The Gandak megafan of eastern Uttar Pradesh and northwestern Bihar lies in the Middle Gangetic Plains. The Gandak River has shifted about 80 km to the east due to tilting in the last SO00 years. This has created a soil chronoassociation similar to the chronosequences found on some flights of river terraces. This chronoassociation has five members, QGD 1-5. They are distinguished on the basis of profile development, clay mineralogy and calcium carbonate content. Chlorite transforms to vermiculite on a large scale from QGDl to QGD3 and decreases drastically in member QGDA Kaolinite and interstratified kaolinite-smectite are abundant in the older members of the chronoassociation. The youngest soils (QGD1: ? < 500 b.p.) are found on the floodplains of the major rivers. QGD2 soils, like those of the Young Gandak Plain, date from ? =-500 b.p., while QGD3 soils, like those on the Older Gandak Plain and Old Rapti Plains date back to 2500 b.p. QGD4 soils, like those on the Oldest Gandak Plain, are dated as ? 5000 years b.p., whilst the oldest QGD5 soils, as on the Old Ghaghra Plain and Ganga-Ghaghra Interfluve, date back to 1OO00 b.p. These soils, which include pedogenic calcite and a ? saline epipedon, indicate a dry climatic spell during the period 9 m 1 1 000 b.p. Faults developed on the megafan are not related to the basement structures.
203 km long, 30?? dia sub sea pipeline transports Mumbai High crude oil to Uran onshore terminus (BUT oil line). In order to ensure that there is no congealing of crude and restartability is easy after prolonged shutdown, Pour Point Depressant (PPD) was being dosed. The average cost of treatment for flow assurance was very high (to the tune of 10 million USD per annum). Expanding database, infrastructure development has led to the present studies to explore the possibility of flow assurance without PPD usage. Extensive rheological studies have been carried out at BHS platform on live Mumbai High crude to analyze the effect of temperature, pressure, shear history, water cut, ageing etc. Results of field and laboratory studies were integrated with the observations made during rupture/ repair of BUT oil line in since1992. Case studies of BUT pipeline rupture in recent past have given authentic information about heat losses and gel strength of the aged crude. Concept of estimation of pour point of live crude (with pressure and lighter cuts) was used for the first time on PPD treated and untreated crude to understand the crude behavior under pipeline conditions. Field experiments in 18 km long BHN-SA sub sea well fluid line were also carried out to understand heat losses and restartability behavior. Bathymetry data from IPSHEM, Goa and software modeling has also been used.
It was observed that cooling of crude oil in the sub sea pipeline is less pronounced than estimated earlier. Restartability of crude oil after prolong shutdown (˜30 days) would not pose any problems. Rheological behavior of crude under pipeline conditions is much better than observed in laboratory. Flow assurance with out PPD usage can be attained. PPD usage has been completely stopped and pipeline is functioning smoothly without any increase of pressure drop / wax deposition.
INTRODUCTION:
Mumbai High- Uran sub sea trunk crude oil pipeline (BUT oil line) is 30?? dia, 203 km long pipeline carrying Mumbai High crude oil to Uran onshore terminus. The pipeline is buried and insulated. The pipeline was commissioned in 1979 and adequate data and information is now available to have relook into the salient aspects of its operation.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.