Predicting the Rate of Penetration in Percussive Drilling by Finite Elements Simulation
Tutkimustuotos: Konferenssiesitys, posteri tai abstrakti ›
|Tila||Julkaistu - 2018|
|Tapahtuma||13th Middle East Geosciences Conference and Exhibition - Bahrain Intenational Exhibition Center, Manama, Bahrain|
Kesto: 5 maaliskuuta 2018 → 8 maaliskuuta 2018
|Conference||13th Middle East Geosciences Conference and Exhibition|
|Ajanjakso||5/03/18 → 8/03/18|
understanding of these fracture mechanisms is crucial. In the present work, a finite elements based numerical code is employed in an attempt to predict the rate of penetration during percussive drilling with a typical multiple-button bit. In this method, the rock is described as a viscoplastic damaging material and the bit-rock interaction is modelled by contact mechanics approach while solving the system equations with explicit time marching. The stress states leading to material damage are indicated by a rate-dependent three-surface yield surface consisting of the Drucker-Prager criterion, Rankine criterion as a tensile cut-off, and a parabolic cap surface as a compression cut-off. Thus, porous rocks can also be modelled. Due to the high asymmetry of the rock behavior in tension and compression, separate scalar damage variables are defined to account for failure in tension and compression. Thereby, the material removal is indicated by critical values of these damage variables. A criterion to predict the ROP based on single impact is first developed. Then, multiple impacts while rotating the bit between the impacts (indexing) are simulated in order to demonstrate the validity of the single impact ROP prediction scheme.