Abstract:
At least some disclosed resistivity logging system embodiments include a logging tool and a processing system. The logging tool provides multi-component transmitter-receiver coupling measurements to the processing system. The processing system derives from the measurements initial formation parameter estimates based on a first formation model such as a radially-symmetric formation model having anisotropic, but otherwise homogenous dipping formation. The processing system further derives in one or more selected regions a second set of formation parameter estimates based on a second formation model such as a model having a dipping borehole through a series of horizontal formation layers, each having a vertical transverse isotropy. The processing system produces an output set of formation parameter estimates which, in the selected regions, depend on the second set of formation parameter estimates, and in at least some regions outside the selected regions, solely depend on the initial formation parameter estimates.
Abstract:
An estimated value for invasion depth of an invasion zone in a subsurface measurement zone is calculated in a one-dimensional optimization procedure based on multi-array laterolog measurement data. A one-dimensional optimization problem is defined as having the invasion depth as a sole variable measurement zone parameter. The one-dimensional optimization problem is then solved by automated, iterative modification of the invasion depth value. The one-dimensional optimization problem can be a function to minimize a misfit error between (a) multi-array measurement values for resistivity of the subsurface measurement zone, and (b) predicted measurement values calculated in accordance with a simulated measurement zone model based at least in part on the invasion depth. In one embodiment, the optimization function defines a misfit error between (1) normalized differences between respective measurements of neighboring measurement arrays of the multi-array laterolog tool, and (2) normalized differences between respective predicted measurement values for neighboring measurement arrays.
Abstract:
Formation properties may be more efficiently derived from measurements of multi-frequency, multi-component array induction tools, by emphasizing the measurements associated with shorter spacings/lower frequencies in certain regions and short-to-middle spacings/higher frequencies in other regions. In at least one embodiment, a disclosed logging system includes a logging tool that when conveyed along a borehole through a formation obtains multi-component transmit-receive antenna coupling measurements with multiple arrays having different antenna spacings; and a processing system that operates on the measurements. The processing system derives from said measurements one or more formation parameter estimates; determines measurement weight coefficients for a cost function based on said one or more formation parameter estimates; and inverts said measurements with said cost function to obtain one or more enhanced parameter estimates.
Abstract:
In some embodiments, an apparatus and a system, as well as a method and an article, may operate to obtain a plurality of measurements of a formation parameter, each measurement obtained in response to energy propagated into the formation at a plurality of frequencies of propagated energy; to process the measurements over each of the plurality of frequencies to obtain estimated values of the formation parameter; to select an estimated value from the obtained estimated values for each logging depth as a true measurement value for the logging depth based on one or more of the plurality of frequencies and a resistivity range; to generate a combination log that combines a plurality of the true measurement values for each logging depth; and to control a drilling operation based on the combination log. Additional apparatus, systems, and methods are disclosed.
Abstract:
Fast-changing dip formation resistivity estimation methods and systems, including a formation resistivity estimation method that includes estimating an initial horizontal resistivity based upon acquired formation logging data and determining an initial value set of one or more value sets. The method further includes determining each additional value set of the one or more value sets using a 1-dimensional inversion initialized with a previously determined value set of the one or more value sets, and displaying a final value set of the one or more value sets. Each of the 1-dimensional inversions is performed using a cross-bedded formation model, and each of the one or more value sets includes one or more parameters selected from the group consisting of a horizontal resistivity, a vertical resistivity, a formation dip angle, a formation azimuth angle, a tool inclination angle, a tool azimuth angle and a depth.
Abstract:
A corrosion monitoring method includes obtaining electromagnetic (EM) log data along a casing string. The method also includes processing the EM log data to estimate casing thickness of the casing string as a function of position, where the processing includes correcting for junction effects in the casing string.
Abstract:
Various embodiments include apparatus and methods that perform a homogeneous inversion processing to data or signals acquired from a multicomponent induction tool operating in a wellbore. The homogeneous inversion processing can be used to provide a quality check of results from radial one dimensional borehole correction processing. Also, the homogeneous inversion processing may be employed as a dip indicator of conventional array induction logging processing. Additional apparatus, systems, and methods are disclosed.
Abstract:
A system and method of correcting induction logging data for relative dip, wherein an induction logging tool is utilized to collect initial induction logging data at a plurality of frequencies. The initial induction logging data is then corrected for skin effect and borehole effect, after which, inversion is performed on the processed induction logging data to determine a dip effect correction. The dip effect correction is then applied to the initial induction logging data in order to yield induction logging data that is dip corrected to reflect a zero relative dip. Once dip corrected, the induction logging data can be used with resistivity methodologies generally designed for instances where no dip is present in the formation under analysis. In certain embodiments, the inversion step utilizes an additive correction for the dip effect correction.
Abstract:
A first broadband magnetic field is induced at a first transmitter position in a well bore drilled through a formation. A first formation magnetic field induced by the first broadband magnetic field is detected at a first receiver position. A second formation magnetic field induced by the first broadband magnetic field is detected at a second receiver position. A second broadband magnetic field is induced at a second transmitter position in the well bore. A third formation magnetic field induced by the second broadband magnetic field is detected at the first receiver position. A fourth formation magnetic field induced by the second broadband magnetic field is detected at the second receiver position. A formation property is computed using a function of the first, second, third, and fourth formation magnetic fields, wherein the function reduces the effect of a casing on the computation of the formation property.
Abstract:
Evaluation of formation and fracture characteristics based on multicomponent induction (MCI) log data includes automated calculation of inverted biaxial anisotropy (BA) parameters for the formation by performing an iterative BA inversion operation based on the MCI log data and using a BA formation model that accounts for transfers by axial formation anisotropy to resistivity. The BA inversion operation can be combined with a transversely anisotropic (TI) inversion based on the MCI log data and using a TI formation model, to calculate inverted TI parameters for the formation. The inverted BA parameters and the inverted TI parameters can be used, in combination, to calculate a quantified value for an identification function, to indicate estimated presence or absence of a fracture in the formation