摘要
酸化压裂技术是解决水热型地热系统增产增灌的有效手段,针对北京地区低孔低渗的碳酸盐岩热储层酸化压裂改造机理开展研究。以北京蓟县系雾迷山组白云岩为研究对象,在理论模型建立、室内酸盐反应实验、GCTS三轴岩石抗压强度实验的基础上,考虑表皮系数,优化了传统地热井产量计算模型,并对碳酸盐岩储层酸化压裂作用机理开展研究。研究结果表明,酸化作用会在井筒周围形成蜂窝状结构,降低储层强度,有利于压裂形成人工裂缝。改造效果与储层构造特征、矿物组成相关,天然裂缝、岩脉、矿石条带以及节理等结构弱面越发育,酸化压裂效果越好,碳酸盐岩含量越高,酸化压裂效果越好。最后针对北京某地热井建立酸化压裂增产技术方案,实现出水量增产123%以上,出水温度增温2.5℃。
Acid fracturing technology is an effective way to increase the production of hydrothermal geothermal system.It plays an important role in realizing the efficient development and utilization of geothermal resources in hydrothermal carbonate geothermal reservoirs.In most cases,these reservoirs are low permeability or ultra-low permeability reservoirs.The geothermal energy is abundant in Wumisan Fm.carbonate rocks of Jixian System in Beijing area.Aimed at this hydrothermal geothermal reservoir in Beijing,the mechanism of acid fracturing is studied in this paper.At first,a new geothermal well production model is proposed based on the traditional theoretical model.Laboratory acid-salt reaction experiment and GCTS tri-axial rock compressive strength experiment are carried out to study the mechanism of acid fracturing of carbonate reservoirs.Experimental samples have different characteristics.The purpose is to study the effect of carbonate content and rock micro-structure on acidification.The rock samples with high clay content did not change significantly before and after acid etching.Those rock samples composed of small sized minerals,with high and homogeneous carbonate content,appear to uniform acid erosion.There are large acid corrosion cracks in the rock samples that weak structural planes are developed(micro-fractures,mineral strip etc.).The effect of alteration is exceptionally obvious in such rock samples.With GCTS tri-axial rock compressive strength experiment,the Mohr-Coulomb stress circle is gotten.Then,the acid fracturing stimulation mechanism in hydrothermal carbonate geothermal reservoir is proposed:acidification enhances reservoir permeability by creating a honeycomb structure,and that will also create radial cracks for seriously reducing the rock skeleton strength.But the effects of stimulation are depending on reservoir structural features and mineral composition.The more developed the structural weakness,the better the effect of acid fracturing;the higher the carbonate content,the better the acid fracturing effect.Finally,acid fracturing technology is applied to a hydrothermal-carbonate geothermal well in Beijing.The results show that the water production increases more than 123%,and the water temperature increases as 2.5℃.The stimulation effect is very significant.
作者
林天懿
柯柏林
杨淼
刘庆
熊馨
牛升晟
黄璐
LIN Tianyi;KE Bolin;YANG Miao;LIU Qing;XIONG Xin;NIU Shengsheng;HUANG Lu(Beijing Institute of Geothermal Engineering,Beijing 102218)
出处
《城市地质》
2018年第3期21-26,共6页
Urban Geology
基金
北京市科技计划(2161100004516016)
关键词
碳酸盐岩
地热系统
酸化压裂
天然裂缝
Carbonate
Geothermal system
Acid fracturing stimulation
Natural fissure
作者简介
第一作者简介:林天懿(1984-),男,硕士,高工,主要从事地热地质及非常规油气地质研究。E-mail:35705370@qq.com;通信作者:柯柏林(1965-),男,教高,主要从事地热资源勘查评价、酸化压裂增产技术研究。E-mail:Kebailin@sina.com。
