超深超高温裂缝性气藏固井水泥浆技术

Cementing slurry technology for ultra-deep and ultra-high temperature fractured gas reservoir

顺南井区属于裂缝性气藏,漏失风险大,且水泥石在超高温条件下易发生强度衰退,导致气层固井质量无法满足后续施工要求,为此,开展了抗高温防漏水泥浆固井技术研究。通过探究硅粉加量对水泥石强度的影响,得到水泥石强度衰退预防的方法;利用水泥浆静态堵漏仪,评价纤维体系的堵漏能力,形成防漏水泥浆技术;综合水泥石强度衰退预防及漏失控制方法,优选关键外加剂,形成气藏固井用抗高温防气窜水泥浆体系。实验结果表明:井温大于180℃时,硅粉含量大于50%水泥石强度不易衰退;封堵1 mm裂缝和2 mm孔分别需加0.6%的6 mm纤维、1%的8 mm纤维。新型水泥浆体系具有较好的防气窜性能,且在顺南井区得到了成功应用。该抗高温防漏水泥浆固井技术对顺南井区具有一定的适应性,可为该区块勘探和开发提供技术保障。

In Shunnan well block,it is a fractured gas reservoir with great leakage risk and the set cement tends to suffer strength degradation under ultra high temperature.And consequently,the cementing quality in gas layers cannot satisfy the needs of subsequent construction.In this regard,the cementing technology of reinforced leakage control slurry was researched in this paper.Firstly,the method to prevent the degradation of slurry strength was developed by investigating the effect of fine silica dosage on the set cement strength.Then,the plugging capacity of fiber system was evaluated by using the slurry static plugging device,and the leakage control slurry technology was formed.Finally,by means of the slurry strength degradation prevention and leakage control method,the key additives were optimized and thus the high-temperature reinforced gas channeling prevention slurry system used for the well cementing in gas reservoirs was worked out.The experimental results show that when the well temperature is higher than 180 ℃,the strength of the set cement with fine silica content higher than 50% doesn’t degrade easily.To plug 1 mm fractures and 2 mm fractures,it is necessary to add 6 mm 0.6% fibers and 8 mm 1% fibers,respectively.The new slurry system has better capacity of gas channeling prevention,and its application in Shunnan well block is successful.This cementing technology of high-temperature reinforced leakage control slurry is applicable in Shunnan well block and provides the technical guarantee for the exploration and development of this block.