华北地区碳酸盐岩热储层酸化压裂模拟方法与应用

Numerical study and application of acid-fracturing in the carbonate geothermal reservoirs from North China

碳酸盐岩地层是我国华北地区最重要的热储岩层之一,不同次级构造单元的碳酸盐岩地热井产量和回灌量存在较大差异,严重制约了碳酸盐岩热储的规模化开发。酸化压裂是碳酸盐岩热储增产稳产的有效手段,其涉及溶质运移、酸岩反应、渗流传热、反应放热等一系列复杂过程。本文提出了一种模拟工程尺度碳酸盐岩热储酸化压裂过程的数值方法,可考虑碳酸盐岩热储酸化压裂过程中热、水、力、化四场之间的耦合作用。通过与前人试验和模拟结果的对比,验证了该方法的正确性,并建立了碳酸盐岩热储非均质裂隙模型,对其酸化压裂效果进行了模拟。

Carbonate layer is one of the most important geothermal reservoirs in North China Region.The production and injection of carbonate geothermal wells in different secondary structural units is highly variable,seriously restricting regional development of the carbonate geothermal field.Acid-fracturing technology is efficient in increasing the yield and in maintenance of the carbonate reservoirs,which involves mass transport,acid-rock reaction,seepage and heat transfer,chemical heat release,and other complex processes.In this paper,a numerical method is proposed to simulate the acid-fracturing processes in the carbonate reservoirs taking the coupled thermal-hydraulic-mechanical-chemical interactions into consideration.The numerical method is verified by comparing with the previous experimental and numerical results.A model with heterogeneous fracture apertures in the carbonate reservoir is established to simulate the acid fracturing process and to evaluate the stimulation effect.