About This Item
Share This Item
Geophysical exploration by PETROBRAS started in 1954 in the onshore basins and in 1968 in the offshore basins of the Brazilian continental margin. The major problems that these basins share are: (1) short-range lateral velocity variations; (2) poor seismic data quality in many areas, especially on land, and (3) small traps with some degree of stratigraphic control.
In the search for the solution to these problems, the best techniques available have been tried. CDP was introduced in the early 1960s; digital recording and processing in 1968; bright-spot methodology in 1973; trace inversion in 1976; 3-D migration in 1978; and image-ray depth migration in 1981.
Facilities for computer-generated display for geophysical interpretation were made available in the early 1970s. Presently, an interactive interpretation mapping system with graphic stations is in use.
Examples of techniques applied to exploration and field development activities include time-to-depth conversion, generation of seismic synthetic logs, and porosity prediction.
Geophysics plays an important role in the exploration of the Brazilian continental margin, where recoverable volumes of oil have increased in onshore basins from 86.342 million BOE in 1954 to 2,132.81 million BOE in June 1983, and in offshore basins from 0.069 million BOE in 1968 to 1,626.73 million BOE in June, 1983. These volumes correspond to 246 bbl onshore and 520 bbl offshore per drilled meter for the same periods.
End_of_Article - Last_Page 451------------