Experimental Study on Temporary Plugging Diverting Acidification of Heterogeneous Sandstone Reservoirs

Abstract Matrix acidizing is the primary well stimulation method applied to increase the oil and gas production of sandstone reservoirs. However, for reservoirs with many small layers and strong heterogeneity, the permeability of the thief zone is increased because a large amount of acid is easy to enter it, and the less permeable layer that needs to be stimulated cannot be improved, which lead to the interlayer heterogeneity more serious. The method of uniform distribution acid in heterogeneous sandstone reservoirs has been rarely studied. In this paper, temporary plugging and diverting acidizing is suggested to solve the problem of uniform acid distribution in heterogeneous sandstone reservoirs. The temporarily plugged powder is trapped in the front edge of the high-permeability core to form a filter cake. The acid is forced to enter the low-permeability core to achieve uniform acidification. The results show that the dissolving rate of 50 and 100 mesh temporarily blocked powders is more than 99% under the condition of reservoir temperature and can flowback entirely to the surface without harming the reservoir. The core flooding experiment shows that a 2MPa diverting pressure was induced by 0.1% temporary plugging powder. when the permeability level difference is 50, the permeability of the low permeability core can be improved by more than 50%. It indicated that the temporary plugging powder has a strong plugging ability for high permeability core and a good stimulation effect for low permeability core. Laboratory experiments show that temporary plugging diverting acidification (TPDA) has an excellent stimulation effect on the reservoir with strong heterogeneity in the long well section, which will be an important reference for the realization of uniform acidizing.