A 1D Mechanical Earth Model (MEM) was built for the Albian section of a planned horizontal well in the south Campos Basin area in order to reduce risks for well placement, completion and stimulation in a fast track development program with reduced number of appraisal wells. Mechanical properties and stress profile along the wellbore for the design were determined from multiple data sources including core testing, advanced acoustic, wellbore image, processed petrophysics, micro-fracturing and in-situ formation pressure. These measurements enabled the definition of local correlations for the studied carbonate reservoir, estimation of geomechanical properties, and the creation of input for the completion design. The calibrated geomechanics model was used to evaluate the completion options for a horizontal well in carbonates to optimize reserves and maximize well productivity. Based on field characteristics and mechanical properties determined from this study, the horizontal well placement and drilling design was adjusted and an open hole completion with mechanical isolation was proposed to enable multiple fracturing in one continuous and efficient operation.

The exploration campaign that started with the creation of the new company, in 2007, took another step forward with the drilling and completion of it's first horizontal producing well in the Campos Basin. The Waimea accumulation was discovered in the third exploratory well drilled in December 2009 (1-OGX-3-RJS), and confirmed with formation tests. The main reservoir drilled in well 1-OGX-3-RJS contained high energy carbonates intercalated with shales, occurring in structural and stratigraphic traps limited by normal and compressive geological failures in the NE-SW direction. To ensure the commercial production of this accumulation, the development plan will require the drilling of several horizontal wells with high productivity index. This paper explains how careful planning along with well placement technologies were used to mitigate the geological uncertainties involved in drilling a horizontal well in a carbonate reservoir. The result was a successful production well at an early stage in the exploratory campaign. Some of the key design and operation aspects which contributed to the success of the well were:–The initial design objective for the Waimea Extension well was to define a directional well profile and a linked horizontal profile such that both intersected at the planned entry point of the horizontal section, this challenging approach was key to obtaining further knowledge of these highly fractured carbonate reservoirs.–The evaluation of several alternative trajectories with the seismic data and, proper petrophysical properties analysis from the pilot hole log data to maximize well bore contact with the reservoir, to achieve the highest possible net pay in 1000 meters of horizontal geosteering.–The development of a geomechanical study to review these trajectories and define mud weight windows for safe drilling with minimum fluid invasion.–The use of well placement technologies with the support of, fit for purpose, rotary steerable system with logging while drilling tools which provided vital real time formation evaluation data for geosteering. The planning and execution of the well culminated in excelent results for this first horizontal producer, with high net pay over the 1000 meters drilled and well testing confirming the well's high production potencial.