酸压技术提高深部碳酸盐岩地热井出水量的应用

Application of acid fracturing technology to improve water yield of deep carbonate geothermal wells

为实现“碳达峰”目标,能源的绿色低碳发展是关键。地热能作为五大非碳基能源之一,对实现“双碳”目标具有重要意义。我国水热型地热资源非常丰富,碳酸盐岩热储是水热型地热资源开发的主战场。目前,我国初步形成地热能产业,雄安新区是我国中东部地热资源开发利用条件最好的地区,碳酸盐岩热储层是雄安新区主要的地热开发利用层位。通过盐酸和碳酸盐岩主要成分方解石CaCO_(3)和白云石CaMg(CO_(3))_(2)的化学反应原理,对4份地热井的岩石样品分别用15%和20%浓度的盐酸进行了溶解反应,比较得出了15%浓度的盐酸更经济有效。通过渗流能力实验测试酸溶解裂缝的渗流能力,确定最佳酸液加量为2~8 PV,验证了酸溶解有助于提高裂缝渗流能力。通过酸压技术在雄安新区的应用,验证了现场实施多级酸压增产效果明显。最后得出两个结论:一是利用酸液溶解作用提高深部碳酸盐岩地热井出水量的方法可行;二是多级酸压技术适用于深井,提高地热井的出水量,具有很好的推广价值。

To achieve the“carbon peak”goal,green and low-carbon energy development is the key.As one of the five non-carbon-based energy sources,geothermal energy is significant to achieving the dual carbon goal.Hydrothermal geothermal resources are very abundant in China,and carbonate rock thermal reservoirs are the main battlefield for the development of hydrothermal geothermal resources.At present,the geothermal energy industry has initially formed in China.Xiong’an New Area is the area with the best conditions for the development and utilization of geothermal resources in the central and eastern parts of China,and the carbonate thermal reservoir is the main geothermal development and utilization layer in Xiong’an New Area.Based on the principle of chemical reaction between hydrochloric acid and the main components of carbonate rock,calcite CaCO_(3)and dolomite CaMg(CO_(3))_(2),four rock samples from geothermal wells were dissolved with 15%and 20%hydrochloric acid,respectively.The comparison showed that 15%hydrochloric acid was more economical and effective.The percolation capacity of acid dissolution fractures was tested through percolation capacity experiments,and the optimal amount of acid solution was determined to be 2-8 PV.It was verified that acid dissolution helps improve fracture percolation capacity.Through the on-site testing of acid fracturing technology in the Xiong’an New Area,it has been verified that the on-site implementation of multi-stage acid fracturing has a significant effect on increasing production.Finally,conclusions are drawn.The method of using acid solution dissolution to increase the water yield of deep carbonate geothermal wells is feasible,and the multi-stage acid fracturing technology is suitable for deep wells and can increase the water output of geothermal wells,which has good promotion value.