ナイジェリア沖合地域における炭化水素直接探知法(ブライト•スポット)

抄録

The seismic field survey was commenced on Offshore Nigeria operated by Japan Petroleum Co. (Nigeria) Ltd. (J. P. N) in 1972. During the processing and interpretation works of this survey, we could recognize some characteristic patterns, so called "bright spot" on the seismic sections.
As a result of hydrocarbon identification and comparison between the bright spot on the seismic sections and well data, the bright spot is sure to be an efficient means for exploration in Nigeria area.
Then, the result of the study of the bright spot up to this stage was discribed briefly in this paper.
The main points are as follows:
a) With reference to the difference in the value of the velocity and the bulk density between hydrocarbon (Oil and Gas) layer and non-hydrocarbon (sand and shale) layer, the more remarkable it is, the easier it is for the explorationists to detect the bright spot.
However, there seems to be no eminent difference between the former and the latter, so it is not so easy to detect the bright spot.
b) The bright spot pattern changes into many types according to the distribution in the value of velocity and bulk density.
c) The bright spot is not an independent phenomenon but a complicate one influenced by hydrocarbon etc., so it is necessary for the explorationists to interpreate it synthetically.
d) In order to detect the bright spot, it is important to select the most suitable processing parameters, if not, there is some possibility to extinguish the bright spot by using ordinary processing for structure section only.
e) There are many pseud-bright spot on the seismic section, so it is important to study carefully the bright spot phenomena.