Banca de QUALIFICAÇÃO: GLAUCO SOARES BRAGA

Uma banca de QUALIFICAÇÃO de DOUTORADO foi cadastrada pelo programa.
STUDENT : GLAUCO SOARES BRAGA
DATE: 02/06/2023
TIME: 09:00
LOCAL: Labcim
TITLE:

New Acid Soluble Slurry System for Lost of Circulation in Macroporous Carbonate Reservoirs

KEY WORDS:

Soluble cement, Lost of Circulation plug, lost of circulation

PAGES: 113
BIG AREA: Engenharias
AREA: Engenharia de Materiais e Metalúrgica
SUMMARY:

The pre-salt drilling brought gigantic challenges, among the main ones, we can highlight the circulations losses. Fluid loss to the formation is one of the most critical problems that can be encountered during oil well drilling. In well design, drilling fluids represented 5 to 10% of the total costs. Therefore, any loss of circulation increases the total cost significantly when added to the non-productive times (NPT) to contain the problem. During drilling of pre-salt carbonate reservoirs, when intruding macroporosity intervals such as vugs and natural fractures, there is a risk of severe drilling fluid loss, reaching in some cases a loss rate of more than 700 barrels/hour. In most cases, traditional combat techniques are not effective against severe circulation losses in macroporous carbonate reservoirs with vugular structures and/or natural fractures, due to the nature of the rock formation. Cement plugs are effective in combating the loss of circulation in carbonate reservoirs, but cause irreversible damage. The permanent damage caused by the cement plug changes the original permoporosity conditions of the reservoir, strongly interfering with the production of the reservoir in question. To mitigate the problems caused by the use of cement plugs, it is necessary to study and develop new alternative materials that replace the use of cement with constituents that can be reversible, in terms of damage to the formation, when applied in order to combat the loss of circulation in the reservoir. Acid soluble slurry systems formulated with W/RM ratios were studied to evaluate their potential as a buffer to combat circulation loss. From the paste systems first the consistometry study was performed at 9500 psi and 54 °C conditions, mechanical strength tests, and phase identification by x-ray diffraction of the systems cured at 9500 psi and 80 °C. Partial results indicate that the consistometry time and mechanical strength are consistent with the intended application. The cured paste systems underwent static acid attack testing in 9 and 15% HCl, showing excellent results with complete dissolution of the specimen. The effects of the saturated CO2 atmosphere on specimens for 30 and 45 days were also evaluated. The partial results indicate that the specimens suffered alterations in their microstructure, causing physical-chemical changes in the specimens. Finally, the plugging and acidification tests were performed, where the paste was injected under pressure into the pores of a carbonate rock core. This rock was previously evaluated by µtomography, in addition to the basic petrophysical properties. After injection of the paste into the core rock, the µtomography and basic petrophysical data will be collected once more. Subsequently the buffered plug will be acidified in coreflooding to evaluate the removal of damage caused by the acid soluble paste.

COMMITTEE MEMBERS:
Presidente - 1804366 - JÚLIO CÉZAR DE OLIVEIRA FREITAS
Interno - 1298936 - ANTONIO EDUARDO MARTINELLI
Externo ao Programa - 1995142 - RODRIGO CÉSAR SANTIAGO - UFRN