Summary 3D Vertical Seismic Profile (VSP) has long been viewed as conceptually attractive for illuminating targets under complex overburden, both for exploration purposes and for time-lapse monitoring of reservoirs. However, the widespread use of 3D VSP has been hindered by the cost and risk of deploying geophones in a borehole, by the limited availability of accessible wells and long operational acquisition time (Mateeva & al., 2014). These hurdles are largely removed when acquiring downhole seismic with a new measurement called heterodyne Distributed Vibration Sensing (hDVS) which is an innovative technology to improve the duration of borehole seismic operations. The hDVS technology uses optical fiber as a vibration sensor that can be used along the entire well depth as a sensor. We designed a pseudo 3D VSP survey (four Walkaway VSP lines and 2 circles) with the optical fiber clamped permanently to the well completion tubing. The main objective of acquiring the survey was to further investigate the Silurian and Ordovician formations by integrating VSP measurements with the available surface seismic surveys using the optical fibre measurements as well as to assess hDVS technology for Imaging. In this paper, we present the results achieved after processing the pseudo 3D VSP survey.

Summary In 2017, Eni drilled a deviated exploration well. The well presented challenges due to a complex subsurface with depth uncertainty and close proximity to a salt structure. This structural uncertainty created a risk that the target true location could be significantly different to the pre-drill prognosis. This case study describes how the operator helped to mitigate against this risk and map the position of the wellbore in the surface seismic cube by utilizing Seismic While Drilling (SWD) to acquire real-time (RT) seismic checkshot’s and up-going reflection measurements. The technology was successfully deployed over three hole sections to efficiently acquire the RT checkshot survey, a Zero Offset Vertical Seismic Profile (ZVSP), a RT Vertically Incident Vertical Seismic Profile (VIVSP) and an Offset Vertical Seismic Profile (OVSP) surveys without using any rig time.

Summary Velocity anisotropy calibration using Walkaway VSPs or sonic data has been shown to deliver net quality improvements in seismic imaging. Nevertheless, common industry workflows still do not take full advantage of all available data. In this study, advanced borehole sonic and Walkaway VSP data acquired in a single presalt vertical well were combined to estimate continuous depth profiles of Thomsen parameters. These parameters were successfully propagated away from the well in the surface seismic velocity model, in order to minimize the Walkaway transit time residuals.

Drill-bit seismic while drilling provides reverse VSP, makes it possible to predict the formation changes ahead of the bit, and to image 2D and 3D structures without interference with drilling activity. When the pilot signals used for crosscorrelation with the seismic signals are recorded at the surface, an issue in the application of this methodology may be the loss of the drill-bit-vibration signal during its propagation from the bottom to the surface through the drill string. With PDC bits, as well as during drilling by sliding condition without pipe rotation, and in highly deviated or horizontal wells, the pilot signal recorded at the surface may be weak and consequently the SWD results poor. A solution is to use near-bit downhole tools to get good-quality measurements of the pilot signal. Literature reports examples of SWD with the use of downhole memory systems, from which the data are downloaded after the bit retrieval at the surface. In this paper we present the new results obtained using a drill pipe equipped with a wireline communication system from bottom hole to the surface. The results demonstrate the applicability of this method providing good-quality RVSP data, in terms of S/N and frequency content.

ndent imaging technique for the simulation of common-offset sections with improved signal-to-noise ratio. Applied in a continuous manner, the CO CRS can be utilized to create a “new” regularized prestack dataset which provides an improved input for a subsequent prestack depth migration. We discuss an adapted strategy for eni’s CO CRS implementation which handles 3D VSP geometries and show for the first time 3D results from a complex real data case.

The drill-bit seismic while drilling (SWD) method provides reverse VSP (RVSP) profiles andhas important analogies with the Vibroseis one.

This paper describes the application of elastic inversion on real crosswell data, with the objective of discriminating sand and shale with high resolution at the reservoir level. For this work we used crosswell seismic profiles acquired at Belayim Land field, Sinai, Egypt. The results showed that elastic inversion of crosswell seismic data is able to discriminate between sand and shales with a resolution of 5m. Knowledge of Vs information at the reservoir level is important in order to obtain absolute results from the elastic inversion.

H009 Seismic Interferometry in a Crosshole-RVSP Experiment F. Poletto* (OGS) L. Petronio (OGS) & F. Miranda (Eni E&P) SUMMARY Seismic interferometry uses the correlation of traces recorded at different locations to simulate virtual sources where only receivers are used. The process provides virtual seismograms with the advantage of enlarging the coverage in seismic exploration. We apply seismic interferometry by using the traces of a mixed borehole/surface survey and process virtual reverse VSP (VRVSP) signals together with crosshole signals. Wireline VSP and surface seismograms were acquired by using vibrator sources at different offsets and receivers installed into two instrumented wells and

