Reliable and economical high-temperature deep-borehole seismic recording

1996 ◽  
Vol 86 (1A) ◽  
pp. 204-211
Author(s):  
Derek V. Manov ◽  
Rachel E. Abercrombie ◽  
Peter C. Leary
Keyword(s):  
Site Effects ◽  
Oil Well ◽  
Deep Borehole ◽  
Reliable System ◽  
Active Sensors ◽  
Near Surface ◽  
Active Tectonic ◽  
Seismic Recording ◽  
Source Scaling ◽  
Borehole Seismic

Abstract Recording earthquakes with borehole seismometers has become increasingly popular in recent years as the advantages in noise reduction and also the distorting effects of near-surface rocks, especially sediments, have become well known. Borehole recording can be extremely complex, involving active sensors, special cables, and downhole electronics. Such installations, however, are often not very reliable at the high temperatures reached in active tectonic areas at depths of 1 km and greater. Here we describe a simple and reliable system for 3-component recording of local earthquakes at single and multiple depths greater than 1.5 km and temperatures up to 120°C. Our system was designed and developed for experiments in the Cajon Pass Scientific Drillhole of Southern California. The borehole packages are made of titanium with spring-loaded clamping, allowing easy retrieval. Standard seven-conductor oil-well logging cables are used together with a specially designed cablehead. The data recorded have been used for investigating earthquake source scaling, attenuation in the mid-crust, and also near-surface site effects.

Application of Site Amplification Factors to Determine the Local Magnitude from Borehole Seismic Stations in Taiwan

2020 ◽  
Author(s):  
Tz-Shin Lai ◽  
Yih-Min Wu ◽  
Wei-An Chao
Keyword(s):  
Site Effect ◽  
Site Amplification ◽  
Force Balance ◽  
Earthquake Catalog ◽  
Local Magnitude ◽  
Broadband Seismometer ◽  
Near Surface ◽  
Amplification Factors ◽  
Attenuation Function ◽  
Borehole Seismic

<p>Since the inception of 62 borehole seismic arrays deployed by Central Weather Bureau (CWB) in Taiwan until the end of 2018, a large quantity of strong-motion records have been accumulated from frequently occurring earthquakes around Taiwan, which provide an opportunity to detect micro-seismicity. Each borehole array includes two force balance accelerometers, one at the surface and other at a depth of a few ten-to-hundred (30-492) meters, as well as one broadband seismometer is below the borehole accelerometer. In general, the background seismic noise level are lower at the downhole stations than surface stations. However, the seismograms recorded by the downhole stations are smaller than surface stations due to the near-surface site effect. In Taiwan, the local magnitude (M<sub>L</sub>) determinations use the attenuation function derived from surface stations. Therefore, the M<sub>L</sub> will be underestimated by using current attenuation function for downhole stations. In this study, we used 19079 earthquakes to investigate the site amplification at subsurface materials between downhole and surface stations. Results demonstrate the amplification factors ranging from 1.11 to 5.74, provide the site effect parameter at shallow layers and have a strong relationship with Vs30. Further, we apply the amplification factors to revise the station local magnitude for downhole station. The revised M<sub>L</sub> at downhole stations correlate well with the M<sub>L</sub> at surface stations. Implement of the downhole station in the M<sub>L</sub> determination, it enhances the ability to detect the micro-earthquake and makes the earthquake catalog more comprehensive in Taiwan.</p>

scholarly journals Apparent break in earthquake scaling due to path and site effects on deep borehole recordings

2003 ◽  
Vol 108 (B5) ◽  
Author(s):  
Satoshi Ide ◽  
Gregory C. Beroza ◽  
Stephanie G. Prejean ◽  
William L. Ellsworth
Keyword(s):  
Site Effects ◽  
Deep Borehole ◽  
Earthquake Scaling

scholarly journals Ground surface-temperature reconstruction based on data from a deep borehole in permafrost at Janssonhaugen, Svalbard

2000 ◽  
Vol 31 ◽  
pp. 287-294 ◽  
Author(s):  
Ketil Isaksen ◽  
Daniel Vonder Mühll ◽  
Hansueli Gubler ◽  
Thomas Kohl ◽  
Johan Ludvig Sollid
Keyword(s):  
Surface Temperature ◽  
Phase Speed ◽  
Ground Surface ◽  
Temperature Reconstruction ◽  
Geothermal Gradient ◽  
Temperature History ◽  
Deep Borehole ◽  
Near Surface ◽  
Ground Surface Temperature ◽  
Average Value

