低活度高钙聚胺钻井液在准北101井的应用

Application of a Low Activity High Calcium Content Polyamine Drilling Fluid on Well Zhunbei101

针对准北区块地质构造复杂多变、存在多个破碎带且裂缝发育、容易引发严重井壁失稳问题,研制出低活度高钙聚胺钻井液体系,该体系容钙量可达3.0%,活度可调节至0.95以下,膜效率保持在0.2以上,起到了稳定泥页岩井壁的作用。在准北101井应用结果表明,从2000~4200 m开始,维持钻井液活度在0.95以下,Ca2+浓度维持在6000 mg/L以上,全井无漏失,无井壁失稳问题,二开平均井扩大率为6.96%,三开平均井扩大率为0.59%,取得了很好的井壁稳定效果。进一步优化固控设备,降低钻井液劣质固相含量,同时提高钻井液润滑性能,为准噶尔盆地北部地区油藏高效开发提供了可靠保障。

The geological structure of the Zhunbei block is complex and volatile.Coexistence of several fractured zones and fracture development in this block have frequently resulted in severe borehole wall instability.A low activity high calcium content polyamine drilling fluid was developed to deal with these problems.The drilling fluid has calcium content of 3.0%at most the activity of the drilling fluid can be adjusted to less than 0.95,and the membrane efficiency of the drilling fluid can be maintained above 0.2;all these properties are beneficial to borehole wall stabilization.Application of this drilling fluid on the well Zhunbei101 showed that,between well depth of 2000 m and 4200 m,the activity of the drilling fluid was kept at below 0.95,the Ca2+concentration was maintained at above 6000 mg/L.No mud loss and borehole wall collapse happened throughout the whole drilling operation.The average rate of hole enlargement of the second interval was 6.96%,and that of the third interval was 0.59%.The drilled cutting content of the drilling fluid was reduced by optimizing the solids control equipment.The lubricity of the drilling fluid was improved using drilling lubricant.The use of the drilling fluid has provided a reliable guarantee to the efficient development of the reservoirs in the north of Junggar Basin.