shows surface measurements of CT weight (blue) during the operation while running in hole to set the packer and subsequently pull out of hole to surface. When pulling out of hole, overpulls (increase of CT weight) were clearly identified at several different points. Without the additional information of downhole forces, the operator would have to assume that this is due to drag forces on the BHA, meaning in this case a potential unset packer not disconnected from the BHA returning back to surface. As a result, action would have to be taken to release the BHA without confirming that the overpulls were artificial. But as downhole force measurement (green line) was available, the operator was able to confirm that the observed surface overpull was caused by the CT interacting with the wellbore and surface equipment. One can observe that there was no change in DH Force applied to the BHA during CT movement, only observed changes occurred first while inflating the packer and second during the straight pull to disconnect the packer in place. The use of the ACTive TC tool gave confidence to the operator to decide and continue the trip to surface.
Example 2: Downhole Tractor Operation
A CT job during an ER intervention in a horizontal well using a CT tractor and downhole force measurement allowed the operator to make informed decisions at the wellsite. During a conventional operation without access to downhole data, the operator will monitor the changes in CT weight (blue line) and Pump Rate (purple line) in an attempt to understand performance of the downhole tractor (see fig.). Without a CT tractor, the surface acquired CT weight will decrease once the CT is in the horizontal section until helical lockup condition occurs, limiting the capability to reach total depth (TD). In this example, CT depth (red line) is increasing over time as the CT is pushed into the hole. Due to the activation of the CT tractor under constant pumping rate, as real-time downhole force is available from the ACTive TC tool, the operator is also able to monitor this force (downhole force in green). One can effectively see that a pulling force of 2,800 lbf is enabling the ER keeping CT weight relatively constant at 11,000 lbf. However, when the end of the CT started to approach 23,500 ft, the surface CT weight drastically decreased to 1,600 lbf, indicating a lockup condition even though the tractor is operating at the designed condition. Tractor operations are highly dependent on external environmental factors – section length, hole ID, well deviation, and wellbore friction. It is obvious that having real-time downhole information increases the success of ER operations.
Live Downhole CT in Action
While real-time downhole force measurements are very helpful for traditional mechanical CT tools in highly deviated and horizontal wellbores, this data is essential for most hydraulically-actuated CT downhole tools. This is due to the smaller operating envelope dictated by the nature of the elastomers or load sensitive shifting devices. In a pilot