AbstractAnalyses of the geothermal gradient in permafrost areas constitute a key signal of the ground-surface temperature history. Permafrost temperatures in selected areas are particularly well suited to reconstructing past surface-temperature changes, mainly because there is no thermal disturbance due to circulating groundwater. One year of temperature data from an instrumented 102 m deep borehole in permafrost on Janssonhaugen, Svalbard, is presented. Ground thermal properties are calculated. The average value for the thermal conductivity is 1.85 ±0.05 W m–1 K–1 , and the average value for the thermal diffusivity is 1.1m2 s–1, which gives a phase speed for the annual wave of 5.65 × KT2 m d–1. The depth of zero annual amplitude is 18 m The permafrost thickness is estimated as approximately 220 m. Analysis of the temperatures reveals an increasing temperature gradient with depth. Using a heat-conduction inversion model, a palaeoclimatic reconstruction is presented, showing a warming of the surface temperature over the last 60–80 years. The temperature profile represents a regional signal on Svalbard, which shows an inflection associated with near-surface warming of 1.5 ± 0.5°C in the 20th century.

Characteristics of Cementitious Paste for use in Deep Borehole Disposal of Spent Fuel and High Level Wasteforms

2015 ◽  
Vol 1744 ◽  
pp. 205-210 ◽  
Author(s):  
Nick C Collier ◽  
Karl P Travis ◽  
Fergus G F Gibb ◽  
Neil B Milestone
Keyword(s):  
Spent Nuclear Fuel ◽  
High Level Waste ◽  
Hardened Cement ◽  
Oil Well ◽  
Deep Borehole ◽  
Sodium Gluconate ◽  
Spent Fuel ◽  
High Temperature And Pressure ◽  
Temperature And Pressure ◽  
High Level

ABSTRACTDeep borehole disposal (or DBD) is now seen as a viable alternative to the (comparatively shallow) geologically repository concept for disposal of high level waste and spent nuclear fuel. Based on existing oil and geothermal well technologies, we report details of investigations into cementitious grouts as sealing/support matrices (SSMs) for waste disposal scenarios in the DBD process where temperatures at the waste package surface do not exceed ∼190ºC. Grouts based on Class G oil well cements, partially replaced with silica flour, are being developed, and the use of retarding admixtures is being investigated experimentally. Sodium gluconate appears to provide sufficient retardation and setting characteristics to be considered for this application and also provides an increase in grout fluidity. The quantity of sodium gluconate required in the grout to ensure fluidity for 4 hours at 90, 120 and 140°C is 0.05, 0.25 and 0.25 % by weight of cement respectively. A phosphonate admixture only appears to provide desirable retardation properties at 90°C. The presence of either retarder does not affect the composition of the hardened cement paste over 14 days curing and the phases formed are durable under conditions of high temperature and pressure.

scholarly journals Specificity of the seismic material obtained in complex seismo geological conditions (swamp zone)

2019 ◽  
Author(s):  
А.А. Левицкий ◽  
А.В. Рудаков ◽  
М.С. Левицкая
Keyword(s):  
Negative Impact ◽  
Seismic Source ◽  
Integrated Approach ◽  
Seismic Exploration ◽  
Near Surface ◽  
Factors Affecting ◽  
Geological Conditions ◽  
Seismic Recording ◽  
Surface Section

