A field test well was conducted on the 28th of March 2011 and finished on the 1st of April in Oklahoma State. It took place on gti-catoosa test rig, in Owasso. The BHA included a PDS Motary Steerable tool, a sonic LWD tool and a HAGR tool. The well is an S-shape trajectory, and was completed successfully.
This is the second generation design of the tool, the first generation was only a 6 ¾" tool size and 11 tools were manufactured with the first generation design. Two 8 ¼" Sonic tools are manufactured with the second generation design one of which was deployed in the field test.
This new design in brief is in the Attenuator section and the main purpose of the test was to assure the tool is getting good readings with the new design. The Attenuator function is to minimize the acoustic waves that travel through the steel body of the tool directly from the transmitter up to the receivers. These direct acoustic waves are named Tool Mode. It affects the tool efficiency and decreases the signal to noise ratio, leaving the actual formation arrivals more vulnerable and less distinguishable. Therefore, the optimum efficiency will be reached when the Tool Mode waves are minimized and most if not all what reach the receivers are waves coming from the formation.
The SST was giving good semblance image, with a clear casing signature and a unique compressional arrival in the shale.
Mud line is on the left and Max Coherence on the right; a screen capture of the original log.
A comparison between the mud line and the max coherence log shows some tool mode in the shale regions in the max coherence track, however, it is very minimal and not coherent.
In conclusion, the field test for the 8 ¼" sonic tool is considered successful and the new Attenuator design is accepted by the R&D department. Thus all the coming tools for the SST will have the new Attenuator design.
Source: Weatherford News, The Link,
June 2, 2011 · Issue 45
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