Bitumen seepages

Because of the abundance of bitumen seepages in the Middle East, no people made such extensive use of it as did those of Southeast Asia. An early use may well have been as a hafting cement— first to affix stone weapon points to wooden shafts and later to secure tool heads onto wooden handles. Traces of bitumen have been found indeed on a sickle tooth unearthed at the eighth-millennium village of Jarmo (I) and on stone tools from the fifth-millennium town of Tell Hassuna (2), both in Northern Iraq. 

Within the area of Figure I are several hundred seepages of gas, oil, and bitumen or deposits of asphalt— large or small. Most of the oil fields of the Middle East were discovered by drilling at such locations, notably Masjid-i-Sulaiman (M-i-S) which opened up development of the area. A few bitumen seepages that are well known and have been described adequately are indicated by dotted circles. Others that have been destroyed or lost or cannot be located precisely are indicated by open circles. 

Asphalts that are found in many ancient sites of the Middle East deserve continuing study. Closer examination by sharper techniques promises to better define where the bitumens were found, with what they were mixed, and how they were used. That information on various sites would help to outline areas of influence, to trace favored trade routes, and to suggest patterns of exchange. The greatest deterrent to such research is a lack of samples of the bitumen seepages that were available to ancient technologists. 

Most of the crude oil currently recovered is produced from underground reservoirs. However, surface seepage of crude oil and natural gas is common in many regions. In fact, it is the surface seepage of oil that led to the first use of the high boiling material (bitumen) in the Fertile Crescent. It may also be stated that the presence of active seeps in an area is evidence that oil and gas is still migrating. 

Four asphalts from highland sites were atypically high in bitumen the two from Farukhabad mentioned above and two others from Djaffara-bad in Table VI. One of each pair had a bitumen content near 33%, only moderately higher than typical asphalts, but the other two had 48 and 61%, two or three times the typical percentages. They were probably raw or hardened seepages, an indication supported by the presence of vegetal matter. They provide direct evidence that at least some asphalts... 

Bitumen Sources. Analyses of possible source materials are given in Table VIII. The seepages of Hit and such bitumen lakes as Abu Gir are the traditional sources for asphalts of the cities of lower Mesopotamia. Despite repeated attempts, samples could not be obtained for analysis. 

All other sources in Table VIII are from Zagros locations, especially the foothills and valleys from Ain Gir to Bebehan from which multiple samples were obtained. The seepages of Ain Gir contained more bitumen and less sand than the dried and rock asphalts, which are much alike. Weathered and unweathered rock asphalts from Mordeh Pel were hardly distinguishable, as were the Bebehan samples in other respects than bitumen content. The samples from M-i-S, Mordeh Pel, and Rijab are probably too lean to have been used as source materials. But the similarities at Ain Gir and Mordeh Pel suggest that the bitumen in any seepages at other sites would have resembled that in the asphalts there. 

Use of asphalt in the Zagros settlements dates at least as far back as 7000 B.G., four millennia before it became an essential construction material in the Mesopotamian cities. By 5000 B.C., seepage bitumen was converted to asphalt with considerable sophistication, the only subsequent... 

Geochemical studies of the natural oil seeps in water of the California borderland show the complexity and problems related to determining sources of seep oil and of correlating it with produced crude oil, sediment bitumen, and coastal tar residue or tarballs (Reed and Kaplan, 1977 Stuermer et al, 1982). Hartman and Hammond (1981) were the first to correlate tarballs with natural oil seeps. They showed that tarballs on beaches of Santa Monica Bay originated from seepage within the Bay but also from seeps as far away as Coal Oil Point (Fig. 1). 

Considerable effort has been applied to the analysis of the hydrocarbon content of non-oil-bearing sediments and rocks. Recent non-reservoir sediments may contain 30 to 60 ppm hydrocarbons, whilst the levels in non-reservoir ancient sediments may increase to 300 ppm, probably due to seepage (up) from reservoir sediments over the course of geological time. Studies have centred on three broad, ill-defined classes of material soil waxes—the organic material extracted by ether or benzene-methanol mixtures from very recent deposits (e.g. soils), bitumens—the material similarly extracted from sedimentary fossiliferous rocks or shales and kerogens—the organic material in shales and older sediments that is insoluble in the commonly used petroleum solvents and is probably derived from lignin. 

Major uses for creosotes have been as a timber preservative, as fluxing oils for pitch and bitumen, and in the manufacture of lampblack and carbon black. However, the use of creosote as a timber preservative has recently come under close scrutiny, as have many other ill-defined products of coal processing. Issues related to the seepage of such complex chemical mixtures into the surrounding environment have brought an awareness of the potential environmental and health hazards related to the use of such chemicals. Stringent testing is now required before such chemicals can be used. 

The gaps along the periphery of tanks mounted on a masonry platform should be closed with tar or bitumen to avoid seepage of rainwater. Vessels and tanks should be designed to provide complete drainage, thereby preventing the buildup of solid deposits on the bottom. 

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