Geophysical Technologies Research Articles

Exploiting deep-gas resources through advanced geophysical technology

An outstanding SEG workshop on deep-gas resources was held in Muscat, Oman, on 3–5 November 2014. Seventy-five professionals attended from 14 countries, predominantly from the Middle East but also from around the world. The objective of the workshop was to bring geoscientists together to meet and exchange their experiences and views on geophysical-technology applications in exploiting deep-gas resources.

Mathematical modeling problems connected with pulsed neutron-gamma logging

The work is devoted to direct and inverse problems of the transport equation in the context of a nuclear geophysical technology based on pulsed neutron-gamma logging of inelastic scattering (PNGL-IS). In the first part of the paper we analyze the distribution of fast neutrons from a pulsed source of 14.1 MeV and study distributions of gamma-quanta of inelastic scattering. The particle distributions are computed by the Monte Carlo methods. In the second part of the paper we consider the problem of evaluating the elemental composition of the rock from the PNGL-IS measurement data. In its solution we use the method of successive approximations over characteristic interactions, which can be classified as a simple iteration; at each iteration step we solve the corresponding direct problem for the system of neutron and gamma-quantum transport equations. The main aspects of the employed method and the results of the numerical experiments that prove the convergence to the exact solution are presented.

Technology Focus: Seismic Applications (March 2014)

Technology Focus Some remarkable breakthroughs in data quality have been shared in recent reviews, and the ongoing technical developments in data acquisition and processing remain truly exciting. With an ever-growing toolbox of geophysical technologies, selecting the right technology solution, however, can be challenging. Fueled by many published success stories—for instance, about marine broadband streamer seismic or wide-azimuth surveys combined with reverse time migration—business expectations about achievable data quality and turnaround times are high. At the same time, the industry has to respond to increased public concerns about the effect of seismic activities on the environment. Tighter environmental and safety regulations are evolving for all areas, and, more than ever before, the industry has to demonstrate that seismic operations are managed in a responsible way. Detailed planning and survey design are needed to reduce the operational footprint and to minimize the environmental impact. The effect of sound and seismic measurements on marine life has been and remains a particular focus. Continued joint industry research efforts including environmental studies and marine source technologies have to alleviate public concerns and ensure that the dialogue with the public and regulators is supported by adequate scientific evidence. Scalable data-acquisition solutions are essential to meeting the high demands on data quality, survey productivity, reduced environmental impact, and cost. Scalable technologies enable smart, flexible, and cost-efficient survey designs that cope with the operational conditions and environmental constraints in the field while still meeting all processing and imaging requirements. The optimal balance between source and receiver efforts will always be a key design parameter, though the actual ratio obviously will vary with changing environments, survey sizes, and acquisition techniques. Ocean-bottom seismic surveys with cables or autonomous nodes do not yet offer the high channel count of advanced streamer seismic and generally depend on higher source efforts compared with towed-streamer seismic. For onshore surveys, the source density and achievable channel count will largely depend on terrain conditions, and solutions will differ between open desert environments and more challenging terrains with limited access. Against this background, the papers selected for this review should provide interesting examples for exploration, development, or reservoir monitoring in various settings and terrains. The commonality in the selected papers is the ability to tailor technology solutions to the dominating technical, operational, and environmental challenges, and to the prevailing business challenges. A career in geophysics has never been as integrated, as challenging, as interesting, and as rewarding as it is today. JPT Recommended additional reading at OnePetro: www.onepetro.org. IPTC 16907 Seismic-Velocity Uncertainty Analysis in an Underexplored Basin by R. Bacenetti, Eni, et al. IPTC 16804 Variable-Depth Streamer: Benefits for Rock-Property Inversion by L. Michel, CGG Veritas, et al. IPTC 16763 Marine Seismic Acquisition at Scott Reef, Western Australia: Minimizing Environmental Impacts in a Sensitive and Remote Location by Mark Taylor, Woodside Energy, et al.

Revisiting the International Exposition and 83rd Annual Meeting

The key numbers were expected to hit multiyear highs at SEG's International Exposition and 83rd Annual Meeting, held 22–27 September at the George R. Brown Convention Center in Houston, USA. Everything seemed in perfect alignment: first, the meeting was in Houston, where a significant fraction of the SEG membership is located; second, a vibrant business background buzz with major activity all around the world; and third, impressive advances in geophysical technology which have seen applications exploding in all directions.

