摘要:
A transmitter on an instrument is used to induce currents in an earth formation when it is turned on or off. A Fourier transform is applied to transient measurements made in the receivers. A multifrequency focusing of the transformed data is used for applications like determination of a distance to an interface in the formation, controlling the drilling direction, determination of formation resistivities and formation strike directions.
摘要:
A transmitter on an instrument is used to induce currents in an earth formation when it is turned on or off. A Fourier transform is applied to transient measurements made in the receivers. A multifrequency focusing of the transformed data is used for applications like determination of a distance to an interface in the formation, controlling the drilling direction, determination of formation resistivities and formation strike directions.
摘要:
A method for estimating a property of a portion of an earth formation ahead of a borehole penetrating the formation, the method includes: conveying a logging tool through the borehole; receiving one or more first signals from a previous depth of the logging tool; constructing a model of the earth formation using the one or more first signals; predicting one or more second signals from the portion of the earth formation ahead of the borehole using the model; receiving one or more third signals from the portion of the earth formation ahead of the borehole; calculating a difference between the one or more third signals and the one or more second signals; and estimating the property from the difference.
摘要:
A method for presenting a formation property to a user includes estimating an initial property of the formation using a tool conveyed in a borehole and estimating a relationship between the tool and the formation based on information received from the tool. The method also includes presenting the user a first output based at least in part on the initial property and presenting a second output based at least in part on the relationship proximate the first output.
摘要:
A multicomponent induction logging tool includes a transmitter antenna and two receiver antennas, one of which is aligned parallel to the transmitter. Using measurements made at a plurality of rotational angles, a misalignment angle between the transmitter antenna and the second receiver antenna is estimated.
摘要:
Skin-effect corrections are applied to measurements made by a transverse induction logging tool to give corrected measurements indicative of vertical conductivities of a formation. Data from a conventional induction logging tool are inverted or focused to give an isotropic model of formation resistivity. A forward modeling is used to derive from the isotropic model measurements that would be expected with a transverse induction logging tool. Skin-effect corrections are applied to these expected measurements. The formation anisotropy is determined from the skin-effect corrected transverse induction measurements, the skin-effect corrected expected measurements and from the isotropic model conductivities.
摘要:
A method of determining a plurality of formation models each of which will simulate the response of a well logging instrument. A measured response of the well logging instrument is used to generate an initial model using inversion processing. A response of the instrument to the initial model is synthesized. A singular value decomposition is performed on the synthetic response to generate eigenparameters of the initial model. Eigenparameters having the least significant overall contribution to the synthetic response are sequentially substituted with linear equations representing prior constraints on the initial earth model. A linear system, including the remaining ones of the eigenparameters and the linear equations is solved so that the eigenparameters are preserved exactly and the linear equations satisfy a least squares fit. An additional synthetic instrument response is generated for each solution to the linear system which falls below a predetermined error threshold. The additional instrument responses are compared with the synthesized response to the initial model. The one of the solutions to the linear system which represents an earth model providing minimum misfit with respect to equations representing the prior constraints is selected as the best fit model.
摘要:
Measurements made by a multi-component logging tool in a borehole are inverted to obtain three principal resistivities (or conductivities) and three associated angles of a bi-axially symmetric formation traversed by the borehole.
摘要:
Measurements made by a multi-component logging tool in a borehole are inverted to obtain three principal resistivities (or conductivities) and three associated angles of a bi-axially symmetric formation traversed by the borehole.
摘要:
A multicomponent induction logging tool is used on a MWD bottomhole assembly. Multifrequency focusing that accounts for the finite, nonzero, conductivity of the mandrel is applied. Using separation of modes, the principal components and a direction of a conductivity tensor are determined. The results are used for reservoir navigation in earth formations. It is emphasized that this abstract is provided to comply with the rules requiring an abstract which will allow a searcher or other reader to quickly ascertain the subject matter of the technical disclosure. It is submitted with the understanding that it will not be used to interpret or limit the scope or meaning of the claims. 37 CFR 1.72(b)