An emphasis on optimizing efficiencies and keeping costs down underscores the thrust of technology advances in the drilling industry.
That emphasis is growing because the industry is pressing further into the arenas of challenging environments and complex wells. And it most do so with greater care for the environment than ever before.
Industry experts interviewed for this article weighed in on some of the key technology areas where game-changing advances are occurring.
Rotary steerable systems
Rotary steerable technology helps operators but hurts drilling contractors, according to Jim Nixon, president and CEO of Varel International, Dallas.
“After being introduced commercially, drilling engineers in the Gulf of Mexico discovered that rotary steerable directional drilling could reduce the number of days drilling for a project by nearly half,” he notes. “Although rotary steerable systems cost twice as much per day, only half the days were required, so total directional costs were neutral. The big savings came in offshore contract drilling costs: cutting 20 days off a drilling project could shave $4 million off the cost of renting the offshore rig.
“However, the impact has been even greater than this. An operator who wanted to drill 24 wells in the Gulf [of Mexico] for 1 year no longer needed to employ four rigs; he needed only three. In a few short years, a Gulf of Mexico market that had required 120 drilling rigs now needed only 90 to the same amount of work. The technology is now employed around the world and is growing rapidly in land applications.”
Nixon contends that, within 5 years, sales for rotary steerable directional drilling systems, when paired with customized PDC products, will surpass conventional directional drilling sales.
Drill bits
Nixon sees a comparable sea change occurring in the design of drill bits.
In 2006, he notes, industry sales of PDC bits exceeded roller cone bits for the first time. In 2007, projections are that almost $2 billion worth of PDC bits will be sold, roughly double the forecast for roller cone bits.
“So what influenced this?” he asks: “The US land drilling market.”
Nixon explains that “technological advances in vibration reduction, balanced design, and cutter technology have allowed PDC bits to drill aggressively and reliably in hard, abrasive rocks, particularly those formations found throughout the US Lower 48. In recent years, these advances, which reduced the number of days drilling by 30-50%, have enabled the operator to control well costs during a time when rig rates doubled. So while operators utilized advances in drill bit technology and were drilling projects in fewer days, this only partially offset the increased rig costs.
Nixon contends that the major bit companies, including Varel, had a lock on the roller cone market due to the significant technological and economical barriers to entry.
“These barriers do not exist at nearly the same level in the PDC segment,” he points out. “Here the new PDC drill bit entrants, like Varel, are giving the majors a real run for their money on both product performance and service.”
Extended-reach drilling
Many technical challenges to extended-reach drilling have been overcome, with the industry’s capability now achieving access to reserves more than 6½ miles from the rig’s surface location, notes David Mannon, senior vice-president and chief operating officer for Parker Drilling Co., Houston.
“Throw ratios have increased from 2:1 to 6:1 by employing special techniques for running casing; high-torque top drives and connections; high-capacity, high-pressure mud pumps; and large drill strings,” he says. “Drilling rig, directional drilling, and completion technologies to date have focused mainly on overcoming drag forces preventing pipe from sliding, rotating friction forces increasing torque required to rotate pipe, and structural capacity for handling extended-well tubulars.
“Other bases of design for extreme-reach rigs include efficient and automated tubular handling, offline stand building, and increased power, hydraulic, and derrick requirements to reach total depth.”
HP/HT drilling
Pursuing natural gas targets in deeper pay, such as the deep Miocene play in the shallow-water Gulf of Mexico and Gulf Coast areas, calls for equipment that can withstand the extremely high temperatures and pressures at such depths.
Key challenges in this environment have been slow penetration rates in compacted formations, an unpredictable South Louisiana pore pressure profile, long liner sections, and “breathing formations” that mask influx, according to Mannon.
The design and operation of Parker Drilling’s deep barge fleet have been crucial to the success of this type of drilling program, he contends.
“Large wellbores and associated casing programs require the appropriate set-back and hookload capacity to handle, store, and run tubulars. As directional work is performed in large hole sections to take advantage of faster penetration rates and lower temperatures, the rig’s capacity for handling high-volume and large-size cuttings removal and hole cleaning plays a significant role in maintaining high penetration rates and avoiding trouble time due to hole conditions.
“Engineered rig power supply, distribution, and control enables simultaneous operation of large mud pumps, top drive, and drawworks reliably for long drilling sections. Higher flow and mud circulation also impact directional and measurement-while-drilling tools, which…have flow limitations due to electronics chassis design. Reliable pulsation dampening and clean drilling fluids impact real-time measurements critical for monitoring annular pressures, deducting circulating densities, and managing pressure while drilling through formations with varying pore pressure regimes.
