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Instrumenting wells with distributed acoustic sensors (DASs) and illuminating them with passive or active seismic sources allows precise tracking of temporal variations of direct-wave traveltimes and amplitudes, which can be used to monitor variations in formation stiffness and density. This approach has been tested by tracking direct-wave amplitudes and traveltimes as part of a carbon capture and storage project where a 15 kt supercritical CO2 injection has been monitored with continuous offset vertical seismic profiling using nine permanently mounted surface orbital vibrators acting as seismic sources and several wells instrumented with DAS cables cemented behind the casing. The results indicate a significant (from 15% to 30%) increase of strain amplitudes within the CO2 injection interval, and traveltime shifts of 0.3–0.4 ms below this interval, consistent with full-wave 1.5D numerical simulations and theoretical predictions. The results give independent estimates of the CO2 plume thickness and the associated P-wave velocity reduction.

Seismic velocities and elastic moduli of rocks are known to vary significantly with applied stress, which indicates that these materials exhibit nonlinear elasticity. Monochromatic waves in nonlinear elastic media are known to generate higher harmonics and combinational frequencies. Such effects have the potential to be used for broadening the frequency band of seismic sources, characterization of the subsurface, and safety monitoring of civil engineering infrastructure. However, knowledge on nonlinear seismic effects is still scarce, which impedes the development of their practical applications. To explore the potential of nonlinear seismology, we performed three experiments: two in the field and one in the laboratory. The first field experiment used two vibroseis sources generating signals with two different monochromatic frequencies. The second field experiment used a surface orbital vibrator with two eccentric motors working at different frequencies. In both experiments, the generated wavefield was recorded in a borehole using a fiber-optic distributed acoustic sensing cable. Both experiments showed combinational frequencies, harmonics, and other intermodulation products of the fundamental frequencies both on the surface and at depth. Laboratory experiments replicated the setup of the field test with vibroseis sources and showed similar nonlinear combinations of fundamental frequencies. Amplitudes of the nonlinear signals observed in the laboratory showed variation with the saturating fluid. These results confirm that nonlinear components of the wavefield propagate as body waves, are likely to generate within rock formations, and can be potentially used for reservoir fluid characterization.

The 4D surface seismic monitoring is a standard method for reservoir surveillance during the production of hydrocarbons or CO2 injection. However, land 4D seismic acquisition campaigns are often associated with high cost and disruptions to industrial operation or agricultural activities in the area of acquisition. An alternative technique for time-lapse monitoring of the subsurface is the 3D vertical seismic profiling (VSP), which becomes particularly attractive when used with distributed acoustic fiber-optic sensors (DAS) installed in wells. The advantages of 3D DAS VSP include its relatively low cost, minimal footprint on the local area during acquisition, and superior spatial resolution compared to the resolution of geophones. The potential of this technique is explored by processing and analyzing multiwell 3D DAS VSP data acquired at the CO2CRC Otway Project site in Victoria, Australia. The DAS data were recorded using an engineered fiber with enhanced backscattering cemented behind the casing of five wells. The data from each well are processed individually using the same processing flow and then migrated using a 3D migration code tailored to DAS data. Having DAS along the full extent of multiple wells ensures adequate seismic coverage of the area of CO2 injection. The migrated images provide detailed information about the subsurface up to 700 m away from a well and up to 2 km depth. The images are consistent with previously acquired geophone VSP and surface seismic data. The quality of the 3D DAS VSP imaging is comparable or superior to the quality of conventional imaging using geophone data. Therefore, 3D DAS VSP is a demonstrably optimal solution for reservoir monitoring.