PreviousNext No AccessSEG Technical Program Expanded Abstracts 2006Enhancing crosswell acquisition efficiency with combined up‐going and down‐going imagingAuthors: C. D'AgostoM. AntonelliF. MirandaC. D'AgostoEni E&PSearch for more papers by this author, M. AntonelliEni E&PSearch for more papers by this author, and F. MirandaEni E&PSearch for more papers by this authorhttps://doi.org/10.1190/1.2370262 SectionsAboutPDF/ePub ToolsAdd to favoritesDownload CitationsTrack CitationsPermissions ShareFacebookTwitterLinked InRedditEmail Abstract More rapid acquisition will reduce deferred production by keeping wells offline for less time during an Integrated crosswell Seismic (ICS) survey. One method to speed up acquisition is to increase the vertical range of coverage for a given shooting chart by performing both up‐going and down‐going imaging and appropriately combining the two sections into a combined up/down‐going image. Up‐going reflection images use reflections from below the source and receiver positions, whereas down‐going images use reflections from above the source and receiver positions.Based on the analysis of the synthetic data, we have derived a procedure for imaging and displaying the combined up‐going and down‐going reflection data with no loss in interpretability. The combined image is produced with a polarity flip of the down‐going reflection data and a splice point in both the combined image and any synthetic seismograms. The splice point is to be clearly marked so that the interpreter realizes that velocity effects (depth missties, event sag, etc) may change at this point in the image. Placement of the splice point is typically between 2 zones of interest in the image. We have also shown in this paper an analysis of the days saved using combined up‐going and down‐going imaging.In summary, the method of combined up‐going and down‐going imaging can significantly enhance efficiency of ICS operations, reducing deferred production and rig costs while resulting in no degradation in the interpretability of the data.Permalink: https://doi.org/10.1190/1.2370262FiguresReferencesRelatedDetailsCited byCrosswell seismic imaging for deep gas reservoir characterizationGang Yu, Bruce Marion, Brad Bryans, Pedro Carrillo, Wankui Guo, Yanming Pang, and Fanzhong Kong5 November 2008 | GEOPHYSICS, Vol. 73, No. 6 SEG Technical Program Expanded Abstracts 2006ISSN (print):1052-3812 ISSN (online):1949-4645Copyright: 2006 Pages: 3541 publication data© 2006 Copyright © 2006 Society of Exploration GeophysicistsPublisher:Society of Exploration Geophysicists HistoryPublished Online: 06 Oct 2006 CITATION INFORMATION C. D'Agosto, M. Antonelli, and F. Miranda, (2006), "Enhancing crosswell acquisition efficiency with combined up‐going and down‐going imaging," SEG Technical Program Expanded Abstracts : 349-353. https://doi.org/10.1190/1.2370262 Plain-Language Summary PDF DownloadLoading ...

M. Antonelli, F. Miranda, L. Terzi and G. Valenti, Eni E&P Division, provide an updated version of a paper first presented at the Offshore Mediterranean Conference and Exhibition in Ravenna, Italy, in March 2003 in which they illustrate the role of integrated crosswell seismic in reservoir management strategies with a number of case histories.

Drill‐string waves can be successfully used as reference pilot signals for drill‐bit seismic‐while‐drilling (SWD) purposes. The seismic signals obtained by correlating pilot and geophone measurements are disturbed by the drill‐string reverberations because the pilot waves are reflected at each interface between string sections with different acoustic impedances. Inverse filtering of these reflections, using a reference‐pilot deconvolution calculated in the presence of additional noise, may cause signal distortion. To overcome this problem, we consider using dual‐sensor measurements in the drill string to remove the reflections of the drill‐bit waves in the acquisition phase and to improve pilot deconvolution. We measure acceleration and strain of drill‐string dual fields, which have opposite reflection coefficients and, in a string of constant elastic properties, the same transmission coefficients. These quantities are scaled to fit the amplitude of the direct arrivals, summed to remove the reflections in the drill string and in the rig, and may be deconvolved by Einstein deconvolution to characterize the reflection coefficient between the drill bit and the formation. Synthetic numerical examples and real measurements acquired downhole in a location close to the bit show that upgoing and downgoing drill‐string pilots can be separated using dual fields and jointly used to improve the SWD seismograms.

T017 INTEGRATED CROSSWELL SEISMIC – ADVANCED TECHNOLOGY TO IMPROVE RESERVOIR DESCRIPTION IN EL BORMA FIELD (TUNISIA) SUMMARY 1 This paper describes the results achieved applying the Integrated Crosswell Seismic (ICS) an innovative technology to improve the description of the internal geometries of the reservoir in El Borma Field (Tunisia) The results obtained have been used to describe in detail the complex internal geometries of the reservoirs to improve the geological model and to plan of new producer well with more confidence. INTRODUCTION Fig. 1 El Borma Field location extended to all reservoir levels. Infilling wells have been drilled since the

P221 PREDICTION AND 3D IMAGING WHILE DRILLING BY DRILL-BIT 3D RVSP Abstract 1 3D imaging by drill-bit SWD data was successfully demonstrated in a first survey performed in Sicily (Italy) in 2000. However in this first survey the final 3D imaging results were achieved only after the well was completed. Following the experience of this pilot survey a second 3D RVSP was acquired in another exploration well drilled in Southern Apennines (Italy) in 2002. In this work we present the 3D imaging results obtained and used for prediction while drilling in the new 3D drill-bit RVSP application. The goal of

