A consistent leadership team and cutting-edge technology have resulted in successful drilling at the ConocoPhillips Alaska-operated Alpine field.
Chip Alvord, ConocoPhillips’ Alpine drilling team leader, told Petroleum News the combination of an experienced drilling team from Doyon Drilling, geo-steering technology from Schlumberger and rotary steerable technology from Sperry Drilling Services can be credited for continuous improvement in drilling results at the western North Slope field and its satellites.
Alvord said Doyon rig 19 has been used from the beginning for Alpine and Alpine satellite development drilling. Doyon has done a good job of keeping its key people on the rig, the tool pushers, while ConocoPhillips has also been fortunate in keeping its drilling team at Alpine, the company rig supervisors — company man — and the geologists.
“We don’t relearn lessons too often,” Alvord said.
ConocoPhillips has a 78 percent interest in Alpine and Anadarko Petroleum has the other 22 percent. Alvord said Anadarko has been supportive. “These are pretty aggressive wells,” he said, and Anadarko has “never told us not to try something different, which you have to do sometimes.”
Alpine and its satellites produce from four reservoirs: Alpine, Nechelik, Nanuq and Kuparuk. The wells are all horizontal. As of about six months ago more than half a million feet of horizontal interval had been drilled, he said.
Rotary steerable world recordsUsing Sperry’s rotary steerable bit the drilling team at Alpine has set three world records in recent months: 9,002 feet for a single 6-1/8 inch rotary steerable run in the CD3-110 well (Fiord); 12,299 feet for a single 8-1/2 inch rotary steerable run in the CD1-07 well (at the main Alpine pad); and 12,197 feet for a single 8-3/4 inch rotary steerable run at the CD2-02 well (at the CD2 pad in the main field).
The latest technological innovation in use at Alpine is Schlumberger’s PeriScope geo-steering tool. The first use of the geo-steering tool on the North Slope — also the first use of the tool in North America — kept drilling 93 percent within the zone in a faulted, eight-foot thick sand.
The geo-steering tool uses resistivity to provide a real-time image of the top and bottom of the target horizontal sandstone.
The tool has been available for about a year and a half but it took a while to get it in the smaller hole size that ConocoPhillips needed for Alpine, Alvord said. The tool was first used in Alaska in October-November of 2005.
ConocoPhillips had previously used the geo-steering tool in Norway and in Indonesia. Because the company has an “initiative on knowledge transfer, knowledge sharing in the geosciences,” Alaska knew about the tool and thought Alpine might be a good application because it has really thin sandstone, six to eight feet thick. The 6,000 foot section drilled last year on the North Slope was a world record for the PeriScope, Alvord said.
ConocoPhillips used tool elsewhereSeismic is used to plan wells, but there are sub-seismic faults, Alvord said, faults you can’t see on seismic. Because the geo-steering tool shows the top and bottom of the formation, it lets you get back in the pay zone quickly when it is crossed by sub-seismic faults.
You really can see what is going on: an image on a computer screen shows the top and bottom sand boundaries, the planned trajectory for the well and the actual trajectory being drilled.
Doug Hupp, Schlumberger Data and Consulting Services principal petrophysicist, was monitoring progress on an Alpine well from ConocoPhillips’ Anchorage headquarters via computer. A screen (see printout of a portion of a screen graphic on this page) shows the bottom and top boundaries of the sandstone zone which is the drilling target, the planned trajectory of the well and the drilled trajectory, as adjusted to follow the sandstone zone, even where faults have shifted it out of alignment.
“We’re monitoring in real time as we go along,” Hupp said. The color represents resistivity, he said, with the light representing high resistivity, the pay zone, and the dark low resistivity or shale.
Hupp said the measurements are taken about 30 feet from the end of the drill bit. The information coming from the tool shows when the bit is approaching the bottom or top of the sandstone, so the bit can be turned up or down as needed to stay in the bed.
Data goes from the rig via the Internet to Schlumberger’s server in Denver and then back to Anchorage where it is downloaded.
Tool used in Kuparuk sandsAlvord said geo-steering tool works well in the Kuparuk sands at Alpine, but not in the Nechelik or Nanuq sandstones. The Kuparuk sand is pretty well developed at Nanuq, the satellite south of Alpine at the CD4 pad, so they’ve been using the geo-steering technology there.
The tool looks at resistivity contrast, so in “good clean sandstone like the Kuparuk … you can pick up the contrast between the shales above and below and the sandstone.” He said ConocoPhillips has tried PeriScope at West Sak, but there the sand has more clay content, and the resistivity contrast isn’t as high so you don’t get the clear curtain — the sharp distinction — between sandstone and shale that shows you where you need to be as you drill.
ConocoPhillips has used the Sperry Drilling Services’ rotary steerable technology at Alpine and West Sak in the last two or three years, allowing it to drill wells faster and to drill longer sections, and to set those world records for rotary steerable technology.
Fiord like an exploration operationDoyon has set drilling records at both Alpine and its satellites, some of those at Fiord, where drilling is done only in the winter.
ConocoPhillips had 97 days at Fiord last winter, Alvord said. Fiord is being developed from CD3 as a road-less development. The satellite, north of Alpine, is not yet in production.
The operation is more like an exploration project, he said, because an ice road is required to move the rig and other equipment in at the beginning of the winter drilling season and out at the end of winter drilling.
Some 50 to 55 people support that operation: four from ConocoPhillips (day and night company man; day and night geologist), some 25 with Doyon Drilling, 10-12 with MI Swaco, the drilling fluids company, and people from AES (ASRC Energy Services) doing drilling support. Alvord said Fiord is road-less because it’s a sensitive bird habitat and a road would be a bigger disturbance, so construction and drilling are done in the winter when there are no birds around. Two wells at Fiord were suspended and five completed.
“We’re going to try to start the pad up later this year,” Alvord said, along with CD4 (Nanuq), south of Alpine and connected to the field’s main production pad by a four-mile road.