Drilling technology forges ahead

By all accounts, 2010 was a better year for oil and gas than the two preceding it. While prices remained stable, technology did not stand still. Despite the lag in activity due to the financial crisis and the hyphenated activity in the Gulf of Mexico following the Deepwater Horizon incident, the industry managed to set records this year with the benefit of new technology.

Extended-reach drilling
With the advance in rotary steerable technology and improved bit design, extended reach drilling has provided greater access from a single well especially in offshore operations where fixed platforms can often limit the area to be drilled.

For many operators, one of the main challenges associated with extended reach drilling is successful running and cementing casing strings in the long lateral sections. These operations must be carried out successfully to capitalize on the extra expense of the drilling process.

There are two approaches to running casing in these ERD lateral sections; (1) fill up the casing string with drilling mud while running (this process creates high frictional forces making it difficult to reach TD), or (2) not to fill up the casing string while running (leaving the string buoyant and also making it difficult to reach TD). Both potentially require “push down” of the string.

Pride International’s latest addition to its fleet, the Deep Ocean Ascension, is an ultra-deepwater drillship,
designed for exploration and development drilling in excess of 40,000 ft (12,192 m), operating in 12,000 ft (3,658 m) water depth. (Image courtesy of Pride International Inc.)

Earlier this year, Weatherford International assisted a major operator in overcoming this challenge offshore California in the US deploying its OverDrive System featuring the TorkDrive 750HD tool.

TorkDrive is the main component of the OverDrive System; it is connected directly to the top drive system and designed to combine the functions of many conventional casing tools – main hoisting elevator, power tongs, fill-up and circulating tools, weight compensator, and bails/single joint elevators – into one remotely operated system.

“We wanted to extend the functionality of the top drive to handle casing in addition to drill pipe,” said Tracy Cummins, Global Product Line Champion, OverDrive Systems.

Also included in the TorkDrive technology is the patented “grapple” external gripping system, designed specifically for ERD applications. The grapple system pre-loads 60 metric tons of gripping force onto the casing string, allowing the entire weight of the top drive to be applied to safely push down and/or rotate the entire casing string while running. The OverDrive system was designed as a portable mechanized tubular running/ handling system with no permanent interface into the rig structure. “The challenge was to design all the functionality and features of conventional casing equipment into one tool that is safe, small, reliable, and cost competitive enough to commercialize,” Cummins said. Other design considerations included an integral electronic load cell (torque-sub) to accurately monitor torque and rpm’s during connection makeup and rotating/reaming operations.

Now three years in, the OverDrive System is proving its ability to mitigate risks associated with running casing in many ERD and Ultra ERD wells globally. The system’s design eliminates the need for the pipe stabber in the derrick and minimizes the need for rig floor personnel and manual equipment handling. A typical casing crew can be reduced by 40-50%. Not only does this reduce risk exposure for the operating company but it also reduces bed space on the rigs as well as logistics needs for personnel.

For the offshore California project, Weatherford’s OverDrive System managed to set a world and record for the longest extended-reach fixed platform well. Connections were made up using the company’s casing running system with the TorkDrive 750 HD tool. A JAMPro torque-turn monitoring system with the integral TorkSub electronic load cell recorded each connection to the specified torque and monitored torque while reaming.

Storing and handling large volumes of water used during hydraulic fracturing is a challenge for many operators. Superior Well Services Inc. assisted Cabot Oil & Gas Corp. in delivering its first frac job using 100% recycled water in the Marcellus shale. (Image courtesy of Superior Wells Services Inc.)

The OverDrive was used continuously for 83 hours with no technical problems and achieved run rates of up to 17 joints per hour. In the end, rig crews used the system to float, push negative weight, and rotate the entire casing string to a record depth of 27,255 ft (8,307 m) on the first trip. The remotely operated system eliminated the need for a stabber and the manual handling of power tongs on the rig floor. Only two of 682 casing connections were backed out during the entire operation.

The company has completed more than 1,000 commercial jobs in 26 countries using its OverDrive System. Innovative technologies will continue to enhance the growing market for extended reach drilling. “The technology is helping to push the design limits of Ultra ERD wells and shale oil and gas wells where the ability to safely push the casing while rotating and circulating is advantageous,” Cummins said.

Rotary steerables, real-time advantage
In January 2010, Baker Hughes tested the first rotary LWD system. From Statoil’s Brage platform in the Norwegian sector of the North Sea, the company drilled and logged a 3-D well profile with a liner attached directly to the drillstring. This new system was designed to withstand high circulation rates and high torque loads while providing liner connect and disconnect capabilities.

