The interpretation method iteratively ray traces and then updates the velocity model. Application of seismic methods for geotechnical site characterization p. This method is also called cross hole seismic method. Estimation of seismic velocities using crosshole method yielded best results at heavy engineering structure sites dobecki, 1979. Crosshole electromagnetic and seismic modeling for co2. Crosshole seismic reflection surveying in coal measures.
Crosshole seismic testingprocedures and pitfalls seg library. In a seismic crosshole test, the accuracy of a velocity tomogram depends on several factors such as the distance between the source and receivers, measurement of the seismic wave travel time, ray tracing technique, among others. Timepicking methods for seismic crosshole data with low signaltonoise ratio. Seismic reflection methods environmental geophysics us epa. There are two modes of operation for crosshole seismic methods. The research of reversetime migration for crosshole seismic. D4428 d4428m14 standard test methods for crosshole seismic testing precision cross hole seismic test seismic crosshole method. Fewer boreholes are needed to achieve a continuous picture of the subsurface thereby reducing overall costs and the risk of missing target features. Seismic rays are used instead of the wave front to describe the wave propagation.
Crosshole or crosswell seismic measures the velocity of seismic waves between boreholes. Seismic crosshole method the seismic crosshole method consists of measuring the travel time of seismic waves propagating from a seismic energy source downhole hammer located in one borehole, to detectors downhole geophones placed at the same depth in adjacent boreholes. The experiments were composed of crosshole electromagnetic surveys between fiberglass cased boreholes in both frequency domain and time domain methods together with seismic tomography. Drilling at the barrage site of a hydropower project usually gives a reasonable picture of the subsurface rock mass condition. However, crosshole geophysical testing may show that the ground has been suitably improved in some cases where cone penetration tests are unable to demonstrate an equivalent level of improvement. Each crosshole test consisted of a set of three boreholes oriented in a linear fashion, spaced 2. Crosshole seismic tomography geophysics geoscienceworld. This alone justifies use of the crosshole seismic method in. This procedure is covered by an astm guideline but has several variants.
Highlights we develop a rockphysics methodology of electromagnetic and seismic propagation. Pdf soil exploration and geophysical methods find, read and cite all the research you need on researchgate. The crosshole seismic method generally results in more accurate and detailed profiles than other seismic methods 5, 11,26,27. The conventional approach involves lowering a 3component borehole geophone down one hole while lowering a source down an adjacent holes, firing the source at some prescribed depth interval. The crosshole seismic reflection method in opencast coal. A sleeve surrounds this section of the drill pipe and includes a cam follower, a. Pdf crosshole seismic testing is a valuable technique for determining seismic velocity profiles for critical structure siting investigations. Users of these test methods are cautioned that compliance with practice d3740 does not in itself assure reliable results. The standard assumes that the method used to analyze the data obtained is based on first arrival times or interval arrival times over a measured distance. When both test methods are used in conjunction, certain characteristics of a potential defect may be clari.
Seismic survey, method of investigating subterranean structure, particularly as related to exploration for petroleum, natural gas, and mineral deposits. The investigation was conducted in accordance with the requirements in astm d4428 standard test methods for crosshole seismic testing and astm d7400 standard test methods for downhole seismic testing. Second, it significantly increases the resolution capability of observations. The cross hole seismic technique provides good results compared to laboratory methods in certain cases young, 1961. Cross hole shearwave electromagnetic hammer with inflated tube clamping system. Ye yincan et al, in marine geohazards in china, 2017. Quantifying compressible groundwater storage by combining. Improved hydrogeophysical characterization using joint. Crosshole electromagnetic and seismic modeling for co 2 detection. Standard test methods for downhole seismic testing1. This, in conjunction with a thorough analysis using our new method, demonstrates that specific storage has a physical upper limit.