The deep structure and paleogeodynamics of Siberia and Central Asia in studies of the Institute of the Earth’s Crust, SB RAS (2009–2013)

The deep structure and paleogeodynamics of the Siberian craton and the Central Asian folded belt are studied by two specialized laboratories of the Institute of the Earth’s Crust, SB RAS – the Laboratory of Complex Geophysics and the Laboratory of Paleogeodynamics. A variety of modern geophysical methods is applied. Surface wave tomography is focused on determination of 3D velocity structure of the upper mantle. Seismic, gravimetric and electrical surveys are aimed at stu­dies of structures of the crust and the upper mantle. Geothermic parameters of the lithosphere in Central Asia are measured. In search for mineral resources, new geophysical prospecting technologies are developed. Quality paleogeodynamics reconstructions require a proper understanding of the structural evolution of the Siberian craton and the Central Asian folded belt. Researches in this scientific field are conducted by the Laboratory of Paleogeodynamics. Besides, the Laboratory studies new minerals and conditions of their formation. Some of the scientific research projects are jointly implemented by the two laboratories, and research results are regularly published in Russia and abroad.

Study of Luming Molybdenum Mine West Zone EH4 Geophysical Prospecting and the Geological Structure Influence on Slope Stability

As the geological condition of western Luming molybdenum mine is broken and there are faults through, to find out the geological structures of west mine is quite significant for the study of Luming mine slope stability. With EH4 geophysical technology to detect west Luming molybdenum geological condition, the data of the detection point was collated and sorted out, through the inversion method, two faults F3 and F4 was inferred in the west zone of LuMing mine, which is likely to cause slope instability phenomena. What is more, at the northwest of the pit, lithology with water was composed of alluvial deposits and broken sediments, the depth of the strata with water is more than 80 miles. So the impact of water on slope stability should be fully considered during mining process.

Application of 3D fine seismic interpretation technique in Dawangzhuang Area, Bohai Bay Basin, Northeast China

One of the major problems in subsurface seismic acquisition, procession, and exploration we are facing today is the uncertainty in geologic interpretation because of the complexity of subsurface geology and the limited dimension of the subsurface data available (including drilling data, well logging, and core samples). Case studies from worldwide exploration projects indicate that an integrated, three-dimensional seismic volume visualization and interpretation workflow contributes greatly to resolving the problems we mentioned by extracting critical geologic information from within 3D seismic datasets. Over the last decade, with the increasing employment and improvement of geophysical technology and following 3D seismic data acquisition and processing, the subsurface seismic interpretation workflow is composed of four integrated stages from data selection and pre-procession, to structures, stratum, and facies characterization; to prospect prediction and evaluation; and to well-bore planning. In the data selection and pre-procession phase, the most favorable and frequently used datum is the full and limited angle and limited azimuth post-stack amplitude with significant structures, stratum, and facies enhancements. Signal-to-noise ratio, color scheme, dynamic range, bit resolution, and visual contrast all affect the visibility of features of interest. During the structures, stratum, and facies characterization phase, vertical slicing along arbitrary traverses demonstrates structure styles, stratigraphic architecture, and reservoir geometry in the cross-sectional view. Time/depth slicing defines lateral and vertical variability in the structural trend and areal extent in the map view. Stratal slicing and fault slicing suggest chronostratigraphic seismic facies, associated depositional information, and cross-stratal, along fault seismic signature. Volume flattening and structure restoration aid in unraveling paleo-structural framework, stratigraphic architecture, evolution, and filling histories. In the prospect prediction and evaluation phase, a combination of volume trimming, co-rendering, transparency, attribute analysis, and attribute body detection is instrumental in delineating volumetric extent and evaluating spatial connectivity of critical seismic features. Finally, in the well-bore planning phase, decision making relies on the integration of all the information and knowledge extracted from 3D seismic datasets. Most importantly, interpreters' geologic insights and employments of geophysical technology are crucial to optimal well-bore planning with high geologic potential and low economic risk. The structure of the study area, which is poorly understood to be primarily due to the complexity of subsurface geology and the limited dimension of the subsurface data available, and therefore, we design the integrated workflows and use some of the methods mentioned above to carry out fine seismic interpretation in an analysis of high-resolution 3D seismic data and other geological data in the study area. Finally, we finished the fine interpretation of 3D seismic data and achieved a series of success and good application results. The evolution of tectonics resulted in sub-tectonic units containing the sequences of Ek, Es, Ed, Ng, and Nm. Interpretation reveals that tectonic transition zone which controlled the evolution of the sequences because of its strength, and also, the structural pattern resulted in types of fault (such as “Y” type). The seismic interpretations provide new information on subsurface geology, including the recognition of complex structural patterns in rift lacustrine basin and the presence of a tectonic transition zone at the structural center. The interpretation of these seismic reflection profiles provides new insights into the structure, geological evolution, and petroleum potential of the study area.

