Evaluation of ceramsite loss control agent in acid fracturing of naturally fractured carbonate reservoir

Abstract

In the acid fracturing of naturally fractured carbonate reservoirs, excessive acid leak off is the main factor limiting fracture propagation and live acid penetration distance. To reduce acid leakage and enhance the stimulation effect, ceramsite loss control agents have been widely applied in acid fracturing. However, the leak off reduction behavior of ceramsite has not yet been systematically investigated. Therefore, a conventional core-flooding acidizing system with a hollowed-out Hastelloy cylinder was used to perform a series of acid leak off experiments. Experimental results show that 1. the smaller the size of the ceramsite, the better the filtration reduction effect; 2. the higher the injection rate, the greater the acid carrying capacity, which is conducive to the loss of the control agent entering the fracture and acid-etched grooves; and 3. under laboratory conditions, the optimal ceramsite dosage is 4 g. This study deepens the understanding of acid leak off in carbonate reservoirs and provides fundamental information for field acid fracturing design.

Keywords

• Acid leak off
• Loss control agent
• Ceramsite
• Core-flooding