水平井裸眼分层酸化管柱严重堵塞的解除方法——以华涞1井为例

水平井裸眼分段压裂改造是近几年发展起来的一项新型增产工艺措施，管柱下入作业在钻井液中进行，下完管柱后再用清水或保护液替出井内钻井液，因井下清水与钻井液混合、替出钻井液不及时、循环不彻底等原因，有可能发生钻井液固相物沉淀或井内残留物沉淀，堵塞管串内径通道，直接影响分段压裂作业的进行。位于四川盆地华蓥山构造带西部的华涞1井在悬挂封隔器以下管柱就形成了含水泥块、铁屑的致密沉淀物，在应用连续油管循环冲洗、文丘里打捞筒打捞无效后，交替采用了平底磨鞋磨铣和光油管带笔尖大排量冲砂工艺，对大斜度井段管柱内的致密砂环、砂床进行了钻磨和冲洗，成功地解除了全部油管堵塞，并由此取得了宝贵的经验：①避免管串内沉淀物堵塞的根本方法是优化水平井裸眼分段压裂作业的替浆、洗井等作业工艺；②对待油管内严重堵塞，应采用钻磨为主、冲洗为辅的处理手段；③加强水平井裸眼分段作业工艺安全分析，认真识别、削减工艺风险，细化工艺措施才能控制次生事故的发生。

Unblocking technology for staged acidizing column in horizontal open-hole wells:A case study of Well Hualai 1 in the Huayingshan Structure, Sichuan Basin

The staged fracturing technology for horizontal open hole wells is newly developed in recent years to improve the production capacity of wells. Casing running is first completed in drilling fluids, and then the drilling fluids in the well will be displaced by clean water or protection fluids. Under this situation, borehole residues or solid substances of drilling fluids will be easily deposited as blockage in the casing strings for many reasons such as the clean water mixed with drilling fluids, untimely drilling fluid displacement, poor circulation, etc., thus the staged fracturing operation will be severely influenced. In the case study of Well Hualai 1, Huayingshan, Sichuan Basin, tight deposit containing cement block and iron chippings were accumulated in the pipe string below the wall hook packer. Therefore, when the blockage was still not mitigated through repeated circulating flushing with coiled tube and application of Venturi overshot, flat bottom milling shoe and large volume blank tubing with nibs were alternately applied to grind and flush the tight sand rings and beds in the highly inclined pipe column in highly deviated laterals. Finally, blockages in all pipes were eliminated and valuable experience was obtained as follows: a. the fundamental method for avoiding pipe string blockage caused by deposits was to optimize such processes as mud displacement and well flushing during staged fracturing of horizontal open hole wells; b. severe blockage in the pipe string was treated by means of milling dominated and flushing assisted; and c. safety analysis for staged operation of horizontal open hole wells was first intensified, process risks were then carefully identified and eliminated, and process measures were scheduled in details, thus secondary accidents were controlled.