Seismic-sequence stratigraphy and hydrocarbon potential of the “UYI” Field, Niger Delta Basin
摘要
Seismic-sequence stratigraphy and hydrocarbon potential of the “UYI” Field, located on the onshore Coastal Swamp depobelt of the Niger Delta, were carried out to ascertain the gross stratigraphic framework, predict lithology, depositional environment, and the implications for hydrocarbon exploration within the field. A combination of composite wireline logs and 3D seismic data was utilized to delineate nine stratigraphic surfaces (which comprise four sequence boundaries, SBs, eight maximum flooding surfaces, MFSs, and two transgressive surfaces, TSs) through the integration of log pattern and motifs, and information from biostratigraphic report. Also, grey level co-occurrence matrix (GLCM) seismic attribute was used to identify few subtle reflection terminations and an erosional channel incision that characterizes stratigraphic surfaces on the seismic. The four sequence boundaries (SB1 to SB4) subdivide the interval of study, within the Agbada Formation, into three Upper Miocene 3rd-order depositional sequences (SQ1 to SQ3) and their associated progradational to retrogradational cycles of system tracts (highstand, HST, lowstand, LST, and transgressive, TST). The thicknesses of these sequences, which are affected by the faults identified in the field, tend to increase towards the south and south-westerly directions (the general depositional trend of the Niger delta). Seismic facies analysis, integrated with lithologic interpretations from gamma ray log from the wells, shows sand and shale lithologies deposited on a broad shelf (upper to lower shoreface) to slope environment in a mixed high and low energy settings with good exploration prospects. Good sand distribution in the LSTs and HSTs may form favorable reservoirs while the shales of the HSTs and TSTs may constitute good source and seal rocks. The ubiquitous growth faults, with their associated rollover anticlines, within the field form the trapping mechanism.