超深-特深层碳酸盐岩储层酸压关键技术进展OA

Acid fracturing is a critical technology for reserve control and production enhancement in ultra-and extra-deep carbonate reservoirs.However,its application under extreme engineering and geological conditions such as high temperature,high stress,and strong heterogeneity,faces severe challenges.After analyzing the challenges of acid fracturing in ultra-and extra-deep carbonate rocks,this paper systematically reviews research progress across five core elements:fracture initiation and propagation,conductivity construction,acid systems,downhole staged tools,and wellhead equipment,and then identifies current technical bottlenecks and future research directions.The following results are obtained.First,the coupled effects of ultra-high temperature and pressure,multi-scale media,and foreign fluid disturbance make it difficult to accurately predict fracture pressure and initiation location and to determine the reservoir applicability of depressurization and initiation-point control techniques.Second,the rock samples and stress states applied in the current true triaxial physical simulation experiments fail to reproduce the ultra-and extra-deep environments,and numerical simulation methods can hardly achieve the dual objectives of predicting fracture morphology under the influence of multi-scale fractures and vugs while controlling fracture height for water layer avoidance.Third,full-length fracture acid-etching experiments at 210℃preliminarily reveal an evolution pattern of acid-etched morphology along the fracture length,i.e.,"rough-channel-uniform,"with a conductivity difference of up to 5 D·cm between the fracture heel and tip under high closure stress.Fourth,under ultra-high temperature conditions,the retardation,corrosion-inhibition and other properties of acid systems are mutually constrained,accompanied by pronounced issues of acid aging and additive failure.Additionally,the adaptability of downhole staged tools at ultra-high temperature and pressure and large wellbore-enlargement ratio remains poorly understood.In conclusion,to ensure efficient acid-fracturing stimulation of ultra-deep and extra-deep carbonate reservoirs,there is an urgent need to develop ultra-high-temperature/pressure-resistant physical simulation apparatus and testing methods for acid fracturing,establish cross-scale numerical simulation theories for ultra-high-temperature multi-field-coupled fracture propagation,prepare new ultra-high-temperature-resistant acid systems,promote material innovation and intelligent development of staged tools,and form intelligent three-dimensional acid fracturing technologies based on fine reservoir characterization.