LAUSR

Many oil fields within the Niger Delta have been abandoned after serving their estimated life time largely due to large uncertainties and risks associated with many subsurface complexities and often limited and/or inconsistent surveillance data coupled with the convectional static characterization of the reservoir bodies as is the case of the X- oil Field, south eastern onshore, Nigeria. This research presents a pragmatic approach of integrated dynamic reservoir modelling with uncertainty management techniques, which resulted in robust productivity of the abandoned oil field. The objective is to run and improve comprehensive sensitivity analysis of petrophysical properties in the reservoir, develop PVT analysis, and predict acceptable original oil in place (OOIP), comprehensive production history and expected cumulative oil recovery factor (RF). Integrated dynamic reservoir modelling of static interpreted reservoirs of two vertically stacked reservoirs (A and B) was done. The analysis identified reservoir A with an OWC at 5520 ft with thickness of about 300 ft and STOIIP of 59 MMSTB has an underlying reservoir B with OWC at 6100 ft with thickness of about 300 ft and STOIIP of 21 MMSTB. Average permeabilities and porosities of both reservoirs range from 2.54 to 1115.2 md and 0.2 to 0.33 respectively, with estimated cumulative oil production of 46.62 MMSTB at 55% RF in reservoir A and 17.21 MMSTB at 48% RF in reservoir B. This was estimated to correspond to maximum cumulative oil production of 40 MMSTB by August 2020 indicating that the overall recovery from the field could potentially be increase by 6% from drilling infill wells with drainage targets. Production data analysis indicates that the recovery factors and well recoverable volumes are highly correlated to average net oil pay. The correlations may be used for reserve quality control. It is recommended that improved quality of data couple with integration of statics with dynamic modelling should be a priority to reduce uncertainties and solve problems in situ in field operations leading to increase in oil recovery during activation of abandoned oil field.