Spatio-temporal variations in floodplain soil/sediment conductivity: Great Darling Anabranch

SUMMARY Spatio-temporal information on the distribution of salt in floodplain soils and groundwater is integral to effective floodplain management strategies along the Great Darling Anabranch in NSW. Geophysical technologies have the potential to provide detailed spatial information on the variability of salt stored in the near surface and for monitoring surface water -groundwater interactions across the floodplains, and in particular looking at the spatial controls on those processes. The research sought to examine the role of hydrogeophysical methods in monitoring changes in floodplain sediment condition, linked to ecological investigations. A two stage investigation, to examine the role of a low cost, near surface, geophysical method for monitoring changes across several sites located adjacent to the Anabranch. It represented a short term spatio-temporal investigation of inundation on salt in the floodplain. Our results clearly show changes in the near-surface conductivity distribution at the sites surveyed. These changes are attributed to variations in the flows over the year, pumping of groundwater and changes in vegetation. The survey shows that EM techniques are a useful tool in aiding our understanding of floodplain processes resulting from changes in flows along the Anabranch and can be applied in other floodplain environments as a lowcost survey to observe changes in conductivity in the near surface. It is an effective method to monitor variations in conductivity in the floodplains due to changes in environmental flows and can aid in understanding changes in sediment conditions and be used to validate floodplain processes, contributing to ecological investigations of river floodplains.

Engineering Geophysics for Geotechnical Characterisation of LNG Processing Plant Sites

New Liquefied Natural Gas (LNG) processing plants are being developed and constructed along the eastern and western seaboards of Australia. In support of tendering processes for engineering design and construction, geotechnical site investigations are required over these large construction site foot print areas. The foot print areas often span across remote and inaccessible onshore and nearshore marine environments. Previously the domain of the resource exploration industry, geophysical technology is now being increasing used to support traditional site investigation techniques in order to provide complete and accurate geotechnical characterisation of large LNG construction sites. High resolution and near-surface geophysical techniques, when integrated with intrusive sampling and testing, are proving to be a cost effective and reliable way to image and test large volumes of onshore and nearshore footprint areas. Geophysical techniques are particularly helpful where borings and intrusive testing are limited for reasons that may include investigation budget limitations, inaccessibility and environmental disturbance constraints. Integration of geophysics with geotechnical investigative techniques offers the potential to improve management of project risks and costs, as well as enhance understanding of site conditions. This article describes some proven geophysical techniques in geotechnical investigations of large footprint LNG construction sites.

SEAM Update

In September, SEAM Corporation signed a contract with Advanced Geophysical Technology to carry out simulations of 3D land-seismic data acquisition on the SEAM Unconventional Model. This model of shale reservoirs set in the stratigraphic sequence of a typical midcontinent basin was designed by members of SEAM Phase II to represent challenges in the exploration and characterization of unconventional plays with seismic methods. Previous articles in this series have described the geology of the Unconventional Model and its digital construction through work that was carried out on behalf of the consortium largely by BP, using its internal geologic modeling software, including a novel program for simulating the deposition of fine stratigraphic layers controlled by a set of geologic rules (Figure 1; see TLE March 2013, page 346). This article describes the acquisition plan for the simulations and some numerical features of the model.

Applying surface and borehole seismic methods to trenchless construction problems

Within cities and urban areas trenchless construction and tunnelling are preferred methods for providing new infrastructure mainly because of their social and environmental benefits. However, problems can occur when unexpected subsurface conditions are encountered or when relatively 'minor' geotechnical factors interact with the construction process in unexpected ways that create adverse outcomes. These can cause extensive project delays, major cost over-runs and legal disputation. Advanced geophysical technologies using combinations of marine, land and borehole seismic methods can assist with identifying and overcoming geotechnical problems encountered during trenchless construction. Case studies from recent civil infrastructure projects in Australia and China demonstrate the application of various seismic methods to a range of trenchless construction problems. These projects involve horizontal directional boring, pipe-jacking and micro-tunnelling in soils, mixed material and rock for pipeline and buried power cable installations. The case studies clearly show that appropriate seismic methods can assist in the solution of construction problems of a geological or geotechnical nature. This provides a new application area for engineering geophysics.