Основная цель работы – описание новых технических и методологических средств, используемых АО «Южморгеология» при проведении полевых сейсморазведочных работ МОГТ 3D в лиманно-плавневых зонах Славянского района Краснодарского края в 2014-2015 гг. Представлены основные результаты опытных работ, обоснован выбор параметров съемки и их влияние на качество сейсмической записи: заглубление пневмоисточников BOLT 2200LL-BHS, количество накоплений возбуждения и необходимая глубина погружения датчиков регистраторов. В качестве датчиков регистраторов использовались маршфоны «СВГ-6», которые задавливались с помощью металлического шеста с креплением на конце на глубину 1,0–2,5 м до достижения уверенного контакта с твердой поверхностью (плотный грунт, глинистая подошва), снижая негативное влияние шумов (микросейсм) от корневой системы камышей (рис. 2А, В). Группирование «СВГ-6» шестью последовательно соединенными геофонами (GS-20DX) увеличило чувствительность датчика к слабым сигналам, возбуждаемым, в слабо консолидированной толще, а его прочная конструкция и металлическая проушина, позволила извлекать маршфон из скважины, полностью заполненной водой и шламом.  Приведены основные свойства верхней части разреза (ВЧР) исследуемой площади по данным бурения с кратким описанием литологической характеристика разреза до глубины 10 м. Показаны сейсмограммы, полученные на одном участке в разных сейсмогеологических условиях. Выявлена зависимость распределения значений среднеквадратичных амплитуд и доминантных частот по площади от поверхностных условий возбуждения и приема колебаний. Данная зависимость также прослеживается на предварительных временных разрезах. Были проанализированы основные факторы, влияющие на качество получаемого сейсмического материала. На основе проведенного исследования авторами обосновывается необходимость использования комплексного подхода к анализу качества сейсмических данных при работах в сложных сейсмогеологических условиях. В качестве вывода приведены основные рекомендации к проведению сейсморазведочных работ в лиманно-плавневых зонах. The main objective of the work is the description of new technical and methodological tools used by Yuzhmorgeologiya JSC when conducting CDP 3D field seismic surveys in the estuaries of the Slavyansk district of the Krasnodar Region in 2014-2015. The main results of the experimental work are presented; the choice of survey parameters and their impact on the quality of the seismic recording is validated: digging-in of the seismic source points BOLT 2200LL-BHS, the number of excitation accumulations and the required depth of recorder sensors. Geophones “SVG-6” were used as sensors of the recorders, which were crushed with a metal pole with a fastening at the end to a depth of 1.0–2.5 m until steady contact with a solid surface (dense soil, clay base) was achieved, reducing the negative impact noise (microseism) from the root system of reeds (Fig. 2A, B). Grouping the SVG-6 with six consecutive geophones (GS-20DX) increased the sensitivity of the equipment to weak signals being excited in a weakly consolidated layer, and its robust design and metal eye, made it possible to extract the geophone from a well completely filled with water and sludge. The basic properties of the upper part of the section (near-surface section) of the studied area are given according to the drilling data with a brief description of the lithological characteristics of the section to a depth of 10 m. Seismograms obtained at one site in different seismic and geological conditions are shown. The dependence of the distribution of values of root-mean-square amplitudes and dominant frequencies over the area on the surface conditions of excitation and reception of vibrations is revealed. This dependence is also observed in the preliminary time sections. The main factors affecting the quality of the obtained seismic material were analyzed. Based on the present study, the authors validate the need for the use of an integrated approach to analyzing the quality of seismic data when working under complex seismic and geological conditions. As a conclusion, the main recommendations for seismic exploration in the estuaries are presented.

Transmission-based near-surface deconvolution

Geophysics ◽  
2020 ◽  
Vol 85 (2) ◽  
pp. V169-V181 ◽  
Author(s):  
Daniele Colombo ◽  
Diego Rovetta ◽  
Ernesto Sandoval-Curiel ◽  
Apostolos Kontakis
Keyword(s):  
Seismic Data ◽  
Reservoir Characterization ◽  
Complex Structure ◽  
Seismic Source ◽  
Time Lapse ◽  
Near Surface ◽  
Early Arrival ◽  
Seismic Recording ◽  
Exploration Area ◽  
Scalar Amplitude

We have developed a new framework for performing surface-consistent amplitude balancing and deconvolution of the near-surface attenuation response. Both approaches rely on the early arrival waveform of a seismic recording, which corresponds to the refracted or, more generally speaking, to the transmitted energy from a seismic source. The method adapts standard surface-consistent amplitude compensation and deconvolution to the domain of refracted/transmitted waves. A sorting domain specific for refracted energy is extended to the analysis of amplitude ratios of each trace versus a reference average trace to identify amplitude residuals that are inverted for surface consistency. The residual values are either calculated as a single scalar value for each trace or as a function of frequency to build a surface-consistent deconvolution operator. The derived operators are then applied to the data to obtain scalar amplitude balancing or amplitude balancing with spectral shaping. The derivation of the operators around the transmitted early arrival waveforms allows for deterministically decoupling the near-surface attenuation response from the remaining seismic data. The developed method is fully automatic and does not require preprocessing of the data. As such, it qualifies as a standard preprocessing tool to be applied at the early stages of seismic processing. Applications of the developed method are provided for a case in a complex, structure-controlled wadi, for a seismic time-lapse [Formula: see text] land monitoring case, and for an exploration area with high dunes and sabkhas producing large frequency-dependent anomalous amplitude responses. The new development provides an effective tool to enable better reservoir characterization and monitoring with land seismic data.

