Optimization and Evaluation of Stabilizers for Tight Water-Sensitive Conglomerate Reservoirs.

The upper Wuerhe formation in the Mahu-1 play is a tight conglomerate reservoir that has characteristics of low porosity and low permeability. During the early stage of field development, it has been noticed that horizontal wells typically have a high flowback ratio and an extremely low oil production rate during the early production, and this is likely attributed to the water-rock interaction that causes the closure of generated hydraulic fractures. In this study, a stabilizer and its dosage in a fracturing fluid are optimized, and its effect on clay antiswelling and rock stabilization is evaluated. Experimental results indicate that a mixture of a salt and an inorganic cationic polymer can effectively inhibit the water-rock reaction by minimizing the clay swelling and compressing the electric double layer on the rock surface. The antiswelling rate of montmorillonite can reach 93.56%, and that of the reservoir rock powder can reach 75.32%. Meanwhile, Brazilian splitting tests are conducted to evaluate the mechanical property change of reservoir rocks before and after being submerged in fracturing fluids with different stabilizers. Compared to 4% KCl, which is currently used in the field, the new formula can enhance the breakdown pressure by more than 10% without increasing the cost. The findings of this work provide a solution for fracturing water-sensitive reservoirs and also establish a set of laboratory methods for optimizing stabilizers as fracturing fluid additives.