Banca de QUALIFICAÇÃO: STÉPHANIE CAVALCANTE DE MORAIS

Uma banca de QUALIFICAÇÃO de DOUTORADO foi cadastrada pelo programa.
STUDENT : STÉPHANIE CAVALCANTE DE MORAIS
DATE: 09/12/2019
TIME: 10:00
LOCAL: LAPET
TITLE:

Evaluation of polyelectrolyte complexes based on cationic polyacylamide and poly (4-styrene sulfonic acid-co-maleic acid) in the delivery of polyphosphates for oil wellbore scale control

KEY WORDS:

Scale; Calcium carbonate; Sodium hexametaphosphate; Polyelectrolyte complexes; Cationic polyacrylamide; Poly (4-styrene sulfonic acid- co maleic acid).

PAGES: 72
BIG AREA: Ciências Exatas e da Terra
AREA: Química
SUBÁREA: Química Orgânica
SPECIALTY: Polímeros e Colóides
SUMMARY:

Calcium carbonate (CaCO₃) scale is a problem in many departments in the industry, and its formation reaction is strongly pH-depending. The research proposed in this work is to study the inhibition efficiency of calcium carbonate scale by sodium hexametaphosphate (SHMP), as a function of pH and SHMP concentration, under drastic conditions of temperature, scale ions concentration and pressure. SHMP is a polyphosphate that has six phosphate groups in its structure capable of interacting with calcium and preventing CaCO₃ formation. To prevent and/or retard scale formation, the inhibitor is injected into the wellbore by a scale inhibitor squeeze treatment and this inhibitor will be produced by protecting all wellbore locations and surface equipment. The treatment efficiency is mainly based on the interaction between the inhibitor and the rock formation, allowing its gradual release into the brine produced over an extended period. Since nanoparticles formed by polyelectrolytic complexes are promising nanocarriers for release of active molecules and the use of inhibitors to scale control is limited by their short residence time at the absorption site, it is proposed to develop nanoparticles based on the polyelectrolytic complex of cationic polyacrylamide (CPAM) and poly (4-styrene sulfonic acid-co-maleic acid) (PSSMA) for SHMP encapsulation in order to improve its inhibition efficiency. This document will present the results achieved so far (34th month of doctorate) and future activities in the proposed research. The relationship between pH and CaCO₃ formation was evaluated by static tests, dynamic tube blocking and scanning electron microscopy (SEM) images. At pH 6.5, excellent results were found with complete inhibition of CaCO₃ deposition in the capillary with only 2.5 mg L^-1 SHMP and a deformed structure of CaCO₃ crystals by SEM images was observed. However, at pH 7.5 and above, SHMP showed a significant decrease in scale inhibition efficiency even at high concentrations. These results were attributed to the precipitation kinetics of CaCO₃ under the drastic conditions evaluated. Regarding the polyelectrolytic complexes, stable complexes were formed using the 10: 1 CPAM: SHMP ratio and the PSSMA ratio ranging from 2 to 10, with particle size around 60/70 nm and zeta potential between + 25 and 28 mV.

BANKING MEMBERS:
Presidente - 1149440 - ROSANGELA DE CARVALHO BALABAN
Interno - 1859346 - MIGUEL ANGELO FONSECA DE SOUZA
Externa ao Programa - 1755267 - MARIA CAROLINA BURGOS COSTA DO NASCIMENTO