With new developments of fiber-optic sensing and rotary sources, continuous active seismic monitoring for onshore applications has now the opportunity to be fully realized and applied to enhance subsurface resource extraction and use. To date, conventional seismic monitoring deployments have primarily consisted of receiver arrays, either fixed or not, with periodic data acquisition campaigns using temporarily deployed sources, resulting in time-lapse data with poor temporal resolution. Only a few niche efforts have demonstrated continuous acquisition using fixed source-receiver networks. We have evaluated the initial results of a network of fixed rotary seismic sources, referred to as surface orbital vibrators (SOVs), coupled with a permanent distributed acoustic sensing (DAS) network at the CO2CRC Otway Field Site. Although rotary seismic sources are not new, our development of the SOV focused on simplifying the cost and complexity of the source hardware while delivering broad frequency spectrum of the source signal. The upgraded hardware is aligned with a robust methodology for autonomous operation and data processing. At the Otway Site, we deployed SOVs at nine locations, monitoring seismic response in seven DAS instrumented wells. Baseline operation of the DAS/SOV sensor array and source system demonstrates its capability with near offsets attaining a signal-to-noise ratio approaching 100 dB with a normalized root mean square of 10%. Furthermore, analyses of traveltime repeatability indicate that the DAS/SOV system can deliver time resolution of ±500 μs.

Time‐lapse seismic reservoir monitoring is used as a way to gain insight into subsurface processes. Yet, the application of standard 4D technology onshore faces challenges, such as high cost, significant environmental footprint and, consequently, relatively infrequent surveys. As part of the Otway Project Stage 3 CO2 injection study, continuous automated borehole‐based monitoring using distributed acoustic sensing has been paired with permanently deployed surface sources, referred to as surface orbital vibrators, as a way to monitor the spreading CO2 plume. The injection of 15,000 tonnes of CO2 in a saline reservoir at a depth of 1550 m is monitored using five boreholes instrumented with enhanced sensitivity fibre optic cables and nine surface orbital vibrators, creating an array of 45 well–source pairs. The data are processed with an offset vertical seismic profiling processing workflow developed to address key challenges of the continuous distributed acoustic sensing acquisition using surface orbital vibrators. The processing flow includes deconvolution with a source sweep recorded by a pilot geophone installed below the surface orbital vibrators. A second deconvolution with a wavelet estimated from direct arrivals compensates for the difference between distributed acoustic sensing measurements and the pilot geophone as well as near‐surface variations. Image quality is noted to be best for short offsets and decreases with increasing offsets and well deviations. As surface orbital vibrators generate unique sweeps in two rotation directions, further processing is applied to stack these rotation signals together, which further improves the images. The resulting 2D transects of each well–source pair visually provide good illumination of the subsurface, suggesting continuous monitoring of the spreading CO2 plume should be possible with some further tuning of the processing workflow for time‐lapse repeatability.

Monitoring changes of formation properties along the well bore associated with the presence of carbon dioxide can be important for both tracking the plume inside of the primary containment and detecting leakage into the zone located above the reservoir. This can be achieved with time lapse wireline logging, but this approach requires well intervention and is not always possible. If the well is permanently instrumented with an optical fibre, it can be used as a distributed seismic receiver array to detect gas behind the casing by monitoring changes in amplitude of the seismic waves generated by active or passive seismic sources. Previous research showed the efficacy of this technique using continuous seismic sources. The Stage 3 Otway Project presented an opportunity to test this technique using passive seismic recording, as downhole fibre-optic arrays recorded numerous regional earthquakes over the period of nearly 2 years before, during, and after CO

Due to their granular nature and presence of fluids, elastic moduli of most crustal rocks show a strong stress dependency. This means that the relationship between stress and strain is nonlinear, which should cause nonlinear wave phenomena. In particular, interaction of seismic waves of different frequencies should generate higher harmonics and combinational frequencies. Analysis of these effects in field data can potentially help find areas of anomalous nonlinear properties, such as fractured zones, mixed saturation or overpressure. To better understand the potential of nonlinear seismology, we observed and analyzed nonlinear seismic effects in field and laboratory experiments. The field experiment was performed using two seismic vibrators generating monochromatic signals of different frequencies. The wavefield was recorded with a fiber optic distributed acoustic sensing (DAS) cable cemented in a 900 m deep borehole. The signals recorded both on the surface and in the borehole show combinational frequencies, harmonics, and other intermodulation products of the fundamental frequencies. The laboratory experiment, which was designed to replicate the setup of the field experiment, shows similar nonlinear products of the fundamental frequencies. Furthermore, the nonlinear effects show a dependency on the saturating fluid. These tests confirm that nonlinear components of the wavefield propagate in a form of body waves, are likely to be generated in rock formations, and have the potential for reservoir fluid characterization.

