Summary
The introduction of new measurements constantly increases the amount of
real-time data from logging-while-drilling (LWD) services, providing better
information for informed decision making. This is matched by telemetry
technologies that provide data rates from bits per second to megabits per
second. During a deployment, the bandwidth is shared between several services
requiring different data rates, leaving the user with the task of aligning
telemetry technology and shared data rates to the application. High-volume
services often allow for data compression. Lossless or near-lossless
compression provides the best data quality but requires large bandwidth. Lossy
compression reduces bandwidth usage dramatically, but may result in degraded
data quality. Thus, telemetry planning must be tied closely to service
objectives and requires expert advice.
We present a planning approach in which we model the real-time-data
compression of an LWD high-resolution imaging tool that uses a flexible
compression algorithm. This system allows lossy compression for telemetry rates
as low as 1 bps, while at the same time delivering memory-data quality using
high-speed-telemetry technology. The compression rate determines the image
resolution and must be adjusted to the detail required in the transmitted
image. Using offset-well data or simulated memory data, the expected real-time
image is simulated and its level of detail quantified. For instance, the
presence and appearance of fractures in real time can be forecasted. This
enables us to optimize telemetry usage and define compression and drilling
parameters for a successful deployment of the imaging service.
This paper will outline the methods and benchmark the technology of the
imaging tool, using real-time data measured during field deployments. We will
then use parameter variations to show how increasing net bandwidth improves the
amount of detail in the images, and how these are used for different levels of
real-time-data interpretation.
© 2012. Society of Petroleum Engineers
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History
- Original manuscript received:
8 October 2011
- Meeting paper published:
26 September 2011
- Revised manuscript received:
15 June 2012
- Manuscript approved:
10 July 2012
- Published online:
22 August 2012
- Version of record:
18 September 2012
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