Identification of a Novel Ester Obtained during Isolation of C₈₀ (“ARN”) Tetraprotic Acids from an Oilfield Pipeline Deposit

Abstract

Solid deposits in some oilfield pipelines and oil-processing equipment include calcium salts of C80−82 polycyclic tetracarboxylic acids (“ARN” acids) probably originating from Archaea. It is thought that such deposits form once calcium in seawater comes into contact with crude oils containing the acids, under relevant conditions. The deposits may cause restriction or blockage of pipelines and equipment, with considerable consequent costs for downtime and cleaning. The accurate measurement of the concentrations of the acids in oils is an important requirement for the development of mathematical models for the prediction of the formation of oilfield deposits. We have now identified, in a deposit from one North Sea oilfield pipeline, in addition to the known C80−82 polycyclic tetracarboxylic acids, a hitherto unreported ester of C80 (“ARN”) acids. We report the evidence for the identification and suggest reasons for the occurrence of the ester. Quantitative analyses which exclude determination of such esters may underestimate the potential for oils to cause flow problems. Calculations for computer models based on such data might then be in error.

Mass spectrometry of polycyclic tetracarboxylic ('ARN') acids and tetramethyl esters

“…These ions at m/z 1322, 1320, 1318 and 1316 are tentatively attributed, respectively, to sodiated molecules of a C 80 acyclic acid and of C 80 mono‐, bi‐ and tricyclic acids. The rigorous identification of other unknowns is reported elsewhere 9…”

Reaction Between Tetrameric Acids and Ca2+ in Oil/Water System

“…18,20−22 An ester of C 80 -TA was detected in one North Sea oilfield pipeline, but it could be the result of esterification of C 80 -TA with production chemicals. 23 This structure led Lutnaes et al to suggest an archaeal origin for the TA. 20 TA is much more oil/water interfacially active than other NA, as shown by Brandal et al 18,24 It is now considered that the presence of TA is a prerequisite to the formation of calcium naphthenate deposits, 16,26 but that does not necessary imply that deposits will be created.…”

“…In the following, these acids will be named C 80 -TA. These acids have four carboxylic acid groups, are aliphatic, and have molecular weights in the 1230 g·mol –1 range (Figure ). ,− An ester of C 80 -TA was detected in one North Sea oilfield pipeline, but it could be the result of esterification of C 80 -TA with production chemicals . This structure led Lutnaes et al to suggest an archaeal origin for the TA .…”

Synergistic androgenic effect of a petroleum product caused by the joint action of at least three different types of compounds

“…High temperature GC-FID was conducted as detailed by Sutton et al (2010). 1 H and 13 C NMR spectra of the 'saturates' fraction were obtained in deuterated chloroform and the chemical shifts were measured relative to the solvent (CDCl 3 ; 1 H: 7.24 ppm; 13 C: 77.0 ppm), using a JEOL ECP-400 NMR spectrometer.…”