44 2033180199

3-Dimensional seismic interpretation and fault seal assessment of Ganga Field, Niger Delta, Nigeria

Okpara Augustine O, Anakwuba Emmanuel K, Onyekwelu Clement U, Udegbunam Innocent E, Okafor Uchenna I

3-dimensional seismic and fault seal assessment were carried out in Ganga, a hydrocarbon bearing field in the Central swamp depobelt of Niger delta basin, Nigeria. The study aimed at assessing the risk associated with fault related hydrocarbon traps by evaluating the fault seal. Fault seal assessment has been identified as an important part of hydrocarbon exploration process especially in the case of exploration for fault-related structural hydrocarbon traps. Fault seal assessment results is also utilized for proper development of faulted reservoirs. Fault seal may occur from a variety of processes such as lithological juxtaposition, shale or clay smear, among others. The approach employed in this study involved structural, stratigraphic interpretations and seismic attribute analysis. The structural framework derived from the interpreted faults, horizons and well logs served as input data in the Midland Valley move software for fault seal assessment, sand on shale lithological juxtaposition and shale gouge ratio. Reservoir assessment was also done to determine prospective intervals. In the Ganga field, the structure is a faulted rollover anticline containing major and minor faults. Faults occur as sets of conjugate synthetic and antithetic syn-depositional normal faults (growth faults). Three distinct structural zones were recognizable on the variance edge attribute volume derived from the seismic volume. Major fault occurrence is restricted to the reservoir interval, the Agbada Formation. Two reservoir intervals were identified from petro-physical analysis. From Fault seal assessment of the major and minor faults for sand on shale lithological juxtaposition seals and fault rock membrane seals (shale gouge ratio), the best sealing interval is above 4200 ft. The reservoir sands identified represent high-risk prospects.

Peer-Review-Publikation für Verbände, Gesellschaften und Universitäten pulsus-health-tech