地热井暂堵型水泥基透水材料的试验研究

Research and development of cement-based temporary plugging permeable material

摘要:

地热开采过程中，考虑到水源补给，地热井一般布置在破碎带或构造带上，在钻井过程中利用水泥进行堵漏，但在钻井完毕后为提高产能必须进行解堵。而常规水泥在对地层封堵后需要恢复储层渗透性时，只能通过采取酸化解堵措施，且解堵恢复能力差。如果利用地热开发过程中的温度变化制得可降解暂堵水泥体系，简化地热资源的勘探开发过程，有利于降低钻井成本和风险。本文利用G级油井水泥、砂石、增强剂和水溶性纤维制备温敏型暂堵高透水水泥基材料。通过测试材料的抗压强度、孔隙度、密度、凝结时间，以评价其降解效果及基本性能。结果显示，水溶性纤维的加入使水泥抗压强度明显降低，而增强剂可以稍微改善这一缺陷，90 ℃水浴养护后孔隙度明显高于对照组，并且随着时间的推移，孔隙度不断提升，为水泥基暂堵透水材料成功研制奠定了基础，增强剂和纤维都会减少水泥的凝结时间，纤维降低凝结时间的效果更为明显。该材料的研制将简化地热资源的勘探开发过程，有利于降低钻井成本和风险。

Abstract:

In the process of geothermal exploitation， considering water recharge， geothermal wells are generally arranged in broken zones or structural zones， and cement is used for plugging during the drilling process； in the end， plugging must be removed after drilling is completed so as to increase productivity. With conventional cement， plugging can only be removed by acidification in case that the permeability of the reservoir needs to be restored， and the ability to remove the plugging is poor. If temperature change in the geothermal development process can be used to prepare a degradable temporary plugging cement system， the exploration and development process of geothermal resources will be simplified， which will help reduce drilling costs and risks. In this paper， G-grade oil well cement， sand and gravel， reinforcing agents and water-soluble fibers are used to prepare temperature-sensitive， temporary plugging， and highly permeable cement-based materials. The material''s compressive strength， porosity， density， and setting time were tested to evaluate its degradation effect and basic performance. The results showed that the addition of water-soluble fiber significantly reduced the compressive strength of cement， while the reinforcing agent can slightly improve this defect. The porosity after curing in a water bath at 90°C was significantly higher than the control group， and the porosity continued to increase over time， which lays the foundation for the successful development of cement-based temporary plugging and permeable materials. Reinforcing agents and fibers will reduce the setting time of cement， while the effect of fibers in reducing the setting time is more obvious. The development of this material will simplify the exploration and development process of geothermal resources and help reduce drilling costs and risks.