AN APPROACH TO ESTIMATING THE RATE OF ORGANIC DEPOSIT FORMATION IN A HOLLOW ROD STRING AND SELECTION OF METHODS FOR DEPOSIT PREVENTION

Background. There is currently a lack of a methodology that can enable highly-precise determinations of rates of asphaltene deposit (AD) formations in case of dual operation of two oil reservoirs via a single multi-zone oil-producing well using small-bore hollow rods as part of downhole pumping equipment. This methodology aims to minimize the costs of oil and gas companies for servicing such oil wells and preventing their failure. Aims. Creating a methodology aimed at accurate quantitative estimations of the organic deposit formation rates at the inner part of the hollow rod strings. Methods. Calculations of temperature distributions along the hollow rod string inner surface; graphic presentations of the calculated data; laboratory tests using a Cold Finger unit for the selected sections of the hollow rod strings and the graphic presentations of the results. Results and Discussion. The suggested algorithm was field-tested at a target multi-zone oil-producing well of Pavlovka oil field in Perm Krai of the Russian Federation. Using the suggested algorithm, a variation in organic deposit formation rates along the hollow rod string length was evaluated, and the depth of the maximum deposit formation rate was determined. To prevent the deposits in question along the hollow rod string at a target oil-producing well of Pavlovka oil field, laboratory tests were conducted to determine the efficiency of employing the chemical technology, i.e., the use of AD inhibitors, as well as a technology for the removal of the formed deposits using AD solvents. Conclusions. The proposed algorithm is more accurate and requires less time and money compared to existing algorithms. It enables the most effective evaluation of the formation depth of the organic deposits and the intensity at these marks. When evaluating the laboratory studies results, it can be noted that the use of the considered technologies to eliminate organic deposits is highly effective and can be used for this purpose.

Geology and paleoecology of a Middle Wisconsin fossil occurrence in Zorra Township, southwestern Ontario, Canada

Nonglacial deposits of Middle Wisconsin age are being discovered with increased frequency across a broad region of southern Ontario, Canada, and provide strong evidence for a time of significant ice withdrawal from the lower Great Lakes region. With each new discovery, a refined understanding of regional climatic and paleoecological environments is emerging. In this paper, we present the results of a sedimentological and paleoecological study of a subtill organic deposit in Zorra Township, southwestern Ontario. The organic deposit, which lies beneath Nissouri Phase Catfish Creek Till (Late Wisconsin), has been dated by accelerator mass spectrometry at between 50.5 and 42.9 14C ka BP. The organic remains are contained within slack water pond deposits infilling a channel incised into till either of Early Wisconsin or Illinoian age. The fossil assemblage appears to be strongly influenced by taphonomic processes, including degradation due to oxidation, bacterial and fungal decay, and glacial overriding. Reworking and (or) recycling and selective sorting as well as long-distance transport has also influenced the composition of the fossil assemblage preserved. Nonetheless, meaningful paleoecological information is still obtained from this record. Collectively, the pollen and plant macrofossils indicate a boreal-type pine–spruce forest with temperatures cooler than present. The absence of arctic tundra plants, as are found in many other deposits of similar age in the lower Great Lakes basin, is notable. A pond or wetland inhabited by shoreline herbs, shrubs, and trees was present at or proximal to the site. The freshwater mollusc and ostracode assemblages are consistent with a shallow water habitat with dense submerged vegetation. The terrestrial mollusc assemblage suggests a taiga or transitional taiga–tundra fauna. Together, these fossil groups provide one of the most comprehensive environmental reconstructions of Middle Wisconsin time (oxygen isotope stage 3 or OIS3) in southern Ontario and serve to build on the ever-increasing database of paleoecological information accumulating for this episode of the late Quaternary.

Shell repair in the clam Ruditapes philippinarum, affected by the Brown Ring Disease (BRD): a biochemical and serological study

For more than two decades, the edible clam Ruditapes philippinarum has been affected by the Brown Ring Disease (BRD), a bacterial infection characterized by the formation of a brown organic deposit in the internal side of the valves. Although this infection is often lethal, in some cases specimens can overcome it by remineralizing over the organic deposit. The goal of the present study is to compare biochemically and immunologically the shell matrices of repaired and healthy zones. Our data suggest that the repair zones exhibit certain variability, which would be the direct consequence of a modification of the secretory regime of calcifying tissues responsible of the repair process.

A Sixteen Thousand Year Old Organic Deposit, Northern Baffin Island, N.W.T., Canada: Palynology and Significance

ABSTRACT A 3 m exposure of sediment containing organics was sampled near the settlement of Arctic Bay, Baffin Island, N.W.T. A total of seven radiocarbon dates have been obtained from the deposit. Three dates between 182.5 and 290 cm depth gave radiocarbon ages between 14,185 ± 760 and 16,849 ± 860. A date from 82.5 to 87.5 cm resulted in an age of 8635 ± 565. An apparent reversal in 14C dates may reflect folding of the sediments associated with the downslope creep of the deposit or rapid accumulation of organics. The three basal dates are the first terrestrial sediments from Baffin Island to date from older than ca. 10,000 BP and less than 20,000 BP. Analysis of the sediment for pollen indicated that it is generally sparse. The pollen assemblage is dominated by Salix, Cyperaceae, and Gramineae pollen and exotic pollen types {Pinus, Picea, Betula, and Alnus) occur sporadically throughout the section.