Análise do comportamento do teor de umidade residual de sólidos retidos em peneiramento vibratório

Abstract

The oil well drilling process consists of several subprocesses, including solids control, which involves the separation of the well cuttings and the drilling fluid, which is injected mainly to lubricate and cool the drill bit during drilling. This fluid must be recognized in order to be reused; therefore, several separation phases are performed. The first of these phases, the vibratory screening phase, may be the most crucial, since other isolated material separation equipment can only function effectively if this phase is performed properly. The objective of this work was to evaluate how the residual moisture of the retained solids behaves in response to the variation of the rotation applied to the vibratory motors. A solid-liquid suspension composed of water, sand and thickener (which has a density and rheology similar to a real drilling fluid) was used. A pseudorandom binary sequence (PRBS) type perturbation was applied. For this task, the vibrating motors of the screen were excited sequentially between 1,200 and 1,800 RPM and between 1,800 and 1,200 RPM. In response to the variations in RPM, the average variation in the moisture content of the retained solids ranged from 17.5% to 22%. It was possible to determine the sensitivity of the response of the residual liquid in the retained solids to the increase in the rotation of the vibrating motor, comparing the values of each parameter with the semiempirical models identified. In the five sections analyzed, the values found for the parameter K_P, which represents the process gain, the parameter τ_P, which represents the process constant time, and the parameter θ_P, which represents the process deadtime, were quite close.