Schlumberger Technology Corporation

Smith International, Inc.

Caimu Tang

Mark S Beattie

Tsili Wang

Borislav J Tchakarov

Thanh H Cao

Rodney S Guenther

A method for receiving an encoded integer includes acquiring a digitized waveform including a first plurality of pulses distributed among a second plurality of time slots, locating each of the pulses in the digitized waveform, computing a confidence value for each of the pulses, selecting a subset of the plurality of pulses, the subset including pulses having low confidence values computed, generating a set of unique waveforms corresponding to various combinations of the subset of pulses selected, computing a cross-correlation between each of the waveforms generated and the digitized waveform acquired, and selecting the waveform having the highest cross-correlation computed.

Telemetry coding and surface detection for a mud pulser

A closed-loop method for geosteering includes acquiring logging while drilling data and processing the logging while drilling data downhole while drilling to obtain a geosteering correction (a correction to the drilling direction based upon the LWD measurements). The geosteering correction is further processed downhole to obtain new steering tool settings which are then applied to the steering tool to change the direction of drilling. These steps are typically repeated numerous times without the need for uphole processing or surface intervention.

Downhole closed-loop geosteering methodology

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 Karh&#xfc;nen-Lo&#xe8;ve like transform for compressing sensor data. A significant reduction in latency is achieved as compared to the prior art.

Data compression transforms for use in downhole applications

A method for encoding a non-negative integer, for example, representative of MWD/LWD data, includes encoding at least a portion of the integer using at least a first order Fibonacci derived sequence. The remainder of the integer may be encoded using conventional Fibonacci encoding. The invention tends to improve coding efficiency, downhole and surface synchronization, and surface detection.

Borehole image data is compressed and transmitted to the surface one pixilated trace at a time. The compression methodology typically includes transform, quantization, and entropy encoding steps. The invention advantageously provides for sufficient data compression to enable conventional telemetry techniques (e.g., mud pulse telemetry) to be utilized for transmitting borehole images to the surface. By compressing and transmitting sensor data trace by trace the invention also tends to significantly reduce latency.

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Sugar Land, TX, United States of America

Caimu Tang