Inventory and risk assessment manual aumira section 3. It allows for direct path measurements associated with each set of impacts. Geotomographie, founded in 1999 in germany, provides complete solutions for borehole and nearsurface seismic surveys to geophysical, engineering and mining companies. This section does not present every detail of the acquisition and processing of shallow seismic reflection data. Crossholedownhole seismic csds investigations provide information on dynamic soil and rock properties. Application of crosshole seismic technique and mafiadoc. It is assumed that downhole and crosshole tests have similar results. In the present case, the depth to the granitic gneiss basement is 45m from the river level and the height of the. Hole seismic surveys and head response to atmospheric tides. Invariant are requirements to measure both p and s waves and to use a reversible source to aid in.
Crossholedownhole seismic csds investigations provide. Crosshole sonic logging csl is a method to verify the structural integrity of drilled shafts and other concrete piles the csl method is considered to be more accurate than sonic echo testing in the determination of structural soundness of concrete within the drilled shaft inside of the rebar cage. Seismic cross hole method the seismic cross hole method consists of measuring the travel time of seismic waves propagating from a seismic energy source downhole hammer located in one borehole, to detectors downhole geophones placed at the same depth in adjacent boreholes. Crosshole seismic method this technique is by far the most reliable method for shear wave velocity determination. Geophysics at the borehole and crossborehole scale carole johnson, john lane and john williams ogwbranch of geophysics. The ultimate product of a seismic reflection survey is a corrected cross section of the earth with reflection events in their true subsurface positions. Geophysical techniques surface and borehole geophysics. Part 1 within a borehole part 2 between the boreholes part 2 deals with the method in which generation is in a borehole and detection is in one or more nearby holes. Application of crosshole tomography for assessment of. Astm d6760 16 standard test method for integrity testing.
The primary advantage, however, is subsurface resolution which is not possible with sur face methods. Specific geologic conditions, such as bedrock fractures or valleys, may be interpreted directly from these timedistance plots or by using several seismic modeling techniques. It plays a key role in the discovery of submarine gas hydrate. Astm d6760 16 standard test method for integrity testing of. Seismic method including single channel seismic and multichannel seismic method is one of the most effective methods for the identification and prediction of submarine gas hydrate. The method is applied to the detection of co 2 in crosswell experiments. It is assumed that down hole and cross hole tests have similar results. From these measurements, parameters, such as poissons ratios and moduli, can be easily determined. We adopt a similar approach to simultaneously invert crosshole ert and mog gpr traveltime data in three dimensions. Seismic tomography, crosshole, downhole geotomographie gmbh. This method provides little indication of concrete soundness outside the cage. Interpretation of seismic crosshole measurements with the.
The crosshole seismic method is a common procedure used to determine. Geosciences free fulltext application of crosshole. Crosshole testing takes advantage of generating and recording seismic body waves, both the p and s. Geophysics at the borehole and crossborehole scale carole johnson, john lane. Standard test methods for crosshole seismic testing1 this standard is issued under the. The geophysical survey called crosshole consists in the determination of horizontally travelling compression p and shear s seismic waves at test. The time domain electromagnetic survey was designed to test the. We compute the magnetic field and synthetic seismograms.
We use the whitecrim relation between seismic velocity and. Disclosed is a seismic source forming part of a drill string which allows geological prospecting while drilling a borehole. Comparing crosshole sonic logging and lowstrain integrity. First it is hammered on one of its ends and a record is made. Crosshole sonic logging csl, also known as cross sonic logging or the sonic logging test is the most accurate and reliable technique for assessing the integrity of deep foundation elements such as newly placed concrete drilled shafts and slurry walls, particularly when drilling below groundwater level.
We propose a crosshole imaging approach based on seismoelectric conversions sc associated with the transmission of seismic waves from seismic sources located in a borehole to receivers electrodes located in a second borehole. General crosshole procedures environmental geophysics. Every point on the wave front is a source of a new wave that travels out of it in the form of spherical shells. Figure 1 illustrates a general field setup for the crosshole seismic test method. The source includes a section of drill pipe having a spiral cam machined into its outer surface and a port for allowing mud to flow from the inside of the drill pipe into the borehole. This thesis is concerned with the development of the crosshole seismic reflection surveying method with particular application to the shallow coal measures strata found in opencast coal mining prospects in the u. Application of crosshole tomography for assessment of soil.
