Houston-based Apache Corp. has become the first producer to use true-cable free wireless seismic technology offshore Alaska to limit the impact of seismic activity on Cook Inlet’s wildlife, communities and environment – including Cook Inlet beluga whales.
The use of wireless 3-D seismic is part of Apache’s commitment to conducting 3-D seismic operations in Alaska’s Cook Inlet “in ways that limit the impact on communities and the environment,” the company said in a July 24 article on its website, addressing criticisms of its seismic program.
Apache is using true cable-free nodal recording systems, designed and manufactured by Sugar Land, Texas-based FairfieldNodal, in order to minimize the impact of its seismic survey on Cook Inlet’s wildlife population and environment.
“Because we’re shooting onshore and offshore, we have to go back and meld and blend the data for the different sections together,” said Lisa Parker.
The company is using the technology for its ongoing 3D seismic survey of Cook Inlet, which will encompass onshore, offshore and the transition zone of Apache’s acreage. The seismic survey will continue for the next two and a half years.
After acquiring leases on 850,000 acres in Cook Inlet in August 2010, Apache began the permitting process for its seismic and exploration programs. In an effort to address concerns over the impact of seismic activity on local wildlife and the environment, Apache conducted a technology test to compare how traditional cable seismic would perform versus a wireless system.
Impressed with what it saw, the company initiated the permitting process to utilize wireless seismic and received approval to use this technology in the spring of 2011.
Apache began its Cook Inlet seismic program in November 2011, and has been working continuously since then, save for a six-week break from Christmas through the first part of February.
Approximately 1.4 billion barrels of oil was discovered in Cook Inlet in its early development in the 1950s and 1960s. Exploration and production in Cook Inlet declined after the discovery of Prudhoe Bay. Only a handful of fields have been discovered in Cook Inlet, but the field size distribution strongly suggests another 1.3 to 1.4 billion barrels of oil remain to be discovered in the Cook Inlet basin, Apache said.
Apache will begin drilling in Cook Inlet in October.
Fairfield’s product is truly cable free, unlike nodes from manufacturers who have elected to keep the power supply, electronics and sensor connected with short cables and connectors, said Roger Keyte head of marketing and business development at FairfieldNodal.
The nodes are placed on the ocean floor or buried onshore. Except for a rope tied to nodes placed offshore to retrieve them – the rope is not involved in the spacing of the node – the nodes have no cables, said Keyte.
Marine nodes weigh 65 pounds and look like a 50-pound free weight, but are a bit thicker, said Lisa Parker, head of government relations for Apache in Alaska. Land nodes weigh 4.8 pounds and look like a two-pound coffee can with a spike on the bottom. Both types of nodes are made of plastic and stainless steel.
The nodes are retrieved after a period time and taken back to the office, where the data is downloaded and the nodes are recharged. The data is then forwarded to Apache’s geoscientists for interpretation.
“Because we’re shooting onshore and offshore, we have to go back and meld and blend the data for the different sections together,” said Lisa Parker, head of government relations for Apache in Alaska. “It’s like putting the pieces of a puzzle back together.”
Since 1924, traditional seismic systems have involved sensors connected to cables. These sensors transmitted signals back to a localized recording system to be converted into digits, said Keyte.
Using a system with heavy, cumbersome cables presents difficulties onshore and offshore, Keyte noted. Offshore, the cables mean seismic vessels can’t get close to structures in the water such as rigs and platforms. Traditional systems also tend to be noisier.
Using cabled system onshore was especially problematic, with electrical leakages occurring due to animals biting or chewing the cables or sweat from the hands of workers, said Keyte.
Utilizing a true cable-free system cuts down on the amount of time crews spend troubleshooting to fix leakages. The cable free system increases the reliability of data and allows the recording time to be controlled.