A multidisciplinary engineering approach enabled the construction of a landmark extended-reach well in Brazil, delivering what the companies involved believe to be the longest high-angle openhole section ever drilled in Latin America and the highest extended-reach drilling (ERD)-ratio ever recorded in the country.
The operation required advanced survey methodology, precise reservoir navigation, gyro measurements-while-drilling, and real-time engineering support. The result was an optimization of well placement within the reservoir to improve field management, providing a repeatable model for future long-reach wells with shallow total vertical depth (TVD), high-displacement environments.
Introduction
The oil and gas industry is searching for higher efficiencies in hydrocarbon recovery and reductions in operating costs. This scenario is especially critical in mature fields, which currently represent about 70% of producing assets worldwide and have accumulated more than 25 years of activity.
Managing such fields depends on precise well placement within the reservoir. To mitigate lateral and vertical deviations, advanced geosteering techniques have been applied, combining magnetic and gyroscopic sensors with deep resistivity technologies. This integration reduces uncertainties in absolute and relative well position, improves the match between acquired data and the actual structure, and strengthens confidence in reservoir mapping-while-drilling (RMWD).
The well presented in this case study was drilled in the Polvo Field, located in block BMC-8, in the southern portion of the Campos Basin, a petroleum province consolidated since the 1970s, with cumulative production exceeding 14 billion BOE.
The area operates in a water depth of approximately 100 m and has had a fixed platform since 2007, producing from Albian carbonates of the Quissamã and sandstones of the Carapebus Formation, under depletion, aquifer influx, and injection projects.
Even after 4 decades of activity, the region remains relevant in the Brazilian market, accounting for about 20% of national production and presenting significant remaining volume. Under the current operator, Brazil’s PRIO, the field has undergone continuous revitalization campaigns, including drilling, recompletions, and the tieback integration with Tubarão Martelo in 2021. These efforts have extended the field’s economic life and reinforce the strategies used for mature-field development.
ERD continues to evolve as operators push the limits of field accessibility, operational efficiency, and enhanced reservoir contact. This well represents a major advancement.
It was a technically demanding project that was executed at shallow TVD depth but with extreme measured depth and lateral displacement. The operation required balancing torque and drag, directional complexity, reservoir uncertainty, and rig limitations, conditions that typically constrain well design in the region.
The engineering strategy aimed to expand reservoir contact and overcome structural and geomechanical limitations typical of long-reach operations. The project resulted in 5,362 m of high‑angle openhole, establishing a new operational record in Latin America.
The well also reached an ERD ratio of 4.37, the highest documented in the country. This demonstrates the feasibility of executing long sections under shallow TVD and mechanical capacity constraints.
Challenges and Applied Solutions
The project execution involved a series of technical challenges that had a direct impact on planning, decision-making, and risk management. The service provider believes these factors support the well being one of the most complex ERD operations the industry has accomplished.
Sidetrack Under Collision Risk. Executing the sidetrack after cutting and recovering the 9⅝-in. casing within a window of about 80 m required strict directional control to preserve the separation factor relative to the remaining section. The kickoff point had to consider the mechanical conditions of the cut casing and the dogleg limitation to enable the long-reach trajectory.
Integrated pre-job planning became an important element of the solution to the above challenges. This involved the drilling, directional, completion, fluids, well placement, and reservoir teams working together to define a number of parameters. This included the sidetrack cement plug, anticollision envelopes, bottomhole assembly (BHA), drill bit, and the hydraulic/directional strategy.
The project execution used a rotary steerable system (RSS) to minimize initial tortuosity, real-time monitoring of separation factor based on position-uncertainty calculations using solid-state gyro-while-drilling (GWD) surveys as the official reference, and a cross-check with statistical and qualitative comparison between gyroscopic and magnetic surveys in real time for maximum quality assurance, ensuring compliance with the anticollision envelope.