Overview historical data and geologic maps surface geophysics borehole geophysics crosshole testing hydraulic measurements hydraulic. Standard test methods for downhole seismic testing1 this standard is issued under the. A number in parentheses indicates the year of last reapproval. Here we report on the development of the crosshole reflection method, making use of open cast exploration boreholes, to provide seismic cross. Shake estimate the soil seismic response for a plane layered model thickness and shear velocity of each layer. We develop a rockphysics methodology of electromagnetic and seismic propagation. Manufacturer of seismic borehole equipment for tomography, crosshole and downhole applications. Abstract in seismic migration, it is important to sample a range of dips around the local structural dip at each image point. Seismic survey is the geophysical method, which is most closely related to rock and soil. View enhanced pdf access article on wiley online library. Crosshole seismic overview a threeaxis geophone is lowered into a speciallyprepared, cased borehole and excited with a hammer source in a similar borehole nearby. Crosshole survey consists in the direct measurements of horizontally travelling. This website beta version contains information on geophysical methods, references to geophysical citations, and a glossary of geophysical terms related to environmental applications.
Timepicking methods for seismic crosshole data with low. Travel times are used to determine p and s wave velocities, which can be used to compute poissons ratio, as well as the other elastic moduli. These advantages and weaknesses are discussed in this paper. Application of modern seismic methods for geotechnical. The estimation of the quality factor q plays a fundamental role in enhancing seismic resolution via absorption compensation in the nearsurface layer.
First, the crosshole seismic tomography method eliminates depthrelated restrictions during observations compared to the surface methods, which allows for the conduction of surveys down in deep depths even given constricted conditions within an urban area. We use the whitecrim relation between seismic velocity and electrical conductivity. In the present case, the depth to the granitic gneiss basement is 45m from the river level and the height of. We present a new geometry that can be used to acquire field data by combining surface and crosshole surveys to decrease the effect of geophone coupling on q estimation. Meaningful images are obtained only where this condition holds. Individually, each test method has its own advantages and weaknesses inherent in the test method. Reservoir monitoring by crosshole electromagnetic and. The crosshole seismic method is a very accurate and detailed profiling method. Crosshole acquisition geometries are common to many geophysical methods. The conventional approach involves lowering a 3component borehole geophone down one hole while lowering a source down an adjacent hole s, firing the source at some prescribed depth interval. Crosshole seismic tomography with crossfiring geometry ying rao1, yanghua wang2, shumin chen3, and jianmin wang3 abstract we have developed a case study of crosshole seismic tomography with a crossfiring geometry in which seismic sources were placed in two vertical boreholes alternatingly and receiver arrays were placed in another vertical.
General crosshole procedures environmental geophysics us epa. A field acquisition technique developed for shallow boreholes utilising explosive sources and hydrophone receivers is described. Crosshole seismic testing is a valuable technique for determining seismic velocity profiles. Read crosshole seismic technique for assessing in situ rock mass conditions around a tunnel, international journal of rock mechanics and mining sciences on deepdyve, the largest online rental service for scholarly research with thousands of academic publications available at your fingertips. Nov 23, 20 drilling at the barrage site of a hydropower project usually gives a reasonable picture of the subsurface rock mass condition. Crosshole and downhole tests can be used to measure vs. These tubes are usually attached to the reinforcement cage along the full length of the shafts. Improper field procedures, however, can result in the acceptance of apparent velocities as true velocities, leading to unconservative design values. Among the geophysical methods used to obtain the insitu seismic velocities. The crosshole seismic cs system and method determine shear and compressional wave velocity versus depth profiles. Pdf seismic refraction and crosshole techniques for. However, when the overburden ob comprising river borne materials is very thick and the basement rock is deep, the drilling results become unreliable. Assessing drilled shaft integrity with crosshole sonic logging.
