Hitoshi Sugiyama

A New Modular Sonic Tool Provides Complete Acoustic Formation Characterization

An improved estimation of sonic slownesses and a comprehensive mechanical characterization of the wellbore rock rely on a complete characterization of the compressional and shear slowness in terms of their radial, azimuthal, and axial variations. The new modular sonic tool accomplishes this by incorporating improved monopole and cross-dipole transmitter technology while featuring an extensive receiver array incorporating 13 axial levels of 8 azimuthal sensors each. Each receiver is individually digitized resulting in 104 waveforms per transmitter firing leading to an extremely reliable and accurate slowness estimation. This comes about through improved borehole mode extraction/rejection and enhanced wavenumber resolution at all frequencies. Formations exhibit wide, and sometimes complex, acoustical behaviors ranging from isotropic, anisotropic with its various mechanisms and significant radial slowness gradients. Radial rock property variations arise because of non-uniform stress distributions and mechanical or chemical near-wellbore alteration due to the drilling process. Anisotropy can be caused by intrinsic shale properties or external differential stresses. The critical data required to invert for these rock parameters underlying these acoustic behaviors are derived from the new tool through the use of broadband dispersion curves associated with propagating borehole acoustic modes. In this paper, we highlight tool features that have an important impact on seismic, borehole seismic, and sonic applications. The acquired high quality waveforms and advanced processing techniques lead to improved compressional and shear slowness estimates, radial profiling of shear and compressional slowness, enhanced anisotropy detection and mechanism identification, and reliable through casing slowness measurements. Examples are shown from several wells in Norway and Mexico.

DEVELOPMENT OF A MONITORING SYSTEM FOR THE JOGMEC/NRCAN/AURORA MALLIK GAS HYDRATE PRODUCTION TEST PROGRAM

Design and construction of long term gas hydrate production facilities will require assessment of the in situ formation response to production at a field scale. Key parameters such as temperature and pressure are critical for the determination of phase conditions, others such as formation resistivity, formation acoustic properties and fluid mobility support the inference of gas hydrate saturation, permeability and porosity. An ability to continuously monitor the response of these parameters during the course of a production test would facilitate tracking of the dissociation front and yield valuable information for engineering design and verification of numerical reservoir simulators. Such a monitoring system has been designed, developed and introduced as a part of the Japan Oil, Gas and Metals National Corporation and Natural Resources Canada gas hydrate production testing program carried out in the winter of 2007 in the Mackenzie Delta, Canada. While the deployment of some sensors and the acquisition of some data sets were limited due to operational problems encountered during the field program, considerable experience has been gained during all phases of the research program. In particular, the acquisition and interpretation of downhole temperature profiles and changes in formation electrical potentials during testing provide insight into the production response of the reservoir and may assist in the understanding of operational conditions and related decision-making

An ultrasonic echo characterization approach based on particle swarm optimization

Presented is a hands-free approach for the extraction and characterization of ultrasonic echoes embedded in noise. By means of model-based nondestructive evaluation approaches, echoes can be represented parametrically by arrival time, amplitude, frequency, etc. Inverting for such parameters is a non-linear task, usually employing gradient-based, least-squared minimization such as Gauss-Newton (GN). To improve inversion stability, suitable initial echo parameter guesses are required which may not be possible under the presence of noise. To mitigate this requirement, particle swarm optimization (PSO) is employed in lieu of GN. PSO is a population-based optimization technique wherein a swarm of particles explores a multidimensional search space of candidate solutions. Particles seek out the global optimum by iteratively moving to improve their position by evaluating their individual performance as well as that of the collective. Since the inversion problem is non-linear, multiple suboptimal solutions exist, and in this regard PSO has a much lower propensity of becoming trapped in a local minima compared to gradient-based approaches. Due to this, it is possible to omit initial guesses and utilize a broad search range instead, which becomes far more trivial. Real pulse-echoes were used to evaluate the efficacy of the PSO approach under varying noise severity. In all cases, PSO characterized the echo correctly while GN required an initial guess within 30% of the true value to converge.

An automated framework for the extraction of ultrasonic echoes embedded in noise

Proposed is an automated framework for the extraction and characterization of the arriving echo in ultrasonic signals embedded in high noise. Commonly, in order to correctly characterize the first echo hidden within a noise-ridden signal, multiple traces are stacked in a gather to improve the SNR, hence facilitating easier extraction and characterization of the recorded echo. Such first order statistical methods require multiple traces and usually fall short in the accuracy of the echo estimate when the variance of the noise does not belong to a known distribution. To mitigate this problem, a framework has been developed comprised of a multi-step procedure, i.e., pre-processing, localization, gating and finally parameterization of the given echo. This automatic framework operates on single traces and does not require the setting of processing parameters. By means of this method, the true echo can be extracted in one-shot from other overlapping noise components. Furthermore, because the method operates on ...

Engineering design and field performance of an array‐type downhole seismic tool for cased hole VSP surveys

An array-type downhole seismic tool was developed for 5level 3-axis simultaneous data acquisition in cased hole. The primary design criteria were (1) mechanical simplicity for reliability and operational safety, (2) high quality acoustic performance and (3) data quality control capabilities. The individual sensor package was made mechanically reliable and acoustically robust by utilizing a permanent magnet as the tool clamping method. The acoustic isolator of each sensor package ias designed to isolate the sensor package from the dynamics of the array cable, and to ensure independent seismic recording at each depth. In-situ calibration and testing capabilities for the acquisition hardware were also implemented to ensure uniform performance among the sensor packages. Examples of the field data are shown to demonstrate the performance of the tool.