Longest High-Angle Openhole. The next challenge involved drilling 5,362 m of openhole at inclinations up to 83°, which raised risks of friction, cuttings transport, instability, and micro doglegs. It would also have a direct impact on the future casing run.
To overcome these issues, the fluid program prioritized effective viscosity at low shear rates, a thin filter cake, and chemical stability.
Hole cleaning combined flow rate and rotation windows to reactivate annular flow in marginal zones. The BHA was optimized to reduce micro doglegs, and the use of RSS kept a smooth trajectory, mitigating torque and drag and facilitating the 9⅝-in. run.
Highest ERD Index. The ERD index increased torque and drag, directional uncertainty, and rig operational limits, and required fine equivalent circulating density (ECD) management during transients.
To solve for this particular challenge, torque-and-drag modeling considered friction factors by lithology and contact type. The model was also calibrated with surface data.
The operational strategy respected topdrive, hookload, and drawwork limits during connections, reaming, and hydraulic transitions. Hydraulics were adjusted via flow rate and nozzle sizing to reduce pressure variations, keeping ECD within the safe window.
GeoSteering in a Narrow Reservoir. The thin productive windows of the reservoir required high‑precision geosteering to prevent exits from the reservoir and preserve borehole quality under high geometric sensitivity.
SLB’s RMWD tool, GeoSphere HD, was used to enable vertical position adjustments for relative placement in the main reservoir target, also mapping oil/water contact. This provides a better understanding of the field when deciding new well locations.
Additionally, the geosteering team integrated absolute well-position uncertainty by analyzing the uncertainty ellipses calculated from magnetic and gyroscopic surveys in the subsurface visualization software. This enabled engineers to make decisions that simultaneously considered absolute and field‑relative positioning, besides optimizing correlation with adjacent wells.
Positional Uncertainty in Large Displacement. Lateral displacement increased the position uncertainty, which required mitigation to meet geological targets and anticollision envelopes.
The approach to manage this displacement involved using a proprietary GWD system in the 12¼-in. section as the official survey.
Quality assurance compared measurements from distinct and independent sensors, magnetic versus gyroscopic, in the same section through various tests:
- Relative instrument performance, which assesses systematic and random components via normalized angular differences.
- Chi-square test with analysis in the highside, lateral, and along-hole coordinates to verify conformity between overlap surveys.
- Comparison of the uncertainty ellipses derived from both surveys at the same depth.
Shallow TVD and High Measured Depth. The combination of a TVD of 1,570 m with a horizontal displacement of 6,845 m intensified drag, hindered ECD control, and reduced hydraulic efficiency. This also resulted in surge and swab risks during drillpipe tripping.
A pumping strategy ensured adequate annular velocity to avoid cuttings buildup, and density was adjusted to balance drag and overbalance. Hydraulic transients were monitored to mitigate pressure spikes, and fluid chemistry was maintained to reinforce borehole stability and filter cake integrity.
Running Casing Through 5,362 m of Openhole. Running the 9⅝-in. casing in high angle and long reach was one of the critical points of the project.
To be successful, preconditioning combined reaming while drilling, selective cleaning trips, and optimized centralization. The casing run adopted continuous monitoring of torque and hookload, and density adjustments to reduce drag. Operational “go/no-go” criteria (i.e., checks of annular pressure, sticking trend, rotation capability) guided real-time decisions.
Borehole Geometric Quality and Tortuosity.
The tortuosity and micro doglegs in an ERD section are known to impair torque and drag, hole cleaning, and a safe casing run.
Borehole quality using a technology called PowerDrive Orbit delivered the directional performance required to maintain a low-tortuosity, smooth wellbore, essential for casing installation and minimizing torque and drag. This was particularly important given the shallow TVD and long displacement.
Operational Orchestration and Response to Performance Deviations. The project’s integrated complexity required standardized execution, early detection of deviations, and continuous alignment among disciplines.
