The Application of Seismic Attributes in Fault Detection and Direct Hydrocarbon Indicator in Tomboy Field, Western-Offshore Niger Delta Basin

Abstract

Seismic attribute analysis is important in subsurface data interpretation, such as seismic interpretation, which could involve seismic stratigraphic and structural interpretation. This interpretation is often hampered by seismic resolution and, sometimes, human inability to identify a subtle feature on the seismic. These factors have frequently led to the poor seismic interpretation of geologic features. Thus, an integral approach to studying structural patterns and hydrocarbon bearing zones using seismic attributes was carried out on the Tomboy field using 3D seismic data covering approximately 56 km2 of the western belt of the Niger Delta. The seismic volume underwent post-stack processing, which enhanced seismic discontinuities. A deep steering volume was first created, and several dip filters were applied to enhance faults in the study area. After that, curvature and similarity attributes were calculated on the dip-steered and fault-enhanced volume. These calculations show detailed geometry of the faults and zones of subtle lineaments. Six faults (F1, F2, F3, F4, F5 and F6) were identified and mapped. These faults range from antithetic to crest growth faults. Two major growth faults (F5 and F6) were revealed to dip in the northeast to southwest directions. A near-extensive crest fault (F4) appeared beneath the major faults. Although several minor fractures were displayed in the southern and central portions of the crest fault of the dipping seismic data, the southwest (F4) and growth fault, F6, are responsible for holding the hydrocarbon found within the identified closures. Using attributes on the seismic data increased confidence in mapping and interpreting structural features. Furthermore, energy attributes were used as Direct Hydrocarbon Indicators (DHI) to visualize viable areas within the study, which allows a more robust interpretation. Time slices were taken in regions of flat and bright spots. The spectral decomposition attribute was run on these slices to display areas of high amplitude reflection typical of hydrocarbon-bearing regions trapped mainly by regional to sub-regional growth faults. The surface attribute calculated on the generated surface shows that the field is predominantly controlled by faults serving as traps for hydrocarbon.

Delineating Plio-Pleistocene channels (gas reservoirs) via seismic attributes in Baltim Gas Field, Nile Delta, Egypt

“…The third type is the re ection strength attribute, in which the hydrocarbon with a color ranging from yellow to orange is shown by the lowest value of re ectivity, with the lowest values at the color bar, as shown in (Figures 23,24)for the rst Pleistocene anomaly and (Figures 25, 26) for the second Pliocene anomaly The fourth type is the spectral decomposition attribute, which was applied by using RGB color bending maps for both Pleistocene and Pliocene anomalies, which created an image composed of detected three-frequency horizons and identi ed the channel fairway direction. The rst Pleistocene anomaly is composed of 10, 20, and 30 HZ frequencies, shown at (Figure 27), which show the turbidity gas sand feature for the Pliestocene Kanaria prospect, and the second Pliocene anomaly is composed of 20, 30, and 40 HZ frequencies, shown at (Figure 28), which show the channelized fairway ow for the Pliocene anomaly from south east to northwest as the main branch, which passes between the BN-3 well, Andaleeb-1 well, and Kanaria Pliocene prospect, as well as other branches to the north east from El-Werwar prospect to BNE-1 dir well.…”

“…This facilitates the identi cation of the seismic data's initial processing step by direct measurement, logical reasoning, or experience-based reasoning. [24].…”

“…Seismic attributes are characterized as the most informative tools to characterize seismic features, such as layer velocity, acoustic impedance inversion [4,24,41], and pore pressure prediction [37], after the emergence of intricate trace theory during the earlier phases of the 1970s, the initial application of seismic attribute analysis was directed towards the realm of oil exploration in the decades between the 1970s and 1980s [42], the term "attributes" pertains to measurements that are generated from seismic data, for instance, envelope amplitude (commonly referred to as "re ection strength"), velocity, instantaneous frequency, polarity, instantaneous phase, slope, slope azimuth, seismic interpretation methods have made it conceivable to calculate volumes of structural attributes and augment faults in seismic data due to automated fault extraction using a variety of seismic features [25].…”