Drilling Optimization Using Model-Based Design and Stratigraphic Zonation: Successful Application in Brazilian Deep Water Pre-Salt Carbonate Reservoir

Abstract

After findings were made in the pre-salt province that represented a major discovery for the oil industry, drilling activity in Brazil has been focused primarily on economically viable ways to develop these reserves. The pre-salt cluster is a geological formation that consists of organic microbial carbonates and other sediments. The reservoir poses innumerous drilling challenges, including hard silicate nodules and low-porosity layers, which make the formation strength extremely high. Also, the heterogeneity level of such carbonates (within centimeters) imposes extra challenges, especially on drilling shock & vibration, with low rates-of-penetration (ROP), raising pre-salt well construction costs. To offer a technical solution, the service provider applied an innovative approach based on two pillars: a model-based design approach, leading to two drill bit designs with improved cutting structure resistance, with dynamic stability, delivering the entire section in one bit run with higher ROP. Along with the technology, a new workflow called "stratigraphic zonation for drilling" was implemented. This paper reviews the work covering this new stratigraphic zonation workflow, the development of this virtual drilling scenario and some field results with lessons learned and way forward.

Research on the Influence of Deep-Water Drilling Risers on Drillstring Motion Trajectory and Vibration Characteristics

“…Deep-water drilling risers will have a significant impact on drillstring vibration [1,2], which is a crucial factor affecting drilling efficiency. The high levels of shock and vibration experienced during deep water drilling in Brazil [3][4][5] and Mexico [6][7][8] have severely affected the rate of penetration (ROP). Moreover, the presence of complex-coupled vibrations such as stick-slip and whirling phenomena poses great challenges to deep water drilling operations.…”

Análise dos desafios e soluções para aprimorar o desempenho operacional de poços de exploração no pré-Sal brasileiro.

“…In order to achieve rapid drilling in deep and hard formations, the concept of particle impact drilling was put forward and the results proved that particle impact drilling technology can save drilling cost and drilling time, and increase drilling speed by about 2 to 4 times Fang et al (2022). In the exploratory campaign of a pre-salt field called Buzios, Aguiar et al (2019) offered a technical solution to the challenges of pre-salt drilling, the service provider applied an innovative approach based on two pillars: a model-based design approach, leading to two drill bit designs with improved cutting structure resistance, with dynamic stability, delivering the entire section in one bit run with higher ROP. The operator's objective in the exploratory campaign to develop the Bu ´zios field in the Santos basin offshore Brazil, was to minimise drilling costs through elimination of unplanned trips.…”

“…According to Aguiar et al (2019), drilling activity in Brazil has been primarily focused on finding economically viable ways to develop the pre-salt reserves after a major oil discovery was made in the pre-salt province. The Brazilian National Petroleum Agency (ANP) has stated that exploratory activity in Brazil reached an all-time low in 2018, as there had been a halt in bidding rounds from 2008 to 2017, which was broken by an exceptional round in 2013.…”