Within the South West Hub Project we conducted a comprehensive integrated study to map the fault and fracture network surrounding the Harvey 3 well to obtain an understanding of their propensity to...

In the CO2CRC Otway Project, seismic monitoring has evolved from traditional campaign-based seismic acquisition using a large array of seismic receivers and mobile sources, towards the techniques u...

A permanent automated continuous seismic CO2 geosequestration monitoring system for was installed at CO2CRC Otway Project site (Victoria, Australia) in early 2020. The system is composed of five deviated ∼1600 m deep wells equipped with distributed acoustic sensing (DAS) acting as seismic receivers and nine seismic orbital vibrators (SOV) as seismic sources. DAS recording is performed continuously by three iDASv3 units. Each SOV operates for 2.5 h at a time, and hence all SOVs operating sequentially (during daytime only) produce in a single vintage every two days. Each vintage consists of 45 offset VSP transects covering predicted CO2 plume migration paths over ∼0.7 km2 area. An automated data processing implemented on-site reduces data size from ∼1.3 TB/day to ∼500 MB/day with the results transmitted to the office daily. The repeatability analysis based on pre-injection data (acquired from May to October 2020 before the injection start in December 2020) shows that variability of SOV performance is the main source of non-repeatability while borehole measurements are stable. An SOV waveform could reach NRMS value from 20 to 100 % within a few days. However, deconvolution of the seismograms with the waveform of the direct wave reduces the repeatability to within 10–15 % NRMS.

The CO2CRC Otway Stage 3 project is developing low-impact methods for near-continuous monitoring of storage sites. This paper reports on the design, drilling, instrumenting, and early results from an array of an injector and five monitoring wells, spread over a km2. Highlights include the deployment and use of distributed acoustic sensors on casing, and baseline injections and interpretation of pressure tomography.

Summary Distributed acoustic sensing provides a unique opportunity to deploy massive seismic receiver arrays on the surface and in downhole environments. For downhole installation several options including temporary wireline deployment or more permanent setups such as cementing behind the casing, strapping to production tubing or cementing inside the casing during the abandonment operations. CO2CRC Otway project was the first Australian demonstration of CO2 geosequestration commenced in 2006. Stage 3 of the project is focused on the downhole monitoring of a small scale (15,000 t) CO2-rich gas injection utilising a borehole array. This array comprises of existing and several new 1.5-1.7 km deep wells drilled within approximately 1 km2 area and all instrumented with optical fibres. The wells have a combination of fibre optic cables deployed using different approaches, in some cases – one well can have several cables deployed differently. Prior to completion of the wells, we acquired a set of zero-offset VSP surveys using conventional 3C geophones in the four new wells drilled in 2019. A series of DAS tests focusing on the effects of deployment methods on DAS VSP data quality were also performed. In this presentation, we share findings from these experiments.

Summary Time-lapse seismic is the main method in monitoring as well as the industrial-scale carbon capture, utilisation and storage projects. To properly plan a 4D seismic strategy, the appraisal of the geometry, source/receivers positioning, near-surface conditions and seasonal variations, different sources or receivers is crucial to be tested in various geological settings. The South West Hub area has been investigated for its potential of future industrial-scale carbon capture, utilisation and storage projects. In-Situ Laboratory Project was conducted in this area as a small-scale test site which would determine the approach to be taken for larger commercial CO2 geosequestration projects. The monitoring of controlled injection of a cumulative 38 tonnes of CO2 is conducted utilising the application of TL vertical seismic profiling using distributed acoustic sensing in the wells. In this presentation, to assess these key factors, we present the results of the repeatability analyses conducted on the data after the time-lapse processing.

