Hydrocarbon reservoir volume estimation using 3-D seismic and well log data over an X-field, Niger Delta Nigeria

This study delineates and maps the hydrocarbon-bearing reservoir HD2000 from surface seismic sections and well logs within the depth interval of 5,700 ft (1,737 m) and 6,200 ft (1,890 m). The objective is to establish the geometry, reservoir distribution, delineate hydrocarbon-bearing reservoirs from surface seismic sections and well logs. In this process, a 3-D structural interpretation and estimation of the volume of hydrocarbon in place of the reservoirs was carried out. Well-to-seismic tie revealed that hydrocarbon-bearing reservoirs were associated with direct hydrocarbon indicators (bright spots and dim spots) on the seismic sections. Two horizons were studied (HD2 and HD2_version2) and several faults mapped for the purpose of carrying out 3-D subsurface structural interpretation. This was used in generating the time structure maps. From the maps, it was observed that the principal structure responsible for hydrocarbon entrapment in the field was the anticlinal structure at the center of the field which tied to the crest of the rollover structure seen on the seismic sections. Check shots from the control well were used to create a velocity model from which the time to depth conversion was made. Horizon slice taken shows the reservoir spans a thickness of 400 ft. Direct hydrocarbon indicators were used to map the reservoir boundary. They were seen on the reflection amplitude maps as high amplitude zones (bright spots) and low amplitude zones (dim spots). Reservoir area extent estimated by square grid template method revealed that reservoir HD2000 had an area estimate of 5.29 km2. The results show the effectiveness of the estimation techniques in the lateral prediction of reservoir properties, discriminating litho-fluid and determining the porosity, saturation, net-to-gross ratio, and moreover the reserve volume. Hydrocarbon saturation varied between 0.64 and 0.65, while effective porosity varied between 0.31 and 0.32. Estimation of the volume of hydrocarbon in place revealed that the delineated reservoir HD2000 contained an estimate of 776,545,418.22 barrels (123,460,855.4 cm3) of hydrocarbon which shows great potential of considerable size. © 2015, The Author(s).