Fracturing deep, tight rock wells pays with enhanced recovery

El Paso Production translated its techniques for deep well fracing from prolific onshore wells to its prospects offshore. "We set out to be the deep tight rock kings of the world, and it's worked out extremely well for us," El Paso Production President Rod Erskine said.

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By Jennifer Pallanich Hull
News Editor

El Paso Production translated its techniques for deep well fracing from prolific onshore wells to its prospects offshore. "We set out to be the deep tight rock kings of the world, and it's worked out extremely well for us," El Paso Production President Rod Erskine said.

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From left, the Gilbert Rowe, South Timbalier Block 204B Platform, and the B auxiliary platform were required to meet the production needs of the field. On the right, the Main Pass I is drilling another well.
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To earn that title, El Paso began massive hydraulic fracturing of deep wells, pouring an average of 2 million lb of bauxite down each hole to drive up output at its deep onshore wells in south Texas. This technique enabled each well to yield output several-fold over what the well would otherwise have produced. It only makes sense that when large Gulf of Mexico fields became harder to find, El Paso began to tailor its onshore strategy to meet offshore needs. El Paso still concentrates on target zones below 17,000 ft. "We're trying to take that technology offshore," Erskine said.

Fracing offshore

The Houston-based company began fracturing deep wells offshore as early as 1999. After four dry runs, a well at Vermilion Block 47 was treated with a million pounds of bauxite. The first two dry runs resulted in a loss of the wellbore, requiring redrilling. The total project cost $37.5 million, and the well was a non-commercial producer.

"It was a technical success, but an economic failure," Erskine said.

The prince of the five deep prospects El Paso has drilled since then is South Timbalier Block 204, which the company found with in-house seismic reprocessing. El Paso spent three years acquiring rights to the lease in the deep Pleistocene/Miocene trend. El Paso holds 70%, and ChevronTexaco holds 30%. El Paso was so certain of the field's commerciality that the company set the jacket before spudding the discovery well in October 2000.

"It wasn't a big gamble," he said, adding the well came onstream in only 90 days because the jacket was already in place. The El Paso-operated South Timbalier Block 204 consists of six wells, five of which are onstream. Production from the field in 140 ft water depth was higher than expected, so El Paso set a second jacket, constructed a bridge to connect the pair, and drilled the rest of the wells. Of the five onstream wells, South Timbalier Block 204 No. B-6 is the ace producer with an output, constricted by pipelines, of 118 MMcf/d and 8,163 b/d of condensate. Completed on Dec. 5, 2001, it took "$16 million to drill, and it's already paid out," Erskine said in early March. Altogether, the field is producing 380 MMcf/d and 26,000 b/d of condensate. "These are world-class wells."

Deep prospects

So far, El Paso has identified 37 prospects for drilling in the Gulf of Mexico between 13,000 ft and 22,000 ft. While they're going deep, they're not getting much in the way of royalty relief from the US Minerals Management Service. This is because they are not working on new leases. Erskine said this is an unfortunate feature of the program. He believes the government should encourage more activity on existing leases, as these will yield most future production. The existing royalty relief "is a nice start, but it doesn't help that much," he said.

El Paso views the shallow gas fields as pointing to the best potential for new finds in the Gulf of Mexico. South Timba-lier 204, with its much smaller shallow field at 5,000-10,000 ft and its major producing horizon between 17,000 ft and 19,000 ft, is a good example.

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While in-house reprocessing of 3D data pointed to South Timbalier 204, El Paso also watches what the competition does.

"Our best exploration tools are dry holes drilled by other companies," Erskine said.

Erskine said he sees one trend off south Texas and one trend in the Central Gulf area as being particularly interesting. The rocks off south Texas are much tighter, he noted, so he expects the company to make full use of its onshore south Texas technology when it moves to that trend off south Texas.

"I think the Gulf is productive at least down to 30,000 ft," he said.

Technology needs

The hardest part of pulling gas from the deep, tight rocks, Erskine said, is transporting the average 2 million lb of bauxite to each of the offshore prospects.

The company is eager to find a completion vessel that can handle the large amount of bauxite needed to handle the big frac jobs. Erskine said some wells are completed and fractured at as many as six levels. "The equipment is just not there yet," he said.

But it's getting there.

"We just keep trying to push down the technology curve," he said.

El Paso hopes moving its trend-setting, deep moves from the Coastal Plains of Texas to the shallow Gulf of Mexico will keep the company ahead of the pack, and at the edge of the learning curve. Competition drilling deep in south Texas, Erskine said, lags about five years behind El Paso. "I hope we'll have that kind of age in the Gulf."

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