Summary Time-lapse seismic was performed as part of the Otway Stage 3 Project (Victoria, Australia) to monitor the spread of an injected plume of CO2. A permanent seismic monitoring system based on surface orbital vibrators and DAS VSP technology was used to acquire a new vintage survey every two days. SOV/DAS data was collected from the end of May 2020 to April 2021 (~150 vintages), with the CO2 injection commencing in December 2020. We acquired more than 60 vintages to utilize as a baseline, which provided an opportunity to investigate how a selection of a baseline survey impacts the interpretation of time-lapse changes. Two baseline vintages from June 2020 and November 2020 were compared to a monitor survey acquired in April 2021. The NRMS was calculated to be 45% and 60% for the June and November baselines, respectively. We suggest that this non-repeatability is created by seasonal variations affecting near-surface conditions. The pairwise analysis of all possible vintage combinations highlights seasonal changes in the NRMS value. Analysis of the time-lapse VSP wavefield suggests that the main source of non-repeatability is a seasonal variation of near-surface conditions. This variation manifests itself in changes in source performance and the pattern of surface-related multiples.

This study aims to assess the ability of shallow distributed acoustic sensing (DAS) to serve as a cost-effective seismic sensor array for permanent monitoring applications. To this end, as part of the CO2CRC seismic monitoring program, a fibre-optic DAS array was deployed alongside a permanently buried geophone array at the Otway Project site (Victoria, Australia). The DAS array consisted of a standard commercially available tactical fibre-optic cable, which was deployed in 0.8m deep trenches. A custom-designed helically wound (HW) cable was also deployed in one of the DAS trenches for comparison of the cable designs. Simultaneous acquisition of the seismic data was carried out using 3000 vibroseis source points and geophones, DAS standard and HW cables. For initial assessment of the seismic images acquired with DAS and to compare different cable designs, preliminary 2D seismic reflection processing is conducted on both DAS cables and geophone data along a single 2D line. The geophone data processing guided processing of the DAS data. Several shallow structures (100-450ms) and some important reflectors at 450-600ms are observed on the final DAS images. Comparison of the two different DAS cable types demonstrated that seismic imaging would benefit DAS technology. However, the benefit of utilising HW cable is modest compared with the standard cable. The workflows and results of this study pave the way for processing of the 3D seismic data set acquired with the DAS array, as well as further detailed analysis of the DAS cables and the system itself.

Active time-lapse seismic is widely employed for monitoring CO2 geosequestration due to its ability to track the distribution of fluids in space and time. However, standard 4D seismic monitoring suffers from several challenges, including high cost, disruption to other land uses, and, consequently, relatively large intervals between monitor surveys. Some of these challenges can be mitigated using permanently installed sources and receivers. Such an approach was tested at the CO2CRC Otway site by continuous offset VSP monitoring of 15,000 t of supercritical CO2 injected into an aquifer 1,500 m deep with nine permanent seismic sources (surface orbital vibrators or SOVs) and five downhole fibre-optic receivers. This continuous monitoring is complemented by multi-well 4D VSP using a mobile vibroseis source and the same DAS receivers, which included one baseline and two monitor surveys after injection of 4,000 and 12,000 t of CO2. The continuous DAS-SOV monitoring detected an abrupt increase of travel times below the injection interval on the second day of injection (after injection of 300 t of CO2) and tracked the growth of the areal CO2 plume by mapping changes of reflection amplitudes. The plume is also detected by time-lapse changes of reflection amplitudes in multi-well 4D VSPs. The plume images obtained from continuous offset VSP and 4D VSP are broadly consistent with each other but with some differences due to differences in illumination, lateral variations of velocities and seismic anisotropy. These differences also serve as a measure of uncertainty of 4D VSP images.

Time-lapse (TL) (4D) seismic monitoring of injected CO2 in geological formations is being increasingly employed as the principal method for ensuring containment of CO2 and testing conformance of predicted plume behavior. However, to bring further confidence in this method, the CO2 volume detection limit in the seismic monitoring and key factors controlling it need to be quantitatively understood. The CO2CRC Otway Project attempts to improve this understanding by exploring the capability of seismic reflection method to detect and monitor a 15-kt injection of supercritical CO2/CH4 mixture in a saline aquifer at a depth of 1500 m. The monitoring program consists of TL 3D seismic surveys using a buried geophone array, TL 3D vertical seismic profiling (VSP), and offset VSP. Seismic acquisition was carried out at injection intervals of 5, 10, and 15 kt over a 5-month period and also, 9 and 23 months after the end of injection. The TL seismic images clearly show the distribution and evolution of the stored CO2/CH4 plume. The results demonstrate the potential of TL reflection seismic to provide key information to both operators and regulators for confirming the security and behavior of stored CO2 at very small volumes.

