绿色自降解交联凝胶在西宁地热DR2024井堵漏中的应用

Application of green selfdegradable crosslinked gel for plugging of Geothermal Well DR2024 in Xining City

摘要:

漏失是地热资源勘探开发过程中经常遇到的问题，尤其是热储层失返性漏失问题，严重影响井筒安全和钻探效率。西宁地热DR2024井是一口地热开采井，钻进至非目标热储层714~759 m井段时发生了失返性漏失，且存在“涌漏同层”，采用含复合堵漏剂的钻井液随钻堵漏无效。试验应用绿色自降解交联凝胶堵漏3次，井口能实现返浆，取得了较好的堵漏效果，并初步验证了绿色自降解交联凝胶应用于地热储层堵漏的可行性和实用性。研制的绿色自降解交联凝胶由成胶剂、交联控制剂和交联剂等3种材料组成，配方简单，具有自动降解、环保、交联时间可控、自降解时间可调和抗水稀释性强等特点，在地热储层堵漏方面具有广阔的应用前景。本文堵漏应用经验可为从事类似地热钻探工程提供借鉴和参考。

Abstract:

The problem of lost circulation occurs frequently during geothermal well exploration and development， especially the irreversible loss of geothermal reservoir， seriousely affecting the wellbore stability and drilling efficiency. Geothermal Well DR2024 is located in Xining City， Qinghai Province， which is a geothermal producting well. When drilling to the non-target geothermal reservoir well section of 714~759m， the irreversible loss occurred， where the water gushing and lost circulation exist at the same layer. The drilling fluid while drilling containing composite plugging material fails to plug. After the green self-degradable crosslinked gel was used for 3 times for plugging， the slurry can return to the wellhead and good plugging effect was obtained. Furthermore， the application feasibility and practicability of green self-degradable crosslinked gel for geothermal reservoir plugging was preliminarily verified. The gel is composed of gelling agent， retarder and crosslinker， which has the characteristics of simple formula， self-degradation， environmental friendly， controllable gelation time， adjustable self-degradable time and strong water insulation property. It has broad application prospects in geothermal reservoir plugging. The successful experience in this paper can provide reference for similar geothermal drilling project.