Proprietary software was used to enable real-time operational monitoring, continuous optimization, and rapid response to deviations. Remote support connected the multidisciplinary engineering and subsurface team and data across all digital platforms, elevating technical consistency, risk management, and the quality of operational interventions throughout drilling.
Conclusions
The integration of drilling technologies, well geosteering, integrated digital software, uncertainty control, and real-time operational support enabled the construction of 5,362 m of high-inclination openhole, surpassing the previous Latin American record and demonstrating the feasibility of extended sections even under shallow TVD and restrictive hydraulic regime.
The well reached an ERD ratio of 4.37, setting a new national milestone for horizontal displacement and confirming the ability to execute complex trajectories with precise control of torque, drag, and mechanical stability throughout the section.
The placement strategy, grounded in real-time solid-state GWD measurements, reduced positional uncertainty by 87.51%, with quality-assurance approval through cross-checks between magnetic and gyroscopic surveys. This reduction expanded safety margins in anticollision envelopes, mitigated directional drift, and enabled more aggressive, yet controlled, adjustments in building and maintaining the directional profile during drilling of the horizontal section. The use of real-time gyroscopic data also minimized drift during trips and reinforced the geometric consistency required for navigation in narrow productive windows.
Advanced reservoir mapping and characterization through deep-investigation resistivity inversion technology improved the ability to identify formation limits at greater depths of investigation, as well as inner reservoir layers, enabling immediate vertical-position corrections and enhancing reservoir entry. The integration between RMWD and directional position uncertainty ensured more robust geosteering, reducing ambiguous interpretations and improving well placement within the most productive zones.
The borehole geometric quality obtained with an advanced RSS resulted in a low-tortuosity well, a determining condition for the successful run of the 9⅝-in. casing through the entire openhole interval. The smoothed trajectory reduced torque and drag, ensuring that the casing was installed within the planned operational limits, one of the critical factors for the safe completion of large-displacement wells with reduced TVD.
Finally, the real-time support provided by the service provider’s real time, cloud based drilling performance and optimization platform enabled continuous operational monitoring, early identification of deviations, and immediate optimization. This integration reinforced technical consistency across all stages, resulting in execution with greater risk control and high operational quality, consolidating the project as a regional reference in ERD.
Vanderlei Chicanha, SPE, is a senior drilling engineer for SLB in Brazil, bringing more than 19 years of experience in deepwater offshore and onshore drilling operations. His career spans projects across Brazil, Angola, Tanzania, Norway, Gabon, Namibia, and South Africa. As a project lead in well engineering, Chicanha has been involved in drilling system optimization initiatives focused on improving operational efficiency and overall performance. He holds a national diploma in mechanical engineering from the Cape Peninsula University of Technology in South Africa and is an active SPE member and volunteer.
Lucas Isaac Vieira Oliveira is a petroleum exploration and production engineer with experience in wellbore-position quality assurance and directional data analysis using gyroscopic and magnetic measurements. He works as a technical consultant for SLB, providing technical support to operations and contributing to the improvement of job design and data quality practices. He holds a MS from Estadual do Norte Fluminense University, focusing on mathematical modeling of definitive survey methodology to reduce positional uncertainty.
Tiago Laureano dos Santos, SPE, is a well engineer for PRIO with experience in onshore and offshore projects within Brazil’s oil and gas industry. Specialized in well planning, engineering, and execution, he has extensive expertise in trajectory design, bottomhole assembly design, hydraulic simulations, torque and drag analysis, and anti-collision studies. Throughout his career, he has worked for leading companies in the sector, managing complex and multidisciplinary operations, including strategic presalt projects in Brazil. His professional performance is marked by a strong focus on operational safety, technical efficiency, and performance optimization in drilling and completion operations. He holds a degree in oil and gas engineering Universidade Estácio de Sá, along with a postgraduate specialization in well engineering from The Brazilian Institute for Continuing Education (INBEC), and actively contributes to the technical community as a volunteer for the SPE.