超深层碳酸盐岩储层中地层温度较高,闭合应力较大,因此酸蚀裂缝的有效作用距离越长,其导流能力可能会相对越低。以蓬莱气区灯二储层为例,建立了碳酸盐岩酸压改造效果计算模型,结合酸岩反应实验结果,模拟计算了超深层碳酸盐岩的地层温度、闭合压力、岩石物性和弹性模量对酸压改造效果的影响规律。研究结果表明,超深层碳酸盐岩比常规深层碳酸盐岩储层的反应速率快2~3倍,有效作用距离短50%~90%,酸蚀裂缝导流能力高1个数量级；地层温度由100 ℃增至200 ℃,酸液有效作用距离降低88.51%,酸蚀裂缝导流能力增加50.4倍；超深层碳酸盐岩闭合应力由10 MPa增至200 MPa,酸液有效作用距离不变,酸蚀裂缝导流能力降低99.12%；孔隙度由1%增至10%,酸液有效作用距离降低88.1%,酸蚀裂缝导流能力提高18.16倍；弹性模量从20 GPa增至 80 GPa,酸液有效作用距离降低55.01%,酸蚀裂缝导流能力提高9.88倍；超深层碳酸盐岩中酸液有效作用距离主控因素为地层温度和闭合压力,酸蚀裂缝导流能力主控因素为岩石的孔隙度和弹性模量。研究揭示了超深层碳酸盐岩酸压改造的关键控制因素,为高温高压条件下工艺优化与增产效果提升提供了理论依据和工程借鉴。

In ultradeep carbonate reservoirs, due to the high formation temperature and large closure stress, the longer the effective distance of acid etching fractures, the lower the conductivity may be. Taking the Deng 11 Reservoir in the Penglai Gas Field as a case study, this study has developed the calculation model of acid fracturing effect of carbonate rock and the experimental results of acid rock reaction, simulated and calculated the influence of formation temperature, closure pressure, rock physical properties and elastic modulus on the acid fracturing effect of ultradeep carbonate rock. The research results show that the reaction rate of ultra-deep carbonate rocks is 2 to 3 times faster than that of conventional deep carbonate reservoirs, the effective distance is 50% to 90% shorter, and the conductivity of acid-etched fractures is one order of magnitude higher. When the formation temperature is increased from 100 ℃ to 200 ℃, the effective distance of acid solution is reduced by 88.51%, and the conductivity of acid etched fracture is increased by 50.4 times. The closure stress of ultra-deep carbonate rock increases from 10 MPa to 200 MPa, the effective distance of acid solution remains unchanged, and the conductivity of acid etched fracture decreases by 99.12%. When the porosity is increased from 1% to 10%, the effective distance of acid is reduced by 88.1%, and the conductivity of acid etched fracture is increased by 18.16 times. When the elastic modulus increases from 20 GPa to 80 GPa, the effective distance of acid solution decreases by 55.01%, and the conductivity of acid etching fracture increases by 9.88 times. The main controlling factors of acid effective distance in ultra-deep carbonate rocks are formation temperature and closure pressure, and the main controlling factors of acid-etched fracture conductivity are porosity and elastic modulus of rocks. The research reveals the key control factors for acid fracturing stimulation of ultra-deep carbonate rocks, providing theoretical basis and engineering reference for process optimization and production enhancement under high-temperature and high-pressure conditions.