Summary As part of the South West Hub Project to characterise the sedimentary sequences around the Harvey 3 well, a combination of 3D surface and borehole seismic data was acquired in 2017. The geological data from the same area previously revealed that although a conventional seal is absent, residual trapping mechanisms in the form of paleosols are present. To analyse the structural linkages and associated geo-mechanics at Harvey, faults and fracture networks were analysed at various scales and with various techniques. To better delineate the stratigraphic distribution of sandy/shaly units and eventually characterise paleosol rich strata, which would deter the upward migration of CO2, the lithology needed to be tied to the seismic data. To this end, various seismic attributes are tested on the transmitted wavefield of the Zero Offset VSP and are correlated to lithology by comparing to well logs. Additionally, seismic sequence attributes are found to provide good results. Therefore, we apply these attributes to the 3D surface seismic data to facilitate a qualitative interpretation. In conclusion, it was found that the combination of these attributes provides valuable insights regarding the paleosol content.

SUMMARY Investigation of the regolith is an important part of the mineral exploration. Large territories are overlaid by the regolith rocks and recent trends show a clear tendency of discovery major mineral deposits under the thick cover. Thorough regolith exploration involving geophysical techniques is required to push new deep mineral discoveries. Knowledge about the regolith structure and properties is necessary for designing the mine excavation and production as well. A shot 2D seismic was acquired to investigate regolith’s structure and properties at the Hillside prospect, situated on the Yorke Peninsula, South Australia. The small 3D dataset has been conducted to evaluate potential for seismic imaging of deep structures. The survey has been designed to be able to accommodate good data for various seismic methods simultaneously. Data analysis included processing and interpretation of surface, refracted and reflected waves. The study also involved an application of diffraction imaging to detect faults and fracture zones. The experiment has demonstrated a cost effective near surface seismic setup that is capable to obtain a comprehensive set of information about undersurface. The results include imaging of the regolith structure, estimating of dynamic elastic properties of the ground and obtaining images of deep structures.

Neves–Corvo is one of the biggest mining districts on the Portuguese side of the Iberian Pyrite Belt hosting six different lower Carboniferous copper, zinc, lead and tin orebodies including Lombador, Neves, Grac¸a, Corvo, Zambujal, and Semblana. During the past 50 years, geological, geochemical, and geophysical methods were utilized in the exploration of volcanogenic massive sulfide deposits at Neves–Corvo. Electromagnetic, earth resistivity, and principally gravimetry methods played major roles in the geophysical exploration of the area. However, in 2011, as the exploration depth for volcanogenic massive sulfide mineralization became ever deeper, the surface reflection seismic technique was trialled. Initially, elastic property measurements were employed on numerous core samples to determine the seismic properties of the major formations of Neves–Corvo. The contrast in acoustic impedance values derived from these measurements showed that there should be a significant difference in the seismic response of mineralization relative to the surrounding host rocks. Based on this, a high-resolution 3D seismic survey was acquired over the Neves–Corvo mine and its southeastern extension in order to image known deep volcanogenic massive sulfide mineralization to validate the seismic reflection technique and to potentially identify new mineralization targets. As a result, the Semblana and Lombador deposits were successfully imaged, along with key lithological contacts and geologic structures. Additionally, copper sulfide extensions south of Semblana were discovered. Unfortunately, all of the high-priority targets that were identified from the seismic data were subsequently drilled and many of them found to be non-economic. In order to overcome the non-uniqueness of the original seismic data, full-waveform sonic and pseudo-logs were used to model different interfaces and calibrate the seismic data. These results indicated that preserved relative amplitude processing might be of importance to help reduce the ambiguity in direct detection of volcanogenic massive sulfide based on seismic amplitude anomalies. The customized relative amplitude processing of a sub-dataset over the Semblana deposit was then performed. The newly obtained seismic cube was calibrated with existing drillholes, and a volumetric interpretation was performed by utilizing amplitude-based geobodies. Eventually, superior target zonation and precision for the subsequent deep drilling campaign was achieved with the revised interpretation, clearly showing that the high priority targets originally identified from the legacy data would not have passed the targeting criteria in the reprocessed data due to their relatively weak amplitude response. The results obtained from this study inspired the subsequent reprocessing of the full seismic dataset.

