2008
By utilizing the Well Tractor for down hole conveyance in their North Dakota wells, Amerada Hess saved rig time and benefited from improved log quality on multiple open hole logging jobs.
Historically, Amerada Hess had used drill-pipe conveyance to conduct logging operations on their horizontal wells in the Bakken Shale. Considerable rig time consumption as well as quality issues prompted them to consider an alternative technology. The Well Tractor from Welltec proved to be the solution to both reducing rig time used to acquire open hole logs while improving the quality of the log data acquired.
The Bakken Shale Formation consists of an upper and lower shale member with a clastic middle member that can vary from sandstone to siltstone with interbeds of dolostone or limestone. Wells drilled in the Bakken primarily target oil production from this middle member and will typically have long horizontal sections upwards of 9,000 ft. Formation compressive strengths approaching 40 kpsi, have generally yielded “gun barrel” hole conditions, favorable for open hole well tractor technology.
Using a 3 1/8” diameter Well Tractor tool configured for an open hole application, logging tools were conveyed (tractored) approximately 1,000 ft along the horizontal section in just 15 minutes in the first well and about 18 minutes in the second well. On the third well, a washed out section rendered borehole diameters that exceeded the reach of the Well Tractor wheels, preventing the tool string from reaching bottom. Deployment of a tandem Well Tractor configuration typically can overcome the challenge of tractor conveyance through a borehole washout.
Achievements
As of August 2008, the Well Tractor has been deployed successfully on 12 open hole wells in North Dakota. By reducing open hole logging times in these wells from approximately 24 hours to 6 hours, the Well Tractor is helping this client realize significant cost savings as a consequence of reducing rig time. Additionally, quality of the open hole log data has improved by elimination of the disruption to smooth data acquisition that can occur as drill pipe connections are made up.
Well Data
Equipment Used: 318 Well Tractor XR
Tractor Pulling Power: 1500 lbs
Toolstring weight: 1000 lbs
Vertical Depth: 9,500-10,000 ft MD
Maximum Temperature: 215 ° F
Maximum Deviation: 90°
Maximum Dogleg: 11 deg/100ft
