3D SEISMIC INTERPRETATION AND PETROPHYSICAL EVALUATION OF STROH-FIELD ONSHORE NIGER DELTA
ABSTRACT
Petrophysical evaluation and 3D seismic interpretation were carried out on the hydrocarbon bearing reservoirs of Stroh field with the aim of maximizing the benefits of petrophysical evaluation and structural interpretation in the production and development of hydrocarbon in the reservoir of the ‘Stroh field’ in Niger Delta. Eight hydrocarbon bearing reservoirs – sands ST1, ST3, ST6, ST7, ST8, ST11, ST13 and ST14 were identified from well logs and correlated across six Stroh wells. Sand ST11 was missing in Stroh-5 which crossed a normal fault. Fluid types were determined from the well log signatures; neutron density crossplot was used to check for the presence of gas. All the hydrocarbon bearing reservoirs were inferred to be oil with sand ST11 having a gas cap. Stroh-1 well saw 134.5 ft of oil in 7 sands and 26 ft of gas in 1 sand. Stroh-3st has 25.6ft of oil in one sand. Stroh-4 encountered 113ft of oil in 3 sands and 18ft of gas in one sand. Stroh-5 has 100ft of oil in 2 sands and 19ft of oil in Stroh-6. Result from petrophysical analysis shows that porosity ranges from 15.8% to 28.3%, volume of shale from 2.5% to 38.9% and permeability which increases with porosity ranges from <10md to >10000md. Bulk volume of water shows possible variation opf grain size. Top depth structure maps were produced from seismic interpretation for Sands ST6, ST11 and ST13having total (47.23mmbo & 32,319.05mmscf) of oil and gas respectively. One prospects – NE (7.9mmbo low case, 10.81mmbo mid case and 12.03mmbo high case) was also identified for future drilling considerations. The result of seismic data interpretation shows that ten faults were identified F1 to F10 with two main regional bounding faults; F1 synthetic& F2 antithetic faults trending E-W. Trapping mechanisms are fault assisted and fault dependent. Time maps generated and depth converted to show structural variation and fluid contacts. The results of petrophysical analysis of the reservoir properties (NTG,Porosity,Sw) and seismic data interpretation (GRV) showed a perforation interval for ST13 as having the most profilic reservoir with a reserve of 25.28 mmbo, while ST6 has least prolific reservoir with reserve of 8.68 mmbo which serves as a guide for robust future development strategy for the Stroh field.