“As rotary steerable directional drilling expands, reliable mud pump systems facilitate downlinking to communicate revised trajectory plans to bottomhole microprocessors. Due to the significantly higher penetrations rates with fully rotational directional systems, reliable downlinking is critical to avoid sidetracking, missed targets, or downtime spent reprogramming the tools.”
Underbalanced drilling
Significant advances have been made in the area of underbalanced drilling in recent years, due to its capacity to reduce lost circulation, increase drilling rates, and create higher productivity completions due to the minimization of formation damage, according to Mannon.
In southern Mexico, Parker Drilling drilled with seven large land rigs for 2 years in the Iride and Jujo Fields, he notes. “Previous wells drilled by the operator experienced severe fluid losses while drilling 8½-inch target sections in depleted, fractured zones. During the drilling campaign, underbalanced, controlled drilling was used to balance expected ECD [equivalent circulation density] based on offsets (refined while drilling), with minimum annular velocity to ensure maximum hole cleaning.”
Mannon says that several variables challenged the process on the Mexican wells, including well and reservoir pressure variables.
“To address these challenges, a broad range of drilling rates was used among several project wells with a combination of nitrogen to reduce the risk of wellbore losses. The right foam or two-phase mix was critical to prevent loading the well with excess nitrogen to eliminate the possibility of packing off or wellbore collapse. In addition, the introduction of nitrogen eliminated the possibility of formation damage, increasing field productivity.”
Parker Drilling has had some success with another advance in underbalanced drilling: “mudcap” drilling-also known as closed-hole circulation drilling (CHCD). Parker’s arctic barge rig 257 is currently drilling in supergiant Kashagan oil field in the North Caspian Sea, as well as the Kalamkas field appraisal well nearby.
“Previous attempts to drill to the Unit 2 formation after encountering extensive karsts in the shallower Unit 1 were unsuccessful,” he says. “The CHCD technique was used as a contingency to ensure that the bit could safely penetrate both formations.”
The CHCD technique applies when conventional circulation is no longer possible, Mannon explains: “It involves ‘blind’ drilling with the choke completely closed while using a rotating control device to seal the annulus. Mud is periodically injected into the annulus to prevent hydrocarbons and pressure from migrating to the surface. Water is continuously injected down the drill pipe while drilling.”
OCTG outlook
The more demanding drilling environments also mean greater challenges for developers and suppliers of oil country tubular goods, says Nicolas de Coignac, managing director, VAM Drilling, a division of Vallourec & Mannesmann Tubes, Paris.
He notes that added demand for new OCTG designs caused by increased activity in extended-reach and HP/HT drilling “are key for us, a tubular goods designer and supplier, as they imply an in-depth revision of the drill stem design.
“The technology of 50 years ago can’t meet the expectations [of today] in a safe and reliable way.”
He stresses the importance of underbalanced drilling as a critical technology for the future, “as it will allow us to get some additional production out of close-to-depleted reservoirs.
“There is a true challenge there, too, as safety and reliability are compulsory features. Quality of the product (tube, connection) must be at the cutting edge of technology.”
De Coignac emphasizes deepwater OCTG applications as offering the “most exciting and demanding” challenge.
“Drilling efficiency, weight of the string, technical and environmental reliability, and real-time monitoring are some of the challenges that we must be able to respond to,” he says. “For each of them, our marketing and technical support team is in very close contact with our customers’ engineering departments. This relationship is key to be able to address the new technical issues with the shortest lead times.”
Baker Hughes unit Baker Oil Tools has introduced what it considers a revolutionary solution to operators’ casing program challenges with the world’s first expandable monobore liner extension.
Baker Oil Tools Pres. Chris Beaver explains that the innovative liner extension “allows operators to drill wells that in the past may not have been commercially viable because of the typical telescoping casing design and hole size required for production. It can also allow the operator to downsize their drilling rigs but still be able to drill to the required depths with the appropriate hole size.”
Drilling wastes
The management of drilling and production wastes ranks as one of the most critical issues facing the petroleum industry today, says Don McKenzie, president and CEO of M-I Swaco, Houston.
McKenzie also contends that the continued development of environmentally acceptable water-based drilling fluids that match or correlate closely to the high-performance characteristics of invert emulsion fluids is having a “very significant impact” on the industry.
Operators benefit from the value-added performance that oil-based muds deliver, while “also removing the environmental obstacles and associated costs that limit the use of oil-based fluids in many operating theaters.”
Two other areas that McKenzie sees as having a profound impact on managing drilling waste are subsurface cuttings injection and dewatering, or closed-loop drilling, systems.
“The former provides operators a dedicated domain for the permanent storage of solid and liquid waste, thus eliminating the costs and long-term environmental liabilities associated with transporting these materials for off-location disposal,” he says. “The latter is proving to be a viable and cost-effective alternative to environmentally suspect reserve waste pits widely used throughout the western US and elsewhere.”
