低压、小井眼、深井砂埋射孔枪打捞技术——以PX3井为例

Fishing Technology of Sand-buried Perforating Gun in Deep Well with Low-pressure Slimhole:Taking Well PX3 as an Example

PX3井采用深井常见的Φ177.8 mm油层套管+Φ127 mm尾管悬挂的井身结构,修井面临压力系数低、井深、小井眼段(Φ127 mm尾管)有砂埋Φ89 mm射孔枪管柱的难题,类似修井成功先例少。由于射孔枪砂埋牢固,在震击器整体震击解卡无效的情况下,通过采用薄壁铣筒在不破坏射孔枪本体的情况下进行套铣解卡,使环空中板结的砂埋层松动而达到解卡目的,最大程度地减少新增碎片,避免工具管柱遇卡风险;当套铣解卡至单根射孔枪接头位置创造有利倒扣条件后,再下入打捞工具对解卡后的单根射孔枪进行倒扣打捞,如此往复直至处理完全部射孔枪,避免开展大扭矩倒扣作业所面临的扭断钻具风险。针对低压漏失井无法建立循环的情况下,通过“局部循环+大口径捞杯”的方式减少随钻捕捞作业中产生的碎片,保障井筒清洁,进一步提高套铣解卡的成功率。通过“分段套铣解卡+打捞”的思路,配合井筒清洁方面的保障,成功打捞出该井Φ127 mm尾管内全部射孔枪,突破了低压深井小井眼修井技术瓶颈,为同类修井作业提供经验和施工案例。

PX3 well adopts the common wellbore structure of deep wells,that is,"Φ177.8 mm casing+Φ127 mm liner".The workover is faced with low pressure coefficient,large well depth and sand burialΦ89 mm perforating gun string in slim hole segment(Φ127 mm liner),and there are few successful cases of similar workover operations.Because the perforating gun is firmly buried in sand,under the condition that the overall shock of jar is not effective,the thin-wall milling cylinder is used to carry out casing milling without dam⁃aging the body of the perforating gun,so as to loosen the hardened sand layer in the annulus and achieve the purpose of releasing stick⁃ing,reduce the new debris to produce to the greatest extent,and avoid the risk of tool string sticking.When the casing milling to the joint position of a single perforation gun creates favorable back-off condition,the fishing tool is lowered so as to fishing unstuck single perforating gun by back-off.This will be repeated until all the perforating guns are processed so as to avoid the risk of twisting and breaking the drilling tool by blindly increasing unscrewing torque.In the case that circulation can not be established in low-pressure lost circulation wells,the way of"local circulation+large diameter fishing Cup"is adopted to reduce the debris generated in fishing while drilling,ensure the wellbore cleaning,and further improve the success rate of casing milling.All the perforating guns in the Φ127 mm liner segment of the well were successfully fished out by means of the idea of"segmenting casing milling sticking-releasing and fishing"and the guarantee of wellbore cleaning,which breaks through the bottleneck of slim hole workover technology in low pres⁃sure deep wells,and provides experience and construction cases for similar well workover operations.