First Break - Volume 9, Issue 6, 1991

UK North Sea Block 22/11 has had a long history of exploration involving six companies drilling four wells over two decades. The latent exploration potential of the block was recognized by Enterprise in 1985 following geoseismic studies carried out in the neighbouring Montrose and Arbroath fields. The modest reserves attributed to the oil and gas shows encountered in the poor quality Palaeocene reservoir of the first well, 22/11-1, drilled in 1967 were considered uneconomic at the time.

The British Antarctic Survey has commenced a programme of multichannel seismic reflection work over the Antarctic continental ice sheet and surrounding ice shelves. This is part of an integrated geophysical investigation of the crustal development and plate teetonic history of West Antarctica. The data presented here were acquired in the first field season in January and February 1989.

Many theoretical studies have been made of layered systems and their internal wavetrains. A number of interesting theorems have resulted from this work, but very few papers have been published which demonstrate the value of these theorems on field data. In an attempt to redress the balance, this paper looks at one such theorem which is known as the energy-flux theorem or net-downgoing-energy theorem.