普光气田飞仙关组一、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 under-pressured strata of the First and Second Member of Feixianguan Formation， Puguang Gas Field

摘要:

普光气田主力产层飞仙关组一、二段经二十余年开采，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，压力系数分别为1.20、1.10，形成了相对的高?低?高的压力系统。第二层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的常规水基低密度钻井液，则可能会发生严重漏失、压差卡钻、污染主体产层等复杂情况。为了不影响飞一、二段主产层的生产，本文从防漏、堵漏、应用井深5115 m、随钻封堵等方面进行了可行性分析，建议采用绒囊钻井液+随钻封堵方式钻穿该层。

Abstract:

After more than 20 years of production， the pressure coefficient of the main pay zone （First and Second Member of Feixianguan Formation） of Puguang Gas field has been dropped to 0.60~0.70. However， the overlying Third Member of Feixianguan formation and underlying Changxing Formation are still maintaining virgin formation pressure with the pressure coefficient of 1.20 and 1.10 respectively， which forms a relatively high-low-high pressure system. The second intermediate casing penetrates through the Third Member of Feixianguan formation. If conventional low-density water-based mud with a density of 1.03~1.05 g/cm3 is adopted in the under-pressured intervals of the First and Second Member 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， in this paper， a feasibility analysis was carried out covering lost circulation prevention， plugging， operational depth of 5115 m and sealing while-drilling， it is recommended that the formation should be penetrated by combining fuzzy-ball drilling fluid with sealing while-drilling technology.