Paper: OPTIMAL CONFIGURATIONS OF MULTIPLE TUNNELS FOR ACID STIMULATION USING COILED TUBING

The recent growth in applications of a new carbonate stimulation technique, which involves the construction of numerous tunnels or short laterals out of a main wellbore by using coiled tubing, has yielded excellent production improvements. A simplified mathematical model to analyze this acid stimulation process is presented in this paper. From the perspective of reservoir properties, this simulation takes into account the reservoir heterogeneity, drainage size, permeability, fluid characteristics, porosity and skin factor. From a tunnel construction perspective, the simulation considers the influence of acid jetting angle, tunnel geometry, tunnel numbers, and eccentricity in different pay zones on well productivity. Meanwhile, from an acidizing viewpoint, the simulation considers effects of acid concentration for tunnel initiation and extension, rock solubility, and acid spending. These capabilities guide job design and reservoir performance analysis in field operations. As an example, a comparative study of different tunnel configurations for optimizing production is provided.