Abstract

The Sleeve Exploder is a nondynamite marine seismic source developed by Esso Production Research Company to reduce exploration costs and improve safety. Used in groups of four units fired simultaneously) it has produced seismic data comparable in quality and penetration to that from 100 pounds of dynamite. The source is roughly seven-feet long) 11 inches in diameter and weighs 400 pounds. Oxygen and propane are fed in metered amounts to a chamber covered by a rubber sleeve. The mixture is detonated by a spark at 6 to 10 second repetition rates. Burned gases are exhausted through a valve and snorkel tube to the surface. Unique design features reduce the bubble pulse amplitudes to about one-fourth that of the primary pulse.. Maximum explosion pressures of 50 psi inside the chamber drop rapidly to one psi 35 feet away from the source, making it relatively harmless to marine life. Based on worldwide field experience of about 200 crew months, the source is relatively trouble free and is capable of continuous day and night operations at high repetition firing rates.

Introduction

A nondynamite, marine seismic energy source developed by Esso Production Research Company was placed into oil exploration service in 1967. EPR calls this source the Sleeve Exploder; licensees, however, have attached other names to the device--such as Aquapulse, Seisprobe, or Deltapulse.** Although individual devices may differ somewhat in design, the one this paper will describe is essentially that in use today on some 30 worldwide marine exploration crews, with some 200 crew months of usage to date.

Work began on the development of this source several years ago with objectives of lowering marine seismic costs, improving safety, and improving seismic data quality. At that time, there were only a few nondynamite marine seismic sources suitable for oil exploration in deep basins. Now there are at least a dozen. It is not the purpose of this paper to describe or compare results from these, various sources. A handbook by United Geophysical Corporation1 gives an excellent review of such sources. Instead, the data comparisons shown wiIl be from identical lines shot with dynamite and the Sleeve Exploder.

The incentives for this development are well known to the oil exploration industry. Oil found offshore; expressed as percentage of total oil discovered--rose from 8% in 1960 to 16% in 1965, and it is expected to double again by 1975. Ten million square miles of potential oil-producing areas offshore remain to be explored worldwide, a job requiring 70 years at our present rate of exploration. The oil industry needs faster marine surveying speeds, night arid day continuous operation, and better data quality to search effectively and economically for offshore oil. The Sleeve Exploder is an energy source that satisfies these goals.

Requirements and General Description

We wanted a source suitable for a one-boat operation with the following requirements:

  1. A broad frequency band of energy for obtaining shallow and deep reflections with high resolution.

  2. An essentially bubble-free pulse shape to give simple, distinct, reflection returns.

  3. A simple device with few moving parts to give low initial, operational, and maintenance costs.

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