This stage of the South West Hub Carbon Capture and Storage (CCS) project aims to produce an in-depth integrated study of the fault and fracture network surrounding the Harvey 3 well to obtain an understanding of their propensity to act as conduits for the injected CO2. An additional interest to the seismic component of the study was to find an optimum CO2 sequestration monitoring methodology. This was of key importance since acceptance by the farming community across the area of the potential reservoir extent is crucial for successful completion of the project. These two factors were taken into account for the survey design that was comprised of more conventional components consisting of simultaneous recorded 3D surface and 3D VSP data sets and an alternative component that recorded multi-offset VSP (MOVSP) survey along the public roads. A comparative analysis of seismic imaging achieved with different geometries is discussed. One of the important results was that MOVSP surveys produced good results and hence this technique may be preferred for monitoring CO2 sequestration in this area. This was since it caused no disturbance to the farming ground and it was much more likely to gain acceptance with the landowners.

Summary Carbon geosequestration requires the mapping and monitoring of the injected CO2 to assure the gas is safely stored in the formation. In this context, Distributed Acoustic Sensing (DAS) has the potential to reduce the costs of seismic operations and increase equipment survivability. Field demonstrations show that DAS can be used for reservoir monitoring in geosequestration applications but most of its studies are limited to borehole seismic surveys, while very little has been published towards DAS for surface seismic. To bridge this gap, capability for seismic monitoring using a 3D DAS array was tested during a test CO2 injection of the CO2CRC Otway Project (Victoria, Australia). DAS was deployed together with geophones along eleven receiver lines and data were acquired before and after the injection of 5kt, 10kt and 15kt of supercritical CO2. Processing of DAS data is very challenging due to strong angle dependence of its sensitivity and very large volumes of recorded data. Preliminary processing results show that we can identify the main reflectors but noise is still strong. The results also show strong azimuth dependence of DAS sensitivity.

A skyline is a unique fingerprint of a city. The mentalities, diversity, and cultures in a city can often be perceived from its skyline. Istanbul's iconic skyline forms an essential part of the character and appearance of this mega city, so much so that Istanbul's historical silhouette is instantly recognizable; it is a unique asset that is important to protect. Impressive minarets and domes dominate the skyline of Istanbul. On the other hand, Istanbul's skyline has changed dramatically over the last decade since land has become increasingly an opportunity for investment and building of taller structures has become one way to multiply this profit. For those who focus on the esthetics of cities, the analysis of the skyline is not a recent phenomenon. However, skyline extraction and analysis has not usually been available in current GIS functionality. This article investigates the esthetics the urban skyline and its transformation due to high-rise buildings. It does this by tailoring a geomodel within a GIS environment. It is believed that the geomodel developed in this study will form a solid foundation which can be applied to many of the urban skylines and urban areas in Turkey and other cities of the world.

A series of azo dyes containing salicylaldimine-based ligands as side chains were prepared and characterized. Absorption and emission data in five solvents of different polarities were studied. Photoirradiation studies under an oxygen atmosphere in water showed that the Schiff base side chains enhanced the photo-oxidative stability of the azo chromophore. The electrochemical properties of the dyes were investigated by a cyclic voltammetry. The synthesized salicylaldimine-based azo dyes gave two irreversible oxidation potentials. Complexation behavior of synthesized compounds with titanium (IV) ions was illustrated by the change in their absorption spectra. These ligands are appropriate sensitizers for anchoring to the TiO 2 surface chemically in dye-sensitized solar cell (DSSC) productions. Electron injection capacities to TiO 2 and photovoltaic performance of the synthesized salicylaldimine-based azo dyes were tested with DSSC.

