石油钻采工艺2025，Vol.47Issue(3)：304-316,13.DOI:10.13639/j.odpt.202501035
考虑液态二氧化碳延迟效应的破裂压力预测方法
A method for predicting fracture initiation pressure considering time-delay effect of liquid carbon dioxide
摘要
Abstract
During liquid carbon dioxide fracturing operations,it has been discovered that the manifestation of formation fracture initiation pressure is not prominent.The delay in on-site monitoring of breakdown initiation is prone to causing excessive injection of carbon dioxide,thereby escalating the risk of tubing rupture.Based on the wellbore temperature-pressure coupling model,this study establishes a dynamic pressure ramping rate model during liquid carbon dioxide injection.The proposed model incorporates the dynamic variation of volume compressibility and systematically investigates the influence pattern of pressure ramping rate on fracture initiation pressure.The research results indicate the followings:A distinct time-delay effect in carbon dioxide fracturing was observed.According to the model calculations,when the injection rate of carbon dioxide is 4.3 m3/min,the fracture initiation pressure is 14.85%lower than that in the mini-fracturing test(hydraulic fracturing),and the breakdown initiation delay time is approximately 3.5 minutes;The injection rate was found to exert different effects on the bottom-hole temperature and pressure.As the injection rate increases,the bottom-hole temperature decreases.The bottom-hole pressure varies in a parabolic manner with the injection rate,and the critical injection rate of 1.5 m3/min is the turning point at which the bottom-hole pressure transitions from increasing to decreasing;The pressure ramping rate was observed to rise with an increase in the injection rate.Nevertheless,an excessively high injection rate leads to a reduction in the bottom-hole pressure,making it arduous for the formation to fracture.When the pumping displacement exceeds 4.3 m3/min,the frictional pressure loss increases significantly.Therefore,the optimal injection rate should be regulated within the range of 1.5-4.3 m3/min.Through this theoretical research,novel supporting theories have been provided for the rock fracture initiation pressure model of liquid carbon dioxide fracturing,which plays a supporting role in the safety assessment of carbon dioxide fracturing.关键词
液态二氧化碳压裂/破裂压力预测/延迟效应/增压速率/泵注排量/体积压缩系数Key words
liquid carbon dioxide fracturing/fracture initiation pressure prediction/time-delay effect/pressure ramping rate/pump rate/volume compressibility分类
能源科技引用本文复制引用
翟晓鹏,张学龄,白建文,余金柱,许恩剑,郑力会,陶秀娟..考虑液态二氧化碳延迟效应的破裂压力预测方法[J].石油钻采工艺,2025,47(3):304-316,13.基金项目
海洋油气高效开发全国重点实验室开放基金课题"基于注水井堵塞机理的井筒附加阻力表征模型与预测方法研究"(编号:CCL2023RCPS0168RQN) （编号:CCL2023RCPS0168RQN）
中国石油科技创新基金研究项目"排量作用下裂缝转向扩展力学机理研究"(编号:2019D-5007-0206). （编号:2019D-5007-0206）
