Halliburton Energy Services, Inc.

Weatherford Technology Holdings, LLC

Guoyu Hu

Michael S Bittar

William Edward Hendricks

Glenn Smollinger

A technique for processing well logs performs a nonlinear resolution enhancement of raw well logs. The nonlinear enhancement procedure uses a modified Van Cittert nonlinear enhancement technique that avoids instabilities that can arise using Van Cittert techniques. The nonlinear enhancement can provide resolution matched results at a predetermined resolution.

Resolution matched nonlinear resolution enhancement of well logs

Various disclosed resistivity imaging tools and methods provide a high-resolution electrode configuration for imaging in oil-based imaging in oil-based muds. Some tool embodiments have a sensing surface that comprises: a measurement electrode, a focus electrode surrounding the measurement electrode, and a return electrode surrounding the focus electrode. The sensing surface can be provided on an extendable sensor pad or on the wall-contacting portion of a stabilizer. Some method embodiments include measuring the measurement electrode current while driving a voltage signal between the measurement electrode and the return electrode. The voltage signal may simultaneously or sequentially provide energy at different frequencies. The resistivity measurements are combined with tool position and orientation measurements to form a borehole wall image. Robust and reliable performance is expected in the hostile conditions often experienced by logging while drilling (LWD) tools, coupled with the ability to make micro-resistivity measurements with a resolution approaching that of electrode-grid tool designs.

Method and apparatus with high resolution electrode configuration for imaging in oil-based muds

Disclosed herein are electromagnetic resistivity logging systems and methods that employ an antenna configuration having at most two transmitter or receiver antenna orientations that rotate relative to the borehole. The measurements made by this reduced-complexity antenna configuration enable the determination of at least seven components of a coupling matrix, which may be determined using a linear system of equations that express the azimuthal dependence of the measurements. For increased reliability, measurement averaging may be performed in azimuthally spaced bins. The coupling matrix components can then be used as the basis for determining logs of various formation parameters, including vertical resistivity and anisotropy.

Antenna coupling component measurement tool having rotating antenna configuration

Methods and systems for determining the horizontal resistivity, vertical resistivity, and relative dip angle of anisotropic earth formations. Some of the disclosed methods and systems measure sinusoidal variation of azimuthally sensitive resistivity logging tool measurements, determine parameters representative of the sinusoidal variation, and perform inversion based on the sinusoidal parameters. When cast in this manner, the inversion process may yield more accurate and consistent resistivity and dip angle estimates. The sinusoidal parameters preferably take the form of average and peak-to-peak measurements, but may also take other forms. Moreover, use of such sinusoidal parameters enables a condensed representation of the resistivity logging tool measurements, enabling significantly more efficient communication and storage of these measurements. The condensed representations continue to enable directional boundary detection and geosteering.

Robust inversion systems and methods for azimuthally sensitive resistivity logging tools

Systems and methods for look-ahead boundary detection and distance estimation are disclosed. In some embodiments, a drilling method includes extending a borehole with a drill string that includes a resistivity logging tool. The logging tool makes upward-looking and downward-looking resistivity measurements based on radial current flow. The upward looking and downward looking resistivity measurements are processed to estimate the distance to approaching bed boundaries, and drilling can be halted when the estimated distance reaches a desired value. Such information can be used to anchor casing at advantageous points and can further be used to avoid penetrating water-containing formations below a hydrocarbon reservoir.

Drilling systems and methods using radial current flow for boundary detection or boundary distance estimation

A nonlinear iterative deconvolution method and system. In one embodiment, the system comprises a data acquisition module, a storage module, and a processing module. The data acquisition module obtains logging data from measurements made by a sensor tool moving through a borehole, and stores the logging data in the storage module. The processing module processes the logging data to determine a formation model by iteratively updating a set of formation model values which correspond to a set of positions along the borehole. The iterative updating includes (i) calculating an error value; and (ii) applying a linearizing factor to the error value. The iterative updating may be expressible as a weighted sum of a current formation model value with a product of the error value and the linearizing factor. The iterative updating may continue until an adequate match between the logging data and a calculated tool response is achieved.

Simultaneous resolution enhancement and dip correction of resistivity logs through nonlinear iterative deconvolution

A system and related method for obtaining electromagnetic resistivity logs of a formation having fixed depths of investigation that differ from the actual depths of investigation for the tool. The system and related method comprises calculating actual invaded zone and formation resistivities, and then using least-squares curve fitting techniques to find a function that models the relationship between the physical spacing of the transmitters and the depths of investigation. Using the function, it is possible to find a transmitter-to-receive spacing that, though not actually wed, would give the desired depth of investigation. This transmitter-to-receiver spacing is then used in combination with a second function, determined using least-squares curve fitting methods, which models the relationship between the transmitter-to-receiver physical spacing and the measured resistivity to obtain the resistivity reading at a fixed depth of investigation.

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Houston, TX, United States of America

Guoyu Hu