A permanent geophone array along with a fibre optic distributed acoustic sensing (DAS) array were deployed at the CO2CRC Otway Project site in order to conduct seismic monitoring of a CO2 plume during a small-scale injection test. This study aims to assess the ability for a permanent geophone array to overcome issues related to different acquisition (receiver) designs, high ambient noise level and seasonal variations in the near surface, as well as to test the DAS system for performing cost-effective time lapse seismic measurements. The acquisition of 3D seismic data is performed for this purpose using ~3000 vibroseis source points. We show the preliminary results of seismic reflection imaging conducted using DAS data. We observe the differences in performance between a standard commercially available tactical fibre optic cable and a custom helically wound cable. The results of this study and the workflows established will be used for processing a complete 3D seismic dataset acquired with a DAS array before being compared to a conventional geophone array.

Exploration of deep VMS deposits at the Neves Corvo mine on the Iberian Pyrite Belt was further advanced through a specialised application of surface seismic techniques. The contrast in impedances from elastic property measurements of core samples showed that there should be a significant difference in the seismic response of mineralisation compared to the surrounding host rocks. These results indicated that relative amplitude preservation processing may be of importance to help reduce the ambiguity in direct, seismic amplitude anomaly based targeting of Volcanogenic Massive Sulphides. However, such processing was not easy to implement due to an intrinsically low signal to noise ratio, complex 3D geology, high scattering level and often patchy and poor reflectivity. The newly obtained 3D seismic cube was calibrated with the existing boreholes to show superior ore zonation and precision required for the subsequent deep drilling campaign.

Herein, we expand and use the method used by Landa and Keydar (1998) to detect local heterogeneities. The method relies on computing local semblance along the diffraction offset-traveltime curves. We expand the method by taking into account the phase change occurring for edge diffractions. We demonstrate the usefulness of the method on hard-rock seismic data.

Based on physical property measurements of core samples and the often observed difference in elastic properties from these there should be a significant difference in seismic amplitude between mineralisation and the surrounding host rocks. These results indicate that relative amplitude preservation processing may be of importance in the use of seismic data for the targeting of mineral resources, particularly in the case of massive ores. Such ‘true relative amplitude’ processing is not easy to achieve due to intrinsically low signal to noise ratio in hard rock environments, complex 3D geology, steeply dipping structures, high seismic velocities and often patchy and poor reflectivity. To help reduce the ambiguity in targeting and increase the likelihood of success we have worked on careful re-processing of 3D seismic data with the application of true amplitude preservation. We compare the anomalous amplitude zones that are related to massive sulphide bodies using a true amplitude seismic cube and a conventionally processed cube with the application of AGC (automatic gain control). A higher level comparison is conducted after seismic calibration with boreholes. The zonation and precision of targeting is discussed in this paper.

A seismic survey was designed and conducted at the Hillside mineral deposit, York Peninsula, South Australia as part of an experimental program within the Deep Exploration Technologies Corporative Research Centre (DETCRC). By using a low-power seismic source, low number of channels, specific survey geometries and small seismic crew we acquired high resolution 2D and a mini 3D seismic survey in a short time frame. The experiment was aimed as a proof of concept for using cost-effective, integrated high resolution surface seismic methods to map regolith and deeper structures in a complex hard rock environment. The forward outlook of such an experiment is the deployment of dynamic systems for the acquisition of seismic data such as land streamers or draggable geophone arrays. 2D seimic lines were subject to MASW, refraction and reflection studies. Produced P and S-wave velocity profiles provided a detailed map of elastic properties within the regolith, in good agreement with near surface geology inferred from high-density drillhole information. Reflection profiles and a mini 3D cube produced very good indications of sub-vertical mineralised bodies. Results of this comprehensive test survey suggest that cost effective seismic investigations could be a valuable tool for mineral exploration across the Yorke Peninsula.