雄安新区深部地热储层水力喷射酸化压裂技术

Hydra-Jet Acid Fracturing Technology in Deep Geothermal Reservoirs of Xiong’an New Area

地热作为清洁低碳的可再生能源,对促进实现“双碳”目标具有重要意义.我国深部碳酸盐岩地热资源丰富,但是由于岩体基质渗透率极低,亟需采取高效的储层改造技术建立导流通道才能有效开发.水力喷射酸化压裂工艺是一种集喷砂射孔、水力封隔、酸液刻蚀、多段多簇为一体的增产改造技术,可实现定点沟通地质甜点、一趟管柱体积造缝,对碳酸盐岩热储层具有良好的适用性.首次开展了雄安新区容城地热田水力喷射酸化压裂碳酸盐岩深部地热储层现场试验,通过优化喷嘴结构、优选耐腐蚀管柱材料、针对性设计泵注程序、模拟裂缝扩展形态,研发了能够满足深部碳酸盐岩热储的水力喷射酸压工具和配套工艺,采用“交替泵注交联段塞-胶凝酸”的方式,进一步促进酸液刻蚀远端裂缝,充分沟通天然缝洞,促进水力裂缝与天然裂缝沟通、相交、融汇,从而达到扩大造缝总体积、提高裂缝导流能力的储层高效改造目的.本次现场酸压试验入井总液量为492.65 m^(3),其中压裂液为396.76 m^(3),胶凝酸为95.89 m^(3).试验结果表明:酸压后较酸压前单位涌水量从0.024 m^(3)/(h·m)提高到0.288 m^(3)/(h·m),增产12倍,井口水温增加了10℃,增产效果明显;水力喷射酸压工具耐高温、耐高压、耐磨损、耐腐蚀,节约成本,降低作业风险.研究成果可为深部地热储层增产改造提供技术借鉴与思路.

Geothermal energy,as a clean and low-carbon renewable energy,plays an important role in contributing to the carbon peaking and carbon neutrality goals.Deep carbonate geothermal resources are abundant in China.However,because of high temperature,high pressure,and low permeability,an efficient reservoir stimulation method needs to be adopted,and conductive fractures need to be established to develop such resources.Hydra-jet acid fracturing technology is a kind of stimulation technology integrating abrasive jet perforation,hydraulic isolation,acid etching,and multi-stage and multi-cluster stimulation.Hydra-jet acid fracturing technology can realize fixed-point communications to geological sweet spots and volume fracturing in one trip,which has good applicability to carbonate geothermal reservoirs.In this study,the field test of hydra-jet acid fracturing in the Rongcheng geothermal field of Xiong’an New Area was conducted for the first time.By optimizing the nozzle structure,selecting the corrosionresistant string materials,designing the pumping program,and simulating the fracture propagation patterns,the hydra-jet acid fracturing tools and operations that can meet the needs of deep carbonate geothermal reservoirs have been developed.The“alternating pumping cross-linked slug and gelling acid”method is adopted to further promote acid etching of distal fractures,fully communicate with natural fractures/vugs,and improve the connectivity between hydraulic and natural fractures,thus increasing the stimulated reservoir volume and enhancing the fracture conductivity,so that efficient reservoir stimulation can be achieved.In this on-site acid fracturing test,the total amount of fluid pumping into the well is 492.65 m^(3),of which the fracturing fluid is 396.76 m^(3),and the gelling acid is 95.89 m^(3).The field application results indicate that the unit water inflow increases from 0.024 m^(3)/(h·m)to 0.288 m^(3)/(h·m)after acid stimulation,approximately 12 times,and the temperature of water at the wellhead increases to 10℃.The production enhancement is remarkable.Moreover,the hydra-jet acid fracturing tools developed by the authors are resistant to high temperature,high pressure,wear,and acid corrosion.The research results are expected to provide technical references and thoughts for deep geothermal reservoir stimulation.