Data compression transforms for use in downhole applications

摘要

Borehole image data is compressed and transmitted to the surface one or more pixilated traces at a time. The compression methodology typically includes transform, quantization, and entropy encoding steps. The invention advantageously provides an efficient fixed point Karhünen-Loève like transform for compressing sensor data. A significant reduction in latency is achieved as compared to the prior art.

主权项

1. A method for logging a subterranean borehole, the method comprising:
(a) acquiring a pixilated trace of sensor data, the pixilated trace including a plurality of borehole parameter values at a corresponding plurality of discrete tool face angles; (b) causing a downhole processor to apply a non-orthogonal, KLT-like transform to the pixilated trace to obtain transform coefficients, the transform being selected such that the transform times its transpose equals a diagonal scaling matrix; (c) causing the downhole processor to quantize the transform coefficients to obtain quantized coefficients; and (d) transmitting the quantized coefficients uphole.