President's Page

SEG's mission, in part, is to inspire, connect, and propel the geophysicist and the application of geophysics. Therefore, SEG serves as the pipeline between its members and the transfer of geophysical ideas and technology. SEG has worked diligently to facilitate this process and prepare for its future. And as we all know, our young professionals are the future of SEG. So how has SEG supported their career goals?

The Research and Detection Practice of Geological Radar Technology

This document introduces basic principles of transmission in underground rock of ground penetrating radar (GPR) . Then an in-depth analysis on key parameters affecting the detection has been done, and detection resolution of radar are researched. By the technology, exploration experiments on Karst,little faults in coal seam and concealed metal drill pipe have been carried out. The results show that ground penetrating radar technology is a fast, efficient and intuitive geophysical detection technology, which provides a reliable technical means of solving the detection with close range and high precision.

The Applicated Comparation of Three Signal Analytical Methods for Ocean CSEM Signature

Sea is rich in oil and gas resources, the marine controlled source electromagnetic method (CSEM) is a kind of method seabed oil gas geophysical technology rising in recent years. Because of the problem of CSEM about the air wave in the shallow water, the research of time-frequnecy analysis technique is used to suppress the air wave in this paper. The basic idea is: because of the CSEM signals speed are different in the air and submarine, so the time which received by the receiving points are also different through these two kinds of ways. Using the time-frequency analysis technique and theoretical calculation, we can determine which part of the signal is spread over the ocean, so as to suppress the air wave effectively. This paper lists several methods of time-frequency analysis, such as Short-time Fourier transform, W-V distribution, Wavelet transform, Hilbert Huang transform. Through the time-frequency graph,we get the conclusion that HHT is better than others in concentration degree,and W-V distribution is better than STFT.Compared with the original signal, the time-frequency graph is the best in using Smooth Puseudo W-V Distribution.I have a detailed analysis about real case in using SPWVD at last.

Characteristic interactions and evaluation of the parameters of the transport equation and formation, including porosity, from data of measurements by some nuclear geophysical methods

An important but problematic component of nuclear geophysical technologies is computer inversion of measurement data based on the equation of particle transport. In this paper, we propose an approach and iterative methods for this inversion that are applicable to many problems of evaluation formation characteristics, including elemental composition, from data of corresponding logging methods. This approach is based on defining characteristic elements, interactions, and trajectories and using the superposition principle for transport processes, and linear a priori constraints on unknowns are used. In comparison with the previous publications of the author, this paper deals with a broader type of measurement data, including the reading ratio of detectors and normalized measurements. The iterative methods are specified for problems of determining the porosity and density from data of neutron-neutron and gamma-gamma logs, respectively. For the first of them, the results of numerical experiments are presented.

Integrated Application of Marine Geophysical Technology in a Seawall Reinforcement Project

Due to high risk and large investment of marine project, it is essential to obtain detailed seabed formation to support designing work, which is difficult to achieve just using traditional investigating method such as drilling. Based on such geophysical methods as water-depth measurement, side-scan sonar and acoustic shallow stratigraphic profiling, under the aegis of drilling work, the paper provides a comprehensive method to investigate seabed topography, locate embedded objects and identify adverse geological phenomena, which is directive to future study on integrated application of geophysical method to marine project.