Tube-wave monitoring as a method to detect shear modulus changes around boreholes: A case study

Geophysics ◽  
2021 ◽  
pp. 1-69
Author(s):  
Daniel Wehner ◽  
Filipe Borges ◽  
Martin Landrø
Keyword(s):  
Shear Modulus ◽  
Body Waves ◽  
Rock Properties ◽  
Step Method ◽  
Monitoring Method ◽  
Near Surface ◽  
Wave Measurements ◽  
Geological Formation ◽  
Tube Wave ◽  
Borehole Seismic

Monitoring the shear modulus of formations around boreholes is of interest for various applications, ranging from near-surface investigation to reservoir monitoring. Downhole logging tools and borehole seismic are common techniques applied to measure and characterize formation properties. These methods rely on transmitted and reflected waves to retrieve the rock properties. Wave modes travelling along the interface between the well and the formation, such as tube waves, are often considered as noise. However, tube waves are less attenuated than body waves, and contain information about the shear modulus of the formation surrounding the well. Hence, a potential use of this interface wave is of interest. As tube-wave properties depend on several parameters, e.g. well geometry, highly accurate measurements should be performed for use in inferring rock properties. We study the feasibility of tube-wave measurements as a monitoring method. Different experiments are conducted using a hydrophone array in two boreholes, with depths of 30 m and 95 m. The experiments are used to investigate how accurate the tube-wave velocity can be measured, and which parameters have most impact on the measurements. Our results suggest that it is hard to estimate the absolute shear modulus of the geological formation using tube-wave velocities only. However, it seems feasible to use them to monitor changes of the shear modulus, depending on the borehole set up and geological formation. The tube-wave monitoring can be used as a first step method to determine the depth along the well where changes occur before more accurate measurements are performed in a second step.

Fault zone trapped seismic waves

1990 ◽  
Vol 80 (5) ◽  
pp. 1245-1271 ◽  
Author(s):  
Y.-G. Li ◽  
P. C. Leary
Keyword(s):  
Fault Zone ◽  
Seismic Waves ◽  
Fault Plane ◽  
Body Wave ◽  
Velocity Model ◽  
Trapped Waves ◽  
Low Velocity ◽  
Near Surface ◽  
San Andreas ◽  
Borehole Seismic

Abstract Two instances of fault zone trapped seismic waves have been observed. At an active normal fault in crystalline rock near Oroville in northern California, trapped waves were excited with a surface source and recorded at five near-fault borehole depths with an oriented three-component borehole seismic sonde. At Parkfield, California, a borehole seismometer at Middle Mountain recorded at least two instances of the fundamental and first higher mode seismic waves of the San Andreas fault zone. At Oroville recorded particle motions indicate the presence of both Love and Rayleigh normal modes. The Love-wave dispersion relation derived for an idealized wave guide with velocity structure determined by body-wave travel-time inversion yields seismograms of the fundamental mode that are consistent with the observed Love-wave amplitude and frequency. Applying a similar velocity model to the Parkfield observations, we obtain a good fit to the trapped wavefield amplitude, frequency, dispersion, and mode time separation for an asymmetric San Andreas fault zone structure—a high-velocity half-space to the southwest, a low-velocity fault zone, a transition zone containing the borehole seismometer, and an intermediate velocity half-space to the northeast. In the Parkfield borehole seismic data set, the locations (depth and offset normal to fault plane) of natural seismic events which do or do not excite trapped waves are roughly consistent with our model of the low velocity zone. We conclude that it is feasible to obtain near-surface borehole records of fault zone trapped waves. Because trapped modes are excited only by events close to the fault zone proper—thereby fixing these events in space relative to the fault—a wider investigation of possible trapped mode waveforms recorded by a borehole seismic network could lead to a much refined body-wave/tomographic velocity model of the fault and to a weighting of events as a function of offset from the fault plane. It is an open question whether near-surface sensors exist in a stable enough seismic environment to use trapped modes as an earth monitoring device.

Wellbore and Near-Surface Hydraulics of a Blown-Out Oil Well

1981 ◽  
Vol 33 (11) ◽  
pp. 2181-2188 ◽  
Author(s):  
A.R. Clark ◽  
T.K. Perkins
Keyword(s):  
Oil Well ◽  
Near Surface
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