Maximizing the value of existing seismic data in the Bahrain Field with wide-azimuth processing technology

Maili, Eduard; Burns, S.; Jones, N.; Pradalie, F.; Baillon, S.; Verneau, D.

doi:10.3997/1365-2397.2013006

Cited by 6 publications

(3 citation statements)

References 7 publications

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“…The irregularity is also significant for a rather dense wide‐azimuth survey if azimuth‐range data must be migrated separately (Maili et al . ). Pre‐stack merging of surveys with different design for joint pre‐stack migration also meets the problem of migration artefacts.…”

Section: Introductionmentioning

confidence: 97%

“…The problem becomes most challenging for older sparse surveys with large acquisition line spacingsuch data sets may be important if survey areas are no longer accessible for new seismic acquisition. The irregularity is also significant for a rather dense wide-azimuth survey if azimuthrange data must be migrated separately (Maili et al 2013). Pre-stack merging of surveys with different design for joint pre-stack migration also meets the problem of migration artefacts.…”

Section: Introductionmentioning

confidence: 99%

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Eliminating 3D pre‐stack migration artefacts by 6D filtering

Masjukov

Shlyonkin

2015

Geophysical Prospecting

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State‐of‐the‐art 3D seismic acquisition geometries have poor sampling along at least one dimension. This results in coherent migration noise that always contaminates pre‐stack migrated data, including high‐fold surveys, if prior‐to‐migration interpolation was not applied. We present a method for effective noise suppression in migrated gathers, competing with data interpolation before pre‐stack migration. The proposed technique is based on a dip decomposition of common‐offset volumes and a semblance‐type measure computation via offset for all constant‐dip gathers. Thus the processing engages six dimensions: offset, inline, crossline, depth, inline dip, and crossline dip. To reduce computational costs, we apply a two‐pass (4D in each pass) noise suppression: inline processing and then crossline processing (or vice versa). Synthetic and real‐data examples verify that the technique preserves signal amplitudes, including amplitude‐versus‐offset dependence, and that faults are not smeared.

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Section: Introductionmentioning

confidence: 97%

Section: Introductionmentioning

confidence: 99%

Eliminating 3D pre‐stack migration artefacts by 6D filtering

Masjukov

Shlyonkin

2015

Geophysical Prospecting

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“…In exploration seismology, it is now common to acquire and process data with more than 10 km of offset (see, e.g., Colombo, 2005;Maili et al, 2013). There are various reasons for long-offset acquisition.…”

Section: Introductionmentioning

confidence: 99%

Nonstretch normal moveout through iterative partial correction and deconvolution

2014

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Source to receiver distances used in seismic data acquisition have been steadily increasing and it is now common to work with data acquired with more than 10 km of offset. Subbasalt exploration and seismic undershooting are just two applications in which long-offset reflections are sought. However, such reflections are often subjected to muting to suppress normal moveout (NMO) stretch artifacts, thus causing a loss of valuable information. To retrieve these portions of the recorded wavefield, we developed a nonstretch NMO correction based on wavelet estimation and on an iterative procedure of partial NMO correction and deconvolution. We evaluated this methodology using fourth-order traveltime curve approximations to increase the offset of usable reflections, but it can be adapted to traveltime curves of any order. Time- and space-variant wavelets, estimated by means of singular value decomposition along the sought traveltimes, were used to build the desired output for the deconvolution that aims at retrieving the original shape of the partially stretched wavelets. We tested our method on a synthetic gather presenting time and offset varying wavelets, on a real-marine line simulating an undershooting pattern and on true undershooting land-marine data. These examples demonstrated that our new algorithm effectively limits the stretching associated with the NMO correction and enables the recovery of those portions of the stacked sections that are typically lost from muting in the standard NMO correction

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Azimuthal P-P prestack amplitudes in the presence of oil-filled aligned porosity (fracture porosity)

Lynn

Goodway²

2020

Interpretation

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A 3D P-P high-fold full-azimuth full-offset reflection survey was acquired and processed to characterize a naturally fractured carbonate reservoir. The reservoir is a thick carbonate, which will flow commercial oil with a sufficient fracture network. Extensive calibration data include (1) a horizontal borehole’s resistivity image log, (2) the first 24 months cum oil produced, by stage, as known from chemical frac tracer data, (3) pre- and postfrac job instantaneous shut-in pressures, (4) microseismic, and (5) wireline log data. We used the cum oil production to document the spatially varying amount of aligned vertical porosity (aligned compliance or fracture porosity) connected to the stage borehole location. The stages of high oil production exhibited, for the fracture-perpendicular azimuth, the more positive amplitude variation with angle (AVA) gradients, and dimmer near-angle (6°–15° angles of incidence) amplitudes, compared to the fracture-parallel azimuth. The azimuthal variation of the AVA gradient fit the cos 2θ curve well, indicating the presence of one set of vertical aligned fractures dominating the azimuthal amplitude signature. In a similar fashion, the azimuthal variation of the mathematical intercept, physically the near-angle amplitudes, also fit the cos 2θ curve well. We have constructed crossplots of the azimuthal near-angle amplitude versus the AVA gradient on a bin-by-bin basis: We observed a straight line at bins with elevated oil production (elevated fracture density). A straight line crossplot of the (AVA gradient, mathematical intercept) is the signature of change of the (sensed) porosity, as long as the lithology and pore fluid are held constant. In accord with industry knowledge, we found that porosity affects the P impedance and thus the near-angle amplitudes: The aligned porosity yields azimuthal P impedance (measured at the 6°–15° angles of incidence). Legacy high-fold 3D P-P surveys rich in the 6°–20° angles of incidence should be considered for reprocessing and reinterpretation using these techniques.

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Maximizing the value of existing seismic data in the Bahrain Field with wide-azimuth processing technology

Cited by 6 publications

References 7 publications

Eliminating 3D pre‐stack migration artefacts by 6D filtering

Eliminating 3D pre‐stack migration artefacts by 6D filtering

Nonstretch normal moveout through iterative partial correction and deconvolution

Azimuthal P-P prestack amplitudes in the presence of oil-filled aligned porosity (fracture porosity)

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