Integrated Crosswell Seismic (ICS) is set of innovative techniques - devised and proposed to characterize the internal structure of a reservoir - that is now evolved from being primarily an exploration tool to a development and production tool. This paper gives a few examples of such an evolution, presenting the results of some ICS applications that Eni has carried out on its operated producing oil fields - located in Italy and oversea – as a part of a continuous R&D effort for improving the reservoir characterization process. The case histories here presented show how this methodology worked in reservoirs of different lithologies and geological frameworks, and prove how its high flexibility and applicability can substantially assist the reservoir management in providing important information for: ♦ a higher resolution structural & stratigraphic imaging; ♦ a better well-to-well log correlation; ♦ the building and validation of the geological models; ♦ the estimation of petrophysical properties and the detection of flow barriers; ♦ the identification of “infill” drilling targets (e.g. for planning horizontal wells); ♦ the time lapse monitoring and imaging of the fluid flow.

T023 SEISBIT® SEISMIC-WHILE-DRILLING TECHNIQUE – SUMMARY OF RESULTS OBTAINED IN ONSHORE SURVEYS PETRONIO L. 1 MIRANDA F. 2 POLETTO F. 1 AND MIANDRO R. 2 Abstract 1 1 OGS Department of Geophysics of the Lithosphere Borgo Grotta Gigante 42/C 34010 - Sgonico (Trieste) Italy 2 ENI E&P - Italy Seisbit® is a seismic-while-drilling (SWD) technology developed by OGS and ENI E&P. SWD method utilizes the noise produced by drill-bit to obtain interpretable borehole seismic data. Several 2D Seisbit® acquisitions were performed in Southern Italy to monitor exploration wells located in a complex thrust zone. Recently two 3D SWD surveys were

T025 INTEGRATED CROSSWELL SEISMIC – ADVANCED TECHNOLOGY TO IMPROVE RESERVOIR DESCRIPTION IN BELAYIM LAND FIELD (EGYPT) SUMMARY 1 This paper describes the results achieved applying the Integrated Crosswell Seismic (ICS) technology in Belayim Field (Egypt). ICS is an innovative methodology to improve the description of the internal geometries of the reservoir. The results achieved have been used to describe in detail the complex internal geometries of the reservoirs to improve the geological model and to plan of new injector or producer wells. INTRODUCTION Belayim Land field one of the oldest oil field in Egypt is located in the central part

P015 A SWD 3D RVSP ONSHORE SURVEY - IMAGING AND FINAL RESULTS Abstract 1 In the frame of the Seisbit 3D RVSP project partially founded by European Community a 3D onshore seismic-while-drilling survey (SWD) has been acquired in Sicily. About 2.6 Km of drilling was continuously monitored by more than 400 channels deployed around the vertical well. Data acquired were analysed and processed in the field to locate the bit on seismic section calibrate logs and predict acoustic interfaces ahead of the bit. As final results tomographic inversion and 3D Kirchhoff provided an imaging of the well area suited to

Borehole guided waves, other than the extensional waves traveling through the drillstring, can be used as pilot signals to obtain seismic‐while‐drilling (SWD) seismograms and information about the drilling conditions. This occurs when there is no rotation of the drillstring while drilling and when the contacts between the drillpipe and the borehole wall preclude the propagation of the extensional wave. To obtain the velocity of the guided waves, we model the compressional‐wave velocity of drilling mud with different compositions of low‐ and high‐gravity solids, corresponding to a given drilling plan and taking into account the presence of formation cuttings and in‐situ conditions. Then we compute the velocities of the tube wave (with and without casing) and the guided wave traveling in the mud inside the drillstring (pipe wave). The results indicate the pipe wave constitutes a reliable pilot signal in the absence of drillpipe rotation. This allows us to obtain a complete depth reverse vertical seismic profile.

Surface drillstring axial pilot signals are used to predict reflections ahead of the drill bit. We show that part of the drill‐bit signal propagates downward in the formation, reflects upward by a seismic interface, and is then transmitted to the drillstring and the surface pilot sensors. These reflections are interpreted in drill‐bit pilot signals by means of a numerical model of the drillstring coupled to the formation at the bit–rock contact. The result is an additional, low‐cost, reverse VSP (RVSP) in the zero‐offset approximation. These while‐drilling results are integrated with conventional drill‐bit RVSP measurements and compared with other geophysical and well results.

P145 INTEGRATED CROSSWELL SEISMIC - ADVANCED TECHNOLOGY TO IMPROVE RESERVOIR DESCRIPTION IN THE EL BORMA “WAG” PROJECT Summary 1 This paper describes the results achieved applying the ICS technology in El Borma Field during the “WAG” project. Integrated Crosswell Seismic is an innovative methodology to improve the description of the internal geometries of the reservoir. The results achieved have been used to describe in detail the complex internal geometries of the reservoirs and to improve the geological model input to the dynamic simulator obtaining good results in the history match phase. Introduction M.ANTONELLI 1 F. GHADHAB 2 F. MIRANDA 1