中海石油（中国）有限公司重点科技项目“南海西部油田上产2000万方关键技术研究”（CNOOC-KJ 135ZDXM 38 ZJ）
College of Petroleum Engineering, China University of Petroleum, Qingdao
南海A油田注气开发中,油井气油比急剧增大,气窜明显,为此开展了海水基高温冻胶封窜体系的研究。选用非离子聚丙烯酰胺和酚醛体系作为主剂和交联剂,探索增大聚合物浓度、加入除氧剂和高温稳定剂三种方式增强冻胶高温稳定性的效果。结果表明：尽管采用高浓度聚合物能够增强冻胶热稳定性,但125℃下,即使采用高浓度(0.8%)非离子聚丙烯酰胺,冻胶48h脱水率就达90%以上；除氧剂的加入也难以显著改善冻胶热稳定性；高温稳定剂可以明显增强冻胶的耐温性,是构筑海水基高温冻胶体系的关键组分。由此优化形成了海水基高温冻胶体系配方：0.4%PAM+0.3%乌洛托品+0.3%间苯二酚+0.8%稳定剂。该海水基体系125 ℃下成胶时间为10~12 h,60d内仍能维持较好冻胶状态,不破胶；弹性模量大于1500 mPa,脱水率小于10%,具有较强的封堵能力。
During development of NH-A oil field by gas injection, the gas-oil ratio measured in oil wells increases sharply, indicating the obvious gas channeling. To address this issue, a seawater-based and high temperature gel system was researched. Firstly, non-ionic polyacrylamide and phenolic system were selected as the main agent and crosslinking. Three methods were explored to enhance the high-temperature stability of the gel by increasing polymer concentration, adding deaerators to inhibit polymer degradation and adding high temperature stabilizer. Then, the crosslinking agent, high temperature stabilizer and polymer concentration optimization were carried out to form a seawater-based high temperature gel system. Finally, the natural gas tolerance and plugging ability of the system were evaluated. The results show that, although the high-concentration polymer could enhance the thermal stability of gels, the dehydration rate of single-high-concentration (0.8%) non-ionic polyacrylamide gel is a more than 90% after only 48 h. The presence of deoxidizer is also difficult to significantly enhance the thermal stability of gel. Fortunately, high-temperature stabilizer can inhibit the interaction between the calcium, magnesium ions and the polymer, thus, obviously enhance its temperature resistance, which is the key to the construction of seawater based high temperature gel system. The final gel formula formed by component-concentration optimization is: 0.4% PAM+0.3% urotropine+0.3% resorcinol+0.8% stabilizer. It can maintains excellent colloidal state under high calcium, magnesium ion concentration, high temperature of 125 ℃ and natural gas condition, with a elastic modulus greater than 1500 mPa and a dehydration rate less than 10%.