Abstract

A three-dimensional (3D) marine seismic survey was conducted in the Gulf of Thailand to aid in the development of a gas field indicated by three wildcat wells located by seismic reconnaissance programs shot over a period of several years. The key to successful exploration hi the area, basically a hinge line play, was a detailed understanding of the complex faulting controlling the hydrocarbon traps. Because the prospect lies 160-220 kilometers offshore, some specialized surveying techniques were employed to achieve the required accuracy. About 1280 kilometers of seismic data were recorded at 100 meter line spacing over a block roughly rectangular in shape covering about 130 square kilometers. The 40 fold data were processed using a 3D wave equation migration algorithm yielding a set of seismic traces representing the data vertically below a grid of depth points spaced at 33-1/3 meters by 100 meters.

The result of the 3D program showed much better fault resolution and better structural delineation. The additional help of a series of horizontal slices provided by the 3D processing further improved fault resolution. Four wells drilled on the basis of the 3D survey are productive and tie the seismic data closely. As a result of this experience, the 3D seismic data are being utilized for planning additional development wells and potential platform locations.