IDOWU, AYORINDE OLUSEGUN, Nigerian National Petroleum Corp., Lagos, Nigeria

ABSTRACT: The Effectiveness of 3-D Marine Systems as an Exploration Tool in the Offshore Niger Delta

From inception in 1984, three-dimensional (3-D) marine surveys have been used widely for field development where commercial hydrocarbons were known to exist in Nigeria. The high-trace density and full 3-D migration provide a data set that allows detailed interpretation of complex geologic structures and, in many cases, provides good stratigraphic information as well. The result has been better placement of development wells, making field development more efficient and cost effective.

Previous application of the 3-D method (i.e., reconaissance 3-D) as an exploration tool in 1987 has demonstrated its effectiveness for predrilling detailing of prospects in offshore Niger Delta in a situation where a large volume of seismic data were acquired at relatively reduced unit costs. The technique involves acquiring data along a line every 200 m spacing, while interpretation in 3-D data processing is applied for subsequent 3-D migration. Based on pattern recognition of events on the input traces, the links are established to allow traces to be formed between input locations by comparing several attributes of events on neighboring traces.

A case history example from the offshore Niger delta shows that the collection costs for the reconnaissance 3-D method are comparable to two-dimensional detailing based on similar line kilometer and time duration for the survey. A trade-off between cost and technical specifications can be programmed by focusing on the geologic objective. The technique brings the advantage of 3-D methods, but not their costs, to the exploration phase of the search for petroleum, and it is highly recommended for exploration in frontier areas, particularly the deep offshore of the Niger Delta.

AAPG Search and Discovery Article #90990©1993 AAPG International Conference and Exhibition, The Hague, Netherlands, October 17-20, 1993.