Plugging Characteristics of Temporary Plugging Materials at Multi-Perforation Holes in Multiple Clusters Along the Wellbore: A Novel Experimental Study

Conducting perforation temporary plugging experiments and analyzing the plugging characteristics of temporary plugging materials at the perforations are of great significance for the temporary plugging and diversion fracturing in shale gas reservoirs. However, the current experimental apparatus merely contains a short horizontal wellbore with a limited number of perforation holes, without accounting for the erosive effect of proppant on the holes. This shortage makes it difficult to the actual plugging characteristics of temporary plugging materials at multiple perforation holes in multiple clusters along the horizontal wellbore. In this study, a new experimental system for temporary plugging of perforation holes is established, involving a 10-m horizontal wellbore with 6-meter cluster spacing two perforation clusters, and 6 perforation holes per cluster. The average injection rate can reach 66 L/min per perforation, replicating the high pumping rate in the real field. The shale of perforation holes are adjustable and could be either circular or teardrop shapes with equivalent diameters ranging from 12 to 16 mm. This experimental system is used to study the plugging characteristics of various temporary plugging materials at different perforation locations along the wellbore under different dosages and application strategies. The results show that: (1) perforation holes near the well toe and at the wellbore bottom are most likely to be plugged, while those near the well heel and at the wellbore top have the minimal possibility to be plugged. (2) Under the same dosage of temporary plugging balls, adding them in two batches consecutively results in higher plugging efficiency compared to a single-batch addition. (3) As the dosage of temporary plugging balls increases, the number of plugged perforation holes initially rises and then stabilizes. The optimal number of temporary plugging balls is 1.2 to 1.5 times the number of open perforations. (4) Teardrop-shaped perforation holes still allow fluid inflow after being plugged by temporary plugging balls, requiring the use of a temporary plugging agent for complete sealing. However, temporary plugging knots can fully seal teardrop-shaped perforation holes. The experimental system developed in this study closely replicates real-field conditions. The insights obtained from this study have been widely applied in the Weiyuan Shale Gas Field, Sichuan Basin, China. Taking W204H49-3 well as an example, the temporary plugging knots were applied at a dosage of 1.2–1.5 times the number of open perforations in two fractured stages with a 30–50% increase in the perforation hole opening rate.