidizing fluid with original concentration by use of such a method, thus solving the problem of partial intervals' being difficult to contact with the fresh acid because of the long horizontal interval. In addition, the well killing fluid in the horizontal interval may be displaced from the bottom hole and the pest-acidizing liquid nitrogen may be also discharged, thus raising the discharged efficiency of residual acid and reducing the secondary damage caused by well stimulation. A thorough plug removal and reformation of the well after the coiled tubing acidizing may be realized by applying the large-sized empty well acidizing technology. The technological test of the 'horizontal well coiled tubing acidizing was carried out in wells M75-H, M38H and M50 by use of such a technology. The accumulatively increasing wellhead testing productivity of the three horizontal wells was 378.6 × 103 m3/d, which is 4-7 times the average production of the straight well at the same area, thus achieving obvious stimulation effect and economic returns.