RIASSUNTO
ABSTRACT
A direct method of detecting leaks in submarine pipelines using established geochemical technology is discussed including the theoretical basis and available equipment. An operational plan for location and pinpointing of a leak is outlined. This technology offers a superior solution for environmental monitoring for potential leakage, and a systematic means of locating the leaks that actually occur before any significant environmental damage is done.
INTRODUCTION
The purpose of this report is to present the technical aspects of adapting existing technology from the f1eld of exploration geochemistry to detection and pinpointing the location of leaks in submarine pipelines.
A small leak in a pipeline can be difficult and costly to locate. However, in the case where hydrocarbons are involved, it is imperative that it be located and repaired as soon as possible to avoid losses of product and damage to the environment. If the pipeline is under water or ice, the problem is greatly magnified.
Ordinarily, leaks in underwater pipelines are found by visually searching for escaping liquids or gas. Sometimes this search is aided by dyes or sonic devices. In many cases a diver must ""walk"" the line to find the leak. This visual technique is time consuming, and so inherently difficult that it is probable many small leaks go undetected, hydrostatic test notwithstanding. Deep water, poor visibility, waves and currents, depth of burial, and ice cover all tend to seriously aggravate the problem.
Over the past twenty years there have been extraordinary advances in the science of geochemistry (Jones, 1979 Mousseau and Williams, 1979 and Weismann, 1980). This field of science involves the detection of minute quantities of hydrocarbons seeping from the earth's surface. The principle driving force behind this advancement has been the search for petroleum (Jones and Drozd, 1983). Geochemical technology, while applicable to both the onshore and offshore provinces, is particularly effective offshore because of the special sampling techniques that have been devised (Williams and Mousseau 1981). Specifically, this techniques provides for continual sampling of water close to the sea bottom and virtually continuous chemical analysis of the dissolved gas contained in the bottom water samples.
A study of the techniques and equipment used in geochemistry for petroleum explanation review is that the technology is directly applicable to finding leaks in pipelines both onshore and offshore. The technology is particularly applicable in environmentally sensitive areas of the offshore and the Arctic regions.
Also, it is an important fact that all the equipment needed is state-of-the-art, with no further research and development required. All components of the system have been tried and proven in actual practice. The only special activity required will be careful planning to adapt the concepts to be used to the specific program envisioned.
THEORETICAL BASIS
The science of geochemistry, as applied to offshore detection of hydrocarbons combines the technical disciplines of chemistry, marine geology, physics and oceanography. To adapt geochemistry to a workable system for the location of pipeline leakage, the d1sciplines of marine pipeline engineering and ocean engineering are also required.