普光飞一二段欠压地层应用绒囊钻井液的可行性分析

Feasibility Analysis of Fuzzy-ball Drilling Fluid Applied in Underpressured Strata of the 1st and 2nd Members of Feixianguan Formation, Puguang Gas Field

摘要:

普光气田主力产层飞一二段经十余年开采,其压力系数已降至0.60-0.70,而其上、下的飞三段和长兴组目前都为原始地层压力,压力系数在1.10～1.20之间,,形成了相对的高-低-高的压力系统。技术套管封过飞三段,如果在飞一二段欠压层使用1.03-1.05 g/cm3的常规水基低密度浆,也可能会发生严重漏失、压差卡钻、污染主体主产层等复杂情况。为了不影响普光气田飞一二段主产层的生产,在欠压段使用绒囊钻井液,并从防漏、堵漏、应用井深5115m、随钻封堵等方面进行了可行性分析,采用绒囊+随钻封堵方式钻穿该层。

Abstract:

Member 1 and 2 of Feixianguan Formation of PuGuang Gas field have been developed over twenty years, the pressure coefficient decreased to 0.60～0.70. However, the overlying Member 3 of Feixianguan formation and underlying Changxing Formation are still at virgin formation pressure, with pressure coefficients of 1.20 and 1.10 respectively. A relatively high-low-high pressure system has been established. The second intermediate casing penetrates through the Member 3 of Feixianguan formation. If conventional low-density water-based mud with a density of 1.03～1.05 g/cm³ is adopted in the underpressured intervals of the Member 1 and 2 of Feixianguan formation, severe drilling complications such as lost circulation, differential pressure sticking and formation damage to the main pay zone may still occur. To avoid adverse impacts on production from the main pay zone of the Member 1 and 2 of Feixianguan Formation of the Puguang Gas Field, it is recommended to adopt fuzzy-ball drilling fluid in underpressured intervals. A feasibility analysis was carried out covering lost circulation prevention, loss control, operational depth of 5115 m and while-drilling sealing. The formation shall be drilled through by combining fuzzy-ball fluid with while-drilling sealing technology.