Focus on Unconventional Reservoirs Requires Advancements in Technology

This article, written by Editorial Manager Adam Wilson, contains highlights of paper SPE 163988, ’Practical Insights and Benefits of Integrating Technology Into Exploration, Appraisal, and Development of Unconventional Gas and Liquid- Rich Shale Reservoirs,’ by Bora Oz, SPE, David Braun, SPE, Sanjay Vitthal, SPE, Viannet Okouma, SPE, Mathieu Molenaar, SPE, Chandran Peringod, SPE, Sergei Kazakoff, SPE, Yongyi Li, Michele Asgar-Deen, and David Langille, SPE, Shell Canada, prepared for the 2013 SPE Middle East Unconventional Gas Conference and Exhibition, Muscat, Oman, 28-30 January. The paper has not been peer reviewed. In the current high-oil-/low-gas-price North American environment, and considering the new options available for well-completions technology in unconventional reservoirs, recent industry activities have turned their focus to the areas of liquid-rich shale (LRS) and light tight oil (LTO) along with unconventional tight and shale gas. Integrated workflows are important to the successful execution of this portfolio, and cutting-edge integrated technologies must be viewed as key enablers. Introduction Commercially and economically viable shale plays require the presence of some key conditions, which fall into two groups: reservoir quality/productivity and fracability (i.e., the ability to place effective and conductive stimulations). Factors that affect reservoir quality and productivity are the matrix porosity and permeability, organic carbon content, maturity and kerogen type, and fluid composition and pressure/volume/temperature properties. Two key factors that affect fracability are mineralogy and local in-situ-stress magnitude, orientation, and distribution. To develop unconventional gas (UG), LTO, and LRS plays more effectively, significant advancements in understanding geological, geophysical, geochemical, geomechanical, petrophysical, reservoir, and stimulation properties have been made in the last decade. However, we are still just scratching the surface, and rapid integration across disciplines is required for success. In addition, continuous learning from exploration through to the end of field life must occur. Geophysical Practices and Technologies Geophysical technologies have always played a crucial role in the exploration and development of unconventional resources. They are used to define subsurface properties and to detect and monitor microseismic activities in the subsurface during completion and production. The recent, rapid increase in unconventional appraisal activity and the large diversity of geological settings require continuous innovation in geophysical-data collection, processing, and interpretation. Engineering activities, such as well and completion design, hydraulic-fracture monitoring, and production analysis and forecasting, are the major drivers for geophysical technologies. The three most common geophysical technologies are surface seismic, nonseismic methods (mainly potential-field methods), and microseismic or other downhole acoustic techniques (Fig. 1). For exploration and appraisal, a large number of 2D-seismic lines, with limited 3D-seismic surveys, are required data sets. In the development stage, 3D-seismic data are crucial for reservoir characterization and well placement (as well as engineering-related applications). Advanced interpretations have become an essential part of understanding play complexity, optimizing well placement, and mitigating drilling geohazards. Seismic data also play an important role in providing geological boundaries for building geological frameworks and geomechanical models.

Strategies for characterization of fractured rock using cross-borehole electrical tomography

There is an increasing need to characterize fractured rock systems and to monitor the movement of fluids in these systems. Fractured rock aquifers are increasingly exploited for water resources, and are subject to contamination from industrial activities at the Earth's surface. Deep rock repositories of hazardous waste must be carefully characterized in terms of fracture transport characteristics. More recently, there has been a surge in technologies designed to increase permeability of shale reservoirs by creating fractures to promote fluid removal. However, fractured rock systems present unique challenges for characterization and monitoring technologies. Fracturing typically generates highly heterogeneous and anisotropic systems, making the evaluation of the distribution of physical properties from sparse subsurface measurements particularly problematic. Geophysical imaging technologies are increasingly applied in an effort to overcome the limitations of sparsely located direct observations of subsurface properties. However, the application of geophysical technologies to fractured rock systems presents challenges for imaging as appropriate regularization model constraints for complex, heterogeneous systems are hard to define without additional subsurface information.

中国非常规油气物探技术的应用和发展

中国的非常规油气可采资源量巨大，目前仅处于勘探开发的初级阶段。地球物理勘探是油气勘探的关键技术，笔者分别从地震勘探、测井技术、重力勘探、磁法勘探、电法勘探等方面总结了物探技术在非常规油气勘探中的应用现状，并针对非常规油气的赋存特点，以及地球物理勘探技术的进展，提出了非常规油气物探技术的发展建议。 There are huge amount of unconventional oil and gas resources in China, which are still in the early stage of exploration and development at present. As the key technology, geophysical prospecting has played an important role in the exploration of oil and gas. Firstly, the application status of geophysical prospecting technology for unconventional oil and gas are respectively summarized in five aspects, such as seismic prospecting, logging technology, gravity prospecting, magnetic prospecting and electrical prospecting. Finally, some suggestions for the development of geophysical technology for unconventional oil and gas are put forward in order to improve the level of exploration.

Application of Geophysical Technology in Prevention of Mining Geological Disasters

The prevention of geological disasters in the coal mine, integrated geophysical technology was used to avoid geological disasters in coal mine, build a harmonious society and improve economic efficiency is of great significance. In this paper the development of geophysical technology was analyzed, the correct use of geophysical technology and geological disaster prevention are described, It briefly introduced seismic exploration, electrical geophysical technology such as the basic concepts and exploration results and looked forward to the prospect of integrated geophysical technology .By exploration cases it described geophysical exploration methods in the prevention of geological disasters in the coal mine practicality and effectiveness.