Mechanical mechanism of hydraulic sand jet oriented perforation

At present, the construction and design accuracy of hydraulic sand jet perforation is lower.To solve this problem, a practical and reliable method for hydraulic jet mechanic parameter design was searched for to study mechanic mechanisms of hydraulic jet on reservoir rock.According to the principle of conservation of energy and the impulse theorem, the energy equation for the process of hydraulic sand jet oriented perforation through casing, cement sheath and formation system was established, and the model for calculating key mechanical parameters (e.g.critical impact force, critical impact velocity and perforation time) in each stage of jet oriented perforation through casing, cement sheath and formation system were derived.And accordingly, the mechanical analysis chart of hydraulic sand jet oriented perforation was plotted.It is indicated that as for hydraulic sand jet oriented perforation through casing, cement sheath and formation, the required energy is increased significantly and correspondingly perforation time extends, but impact force and impact velocity decrease with maximum amplitude of 5.7% and 8%, respectively.It is revealed that the mechanical chart of hydraulic sand jet oriented perforation established in this paper can well reflect the process of hydraulic sand jet oriented perforation and its application result is good with perforation time error of 6.8%.It provides a new mechanical model and theoretical basis for the mechanical parameter design and optimization of hydraulic sand jet oriented perforation and the fracture initiation criterion of hydraulic fracturing.