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US 8,788,206 B2Granted
Data compression transforms for use in downhole applications
AssigneeSchlumberger Technology Corporation
InventorCaimu Tang
Life of this patent
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Abstract
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.
Claims32
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.
2 more elements
A method for logging a subterranean borehole, the method comprising:
- (a) acquiring a plurality of pixilated traces of sensor data, each of the pixilated traces including a plurality of borehole parameter values at a corresponding plurality of discrete tool face angles;
- (b) causing a downhole processor to re-organize the plurality of borehole parameter values in the plurality of traces to obtain a square matrix of parameter values, the size of the square matrix being greater than the number of pixilated traces acquired in (a);
- (c) causing the downhole processor to apply a non-orthogonal, KLT-like transform to the square matrix of parameter values to obtain a square matrix of transform coefficients, the transform being selected such that the transform times its transpose equals a diagonal scaling matrix;
- (d) causing the downhole processor to quantize the transform coefficients to obtain quantized coefficients;
- and
- (e) transmitting the quantized coefficients uphole.
3 more elements
A method for logging a subterranean borehole, the method comprising:
- (a) acquiring at least one 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 process the at least one pixilated trace of sensor data to obtain a transform matrix;
- (c) causing the downhole processor to apply the transform matrix obtained in (b) to the at least one pixilated trace of sensor data to obtain transform coefficients;
- (d) causing the downhole processor to quantize the transform coefficients to obtain quantized coefficients;
- and
- (e) transmitting the transform matrix and the quantized coefficients uphole.
3 more elements
A method for logging a subterranean borehole, the method comprising:
- (a) acquiring at least one 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 quantize the at least one pixilated trace of sensor data to obtain quantized sensor data;
- (c) causing the downhole processor to apply a non-orthogonal, KLT-like transform to the quantized sensor data to obtain transform coefficients;
- (d) causing the downhole processor to quantize the transform coefficients to obtain quantized coefficients;
- and
- (e) transmitting the quantized coefficients uphole.
3 more elements
A method for logging a subterranean borehole, the method comprising:
- (a) acquiring at least one 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 azimuthally partition the sensor data to obtain a plurality of blocks of sensor data, the plurality of blocks including a first block and at least one other block;
- (c) causing the downhole processor to compute differences between each of the at least one other blocks and the first block to obtain at least one block of residuals;
- (d) causing the downhole processor to apply a transform to the first block to obtain a first block of transform coefficients and to each of the at least one block of residuals to obtain at least one block of residual transform coefficients;
- (e) causing the downhole processor to quantize the first block of transform coefficients and the at least one block of residual transform coefficients to obtain a first block of quantized coefficients and at least one block of residual quantized coefficients;
- and
- (f) transmitting the first block of quantized coefficients and the at least one block of residual quantized coefficients uphole.
4 more elements
Dependencies are inferred from the claim text.