CHARACTERIZATION OF PETROLEUM DEPOSITS FORMED IN A PRODUCING WELL BY SYNCHROTRON RADIATION-BASED MICROANALYSES

Described are results obtained by a set of synchrotron radiation-based microanalytical techniques to investigate depth profiles and heterogeneity of organic compounds and metals in a series of deposit samples formed at different depths in blocked tubing strings from an operational oil well. Micrometer-scale synchrotron Fourier transform infrared (FTIR) spectroscopic and X-ray fluorescence (XRF) analyses using facilities at the National Synchrotron Light Source at Brookhaven National Laboratory are presented. Visualization, compositional mapping, high-resolution, and nondestructive analysis of samples are some of the main advantages of applying synchrotron-based microanalytical techniques. The results indicate that the depth profile of deposits formed along the same well varies and is characterized by the following main trends from deeper to shallower samples: (1) amount of deposits increases, a complete tubing plugging occurs at shallower levels; (2) concentration of inorganic components decreases; (3) sulfur-containing compounds in the deposits shift relative abundances from predominantly reduced to predominantly oxidized forms; (4) carbon content and H/C atomic ratio increase, S/C and N/C atomic ratios decrease; (5) higher molecular weight (HMW) n-alkane mixtures (wax components) shift the maximum of their distribution from higher to lower molecular weight mixtures; (6) maximum concentrations of some elements (V, Ba, Ti, and Cr) are found in the deepest samples; (7) elements present in all samples along the depth profile are Ca, Fe, Ni, Cu, Pb, and Br. The study demonstrates the benefits of applying a set of complementary synchrotron-based microanalytical nondestructive methods for characterization of the deposits. The results demonstrate the suitability of the methods for studying organic solid aggregation and petroleum deposition problems, as well as the potential for testing and developing chemical and microbial methods for solid petroleum deposit remediation