低温浅层气井环空带压封窜工艺

Technology of annular channeling plugging under pressure for low-temperature shallow gas wells

高果成 王文斌 黄伟 杨超

GAO Guocheng WANG Wenbin HUANG Wei YANG Chao

中国石油集团川庆钻探工程有限公司钻采工程技术研究院 低渗透油气田勘探开发国家工程实验室 中国石油集团川庆钻探工程有限公司试修公司 中国石油集团油田技术服务有限公司

Research Institute of Drilling and Production Engineering Technology, CNPC Chuanqing Drilling Engineering Co., Ltd., Xi’an 710018, Shaanxi, China National Engineering Laboratory for Exploration and Development of Low Permeability Oil and Gas Fields, Xi’an 710018, Shaanxi, China Maintenance Company, CNPC Chuanqing Drilling Engineering Co., Ltd., Chengdu 610000, Sichuan, China CNPC Oilfield Technical Services Co., Ltd., Xi’an 710018, Shaanxi, China

采用常规水泥基堵剂进行环空封窜易出现封堵失效、低温浅层难固化、井间窜流的问题，为此，提出了一疏二堵三封环空带压封窜技术。首先通过排液法测定气体排放量，以确定须家河组可燃气体泄漏风险等级，对接近可燃风险等级的情况采用防气窜抗固相离散水泥浆体系，对低于可燃风险等级情况则采用微膨胀低摩阻水泥浆体系挤封；然后采用可提高岩心渗吸效能的纳米前置驱替液疏通蓬莱镇组及浅层；之后挤入高强凝胶形成2 m厚气窜隔离墙暂堵层间见气通道；最后以超细晶须膨胀水泥浆稳定见气通道，并配合高强度油溶性树脂固井工作液封固窜流通道。苏码头区块3口井现场试验表明，挤封须家河组成功后，对蓬莱镇组及上部浅层挤入纳米级二氧化硅前置驱替液，蓬莱镇组地层挤入压力降低了2~3 MPa，治理后环空压力从1.6 MPa降至0，有效解决3口井环空带压问题。该技术可为同类井环空带压治理提供技术借鉴。

The use of conventional cement-based plugging agents in plugging channeling in annular space often leads to issues such as plugging failure, difficulty in solidification in low-temperature shallow layers and inter-well channeling. To address these challenges, the technique of annular space channeling plugging under pressure including the procedure of dredging, plugging and sealing was proposed. Initially, the gas emission volume was determined through a drainage method to assess the leakage risk of combustible gas in the Xujiahe formation. For situations close to the combustible risk level, a gas-tight and anti-channeling solid-phase discrete cement slurry system was employed for sealing, while for situations below the combustible risk level, a micro-expansion and low-friction cement slurry system was employed for sealing. Subsequently, a nanoscale preflush displacement fluid with enhanced core imbibition efficiency was used to dredge the Penglaizhen formation and shallow layers. Then, a high-strength gel was injected to shape a 2-meter-thick gas-proof isolation wall to temporarily block the interlayer gas channel. Finally, an ultrafine crystal whisker expanding cement slurry was employed to stabilize the gas channel, complemented by a high-strength oil-soluble resin cementing fluid to seal and solidify the channeling pathways. Field tests in three wells in the Sumatou block indicate that, after successful sealing of the Xujiahe formation, the injection of nanoscale silica dioxide preflush displacement fluid into the Penglaizhen formation and upper shallow layers reduces the injection pressure in the Penglaizhen formation by 2 MPa to 3 MPa. After treatment, the annular pressure dropped from 1.6 MPa to 0.0 MPa, effectively resolving the annular space pressure bearing issue in the three wells. This technology can serve as a technical reference for annular space treatment under pressure in similar wells.

10.13639/j.odpt.202308005