Banca de DEFESA: MAVYLA SANDREYA CORREIA TENORIO

Uma banca de DEFESA de MESTRADO foi cadastrada pelo programa.
STUDENT : MAVYLA SANDREYA CORREIA TENORIO
DATE: 26/08/2021
TIME: 09:30
LOCAL: Videoconferência (Via Google Meet)
TITLE:

Fluidodynamic analysis of a marine soil in jetting excavation employing rheological models

KEY WORDS:

Jetting excavation; Cohesive Soil; Fluid Rheology; Computational Fluid
Dynamics

PAGES: 157
BIG AREA: Engenharias
AREA: Engenharia Química
SUMMARY:

Due to the exploration of marine oil fields in ultradeep water regions, the need for

different methods of well construction has increased. The technique of laying
conductive casing by jetting is the most widely used for the well starting phase in such
conditions. In this scenario, in initial layers, where the marine soil is in contact with
seawater, this material can present itself as a fine mud, characterizing a cohesive non-
drained soil, with low shear strength and that can be considered as a material with
viscoplastic behavior. Thus, the use of fluid rheology to analyze it can be a valid option,
and it is possible to classify it as a Herschel-Bulkley fluid. One of the alternatives to
understand the behavior of the soil during jetting is the use of computational modeling
and numerical simulation, due to the accuracy of this technique and its development
cost, since the local and budgetary conditions do not always allow more complex
studies and experimental analysis. Thus, this work focused on the computational
modeling of the jetting of marine soil, based on the soil fluid dynamics approach. For
this, the computational fluid dynamics (CFD) software SIMULIA XFLOW©,
developed by Dassault Systèmes, version (2020), was used. Firstly, the present work
sought to investigate the deformation of the seabed in response to an incident vertical
jet, using seawater as the drilling fluid. The profile of the cavity formed by the jet was
quantified in terms of depth and width by tracking the position of the fluid-fluid
interface over the considered jetting time. This was possible thanks to the numerical
method of the software, the LBM (Lattice-Boltzmann Method), which is based on the
Boltzmann Transport Equation. This method provides better support for multiphase
flow simulations compared to the numerical methods used in conventional CFD
software, regarding the modeling of the fluid interface region. Next, parametric analyses
were performed seeking to understand the influence of jet velocity and drilling fluid on
ground deformation in response to the incident jet. The results demonstrated that
increasing the jet velocity provided greater depths and widths to the cavity; however,
varying the drilling fluid did not cause significant differences in the excavated cavity,
except when considering a drilling fluid of higher specific mass, whose jet deformed the
soil at greater depths than the other drilling fluids. In order to observe how the jetting of
the soil would occur while the conductive casing is being laid, a drill bit was
implemented in the analyzed model. The idealized drill bit was modeled according to
the information available in the literature and did not perform adequately for jetting,
even when varying the rotation of the drill bit and the fluid flow rate, since there was
too much soil accumulation in the annulus inside the conductor.

BANKING MEMBERS:
Externa à Instituição - BEATRIZ RAMOS BARBOZA - NENHUMA
Externo ao Programa - 1742402 - JOAO PAULO LIMA SANTOS
Presidente - 1872519 - JOSE LUIS GOMES MARINHO
Interno - 2278469 - LEONARDO MENDONCA TENORIO DE MAGALHAES OLIVEIRA