Logging-while-drilling (LWD) resistivity responses are inevitably contaminated by Gaussian and non-Gaussian noise. Noise contamination can influence the stability accuracy of inversion data. In addition, uncertainty bed-boundary positions complicate inversion. We have developed a novel efficient nonlinear algorithm, called Huber inversion, to accurately estimate layer-by-layer when LWD measurements were affected combines advantages [Formula: see text]- text]-norm inversions, which more...

Transversely isotropic (TI) formation is the most popular anisotropic electrical model for computing electromagnetic (EM) field in multilayered media. However, TI considers only electric parameters such as resistivity along horizontal and vertical directions, which are not always available real-life situations. The realistic parameter distribution mainly depends on sedimentary environment could be arbitrary directions. This article developed a fast-forward algorithm used to calculate EM...

For real-time inversion and fast reconstruction of formation true resistivity, the forward modeling electromagnetic wave logging while drilling is usually based on transversely isotropic model with vertical symmetry axis (VTI medium), but it only considers horizontal resistivity. It has certain limitation during practical application. This paper presents a calculation method in (TTI) strata inclined Dyadic Green's function. Anisotropic angle azimuth are used to characterize TTI formation....

Abstract Petrophysical properties such as acoustic velocity, resistivity and nuclear magnetic resonance are greatly depending on the pore structures. This is because structures could control elastic modulus, conductive path seepage distribution of rock. The theoretical simulation acoustic–electrical–nuclear joint experiments were used to study structure action acoustic, electrical characteristics by taking sandstone samples Nanpu Sag an example which was classified based mercury intrusion...

The relative dip angle and anisotropy of the anisotropic formation are generally determined through an inversion process. We have studied responses novel transient multicomponent induction logging method find that all components measured in instrument coordinate system same decay with time. However, cross component decays much faster than coaxial or coplanar system. adopt algebraic time-domain to calculate coefficient thereby avoid accuracy applicability this pseudoinversion theoretically....

The maximum distance at which an electromagnetic (EM) logging while drilling (LWD) tool detects approaching boundary is defined as the depth of detection (DOD). Ultra-deep capability transient multicomponent EM measurement investigated here. First, we adopt sine and cosine transform to calculate responses. Compared transform, more accurate in solving late-time Then, a time-domain geosignal introduced sense boundary. Results show that DOD this can be up tens meters, including directionally...

Abstract Transient electromagnetic wave logging is one of the key methods for detecting underground formations, especially identifying anomalies near wells using higher frequencies and resolutions. In this paper, 3D TDFD (three-dimensional time-domain finite-difference) simulation method used to investigate detection technique wellbore based on scattered field transient waves its significance in structure identification localization. The research results show that isolated can be effectively...

Aims to accurately evaluate the formation fluid and make up for limitations of one-dimensional nuclear magnetic resonance logging in practical applications, twodimensional has long been focus research. Increasing sequence inversion parameters 2D NMR can effectively improve antinoise resolution inversion, but at same time it will reduce speed significantly increase computer memory occupancy, which put forward higher requirements configuration. The computational cost poses a challenge...

The key of geosteering lies in the detection formation boundary. In order to improve depth investigation, electromagnetic logging methods excited by time-harmonic source usually reduce frequency or increase spacing. Compared with excitation method, transient method measures secondary field without interference primary and is much deeper. This paper presents a time-domain TEM boundary method. Based on scattering from boundary, tool one transmitter two symmetrical receivers proposed here...

Petrophycical properties such as acoustic velocity, resistivity and nuclear magnetic resonance are greatly depend on the pore structures. This is because structures could control elastic modulus, conductive path seepage distribution of rock. The theoretical simulation acoustic- electrical -nuclear joint experiments were used to study structure action acoustic, characteristics by taking sandstone samples Nanpu Sag an example which was classified based mercury intrusion fractal curve.. It...

The electromagnetic fields radiated by electric and magnetic dipole sources in multilayered formation with full-tensor dielectric conductivity anisotropy are formulated this paper. By reformulating the Maxwell's equations spectral domain solving spatial using Fourier transform, responses from can be acquired. total field consists of two parts: direct wave reflected bottom top layers. Generalized reflection transmission matrices derived to express arbitrary numerical results show good...

Summary Due to complex lithology, strong heterogeneity, low porosity and permeability; resistivity logging faces great challenges in oil saturation prediction of tight conglomerate reservoirs. First, 10 typical cores were selected measure analyze petrophysical parameters. Second, an empirical method is proposed for reconstructing NMR T2 spectrum under completely watered condition using MICP curve based on the "three-piece" power function. The parameters different models are calibrated via...