In conventional drilling operations, it is necessary to pull the drillstring before the casing or liner can be run into the borehole. Liner drilling systems eliminate the need to pull the drillstring to run casing, saving time and drilling costs by minimizing the risk of borehole collapse and reducing nonproductive time (NPT). The addition of rotary steerable capabilities helps overcome the challenges of drilling in zones with lower pressure and unstable shale/coal layers and in formations with varying flow and pressure regimes.

Because LWD uses standard drillpipe above a running tool, it can be used without any modification to the rig equipment. “Another advantage of using LWD is that you have drillstring through the blowout preventer and not thicker casing – compared to drillpipe,” said Mathias Mueller, product manager, casing and liner drilling, Baker Hughes.

Another key feature of the system is that the liner itself is decoupled through the modular positive displacement motor located inside the liner, which is free from drilling torque generated by the bottomhole assembly. The only torque affecting the liner is the torque generated by friction if the liner is rotated from surface.

Storing and handling large volumes of water used during hydraulic fracturing is a challenge for many operators. Superior Well Services Inc. assisted Cabot Oil & Gas Corp. in delivering its first frac job using 100% recycled water in the Marcellus shale. (Image courtesy of Superior Wells Services Inc.)

The Statoil pilot was technically successful. The 95?8-in. liner was drilled to total depth and cemented in place. Several key steerable drilling liner (SDL) functionalities were successfully performed such as the procedure for pulling and rerunning the inner string, reconnecting it downhole and continuing drilling.

“We are currently looking into offshore applications due to the high cost associated with NPT, but we are also looking into onshore applications where the system is cost-effective for the project,” Mueller said. The system was developed together with Statoil, which was looking at its mature fields, but Baker Hughes had wider plans for this system. This technology likely will be used in any application where risk of getting the liner/casing down is an issue, such as tar and rubble zones, marginal drilling envelopes, uncertain pressure prognosis, unstable formations, depleted formations/reservoirs, subsalt drilling, moving/swelling formations, excessive hole caving, and loss/thief/ low-pressure zones.

While the application of SDL is somewhat in its developmental stage, Mueller said, “It is important to mention that the system only involves a very few new parts, and that most of the system is based on existing proven technology from Baker Hughes product lines.”

Frac water reuse
Devising successful water management plans has become a key ingredient to operating in many of the North American shale plays. From mobile treatment units to centralized plants requiring transport of millions of gallons of flowback frac fluids, operators consistently are looking for ways to devise a better way of treating water at surface.

On its Susquehanna County, Pa., acreage Cabot Oil & Gas Corp. delivered its first frac job to use 100% frac fluid flowback. The company worked with Superior Well Services and Kroff Inc. to devise a fit-for-purpose water treatment method to process and engineer water on the rig site.

The OverDrive System was designed to combine the functions of many conventional casing tools – main hoisting casing elevator, power casing tongs, fill-up circulating tools, weight compensator, and bails/single joint elevators – into a remotely operated system. (Image courtesy of Weatherford)

Regulatory agencies, landowners, citizens concerned with environmental impact, and municipalities concerned with supplies of freshwater are drivers behind industry efforts to reuse water from which fracture fluids are prepared.

Operating companies and other well service companies have approached the problem of renewable freshwater supply by separating, filtering, and even distilling or crystallizing produced formation waters and frac fluid flowback waters to purify them for future use or surface discharge.

Reuse of the flowback fluid without processing was not considered appropriate due to the geochemical content it had picked up from the reservoir during pumping and flowback sequences. A key to this solution involved a sciencebased assessment of in-situ geochemistry and formation compatibility of the waters and levels of specific cations and anions that needed to be selectively removed.

The flowback fluid was chemically of fair quality, with moderate iron and near-neutral pH. Dissolved constituents comprised high chlorides and hardness; sulfate levels were low. Microbiological content was moderate; divalent cations were a consideration. Processing would feature application of specific mobile water-treatment processes according to specification and engineering of a fracturing fluid that can place proppant into producing intervals while preventing negative geochemical reactions. The processing strategy addressed the main concerns that any operator might have when reusing water: scale, iron deposition, suspended solids, microorganisms that could form in the proppant pack, and good pH and other water attributes needed to achieve adequate friction reduction. An in depth two-step process was used to bring the flowback water to its near-natural state.

Following the hydraulic fracturing operations using the treated water and flowback period, initial production results were obtained over a period of 30 days. Based on these results, it was observed that the well fractured using 100% reused water and associated chemical packaging produced among the best rate of wells in the same geologic setting.