Maju-Oyovwikowhe Gladys Efetobore^1,, Ukpebor Osahon²

The aim of this study is to comprehensively characterize the reservoir and analyze the fluid behavior in the Majosa field located in the Niger Delta. The investigation involved the interpretation of well logs, fluid replacement modeling, and the generation of synthetic seismograms for well-to-seismic tie analysis. Interpretation of the well logs yielded valuable insights into the subsurface characteristics of the study interval. The gamma ray log successfully identified lithology, with leftward deflections indicating sand layers and rightward deflections indicating shales. The neutron-density overlay revealed a balloon structure in the reservoir, suggesting the presence of gas within the study interval. Moreover, the high resistivity kick and low water saturation further supported the existence of gas. Shale intercalations were observed within the reservoir sand, confirming the study interval to be within the Agbada Formation. The reservoir sand was located at an approximate depth of 3,392m, exhibiting 22% porosity and 18% water saturation. To assess log behavior and determine the real fluid composition indicated by the neutron-density overlay, fluid replacement modeling employing Biot-Gassmann's equations and the FRM function in Hampson-Russel Software was conducted. A two-phase fluid model (80% oil, 20% brine) accurately captured the S-wave behavior associated with gas sand observed in the logs. P-wave, S-wave, and density logs exhibited significant changes during the two-phase fluid replacement model. A synthetic seismogram was generated using a statistical wavelet derived from the fluid replacement model logs. The well-to-seismic tie achieved a correlation coefficient of 60.5%, improving subsurface interpretations. This study identified lithology, porosity, and the presence of gas, which impact exploration and production activities. It enhances reservoir management and development planning, emphasizing the potential for enhanced hydrocarbon recovery and the importance of gas monetization strategies. The comprehensive reservoir characterization and fluid analysis inform production optimization and maximize hydrocarbon recovery.

reservoir characterization, fluid analysis, well logs, fluid replacement modeling, synthetic seismogram, well-to-seismic tie, Niger Delta