Browsing by Author "Opara, Alexander I."
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Item Article Open Access QUANTITATIVE PETROPHYSICAL EVALUATION AND RESERVOIR CHARACTERIZATION OF WELL LOGS FROM "DATOM" OIL FIELD, NIGER DELTA(Petroleum and Coal, 2018-07) Lawson-Jack, Osaki; Opara, Alexander I.This paper presents a detailed reservoir characterization of three wells in โDatomโ Oil Field, Niger Delta using well logs data. The distributions and thicknesses of sand bodies were determined within each of the wells in the field using interactive petrophysical (IP) software. The quantitative and qualitative analysis were done for the three exploration wells with the depth ranges of 8700-9200ft for Datom North well , 8900-9400ft for Datom West well, and 9000-9500ft for Datom East well. Two distinctive porous sand bodies were identified across the field (A and B), Datom North has it reservoirs as 1A (8815- 8903ft) and 1B (9100-9157ft), Datom West has its reservoir as 2A (8996-9095ft) and 2B (9263- 9321ft) and Datom East as 3A (9101-9219ft) and 3B (9357-9418ft). Petrophysical evaluation was made from a suite of wire-line logs comprising of gamma ray, resistivity, neutron and density logs of the wells. The average porosity values obtained are in the range of 0.18-0.22 with average net pay permeability values ranging from 322.70mD to 733.20mD. The water saturation obtained for each reservoir unit in combination with the resistivity index was used to prove the presence of hydrocarbon in the sand units. The hydrocarbon saturation of the reservoirs are in the range of 0.6-0.7 across the prospect zones with gas effect of the combination logs of neutron and density indicating the hydrocarbon accumulation is predominantly gas. The average net to gross ratio across the reservoirs (0.7-0.9) is defined using an average porosity (โ ) and volume of clay (๐๐๐๐๐ฆ ) cut offs values of โฅ 0.1 ๐๐๐ โค 0.5 respectively. With a moveable hydrocarbon index (MHI=๐๐ ๐๐๐ โ ) less than 0.7 across the sand units, it shows favorable hydrocarbon moveability in the reservoirs. The results clearly revealed that the gas bearing sand units have good reservoir potentials favorable for hydrocarbon production.Item Research Article 3-D Seismic Attribute Analysis for Enhanced Prospect Definition of "Opu Field'', Coastal Swamp Depobelt Niger Delta, Nigeria(Science Alert, 2018) Opara, Alexander I.; Lawson-Jack, OsakiBackground and Objective: Analysis of seismic attributes has been an integral part of reflection seismic interpretation for over two decades now. Seismic attributes facilitates structural and stratigraphic interpretation as well as offer hints to formation type and fluid content estimation with the potential benefit of detailed reservoir characterization. The current study evaluated the use of seismic attributes generated from 3D seismic and well log data for characterization of the reservoirs of สปสผOpu Fieldสผสผ, Coastal Swamp Depobelt, Niger Delta. Materials and Methods: Root mean square (RMS) amplitude, instantaneous frequency and interval average maps were extracted on seismic events with pronounced bright and dim spots. These maps were used to establish the diagnostic ability of 3D seismic attribute analysis in enhancing seismic interpretation and volumetric estimation of the mid Miocene to Pliocene Agbada Formation reservoirs within the Coastal Swamp Depobelt, Niger Delta basin. The methodology involved a well-defined procedure which included the delineation of the various lithologies from the gamma ray log, identification of reservoirs from the resistivity log, regional well correlation, determination of petrophysical parameters, horizon and fault mapping, time to depth conversion, attribute analysis and reserve estimation. Results: Two main reservoirs identified as Sand-A and Sand-B were mapped in the study area using seismic data. Similarly, seven faults labelled F1-F7 and four horizons were mapped within the field. Depth structure maps generated revealed a massive Northeast-Southwest (NE-SW) trending anticlinal structure. Petrophysical analysis revealed a mean porosity value of 18% while the mean permeability values ranged from 63-540 md across the two reservoirs. Water saturation and volume of shale (Vsh) across the reservoirs ranged from 38-90 and 17-82%, respectively. Conclusion: This study revealed that theโOpu Fieldโ has high hydrocarbon potentials and excellent petrophysical characteristics favourable for hydrocarbon accumulation and production. The benefits of integrating structural interpretation, petrophysical evaluation and seismic attributes analysis in prospect identification and reservoir prediction was therefore highlighted in this study.