| Abstract: | Over the last few years various lead precipitates have been found in natural gas production installations in north-western Europe during routine cleaning operations. We have studied the composition and morphology of these precipitates and will discuss the probable depositional processes. The lead precipitates can be divided into three categories based on morphology and composition. (1) Thin, crustal precipitates containing metallic lead, barite and galena. These precipitates originate from untreated gas–water mixtures, and are found in pipes throughout production installations. (2) Annular, homogeneous precipitates of metallic lead, formed from separated production water in pumps of production installations. (3) Suspended precipitates which are found either in the well tubing, or in pipes or valves downstream from the installations, originating from untreated gas–water mixtures. All lead precipitates contain 210Pb, whereas precipitates of both lead and barite contain 226Ra as well. These naturally occurring radionuclides are most likely derived from 238U-enriched organic sediments or 226Ra-enriched precipitates in or near the gas reservoirs. |