Multihole seismic modeling in 3d space and crosshole. We show how to obtain traveltime picks for electromagnetic and seismic tomography. The crosshole seismic technique provides good results compared to laboratory methods in certain cases young, 1961. Pdf crosshole seismic testingprocedures and pitfalls. Seismic refraction and crosshole techniques for investigate the top soil and water table beneath the high pumping station hall of alhussian water supply. Seismic methods can provide detailed information about rock properties and geological structure between boreholes. Owing to the high cost of this test, the cone penetration test method is generally used.
Many foundation dynamics and soilstructure interaction problems require insitu values of shear wave velocities and elastic moduli, or both, for foundation materials. Quantifying compressible groundwater storage by combining cross. Crosshole survey consists in the direct measurements of horizontally travelling compression p and shear s seismic waves at test sites consisting primarily of. A read is counted each time someone views a publication summary such as the title, abstract, and list of authors, clicks on a figure, or views or downloads the fulltext.
Us8689929b2 excitation device and method for downhole. Measurement of seismicwave travel time is one of the most common geophysical method. Dec 18, 2012 this thesis is concerned with the development of the cross hole seismic reflection surveying method with particular application to the shallow coal measures strata found in opencast coal mining prospects in the u. We propose finite difference scheme of higher order, and then derive its stability condition in crosshole seismic. D676016 standard test method for integrity testing of concrete deep foundations by ultrasonic crosshole testing ultrasonic cross hole test augercast piles bored piles diaphragm walls ultrasonic probes dams drilled shaft. However, this method often cannot detect thin slow strata. Cross hole and down hole tests can be used to measure vs. The cross hole seismic method generally results in more accurate and detailed profiles than other seismic methods 5, 11,26,27. We propose a cross hole imaging approach based on seismoelectric conversions sc associated with the transmission of seismic waves from seismic sources located in a borehole to receivers electrodes located in a second borehole. The technique is based on determining the time interval that elapses between the initiation of a seismic wave at a selected shot point the location where an explosion generates seismic waves and the arrival of reflected or refracted impulses. Crosshole seismic testing is a valuable technique for determining seismic velocity profiles for critical structure siting investigations.
Seismic response are plotted through distance along the geophone array to identify individual layers, and to compute layer thicknesses and seismic velocities. Drilled shafts are prepared for i ntegrity testing by csl during their construction by installation of at least three tubes with a minimum inside diameter of 38mm 1. According to the features of crosshole survey and crosshole data, we put forward a reversetime migration method which is suitable for the wave equation for crosshole seismic data. Crosshole seismic tomography with crossfiring geometry. According to the literature, the seismic piezocone test has proven to be a fast, economical and reliable method to determine go.
Downhole survey a sturdy hardwood board is laid beside the wellhead, and a downhole seismic, three component, clamping geophone is lowered into the hole. Photograph 7 setup for crosshole seismic shear wave measurements. The project engineer has at his disposal several methods for determining these properties in situ. It is then clamped at intervals, commonly five feet, and at each interval the board is hammered.
First, the crosshole seismic tomography method eliminates depthrelated restrictions during observations compared to the surface methods. The present invention is also directed to providing an excitation device for downhole seismic testing and a method for downhole seismic testing using the same, which employs an existing observation hole for observing an underground water level, instead of constructing a separate test hole which requires an operation for abandoning the hole, and. Empirical relation for estimating shear wave velocity from. D4428 d4428m14 standard test methods for crosshole seismic testing precision crosshole seismic test seismic crosshole method. Standard test methods for crosshole seismic testing. A typical seismic crosshole tomographic geometry consists of sources and detectors located in separate boreholes as shown in figure 10.