TAILIEUCHUNG - Penetration rate prediction for percussive drilling with rotary in very hard rock
This paper is the following part of our project to predict the penetration rate for percussive drilling with rotary in very hard rock. As results in [1] have been shown that the rate of penetration was strong influent by Brazilian tensile strength and it was exist the correlation between the rate of penetration and the rock properties. | Tạp chí Khoa học và Công nghệ 54 (1) (2016) 133-149 PENETRATION RATE PREDICTION FOR PERCUSSIVE DRILLING WITH ROTARY IN VERY HARD ROCK Nguyen Van Hung1, *, L. Gerbaud2, R. Souchal3, C. Urbanczyk4, C. Fouchard4 1 Petrovietnam University, Cach mang Thang 8 Street, Baria - Vung Tau, Vietnam 2 3 Ecole des Mines ParisTech, 60 Boulevard Saint-Michel, 75006 Paris, France Drillstar industries, Avenue Frédéric et Irène Joliot Curie, 64140 Lons, France 4 Total, Avenue Larribau, 64000 Pau, France * Email: hungnv@ Received: 11 March 2015; Accepted for publication: 30 November 2015 ABSTRACT This paper is the following part of our project to predict the penetration rate for percussive drilling with rotary in very hard rock. As results in [1] have been shown that the rate of penetration was strong influent by Brazilian tensile strength and it was exist the correlation between the rate of penetration and the rock properties. Yet, the study was valid on six hard rocks in experimental result of test tricone and rotary with percussive. All relationships have been shown but the coefficient R2 is still very low. This paper will present a new relationship with high value of R2 based on previous data and also establish a mathematical relationship, numerical model to predict the penetration rate. Key words: Hard rocks, ROP, drilling, mathematical model, numerical model. 1. INTRODUCTION TO STRESS WAVE THEORY . Longitudinal elastic waves in a rod Consider one long rod, the cross-sectional area of which is equal to A. Let the Young’s modulus and the unit weight of the material that constitute the rod be equal to E and γ (or density of the material, ρ , with ρ = γ / g ), g is the acceleration due to gravity and ν is the Poisson’s ratio. Now, let the stress along section a-a of the rod increase by σ Fig. 1. The stress increase along the section b-b can then give by σ + (∂σ / ∂x ) ∆x . Based on Newton’s second law: ∑ force = (mass)(acceleration) . Nguyen Van Hung, .
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