Influences of target strength and confinement on the penetration depth of an oil well perforator

Oil well perforator (OWP) is a shaped charge used in the oil and gas field to connect the oil well to the reservoir. The performance of OWP is measured in terms of penetration depth into the ASTM C33-C67-concrete target simulating the underground rock according to API-RP43 section II (Quality Control target). The influences of concrete strength and its confinement pressure on the penetration depth are studied in this paper. Four experiments of OWP penetration were conducted for concrete targets with different compressive strengths. Autodyn is used to perform jetting analysis, jet formation and jet interaction (penetration) with target. It shows that the increase of concrete strength leads to large decrease of the OWP jet penetration depth. A modified Allison-Vitalli equation is proposed to include a target strength correction term. Based on Druker-Prager model, the effect of the underground confinement pressure is incorporated into the modified Allison-Vitalli equation. Numerical and empirical models show consistent agreements with experimental results. (C) 2012 Elsevier Ltd. All rights reserved.