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Santa Ynez Unit's long reach for new oil
June 1, 2007
An ExxonMobil well off the coast of Southern California recently set a world record for long-reach drilling from an existing offshore platform. Using a kit of new tools and lessons learned from recent work off Russia's Sakhalin Island, engineers are stretching not only wells, but also the value of one of the company's most productive U.S. ventures.
When geologists and reservoir engineers talk about drilling, it sounds like a drive in the country.
"We came out from under the Heritage platform, went down 2,000 feet, made a big left turn to the northwest and headed out flat," says Chuck Tautfest, geoscience supervisor for ExxonMobil's Santa Ynez Unit (SYU).
"From there, we drove through the shallower sections of the reservoir, through some shales and sands that were above our target formation. When we got over the target, we turned the nose down and came into the reservoir at 27 degrees. At that point, we were headed almost straight down."
The well that Tautfest describes bottoms out more than five miles northwest of the Heritage platform, at the relatively shallow depth of 7,663 feet. The entire long-reach wellbore measures 33,435 feet, or 6.3 miles (10.25 kilometers), a new world record from an offshore platform. It also marks a new stage in the development of SYU.
A long time coming
More than a century ago, drillers near Santa Barbara noticed that wells closer to the beach produced more oil. By 1900, more than 20 companies were producing oil from rows of wooden derricks on 14 production piers that stretched hundreds of yards out from shore.
The wooden piers are long gone, but many companies now have offshore platforms on the Pacific Ocean's Outer Continental Shelf. ExxonMobil operates three of them: Hondo, Harmony and Heritage. They are part of the Santa Ynez Unit, which includes onshore production facilities in Las Flores Canyon, about 20 miles up the coast from Santa Barbara. Operations began at SYU with oil and gas from the Hondo platform in 1981.
Last year alone, the facility produced more than 16 million barrels of oil and nearly 25 billion cubic feet of gas — all of which remained in-state for Californians' use. In short, SYU is helping to meet domestic demand -- domestically.
"After more than 25 years, SYU is still one of ExxonMobil's most productive company-operated ventures in the
United States," says Randy Cleveland, U.S. production manager. "By adopting new technology, the SYU team has maintained operational integrity and healthy production levels."
In fact, SYU has been recognized for its operational excellence. Just last year, the unit's Heritage platform received the Minerals Management Service (MMS) Safety Award for Excellence.
"That was a tremendous honor," says Jon Gibbs, SYU operations superintendent. "The MMS is the agency that governs our offshore operations, and to be presented with its highest award recognizes that we have a daily commitment to safe and environmentally responsible operations."
A prize just out of reach
The Hondo, Harmony and Heritage platforms were installed in that order between 1981 and 1993. From positions five to nine miles offshore, they produce oil and gas primarily from the Hondo and Pescado fields.
Geologists and engineers have known since the 1970s that there was also oil in the smaller Sacate reservoir, but not enough to justify its own platform. As a compromise, a handful of wells from the Heritage platform were completed into the far eastern end of Sacate in the late 1990s. Until now, however, the estimated 20 million barrels of oil in western Sacate remained out of reach.
In 2005, the SYU technical staff decided to attempt reaching the western Sacate field using some new extended-reach drilling tools and techniques that were already proving successful for Exxon Neftegas Limited, the ExxonMobil subsidiary on Russia's Sakhalin Island. Although the Sakhalin wells are drilled from land, the target zone is fairly shallow and from five to seven miles offshore.
Beefing up the rig
Land-based drilling rigs are often larger and more powerful than the ones installed on offshore production platforms, and that is the case on Sakhalin. To equal Sakhalin's capability, SYU engineers needed a kit of new tools.
"We made substantial upgrades to the drilling rig on Heritage," recalls Jon Gean, U.S. field drilling manager. "The biggest part of that investment was replacing the top drive, which is the motorized assembly in the derrick that rotates and handles pipe during the drilling process. The top drive we have now is the same size as what is being used on Sakhalin."
The well itself had to be designed with drill pipe that could handle the increased twisting force of the rig. Drillers also needed more electricity to run the powerful top drive, but there was no easy fix for that.
"For environmental reasons, we limit the amount of combustion equipment, such as power generators, that we use offshore," says Greg Manuel, SYU's senior offshore field superintendent. "Almost everything on our platforms is electric. To get the additional power needed to run the new top drive, we plugged into 93,000 feet of subsea extension cord that connects all three offshore platforms to the generators at Las Flores Canyon."
Down the road
The new long-reach well was completed in February into the prospect known as Spanish Bay. The well is now flowing, and the reservoir performance is being evaluated.
"Our new drilling capability may allow us to reach significant reserves on the western side of the acreage, which was not possible before," Tautfest says. "Future wells could be substantially longer than this one. We are also looking at additional opportunities to use the same type of equipment to reach new offshore reservoirs with land-based rigs."
The advantages of drilling offshore wells from land are clear. You save the cost of an offshore platform, and there is less of a footprint on the environment.
"We do impressive things all the time with technology," Tautfest adds, "and we do it safely and efficiently. Plus, we're able to quickly share these lessons around the globe, then apply them to increase the value of the company to the shareholder. It makes me proud to be on the team."
