Experimental evaluation and process optimization of temporary plugging to acid-frac in fractured carbonate reservoirs

The Maokou formation is widespread in Sichuan Basin, and the characteristics of different areas is varied. The natural fractures are developed in different degrees, the formation heterogeneity is strong, and homo for which the formation can not be sufficiently stimulated by acidizing. It affects the effectiveness of reservoir stimulation. In order to advance the whole stimulation effect of heterogeneous fractured reservoir, the 3D printing is applied to manufacturing the rock plates for experiments. The temporary acidizing technology of different well completions are simulated by experiments. The temporary materials are optimized, which present the performance of high temperature tolerance and pressurization. The best concentration, size grading and plugging capacity of temporary materials are evaluated by experiments. The results show that optimization temporary materials can take up load of 15 MPa, and its degradation can reach 98% at 150 ℃, which are fit for the Maokou formation in Sichuan Basin. The number of temporary ball used for plugging perforation is 1.1-1.3 times of bullet hole numbers, the grouping of temporary fiber and 2 mm particles can successfully plug the 3 mm fracture, and the proportion of grouping is defined. The experiments of temporary acidizing enriches the technologies of non-mechanical uniform acidizing for strong heterogeneous fractured reservoir, which is helpful for improving the stimulation efficiency of gas well and provides a guide of acidizing design for working site.