Schlumberger Technology Corporation

Alain Brie

Henri-Pierre Valero

Kai Hsu

Takeshi Endo

Richard A Plumb

Jahir A Pabon

Hitoshi Sugiyama

Benoit G Froelich

Hiroshi Hori

Hitoshi Tashiro

Vivian Pistre

David Hoyle

Frank Morris

Yoshiyuki Saiki

A method of determining the sonic slowness of a formation traversed by a borehole comprising generating tracks from sonic waveform peaks received at a plurality of depths wherein the peaks that are not classified prior to tracking is set forth. A method for generating a slowness versus depth log is generated for waveform arrivals by classifying long tracks, classifying small tracks; classifying tracks that overlap; filling in gaps; and creating a final log is disclosed. In further improvements, non-classified tracks and interpolation are used to fill in gaps.

Global classification of sonic logs

Methods for determining the best value for at least one slowness-related parameter that has been determined in a number of ways is disclosed. Sonic logging data input in the methods are processed to determine multiple values of at least one slowness-related parameter using slowness/time coherence (STC) processing methods. The error of each determined parameter is determined and the determined errors used in selecting a representative parameter value from the multiple determined slowness-related parameter values.

Processing sonic waveform measurements

A logging tool having a tool body, which can be positioned in a fluid-filled borehole, including a receiver section and a dipole transmitter; wherein the dipole transmitter includes a transducer with a shell having a reaction mass and a motor located therein, the motor operatively connecting the shell and the reaction mass such that only an outer surface of the shell is in contact with the fluid in the borehole. This new type of dipole source for well logging involves shaking all or part (axially) of a dipole tool body to produce a pure, broadband acoustic dipole signal while at the same time coupling as little energy as possible into the tool body. Important variations on this idea include a linear phased array of shaker sources, and active cancellation of tool borne noise.

Dipole logging tool

Methods for processing sonic logging data obtained from a logging tool having an array of R receivers, includes selecting a sub-array size of R receivers where R <R; calculating the number of sub-arrays N possible from the array of R receivers; identifying one receiver R in the array to serve as a reference receiver for each sub-array; processing data in the slowness-time plane for each sub-array with respect to the reference receiver R ; and stacking the processed data in the slowness-time plane for all sub-arrays.

Processing sonic waveform measurements from array borehole logging tools

A method for acoustically investigating characteristics of formations penetrated by a borehole such as fractures by taking differential Stoneley wave acoustic energy measurements between pairs of receivers of an array of receivers carried by a logging tool. The receivers of each pair all have the same spacing. The energy is that detected by the receivers in response to acoustic pulses generated by a transmitter spaced from the receivers on the tool. The differential energy measurements are stacked to obtain a stacked differential energy log.

Differential energy acoustic measurements of formation characteristic

A method and apparatus are described for generating a quick look display of an acoustic investigation of a borehole wherein a parameter of interest is derived from vertically spaced sonic receivers and displayed in a laterally continuous display log where the parameter values from respective receivers are recorded at preassigned positions. A fracture sensitive parameter is measured such as the energy in a low frequency Stoneley wave and when the parameter values are laterally recorded areas indicative of fractures become visually enhanced particularly with a laterally expanded display log. Techniques for the detection and evaluation of fractures are described.

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Versailles, France

Alain Brie