苏丹6区西部Sufyan区块失返性漏失复合堵漏技术

苏丹6区西部Sufyan区块NW-1井二开发生失返性漏失，堵漏浆、水泥浆堵漏无效，液柱有效压力降低导致井塌卡钻，最后填井侧钻。三开钻进过程中又发生失返性漏失，采用常规堵漏浆、水泥浆以及投掷石子和橡胶皮等堵漏方法30次，均未成功，后决定采用反相凝胶堵漏技术进行堵漏，一次性堵漏成功，安全钻进至设计井深。反相凝胶堵漏技术在NW-1井的成功应用，为今后在苏丹6区西部Sufyan区块顺利施工提供了有效经验和技术支持，具有重要意义。 

Compound Lost Circulation Control Technology for Lost Return in the Sufyan Sub-Block in the West of the 6th Block in Sudan

Well NW-1 is located in the Sufyan sub-block in the west of the 6th block in Sudan. Lost return has been encountered in the 2nd interval of the well, and LCM slurries and cement slurries have been used to stop mud losses, but all failed. Borehole wall collapse resulted from mud losses led to sidetrack of the well. In the 3rd interval, lost return happened again. Conventional lost circulation materials, cement slurries, stone particles and rubber fragment, which had been tried 30 times in total, failed to stop the mud losses. The mud losses were finally successfully controlled with a reversed-phase gel LCM in one try, and the well was drilled to the designed depth. The use of reversed-phase LCM successfully in controlling mud losses on the well NW-1 is of great importance and has provided good experience and technical support for the operation in Sufyan sub-block of the 6th block in Sudan.