Point of View: Harsh environments, emerging technologies, organizational capacity to shape future of drilling

The petroleum industry must develop oil and gas reserves where it finds them. Exploration and development drilling have moved to harsher environments and deeper waters, and developing reservoirs that are deep below the mudline creates severe operational and well design challenges.

"The deepwater operating environment is pushing current drilling technology to the limit. This is happening in several dimensions," said Michael L. Payne, senior advisor in BP PLC's upstream technology group, in a recent interview discussing technologies and issues shaping the industry.

He believes that meeting the challenge will not only require new technologies, but companies will have to deal with skill retention issues as worker skill sets become more complicated. Overcoming limitations in organizational capacity will present a challenge equal in magnitude to the technical one.

Deep water

Wellhead size constraints and formation pore pressure and fracture gradient trends create the challenge of getting enough casing strings into deepwater wells to reach the target depths. Payne explains that meeting the challenge requires the industry to design conventional casing strings and liners effectively, as well as apply new technologies such as probabilistic design, custom casing sizes, and expandable tubulars.

"Probabilistic or advanced optimization of tubular designs requires a more accurate understanding of pipe performance properties. It requires integration of advanced pipe inspection techniques and data acquisition into the design process," he says.

Tubular design is a field of study Payne has published extensively and feels that much of the industry is not up to date on state-of-the-art design considerations that are based on accurately quantifying material and dimensional properties of conventional tubulars and increased scrutiny of field conditions.

He points out that deepwater has its own challenges, with many of the wells now in 5,000-6,000 ft water depth approaching high pressure, high-temperature (HPHT) conditions that were previously limited to wells in areas like the North Sea.

"That combination creates serious casing design challenges for these wells. It also impacts design of the drillstrings and landing strings. Even installing these casings from the rig is challenging current equipment capacities in terms of load and slip crushing," he says.

With the industry running long and heavy casings and liners in deepwater operations, the weight may approach 1 million lb or more at the mud line, creating design problems for both the tubulars and the pipe-handling equipment.

Payne is among the engineers working to update the industry's understanding of the slip-crushing phenomenon, which until recently was based on testing and modeling that dated back to 1959.

Annuli pressure buildup is another critical design issue for deepwater wells and results from the heating, during well production, of fluids that are trapped in a casing annulus.

He explained the wellbore temperature at the mud line can change from an ambient temperature of 38-40° F., when the well is shut-in, to 275° F. during flowing conditions, depending on the specific reservoir and production rate.

The elements of deepwater well design, related to pressure and temperature, require high reliability. "Unfortunately the industry has operating experience now that when operators don't design for this thermal expansion, they risk structural failure of the entire well," he says.

New technologies

Payne says that among the most important new technologies for the drilling industry are expandable tubulars, more cost-effective rotary steerable systems, and intelligent drill pipe for high-rate bottomhole data telemetry.

Expandable tubulars are an important tool to alleviate casing string limitations, he says, and will have an impact on the industry. He adds, however, that it was an evolving technology that had to demonstrate its reliability through further testing and field use.

He explains that the industry does not currently consider expandable tubulars for use as production casing, which requires highly reliable connection seal capability for gas and liquid hydrocarbons.

Expanding the pipe by 10-15% dramatically changes the material, and having that change occur in the threaded connections has a significant mechanical impact.

The long-term integrity and reliability of the connections' seals is a critical issue for production casing, says Payne, explaining that for drilling tubulars and liners, which have been the target applications, the connection seal is not as serious an issue.

Such extended-reach drilling operations as the UK's Wytch Farm project have highlighted the need for robust and reliable rotary-steerable systems. "The project made the service companies aware that the industry couldn't drill all of the wells that were needed with the conventional bent motor approach," he says.

"Service companies have launched a number of competitive systems, but they're still very costly and have a niche in the high profile deepwater applications" he says. The next advance is for tool designers to bring down costs so that operators can apply the technology to more cost-sensitive shelf and land-drilling opportunities.

Referring to intelligent drill pipe, Payne says, "The industry is on the verge of very high data rate telemetry capability, opening a series of new capabilities for drill ing-dynamics and LWD data acquisition, directly from the drillbit and bottomhole assembly.

"Researchers have run a hardwired configuration through each joint, protecting it with a sleeve. High data-transfer rates occur through magnetic induction coupling at the tool joints but without the electrical shorting problems that have plagued other electrical drillstring initiatives," he says.

Researchers have built two or three generations of the drill pipe and have run field tests at the Gas Technology Institute's test facility in Catoosa, Okla., he says.

Skill retention, development

"The other challenges I see for the drilling industry are skill retention and personnel development. Everyone talks about changing demographics and the loss of skilled workers, but over the last 10-20 years, the industry has created a lot of different and complicated subdisciplines in drilling," says Payne.

He cites extended-reach drilling, HPHT, deepwater and subsea, multilaterals, coiled-tubing drilling, through-tubing rotary drilling, and underbalanced drilling as examples.

"Each one of these technologies has a level of sophistication that requires experienced personnel, with in-depth knowledge, to mobilize and apply the technology rapidly," he says.

He explains that the ramp-up of these sophisticated technologies has occurred at the same time that the industry has seen attrition of its experienced people, and the problem is not solving itself through college enrollment.

"The question really is, are we technology constrained or constrained by organizational capacity? I argue that we are becoming more constrained by organizational capacity. Technology is out-stripping the personnel's ability to keep up and apply it," he says.

"If you roll back the clock, these different drilling techniques didn't exist. Drilling a well was a standardized overbalanced operation, of a single wellbore, and with simple directional work.

"With no easy solutions to the demographic issues, operators have to emphasize systems and standard ways of doing things, such as operating manuals, technology transfer, and knowledge capture tools. They have to fill the gap by making people more productive and accelerating the learning curve," says Payne.

He adds that the other perspective on the shortage of experienced personnel is to bring the problems to the experts.

For example, if a company has extended-reach drilling operations in four or five areas of the world, could the company transfer the well planning issues to its ERD experts in other locations? Through networking and virtual conferencing, the company could leverage its expertise.

Industry cooperation

Operating company-service company relationships are important for the petroleum industry's success. Proliferation of sophisticated technologies and subdisciplines, along with the organizational limitations of a company staying abreast of the technologies, make cooperation imperative.

Payne feels this collaboration is particularly critical for BP to facilitate the R&D effort and to develop and implement technology as cost effectively and timely as possible. He says, "We recognize that, and BP has been working closely with the service companies for some time. It has brought us closer together than we've ever been."

Operating company relationships with the drilling contractors on the technology front are similar to those with the service companies. "We're very aggressively pursuing the best technologies for rig automation, safety systems, and rig-site practices for safe, efficient operations," Payne says.

"We want to partner with the drilling contractor and get the rig crew's focus on the safe and successful delivery of the drilling objective. By engaging these guys in the well design you see, in return, a lot of proactive response on their part. They point out things that the operating company should consider to make the operation more efficient and be as safe as possible," he says.

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