Abstract: Side-Scan Sonar: Applications in Oil Exploration and Exploitation

W. D. Jenkinson

In the past decade, the use of side-scan sonar within the petroleum industry has developed from a relatively unknown technique to one widely accepted in the exploitation phase, and to a lesser degree in the exploration phase of offshore operations.

With the rapid expansion of offshore production in the 1960s, new remote-sensing methods were needed to map the topography of the water bottom and to help to determine the physical properties of the near-bottom sediments. Remote-sensing devices such as side-scan sonar and high-resolution seismic profilers were developed to satisfy these needs. Side-scan sonar found particular application in the water-bottom mapping phase and in the detection of objects on the sea bed. Probably the most frequent use of the tool has been in the location of objects related to oil production, such as pipelines, sea-floor scour marks, subsea completions, and damaged facilities.

Oil explorationists traditionally have used the seismic technique to map subsurface structure. The methods developed onshore were found to be readily adaptable, with certain hardware modifications, to the offshore environment. And so, as offshore exploration grew, there was not the obvious need for new techniques. However, as experience was accumulated, problems pertaining to water-bottom or near-water-bottom conditions came into focus. The high-resolution seismic and side-scan sonar techniques have application in defining these conditions. Unfortunately, their use is not commonplace and problems recognized on conventional seismic data often go unresolved through lack of complementary data.

Side-scan sonar records have delineated gas seeps emanating from the sea bed, fault scarps, coral reefs capping an intrusive salt feature, the severed legs of a jackup drilling rig damaged during Hurricane Carmen, and the marks left on the sea floor as a drilling rig's legs first were lowered and then dragged into a drilling location.

AAPG Search and Discovery Article #90976©1976 AAPG-SEPM-SEG Pacific Section Meeting, San Francisco, California