Although an old dry gas field dating back to the 1930s, Rio Vista has stepped up its 130-well production in Northern California over the past seven years since Calpine Corp. acquired the majority of producing wells in the 3,000-acre field. But the company now is running into belated resistance to further gas development of the state’s largest dry gas field, which is located near the small town of Rio Vista, CA.

Residents in the 1,000-home Trilogy development in the area have begun to complain about still unspecified plans to drill new gas wells near and on part of the recreational portion of the residential development. They have cited an “accommodation agreement” with the field’s previous owner, Amerada Hess Corp.

Residents are asking Calpine to use directional (horizontal) drilling to take the rigs farther away from the homes, but the company said that option is not feasible from a technical, geologic or financial standpoint in this case.

“The Trilogy development sits upon the single largest dry gas field in California, of which Calpine is the primary producer,” said a Calpine spokesperson. “Simply put, one drills where natural gas exists and natural gas is an important component in meeting our energy needs in an environmentally and economically sound fashion.”

The accommodation agreement, which Amerada Hess originally worked out with the developers of Trilogy, was necessary for the development to move ahead because in California, mineral rights take precedent over surface rights, the Calpine spokesperson added. That agreement specified maintenance of five existing wells and drilling of six new wells in and around the Trilogy development.

At this point, Calpine said it has set no schedule for the additional maintenance on existing wells or for drilling the new wells in any of the six locations identified in the original agreement with the developer. “However, Calpine is currently evaluating possible initiatives in this regard as well as additional maintenance work on one specific unit (No. 139),” the spokesperson said.

Since its original acquisition of production wells at Rio Vista beginning in 1997, Calpine said it has not only offset a previous 15% annual decline in regional natural gas production, but it has taken properties that were collectively producing 40 MMcf/d and boosted that to a current 100 MMcf/d.

“The increased productivity of the Rio Vista gas fields is a result of new and innovative engineering and geo-science practices, utilization of modern seismic processing, detailed geophysical and petro-physical analysis, and the introduction of new operational technology to the area,” according to Calpine’s promotion on Rio Vista. During the past seven years, Calpine has drilled 29 new wells and re-completed 70 wells, most of which were inactive and sitting idle, the company said.

Calpine’s current production, while a substantial increase, is still far below the historic peaks of 500 MMcf/d reached several decades ago.

While individual residents remain concerned from a public health., safety and environmental standpoint, the Trilogy developers told local news media they were confident that some type of added agreement will be worked out to move the actual drilling to more remote locations. So far, Calpine is not indicating that is an option, so a confrontation may still be unavoidable.

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