Experimental evaluation method for acid injection profiles of horizontal wells during a carbonate acidizing process

Abstract In YB carbonate gas reservoirs, taking acidizing measures for horizontal wells is a common practice. In heterogeneous carbonate reservoirs, the acid injection profile of a horizontal well determines the acid distribution along the horizontal well. However, the present methods are not suitable for reservoirs with high temperatures and strong heterogeneity such as YB carbonate gas reservoirs. This work presents an experimental evaluation method for the acid injection profile of horizontal wells during the carbonate acidizing process. Based on the status of horizontal wells in YB carbonate gas reservoirs, an injection experimental apparatus with horizontal wells was designed and implemented. Experiments on the fluid injection profiles of horizontal wells with different formation types in an YB carbonate gas reservoir were performed, and the effects of the permeability combination, drawdown pressure, and wellbore pressure drop on the fluid injection profiles were studied. From the experimental results, a chart of the experimental drawdown‒permeability‒fluid injection volume was generated. By combining this chart with the creation of a permeability‒pore volume multiplier chart, an experimental evaluation method was developed to evaluate horizontal well acid injection profiles. The findings in this research provide a method for acid injection evaluation and selection of target well segments for acidizing horizontal wells in YB carbonate gas reservoirs and similar oil/gas reservoirs.