By Murat Aksoy
For years, the industry has applied discrete drilling technologies and depending on enhancements of these to improve performance. While this has produced notable technical advancements, the logical next step is to fully integrate the well construction process by adopting a holistic, consistent, and collaborative approach to managing the entire drilling system.
The wellbore environment, where drilling takes place, is harsh, requiring technological sophistication and efficient operational execution to deliver success. Every well and reservoir comprises a unique set of conditions, which is one of the reasons the industry has created separate drilling components with optimal performance that can be combined to address the specific needs of each well.
To improve drilling performance, Schlumberger has integrated the entire drilling system—the bottomhole assembly, drilling fluid, drillstring, and surface equipment—with a drilling workflow that uses data from all drilling system technologies.
One of the key objectives of the drilling performance workflow is increasing overall drilling efficiency, which is a function of the rate of penetration (ROP) and the overall time actually spent drilling. This is particularly critical in for the economic recovery of hydrocarbons in the offshore environment.
Drilling performance, including improvements in the rate of penetration, is being enhanced by new developments in drillbit cutters that operate in three dimensions. For example, the new AxeBlade ridged diamond element bit employs a unique geometry that cuts formation in a new way—a combination of shearing and crushing. This cutting method has demonstrated up to 29 percent improvement in rate of penetration compared with similar bit designs using conventional cutters, resulting in significant rig time and cost savings for operators.
Another key to improving drilling performance is a closer collaboration between the operators and service companies to enable the alignment of business objectives and more efficient technology deployment. Gaining a clear understanding of the operator’s goals for a well helps optimize the multidisciplinary team’s insight into the target area and facilitate well construction planning, focusing on key workflows and drilling strategies.
This is particularly true when drilling in a deepwater location. Minimizing drilling time without compromising drilling objectives and health, safety and the environment is a priority for the companies involved in the deepwater operations. Here, the collaborative approach can significantly improve understanding of geological requirements and drilling risks, leading to improved efficiency, increased reliability and delivery of bigger savings to all parties.
These can be achieved when both the operator and the service company work together, side-by-side on identifying common well objectives and comprehensive drilling strategies including the selection of the most suitable technologies for the project.
For example, a close collaboration between Petrobras and Schlumberger helped decrease rig time and improve efficiency during a deepwater hole-enlargement-while-drilling program offshore Brazil. One of the risks in deepwater drilling is a formation of a long, narrow hole space, known as a rathole, between the drill bit and the underreamer has the potential to complicate cementing and other drilling operations.
Rathole-caused problems often necessitate a dedicated cleanout, or hole-opening, which can be a costly procedure.
To avoid adding extra time to the drilling operation, Schlumberger worked with Petrobras to use the Rhino RHE dual-reamer elimination system to enlarge the borehole while drilling and eliminate the rathole without requiring a separate trip. By using the Rhino RHE system, the operator reduced operational time by 21 percent saved approximately $1.4 million.
It has become more evident than ever that the integration of drilling technologies into the total drilling systems combined with the collaborative model of engagement are set to provide a step change in drilling performance that addresses the long-term production challenges the oil and gas industry faces.
Murat Aksoy is president of Bits and Drilling Tools at Schlumberger.